HZB Newsroom

Sear results - Rubric: Science Highlight

  • Science Highlight
    24.02.2021
    Accelerator physics: Experiment reveals new options for synchrotron light sources
    An international team has shown through a sensational experiment how diverse the possibilities for employing synchrotron light sources are. Accelerator experts from the Helmholtz-Zentrum Berlin (HZB), the German federal metrology institute Physikalisch-Technische Bundesanstalt (PTB), and Tsinghua University in Beijing have used a laser to manipulate electron bunches at PTB's Metrology Light Source so that they emitted intense light pulses having a laser-like character. Using this method, specialised synchrotron radiation sources would potentially be able to fill a gap in the arsenal of available light sources and offer a prototype for industrial applications. The work was published on 24 February 2021 in the leading scientific publication Nature.

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  • <p>The liquid solution of perovskite precursor, solvent, and additive flows from a slit-shaped nozzle onto the glass substrate being conveyed below.</p>
    Science Highlight
    22.02.2021
    The perfect recipe for efficient perovskite solar cells
    A long-cherished dream of materials researchers is a solar cell that converts sunlight into electrical energy as efficiently as silicon, but that can be easily and inexpensively fabricated from abundant materials. Scientists at the Helmholtz-Zentrum Berlin have now come a step closer to achieving this. They have improved a process for vertically depositing a solution made from an inexpensive perovskite solute onto a moving substrate below. Not only have they discovered the crucial role played by one of the solvents used, but they have also taken a closer look at the aging and storage properties of the solution.

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  • Science Highlight
    10.02.2021
    World's first video recording of a space-time crystal
    A German-Polish research team has succeeded in creating a micrometer-sized space-time crystal consisting of magnons at room temperature. With the help of the scanning transmission X-ray microscope MAXYMUS at Bessy II at Helmholtz Zentrum Berlin, they were able to film the recurring periodic magnetization structure in a crystal. The research project was a collaboration between scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart, Germany, the Adam Mickiewicz University and the Polish Academy of Sciences in Poznań in Poland.

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  • <p>The electronic structure of complex molecules can be assessed by the method of resonant inelastic X-ray scattering (RIXS) at BESSY II.</p>
    Science Highlight
    28.01.2021
    An efficient tool to link X-ray experiments and ab initio theory
    The electronic structure of complex molecules and their chemical reactivity can be assessed by the method of resonant inelastic X-ray scattering (RIXS) at BESSY II. However, the evaluation of RIXS data has so far required very long computing times. A team at BESSY II has now developed a new simulation method that greatly accelerates this evaluation. The results can even be calculated during the experiment. Guest users could use the procedure like a black box.

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  • <p>TEM-Image of a &alpha;-SnWO<sub>4 </sub>film (pink) coated with 20 nm NiO<sub>x </sub>(green). At the interface of &alpha;-SnWO<sub>4</sub> and NiO<sub>x</sub> an additional interfacial layer can be observed.</p>
    Science Highlight
    26.01.2021
    Solar hydrogen: Photoanodes made of α-SnWO4 promise high efficiencies
    Photoanodes made of metal oxides are considered to be a viable solution for the production of hydrogen with sunlight. α-SnWO4 has optimal electronic properties for photoelectrochemical water splitting with sunlight, but corrodes easily. Protective layers of nickel oxide prevent corrosion, but reduce the photovoltage and limit the efficiency. Now a team at HZB has investigated at BESSY II what happens at the interface between the photoanode and the protective layer. Combined with theoretical methods, the measurement data reveal the presence of an oxide layer that impairs the efficiency of the photoanode.


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  • <p>The phonons distribution is complex (upper curves) and then simplifies with time to a Gaussian bell curve (lower curve).</p>
    Science Highlight
    25.01.2021
    How complex oscillations in a quantum system simplify with time
    With a clever experiment, physicists have shown that in a one-dimensional quantum system, the initially complex distribution of vibrations or phonons can change over time into a simple Gaussian bell curve. The experiment took place at the Vienna University of Technology, while the theoretical considerations were carried out by a joint research group from the Freie Universität Berlin and HZB.

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  • <p>The illustration visualizes the composition of the tandem solar cell.</p>
    Science Highlight
    11.12.2020
    Perovskite/silicon tandem solar cells on the threshold of 30% efficiency
    An HZB team has published a report in the journal Science on the development of its current world record of 29.15% efficiency for a tandem solar cell made of perovskite and silicon. The tandem cell provided stable performance for 300 hours – even without encapsulation. To accomplish this, the group headed by Prof. Steve Albrecht investigated physical processes at the interfaces to improve the transport of the charge carriers.

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  • <p>Schematic illustration: the solvants (ink) are used to produce a thin film of polycrystalline perovskite.&nbsp;</p>
    Science Highlight
    27.11.2020
    Perovskite Solar Cells: paving the way for rational ink design for industrial-scale manufacturing
    For the production of high-quality metal-halide perovskite thin-films for large area photovoltaic modules often optimized inks are used which contain a mixture of solvents. An HZB team at BESSY II has now analysed the crystallisation processes within such mixtures. A model has also been developed to assess the kinetics of the crystallisation processes for different solvent mixtures. The results are of high importance for the further development of perovskite inks for industrial-scale deposition processes of these semiconductors.

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  • <p>The tomogram during the charging process shows the spatially resolved changes in the graphite electrode thickness of a rechargeable aluminium ion battery in a discharged and charged state.</p>
    Science Highlight
    20.11.2020
    User research at BESSY II: Graphite electrodes for rechargeable batteries investigated
    Rechargeable graphite dual ion batteries are inexpensive and powerful. A team of the Technical University of Berlin has investigated at the EDDI Beamline of BESSY II how the morphology of the graphite electrodes changes reversibly during cycling (operando). The 3D X-ray tomography images combined with simultaneous diffraction now allow a precise evaluation of the processes, especially of changes in the volume of the electrodes. This can help to further optimise graphite electrodes.

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  • <p>The distribution of local pH change (&Delta;pH) with time in an electrolyte containing 0.5 M K<sub>2</sub>SO<sub>4.</sub></p>
    Science Highlight
    19.11.2020
    Green hydrogen: buoyancy-driven convection in the electrolyte
    Hydrogen produced by using solar energy could contribute to a climate neutral energy system of the future. But there are hurdles on the way from laboratory scale to large-scale implementation. A team at HZB has now presented a method to visualise convection in the electrolyte and to reliably simulate it in advance with a multiphysics model. The results can support the design and scaling up of this technology and have been published in the renowned journal Energy and Environmental Science.

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  • <p>Nine samples with mixtures from CsPbBr<sub>2</sub>I (ink 1, left) to pure CsPbI<sub>3</sub> (ink 2 right).</p>
    Science Highlight
    16.11.2020
    Solar cells: Mapping the landscape of Caesium based inorganic halide perovskites
    Scientists at HZB have printed and explored different compositions of caesium based halide perovskites (CsPb(BrxI1−x)3 (0 ≤ x ≤ 1)). In a temperature range between room temperature and 300 Celsius, they observe structural phase transitions influencing the electronic properties. The study provides a quick and easy method to assess new compositions of perovskite materials in order to identify candidates for applications in thin film solar cells and optoelectronic devices.

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  • <p>The Fermi surface of multidomain GeTe (111) bulk single crystal&nbsp;measured with high-resolution angle-resolved photoemission at BESSY II.</p>
    Science Highlight
    05.11.2020
    Future Information Technologies: Germanium telluride's hidden properties at the nanoscale revealed
    Germanium Telluride is an interesting candidate material for spintronic devices. In a comprehensive study at BESSY II, a Helmholtz-RSF Joint Research Group has now revealed how the spin texture switches by ferroelectric polarization within individual nanodomains.

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  • <p>Structural model of highly porous a-Si:H, which was deposited very quickly, calculated based on measurement data. Densely ordered domains (DOD) are drawn in blue and cavities in red. The grey layer represents the disordered a-Si:H matrix. The round sections show the nanostructures enlarged to atomic resolution (below, Si atoms: grey, Si atoms on the surfaces of the voids: red; H: white)</p>
    Science Highlight
    29.10.2020
    Order in the disorder: density fluctuations in amorphous silicon discovered
    For the first time, a team at HZB has identified the atomic substructure of amorphous silicon with a resolution of 0.8 nanometres using X-ray and neutron scattering at BESSY II and BER II. Such a-Si:H thin films have been used for decades in solar cells, TFT displays, and detectors. The results show that three different phases form within the amorphous matrix, which dramatically influences the quality and lifetime of the semiconductor layer. The study was selected for the cover of the actual issue of Physical Review Letters.

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  • <p>Ultracold atoms in an optical lattice have been considered for quantum simulation.</p>
    Science Highlight
    27.10.2020
    Modelling shows which quantum systems are suitable for quantum simulations
    A joint research group led by Prof. Jens Eisert of Freie Universität Berlin and Helmholtz-Zentrum Berlin (HZB) has shown a way to simulate the quantum physical properties of complex solid state systems. This is done with the help of complex solid state systems that can be studied experimentally. The study was published in the renowned journal Proceedings of the National Academy of Sciences of the United States of America (PNAS). [...]
  • <p>Scalable large area BiVO<sub>4</sub> photoanode on FTO with Ni current collectors.</p>
    Science Highlight
    26.10.2020
    Solar hydrogen: Let’s consider the stability of photoelectrodes

    As part of an international collaboration, a team at the HZB has examined the corrosion processes of high-quality BiVO4 photoelectrodes using different state-of-the-art characterisation methods. The result is the first operando stability study of high-purity BiVO4 photoanodes during the photoelectrochemical oxygen evolution reaction (OER). This work shows how the stability of photoelectrodes and catalysts can be compared and enhanced in the future. [...]

  • <p>(a,b) Cryo-electron microscopy of the 2D-grating and the diffraction pattern of a section. (c-e) Magnification shows the 2D Pascal triangular pattern, with the inserted protein molecules.</p>
    Science Highlight
    15.10.2020
    Nanopatterns of proteins detected by cryo-electron microscopy
    A team from Helmholtz-Zentrum Berlin (HZB) used cryo electron microscopy to detect regular, two-dimensional structures in the form of Pascal triangles in a shock frozen protein material.  The samples have been synthesized by a Chinese research group. The method of cryo electron microscopy has the potential for new insights into energy materials as well. [...]
  • <p>Dr. Michael Tovar working at FALCON at the neutron Source BER II.</p>
    Science Highlight
    12.10.2020
    Perovskite materials: Neutrons show twinning in halide perovskites
    Solar cells based on hybrid halide perovskites achieve high efficiencies. These mixed organic-inorganic semiconductors are usually produced as thin films of microcrystals. An investigation with the Laue camera at the neutron source BER II could now clarify that twinning occurs during crystallisation even at room temperature. This insight is helpful for optimising production processes of halide perovskites. 

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  • <p>Image of a silicon perovskite tandem solar cell</p>
    Science Highlight
    07.09.2020
    Silicon-perovskite tandem solar cells: New facilities pave the way for industrial-scale production

    Perovskites are regarded as promising materials for solar cells, able to be manufactured at low cost while at the same time being extremely efficient. They are particularly suitable for tandem solar cells that combine a cell made of silicon and one of perovskite. As a result, sunlight is more completely used when generating electrical energy. So far, the advantages of such cells have only been available for use at small laboratory scale. With two new, highly innovative production facilities, researchers at the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) are now creating the basis for future production on an industrial scale. [...]

  • <p>Periodic metasurfaces (grey) can enhance photon upconversion of nanoparticles (yellow) by more than three orders of magnitude.</p>
    Science Highlight
    04.09.2020
    Upconversion of photons at low light intensities – the key to new applications in energy and bioengineering
    The region of the spectrum that can be utilised for producing electrical energy can be considerably extended by converting low-energy (longer wavelength) photons into high-energy (shorter wavelength) photons. But so far, this has only been possible at high intensities of light. Now for the first time, scientists from the Helmholtz-Zentrum Berlin (HZB) and the Federal Institute for Materials Research and Testing (BAM) have been able to produce a usable effect from relatively weak light by combining certain nanoparticles with what is known as a meta-surface. This paves the way for future applications in photovoltaics, for the detection of biological substances, and for electrical-field sensors. [...]
  • <p>Structure of TUB75: the entire MOF architecture (top) and its conductive inorganic unit (bottom)</p>
    Science Highlight
    26.08.2020
    Molecular architecture: New class of materials for tomorrow's energy storage
    Researchers at the Technische Universität Berlin (TUB) have created a new family of semiconductors, the properties of which were investigated by the Helmholtz-Zentrum Berlin (HZB). The researchers christened the first member “TUB75”. The material belongs to the class called metal-organic frameworks, or MOFs for short, and could open up new opportunities for energy storage. The work was published in Advanced Materials. [...]
  • <p>Daniel Abou-Ras and his team identify the microscopic structure of a very good CIGS thin-film solar cell (top). It serves as a model for a computer simulation (below).</p>
    Science Highlight
    21.08.2020
    Research team provides concrete approach to improve the performance of CIGS solar cells

    A team of researchers used electron microscopes and computer simulations to investigate where losses occur in thin-film solar cells. The researchers from the Martin Luther University Halle-Wittenberg, the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) and the Helmholtz Zentrum Berlin (HZB) provide specific information on how the already high efficiency of CIGS solar cells can be improved. The results were published in the journal Nature Communication. [...]

  • <p>Intelligent mathematical tools for the simulation of spin systems reduce the computing time required on supercomputers. Some of the fastest supercomputers in the world are currently located at Forschungszentrum J&uuml;lich (shown here is JUWELS).</p>
    Science Highlight
    14.08.2020
    Mathematical tool helps calculate properties of quantum materials more quickly
    Many quantum materials have been nearly impossible to simulate mathematically because the computing time required is too long. Now a joint research group at Freie Universität Berlin and the Helmholtz-Zentrum Berlin (HZB) has demonstrated a way to considerably reduce the computing time. This could accelerate the development of materials for energy-efficient IT technologies of the future.

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  • <p>The structure of crystalline silicon electrodes changes into a chessboard-like fracture pattern as a result of loading and unloading. At the HZB it has now been observed that these defects do not become larger during charging and discharging but remain in their pattern.</p>
    Science Highlight
    29.07.2020
    Hope for better batteries – researchers follow the charging and discharging of silicon electrodes live

    Using silicon as a material for electrodes in lithium-ion batteries promises a significant increase in battery amp-hour capacity.The shortcoming of this material is that it is easily damaged by the stress caused by charging and discharging.Scientists at the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) have now succeeded for the first time in observing this process directly on crystalline silicon electrodes in detail.Operando experiments using the BESSY II synchrotronprovided new insights into how fractures occur in silicon – and also how the material can nevertheless be utilised advantageously. [...]

  • <p>For the study, the enzyme endothiapepsin (grey) was combined with molecules from the fragment library. The analysis shows that numerous substances are able to dock to the enzyme (blue and orange molecules). Every substance found is a potential starting point for the development of larger molecules.</p>
    Science Highlight
    13.07.2020
    New substance library to accelerate the search for active compounds
    In order to accelerate the systematic development of drugs, the MX team at the Helmholtz-Zentrum Berlin (HZB) and the Drug Design Group at the University of Marburg have established a new substance library. It consists of 1103 organic molecules that could be used as building blocks for new drugs. The MX team has now validated this library in collaboration with the FragMAX group at MAX IV. The substance library of the HZB is available for research worldwide and also plays a role in the search for substances active against SARS-CoV-2.

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  • <p>This is how the experiment went: Two laser pulses hit the thin film of iron-platinum nanoparticles at short intervals: The first laser pulse destroys the spin order, while the second laser pulse excites the now unmagnetised sample. An X-ray pulse then determines how the lattice expands or contracts.</p>
    Science Highlight
    10.07.2020
    Robust high-performance data storage through magnetic anisotropy
    The latest generation of magnetic hard drives is made of magnetic thin films, which are invar materials. They allow extremely robust and high data storage density by local heating of ultrasmall nano-domains with a laser, so called heat assisted magnetic recording or HAMR. The volume in such invar materials hardly expands despite heating. A technologically relevant material for such HAMR data memories are thin films of iron-platinum nanograins. An international team led by the joint research group of Prof. Dr. Matias Bargheer at HZB and the University of Potsdam has now observed experimentally for the first time how a special spin-lattice interaction in these iron-platinum thin films cancels out the thermal expansion of the crystal lattice. The study has been published in Science Advances.

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  • <p>At quantum physics atoms, molecules or photons are used to store information.</p>
    Science Highlight
    20.06.2020
    Benchmarking for quantum technologies
    Does a device do what it's supposed to? This question is not only asked in everyday life. Researchers working with quantum technologies also want to know what novel instruments can do. A team led by Prof. Jens Eisert, a physicist at the Dahlem Center for Complex Quantum Systems of Freie Universität Berlin and at Helmholtz-Zentrum Berlin, together with researchers from the Sorbonne University in Paris, have published an overview of tools that can currently be used to compare and certify quantum devices. The review article is published in Nature Reviews Physics.

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  • <p>Graphic representation of the printing process for the perovskite LED.</p>
    Science Highlight
    12.06.2020
    Printed perovskite LEDs – an innovative technique towards a new standard process of electronics manufacturing

    A team of researchers from the Helmholtz-Zentrum Berlin (HZB) and Humboldt-Universität zu Berlin has succeeded for the first time in producing light-emitting diodes (LEDs) from a hybrid perovskite semiconductor material using inkjet printing.This opens the door to broad application of these materials in manufacturing many different kinds of electronic components.The scientists achieved the breakthrough with the help of a trick: "inoculating" (or seeding) the surface with specific crystals. [...]

  • <p>Illustration of a Cu<sub>x</sub>O<sub>y</sub> structure formed on a AgCu alloy in oxidizing environments described in this work. (c) ACS Applied Materials &amp; Interfaces.</p>
    Science Highlight
    10.06.2020
    User research at BESSY II: Formation of a 2D meta-stable oxide in reactive environments

    The chemical behaviour of solid material surfaces is an important physical characteristic for applications of catalysis, chemical sensors, fuel cells and electrodes. A research team from the Max Planck Institute for Chemical Energy Conversion has now described an important phenomenon that can occur when metal alloys are exposed to reactive environments at the synchrotron source BESSY II.

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  • <p>The publication made it onto the cover of the current issue of SCIENCE.</p>
    Science Highlight
    05.06.2020
    BESSY II: Experiment shows for the first time in detail how electrolytes become metallic
    An international team has developed a sophisticated experimental technique at BESSY II to observe the formation of a metallic conduction band in electrolytes. To accomplish this, the team first prepared cryogenic solutions of liquid ammonia containing different concentrations of alkali metals. The colour of the solutions changes with concentration from blue to golden as the individual atoms of metal in solution transition to a metallic compound. The team then examined these liquid jets using soft X-rays at BESSY II and subsequently has been able to analyse this process in detail from the data they acquired combined with theoretical predictions. The work has been published in Science and appears even on the cover. [...]
  • <p>Perovskite oxides are characterized by the molecular formula ABO<sub>3</sub>, where the elements A (green) and B (blue) are located on specific lattice sites and are surrounded by oxygen (red).</p>
    Science Highlight
    02.06.2020
    Catalysts: Efficient hydrogen production via structure

    Regeneratively produced hydrogen is considered the ecological raw material of the future. In order to produce it efficiently by electrolysis of water, researchers today also investigate perovskite oxides. The Journal of Physics: Energy invited Dr. Marcel Risch from the Helmholtz-Zentrum Berlin (HZB) to outline the current state of research. [...]

  • <p>The illustration shows the changes in the structure of FASnI<sub>3</sub>:PEACl films during treatment at different temperatures.</p>
    Science Highlight
    11.05.2020
    On the road to non-toxic and stable perovskite solar cells
    The promising halide perovskite materials for solar energy conversion show high efficiencies, but this comes at a cost: The best perovskite materials incorporate toxic lead which poses a hazard to the environment. To replace lead by less toxic elements is not easy since lead-free perovskites show lower stability and poor efficiencies. Now, an international collaboration has engineered a new hybrid perovskite material with promising efficiency and stability. [...]
  • <p>Two of the four magnetic interactions form a new three-dimensional network of corner-sharing triangles, known as the hyper-hyperkagome lattice, leading to the quantum spin liquid behavior in PbCuTe<sub>2</sub>O<sub>6</sub>.</p>
    Science Highlight
    11.05.2020
    Future information technologies: 3D Quantum Spin Liquid revealed
    Quantum Spin Liquids are candidates for potential use in future information technologies. So far, Quantum Spin Liquids have usually only been found in one or two dimensional magnetic systems only. Now an international team led by HZB scientists has investigated crystals of PbCuTe2O6 with neutron experiments at ISIS, NIST and ILL. They found spin liquid behaviour in 3D, due to a so called hyper hyperkagome lattice. The experimental data fit extremely well to theoretical simulations also done at HZB. [...]
  • <p>Inside the 3D-structure of a phytochrome a bilin pigment absorbs the photon and rotates, which triggers a signal.</p>
    Science Highlight
    07.05.2020
    User research at BESSY II: Insights into the visual perception of plants
    Plants use light not only for photosynthesis. Although the plant cell does not have eyes, it can still perceive light and thus its environment. Phytochromes, certain turquoise proteins, play the central role in this process. How exactly they function is still unclear. Now a team led by plant physiologist Jon Hughes (Justus Liebig University Gießen) has been able to decipher the three-dimensional architecture of various plant phytochrome molecules at BESSY II. Their results demonstrate how light alters the structure of the phytochrome so that the cell transmits a signal to control the development of the plant accordingly. [...]
  • <p>The material consists of Nafion with embedded nanoparticles.</p>
    Science Highlight
    04.05.2020
    User research at BESSY II: How new materials increase the efficiency of direct ethanol fuel cells
    A group from Brazil and an HZB team have investigated a novel composite membrane for ethanol fuel cells. It consists of the polymer Nafion, in which nanoparticles of a titanium compound are embedded by the rarely explored melt extrusion process. At BESSY II they were able to observe in detail, how the nanoparticles in the Nafion matrix are distributed and how they contribute to increase proton conductivity. [...]
  • <p>A bundled soft X-ray beam with a diameter of less than 50 nanometers writes numerous magnetic vortices, which together form the term "MPI-IS".</p>
    Science Highlight
    23.04.2020
    New interaction between light and matter discovered at BESSY II
    A German-Chinese team led by Gisela Schütz from the MPI for Intelligent Systems has discovered a new interaction between light and matter at BESSY II. They succeeded in creating nanometer-fine magnetic vortices in a magnetic layer. These are so-called skyrmions, and candidates for future information technologies. [...]
  • <p>The CIGS-Pero tandem cell was realised in a typical lab size of 1 square centimeter.</p>
    Science Highlight
    14.04.2020
    Tandem solar cell world record: New branch in the NREL chart
    A special branch in the famous NREL-chart for solar cell world records refers to a newly developed tandem solar cell by HZB teams. The world-record cell combines the semiconductors perovskite and CIGS to a monolithic "two-terminal" tandem cell. Due to the thin-film technologies used, such tandem cells survive much longer in space and can even be produced on flexible films. The new tandem cell achieves a certified efficiency of 24.16 percent. [...]
  • <p>In HoAgGe, holmium spins occupy the corners of triangles that are arranged in a Kagome pattern. The alignment of adjacent spins (left, red arrows) must obey the ice rule: Either two spins protrude into a triangle and one protrude out, or vice versa. As a result the individual triangles behave as if they were magnetic monopoles (right).</p>
    Science Highlight
    07.04.2020
    Neutron research: Magnetic monopoles detected in Kagome spin ice systems
    Magnetic monopoles are actually impossible. At low temperatures, however, certain crystals can contain so-called quasi-particles that behave like magnetic monopoles. Now an international cooperation has proven that such monopoles also occur in a Kagome spin ice system. Decisive factors were, among others, measurements with inelastic neutron scattering at the NEAT instrument of the Berlin neutron source BER II*. The results have been published in the journal Science. [...]
  • <p>In the ground state the magnetic moments are either upward or downward, the spins antiparallel to the external magnetic field (red) are never together (right). By excitation, further spins can align antiparallel and Bethe chains are formed (white spins, left).</p>
    Science Highlight
    06.04.2020
    Condensed Matter Physics: Long-standing prediction of quantum physics experimentally proven
    90 years ago, the physicist Hans Bethe postulated that unusual patterns, so-called Bethe strings, appear in certain magnetic solids. Now an international team has succeeded in experimentally detecting such Bethe strings for the first time. They used neutron scattering experiments at various neutron facilities including the unique high-field magnet of BER II* at HZB. The experimental data are in excellent agreement with the theoretical prediction of Bethe and prove once again the power of quantum physics. [...]
  • <p>This picture shows an X-ray image of the electron beam in TRIB-mode where two orbits co-exist: the regular orbit and the second one winding around it closing only after three revolutions.</p> <p>&nbsp;</p> <p></p>
    Science Highlight
    01.04.2020
    BESSY II: Ultra-fast switching of helicity of circularly polarized light pulses
    At the BESSY II storage ring, a joint team of accelerator physicists, undulator experts and experimenters has shown how the helicity of circularly polarized synchrotron radiation can be switched faster - up to a million times faster than before. They used an elliptical double-undulator developed at HZB and operated the storage ring in the so-called two-orbit mode. This is a special mode of operation that was only recently developed at BESSY II and provides the basis for fast switching. The ultra-fast change of light helicity is particularly interesting to observe processes in magnetic materials and has long been expected by a large user community. [...]
  • <p>Schematic representation of the coronavirus protease. The enzyme comes as a dimer consisting of two identical molecules. A part of the dimer is shown in colour (green and purple), the other in grey. The small molecule in yellow binds to the active centre of the protease and could be used as blueprint for an inhibitor.</p>
    Science Highlight
    19.03.2020
    Coronavirus SARS-CoV2: BESSY II data accelerate drug development
    A coronavirus is keeping the world in suspense. SARS-CoV-2 is highly infectious and can cause severe pneumonia with respiratory distress (COVID-19). Scientists are doing research in order to prevent the viruses from multiplying. A team from the University of Lübeck and from Helmholtz Centre for Infection Research (HZI) has now found a promising approach. Using the high-intensity X-ray light from the Berlin synchrotron source BESSY II, they have decoded the three-dimensional architecture of the main protease of SARS-CoV-2. This protein is involved in the reproduction of the virus. Analysing its 3D architecture allows the systematic development of drugs which inhibit the reproduction of the virus. [...]
  • <p>MXenes are 2D materials forming multi-layered particles (left) from which pseudocapacitors are made. Shining X-ray light on MXenes revealed changes of their chemical structure upon intercalation of urea molecules (right) compared to pristine MXenes (center).</p>
    Science Highlight
    02.03.2020
    Fast and furious: New class of 2D materials stores electrical energy
    Two dimensional titanium carbides, so-called MXenes, are being discussed as candidates for the rapid storage of electrical energy. Like a battery,MXenes can store large amounts of electrical energy through electrochemical reactions- but unlike batteries,can be charged and discharged in a matter of seconds. In collaboration with Drexel University, a team at HZB showed that the intercalation of urea molecules between the MXene layers can increase the capacity of such "pseudo-capacitors" by more than 50 percent. At BESSY II they have analysed how changes of the MXene surface chemistry after urea intercalation are responsible for this. [...]
  • <p>3D architecture of the cell with different organelles:&nbsp; mitochondria (green), lysosomes (purple), multivesicular bodies (red), endoplasmic reticulum (cream).</p>
    Science Highlight
    12.02.2020
    X-ray microscopy at BESSY II: Nanoparticles can change cells
    Nanoparticles easily enter into cells. New insights about how they are distributed and what they do there are shown for the first time by high-resolution 3D microscopy images from the lightsources BESSY II and ALBA. For example, certain nanoparticles accumulate preferentially in certain organelles of the cell. This can increase the energy costs in the cell. "The cell looks like it has just run a marathon, apparently, the cell requires energy to absorb such nanoparticles" says lead author James McNally. [...]
  • <p>Bei 25,8 Tesla findet in dem Urankristall ein Phasen&uuml;bergang statt und ein komplexes magnetisches Muster etabliert sich.</p>
    Science Highlight
    10.02.2020
    Not everything is ferromagnetic in high magnetic fields
    High magnetic fields have a potential to modify the microscopic arrangement of magnetic moments because they overcome interactions existing in zero field. Usually, high fields exceeding a certain critical value force the moments to align in the same direction as the field leading to ferromagnetic arrangement. However, a recent study showed that this is not always the case. The experiments took place at the high-field magnet at HZB's neutron source BER II, which generates a constant magnetic field of up to 26 Tesla. This is about 500,000 times stronger than the Earth's magnetic field. Further experiments with pulsed magnetic fields up to 45 Tesla were performed at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR).  [...]
  • <p>The x-ray tomography shows ruptures (black) in the regions of electrical contacts (white).</p>
    Science Highlight
    07.02.2020
    Battery research: Using neutrons and X-rays to analyse the ageing of lithium batteries
    An international team has used neutron and X-ray tomography to investigate the dynamic processes that lead to capacity degradation at the electrodes in lithium batteries. Using a new mathematical method, it was possible to virtually unwind electrodes that had been wound into the form of a compact cylinder, and thus actually observe the processes on the surfaces of the electrodes. The study was published in Nature Communications. [...]
  • Science Highlight
    31.01.2020
    Perovskite solar cells: International consensus on ageing measurement protocols
    Experts from 51 research institutions have now agreed on the procedures for measuring the stability of perovskite solar cells and assessing their quality. The consensus statement was published in Nature Energy and is considered a milestone for the further development of this new type of solar cell on its way to industrial application. [...]
  • <p>The tandem solar cell was realized on a typical laboratory scale of one square centimeter. However, scaling up is possible.</p>
    Science Highlight
    29.01.2020
    World Record: Efficiency of perovskite silicon tandem solar cell jumps to 29.15 per cent
    In the race for ever higher efficiency levels, an HZB development team has once again pulled ahead. The groups of Steve Albrecht and Bernd Stannowski have developed a tandem solar cell made of the semiconductors perovskite and silicon, that converts 29.15 per cent of the incident light into electrical energy. This value has been officially certified by the CalLab of the Fraunhofer Institute for Solar Energy Systems (ISE) and means that surpassing the 30 per cent efficiency mark is now within reach. [...]
  • <p>Mint plants have been analysed after having grown on contaminated soil samples.</p>
    Science Highlight
    21.01.2020
    Plants absorb lead from perovskite solar cells more than expected
    Lead from metal-organic perovskite compounds can be absorbed particularly easily by plants. The bioavailability is significantly higher than that of lead from inorganic compounds as found in batteries. This is shown in a study by HZB researcher Antonio Abate with partners in China and Italy, published in Nature communications. [...]
  • <p></p> <p>Rhodopsin before (left) and after activation by light (right): The activation causes changes in functional groups inside the molecule (magnifying glass), which affect the entire molecule.</p>
    Science Highlight
    14.01.2020
    Watching complex molecules at work
    A new method of infrared spectroscopy developed at BESSY II makes single-measurement observation and analysis of very fast as well as irreversible reaction mechanisms in molecules feasible for the first time. Previously, thousands of such reactions have had to be run and measured for this purpose. The research team has now used the new device to investigate how rhodopsin molecules change after activation by light – a process that is the basis of how we see. [...]
  • Science Highlight
    18.12.2019
    Topological materials for information technology offer lossless transmission of signals
    New experiments with magnetically doped topological insulators at BESSY II have revealed possible ways of lossless signal transmission that involve a surprising self-organisation phenomenon. In the future, it might be possible to develop materials that display this phenomenon at room temperature and can be used as processing units in a quantum computer, for example. The study has been published in the renowned journal Nature. [...]
  • <p>The study is displayed on the cover of the journal Chemmedchem.</p>
    Science Highlight
    12.12.2019
    Cancer research at BESSY II: Binding Mechanisms of Therapeutic Substances Deciphered
    In tumor cells, the DNA is altered in comparison to normal body cells. How such changes can be prevented or inhibited is an exciting field of research with great relevance for the development of cancer treatments. An interdisciplinary team has now analysed the possible binding mechanisms in certain therapeutic substances from the tetrazole hydrazide group using protein crystallography at BESSY II. [...]
  • <p>The drawing illustrates the interaction of the organic methylammonium cation (CH<sub>3</sub>NH<sub>3</sub><sup>+</sup>) with the surrounding iodide ions. The shift of the iodide atoms out of the common plane with lead causes the breaking of the inversion symmetry.</p>
    Science Highlight
    13.11.2019
    Perovskite solar cells: Possible aspects of high efficiency uncovered
    Using crystallographic analyses at the Diamond Light Source (DLS) synchrotron in the United Kingdom, an HZB team has demonstrated that hybrid halide perovskites crystallise without inversion centre. Interactions between the organic molecules and adjacent iodine atoms can lead to the formation of ferroelectric domains, which, indirectly, can result in higher solar-cell efficiencies. The formation of these ferroelectric domains cannot occur in purely inorganic perovskites. [...]
  • <p>The image shows details such as the vacuole of the parasites (colored in blue and green) inside an infected blood cell.</p>
    Science Highlight
    30.10.2019
    X-ray microscopy at BESSY II reveals how antimalaria-drugs might work
    Malaria is one of the most threatening infectious diseases in the world. An international team has now been able to investigate malaria pathogens in red blood cells in vivo using the BESSY II X-ray microscope and the ALBA and ESRF synchrotron sources. The scientists reveal the mechanisms used by active substances to attack the pathogen. This could contribute to improve treatment strategies and drug design. [...]
  • <p>The illustration demonstrates skyrmions in one of their Eigen modes (clockwise).</p>
    Science Highlight
    15.10.2019
    Dynamic pattern of Skyrmions observed
    Tiny magnetic vortices known as skyrmions form in certain magnetic materials, such as Cu2OSeO3. These skyrmions can be controlled by low-level electrical currents – which could facilitate more energy-efficient data processing. Now a team has succeeded in developing a new technique at the VEKMAG station of BESSY II for precisely measuring these vortices and observing their three different predicted characteristic oscillation modes (Eigen modes). [...]
  • <p>Time-resolved 3D neutron tomography shows the rise of deuterated water in the root system of a lupine plant.</p>
    Science Highlight
    25.09.2019
    Faster than ever - neutron tomography detects water uptake by roots
    A team of researchers from Potsdam, Berlin and Grenoble was able to visualize the transport of water in soil as well as through roots of lupine plants using ultrafast 3D neutron imaging. The high-speed neutron tomography developed at HZB generates a complete 3D image every 1.5 seconds and is thus seven times faster than before. The method facilitates a better understanding of water and nutrient uptake of crop plants. The measurements were performed at the neutron source of the Laue Langevin Institute (ILL) in Grenoble, France. The method can also be applied to investigate transport processes in various porous material systems. [...]
  • <p>Up to three indivudal drops may be placed onto the sample holder.</p>
    Science Highlight
    16.09.2019
    New sample holder for protein crystallography
    An HZB research team has developed a novel sample holder that considerably facilitates the preparation of protein crystals for structural analysis. A short video by the team shows how proteins in solution can be crystallised directly onto the new sample holders themselves, then analysed using the MX beamlines at BESSY II. A patent has already been granted and a manufacturer found. [...]
  • <p>The Pero-CIGS tandem cell achieves a record efficiency of 23.26 percent.</p>
    Science Highlight
    09.09.2019
    World record for tandem perovskite-CIGS solar cell
    A team headed by Prof. Steve Albrecht from the HZB will present a new world-record tandem solar cell at EU PVSEC, the world's largest international photovoltaic and solar energy conference and exhibition, in Marseille, France on September 11, 2019. This tandem solar cell combines the semiconducting materials perovskite and CIGS and achieves a certified efficiency of 23.26 per cent. One reason for this success lies in the cell’s intermediate layer of organic molecules: they self-organise to cover even rough semiconductor surfaces. Two patents have been filed for these layers. [...]
  • <p>The operando cell was developed at HZB and allows to analyse processes inside the battery during charging cycles with neutrons.</p>
    Science Highlight
    06.09.2019
    Nanoparticles in lithium-sulphur batteries detected with neutron experiment
    An HZB team has for the first time precisely analysed how nanoparticles of lithium sulphide and sulphur precipitate onto battery electrodes during the course of the charging cycle. The results can help increase the service life of lithium-sulphur batteries. [...]
  • <p>The nano-antennae werde produced in an electron microscope by direct electron-beam writing.</p>
    Science Highlight
    23.08.2019
    Save time using maths: analytical tool designs corkscrew-shaped nano-antennae
    For the first time, an HZB team has derived analytically how corkscrew-shaped nano-antennas interact with light. The mathematical tool can be used to calculate the geometry that a nano-antenna must have for specific applications in sensor technology or information technology. [...]
  • <p>The rotary sample table turns around its axis at several hundred revolutions per second with extreme precision.</p>
    Science Highlight
    21.08.2019
    World record in tomography: Watching how metal foam forms
    An international research team at the Swiss Light Source (SLS) has set a new tomography world record using a rotary sample table developed at the HZB. With 208 three-dimensional tomographic X-ray images per second, they were able to document the dynamic processes involved in the foaming of liquid aluminium. The method is presented in the journal Nature Communications. [...]
  • <p>A team of researchers examined an ancient papyrus with a supposed empty spot. With the help of several methods, they discovered which signs once stood in this place and which ink was used.</p>
    Science Highlight
    14.08.2019
    Archaeology at BESSY II: “Invisible ink” on antique Nile papyrus revealed
    Researchers from the Egyptian Museum and Papyrus Collection, Berlin universities and Helmholtz-Zentrum Berlin studied a small piece of papyrus that was excavated on the island of Elephantine on the River Nile a little over 100 years ago. The team used serval methods including non-destructive techniques at BESSY II. The researchers’ work, reported in the Journal of Cultural Heritage, blazes a trail for further analyses of the papyrus collection in Berlin. [...]
  • <p class="MsoCommentText">The photomontage shows a sample of solid, pure niobium before coating (left), and coated with a thin layer of Nb<sub>3</sub>Sn (right).</p>
    Science Highlight
    15.07.2019
    Accelerator physics: alternative material investigated for superconducting radio-frequency cavity resonators
    In modern synchrotron sources and free-electron lasers, superconducting radio-frequency cavity resonators are able to supply electron bunches with extremely high energy. These resonators are currently constructed of pure niobium. Now an international collaboration has investigated the potential advantages a niobium-tin coating might offer in comparison to pure niobium. [...]
  • Science Highlight
    10.07.2019
    Oldest completely preserved lily discovered
    Already 115 million years ago, tropical flowering plants were apparently very diverse and showed all typical characteristics. This is the conclusion of an international team of researchers led by Clément Coiffard, Museum für Naturkunde Berlin. The team reported in the renowned journal Nature Plants on the oldest completely preserved lily, Cratolirion bognerianum, which was discovered at a site in present-day Brazil. With the help of 3D computer tomography at the Helmholtz-Zentrum Berlin, details on the back of the fossilised plant could also be analysed. The results raise new questions about the role of the tropics in the development of past and present ecosystems. [...]
  • <p>An X-ray pulse probes the delocalization of iron 3d electrons onto adjacent ligands.</p>
    Science Highlight
    09.07.2019
    Charge transfer within transition-metal dyes analysed
    Transition-metal complexes in dye-based solar cells are responsible for converting light into electrical energy. A model of spatial charge separation within the molecule has been used to describe this conversion. However, an analysis at BESSY II shows that this description of the process is too simple. For the first time, a team there has investigated the fundamental photochemical processes around the metal atom and its ligands. The study has now been published in “Angewandte Chemie, international Edition” and is displayed on the cover. [...]
  • <p>When illuminated by the synchrotron light, nickel emits x-rays itself due to the decay of valence electrons. The number of emitted photons reduces when increasing the temperature from room temperature (left) to 900&deg;C (right).</p>
    Science Highlight
    28.06.2019
    Utrafast magnetism: electron-phonon interactions examined at BESSY II
    How fast can a magnet switch its orientation and what are the microscopic mechanisms at play ? These questions are of first importance for the development of data storage and computer chips. Now, an HZB team at BESSY II has for the first time been able to experimentally assess the principal microscopic process of ultra-fast magnetism. The methodology developed for this purpose can also be used to investigate interactions between spins and lattice oscillations in graphene, superconductors or other (quantum) materials. [...]
  • <p>The illustration is alluding to the laser experiment in the background and shows the structure of TGCN.</p>
    Science Highlight
    05.06.2019
    Organic electronics: a new semiconductor in the carbon-nitride family
    Teams from Humboldt-Universität and the Helmholtz-Zentrum Berlin have explored a new material in the carbon-nitride family. Triazine-based graphitic carbon nitride (TGCN) is a semiconductor that should be highly suitable for applications in optoelectronics. Its structure is two-dimensional and reminiscent of graphene. Unlike graphene, however, the conductivity in the direction perpendicular to its 2D planes is 65 times higher than along the planes themselves. [...]
  • <p>Experiments at the femtoslicing facility of BESSY II revealed the ultrafast angular momentum flow from Gd and Fe spins to the lattice via orbital moment during demagnetization of GdFe alloy.</p>
    Science Highlight
    10.05.2019
    Laser-driven Spin Dynamics in Ferrimagnets: How does the Angular Momentum flow?
    When exposed to intense laser pulses, the magnetization of a material can be manipulated very fast. Fundamentally, magnetization is connected to the angular momentum of the electrons in the material. A team of researchers led by scientists from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI) has now been able to follow the flow of angular momentum during ultrafast optical demagnetization in a ferrimagnetic iron-gadolinium alloy at the femtoslicing facility of BESSY II. Their results are helpful to understand the fundamental processes and their speed limits. The study is published in Physical Review Letters. [...]
  • <p>A green laser pulse initially excites the electrons in the Cu<sub>2</sub>O; just fractions of a second later, a second laser pulse (UV light) probes the energy of the excited electron.</p>
    Science Highlight
    09.05.2019
    Copper oxide photocathodes: laser experiment reveals location of efficiency loss
    Solar cells and photocathodes made of copper oxide might in theory attain high efficiencies for solar energy conversion. In practice, however, large losses occur. Now a team at the HZB has been able to use a sophisticated femtosecond laser experiment to determine where these losses take place: not so much at the interfaces, but instead far more in the interior of the crystalline material. These results provide indications on how to improve copper oxide and other metal oxides for applications as energy materials. [...]
  • <p>Tomography of a lithium electrode in its initial condition.</p>
    Science Highlight
    06.05.2019
    3D tomographic imagery reveals how lithium batteries age
    Lithium batteries lose amp-hour capacity over time. Microstructures can form on the electrodes with each new charge cycle, which further reduces battery capacity. Now an HZB team together with battery researchers from Forschungszentrum Jülich, the University of Munster, and partners in China have documented the degradation process of lithium electrodes in detail for the first time. They achieved this with the aid of a 3D tomography process using synchrotron radiation at BESSY II (HZB) as well at the Helmholtz-Zentrum Geesthacht (HZG). Their results have been published open access in the scientific journal "Materials Today". [...]
  • <p></p> <p>By co-evaporation of cesium iodide and lead iodide thin layers of CsPbI<sub>3</sub> can be produced even at moderate temperatures. An excess of cesium leads to stable perovskite phases.</p>
    Science Highlight
    29.04.2019
    Inorganic perovskite absorbers for use in thin-film solar cells
    A team at the Helmholtz-Zentrum Berlin has succeeded in producing inorganic perovskite thin films at moderate temperatures using co-evaporation – making post-tempering at high temperatures unnecessary. The process makes it much easier to produce thin-film solar cells from this material. In comparison to metal-organic hybrid perovskites, inorganic perovskites are more thermally stable. The work has been published in Advanced Energy Materials. [...]
  • <p>SnSe is a highly layered orthorhombic structure. SnSe undergoes a phase transition of second order at 500&deg;C with an increase of the crystal symmetry from space group Pnma (left) to Cmcm (right).</p>
    Science Highlight
    24.04.2019
    High-efficiency thermoelectric materials: new insights into tin selenide
    Tin selenide might considerably exceed the efficiency of current record holding thermoelectric materials made of bismuth telluride. However, it was thought its efficiency became enormous only at temperatures above 500 degrees Celsius. Now measurements at the BESSY II and PETRA III synchrotron sources show that tin selenide can also be utilised as a thermoelectric material at room temperature – so long as high pressure is applied. [...]
  • <p>The enzyme MHETase is a huge and complex molecule. MHET-molecules from PET plastic dock at the active site inside the MHETase and are broken down into their basic building blocks.</p>
    Science Highlight
    12.04.2019
    "Molecular scissors" for plastic waste
    A research team from the University of Greifswald and Helmholtz-Zentrum-Berlin (HZB) has solved the molecular structure of the important enzyme MHETase at BESSY II. MHETase was discovered in bacteria and together with a second enzyme - PETase - is able to break down the widely used plastic PET into its basic building blocks. This 3D structure already allowed the researchers to produce a MHETase variant with optimized activity in order to use it, together with PETase, for a sustainable recycling of PET. The results have been published in the research journal Nature Communications. [...]
  • <p>The SEM shows Molybdenum sulfide deposited at room temperature.</p>
    Science Highlight
    04.04.2019
    Catalyst research for solar fuels: Amorphous molybdenum sulphide works best
    Efficient and inexpensive catalysts will be required for production of hydrogen from sunlight. Molybdenum sulphides are considered good candidates. A team at HZB has now explained what processes take place in molybdenum sulphides during catalysis and why amorphous molybdenum sulphide works best. The results have been published in the journal ACS Catalysis. [...]
  • <p>At the end of his contribution, Phillippe Wernet makes a great arch from the past (Opticae Thesaurus, 1572) of research with light to the future.</p>
    Science Highlight
    02.04.2019
    HZB contributions to special edition on Ultrafast Dynamics with X-ray Methods
    In the new special issue of the "Philosophical Transactions of the Royal Society of London", internationally renowned experts report on new developments in X-ray sources and ultrafast time-resolved experiments. HZB physicists have also been invited to contribute. [...]
  • <p>Schematic view of carbon structures with pores.</p>
    Science Highlight
    13.03.2019
    X-ray analysis of carbon nanostructures helps material design
    Nanostructures made of carbon are extremely versatile: they can absorb ions in batteries and supercapacitors, store gases, and desalinate water. How well they cope with the task at hand depends largely on the structural features of the nanopores. A new study from the HZB has now shown that structural changes that occur due to morphology transition with increasing temperature of the synthesis can also be measured directly – using small-angle X-ray scattering. The results have now been published in the journal Carbon. [...]
  • <p>Water molecules are excited with X-ray light (blue). From the emitted light (purple) information on H-bonds can be obtained.</p>
    Science Highlight
    20.02.2019
    Water is more homogeneous than expected
    In order to explain the known anomalies in water, some researchers assume that water consists of a mixture of two phases even under ambient conditions. However, new X-ray spectroscopic analyses at BESSY II, ESRF and Swiss Light Source show that this is not the case. At room temperature and normal pressure, the water molecules form a fluctuating network with an average of 1.74 ± 2.1% donor and acceptor hydrogen bridge bonds per molecule each, allowing tetrahedral coordination between close neighbours. [...]
  • <p>The cones represents the magnetization of the nanoparticles. In the absence of electric field (strain-free state) the size and separation between particles leads to a random orientation of their magnetization, known as superparamagnetism</p>
    Science Highlight
    14.02.2019
    Spintronics by “straintronics”: Superferromagnetism with electric-field induced strain
    Data storage in today’s magnetic media is very energy consuming. Combination of novel materials and the coupling between their properties could reduce the energy needed to control magnetic memories thus contributing to a smaller carbon footprint of the IT sector. Now an international team led by HZB has observed at the HZB lightsource BESSY II a new phenomenon in iron nanograins: whereas normally the magnetic moments of the iron grains are disordered with respect each other at room temperature, this can be changed by applying an electric field: This field induces locally a strain on the system leading to the formation of a so-called superferromagnetic ordered state. [...]
  • <p>An extremely thin layer between CIGSe and Perovskite improves the efficiency of the tandemcell.</p>
    Science Highlight
    31.01.2019
    Ultra-thin and extremely efficient: Thin-film tandem cells made of perovskite and CIGSe semiconductors
    An HZB team has fabricated and characterised a thin-film tandem solar cell made of perovskite and CIGSe. They relied on a simple, robust fabrication process that is also suitable for scaling up to large surface areas. The tandem solar cell is a fully thin film device with an impressive efficiency of 21.6 %. With further improvements it might reach efficiencies above 30 %. [...]
  • <p>Neutrons (red arrows) detect the presence of Lithium ions which have migrated into the silicon anode.</p>
    Science Highlight
    28.01.2019
    Batteries with silicon anodes: Neutron experiments show how formation of surface structures reduces amp-hour capacity
    In theory, silicon anodes could store ten times more lithium ions than graphite anodes, which have been used in commercial lithium batteries for many years. However, the amp-hour capacity of silicon anodes so far has been declining sharply with each additional charge-discharge cycle. Now an HZB team at BER II of the HZB in Berlin and the Institut Laue-Langevin in Grenoble has utilised neutron experiments to establish what happens at the surface of the silicon anode during charging and what processes reduce this capacity. [...]
  • <p class="MsoPlainText">The atmosphere can be compared to a bathtub that can only be filled to its rim if global warming is to be limited to a certain level. We could create another small outward flow with negative emissions. However, there is no way around turning off the tap.</p>
    Science Highlight
    16.01.2019
    Climate change: How could artificial photosynthesis contribute to limiting global warming?

    If CO2 emissions do not fall fast enough, then CO2 will have to be removed from the atmosphere in the future to limit global warming. Not only could planting new forests and biomass contribute to this, but new technologies for artificial photosynthesis as well. An HZB physicist and a researcher at the University of Heidelberg have estimated how much surface area such solutions would require. Although artificial photosynthesis could bind CO2 more efficiently than the natural model, there are still no large modules that are stable over the long term. The team published their calculations in "Earth System Dynamics".

    [...]

  • <p>(a) Neutronen-Eigenspannungsmessung an einer Schwei&szlig;probe aus handels&uuml;blichen Stahl, (b) Magnetfeldmessung, (c) Schwei&szlig;nahtquerschliff.</p>
    Science Highlight
    21.12.2018
    Neutronenforschung hilft bei der Entwicklung von zerstörungsfreien Prüfverfahren
    Materialermüdung zeigt sich häufig zuerst daran, dass im Innern des Materials Bereiche mit stark unterschiedlichen Eigenspannungen aneinandergrenzen. An der Neutronenquelle BER II am HZB hat ein Team der Bundesanstalt für Materialforschung und –prüfung (BAM) die Eigenspannungen von Schweißnähten aus ferromagnetischem Stahl analysiert. Die Ergebnisse helfen zerstörungsfreie elektromagnetische Prüfverfahren zu verbessern. [...]
  • <p>Photocathode in superconducting photoinjector system.</p>
    Science Highlight
    07.12.2018
    Milestone for bERLinPro: photocathodes with high quantum efficiency
    A team at the HZB has improved the manufacturing process of photocathodes and can now provide photocathodes with high quantum efficiency for bERLinPro. [...]
  • <p>The molecule organises itself on the electrode surface until a dense, uniform monolayer is formed.</p>
    Science Highlight
    23.11.2018
    Molecules that self-assemble into monolayers for efficient perovskite solar cells
    A team at the HZB has discovered a new method for producing efficient contact layers in perovskite solar cells. It is based on molecules that organise themselves into a monolayer. The study was published in Advanced Energy Materials and appeared on the front cover of the journal. [...]
  • <p>The illustration shows a molecule with an iron atom at its centre, bound to 4 CN groups and a bipyridine molecule. The highest occupied iron orbital is shown as a green-red cloud. As soon as a cyan group is present, the outer iron orbitals are observed to delocalize so that electrons are also densely present around the nitrogen atoms.</p> <p></p>
    Science Highlight
    14.11.2018
    Transition metal complexes: mixed works better
    A team at BESSY II has investigated how various iron-complex compounds process energy from incident light. They were able to show why certain compounds have the potential to convert light into electrical energy. The results are important for the development of organic solar cells. The study has now been published in the journal PCCP, and its illustration selected for the cover. [...]
  • <p>The SEM image shows the cross-section of a silicon perovskite tandem solar cell.</p>
    Science Highlight
    12.11.2018
    New records in perovskite-silicon tandem solar cells through improved light management
    Using microstructured layers, an HZB team has been able to increase the efficiency of perovskite-silicon tandem solar cells, achieving 25.5 %, which is the highest published value to date. At the same time, computational simulations were utilized to investigate light conversion in various device designs with different nanostructured surfaces. This enabled optimization of light management and detailed energy yield analyses. The study has now been published in Energy & Environmental Science. [...]
  • <p>The data show that In the case of the two-layer graphene, a flat part of bandstructure only 200 milli-electron volts below the Fermi energy.</p>
    Science Highlight
    10.11.2018
    Graphene on the way to superconductivity
    Scientists at HZB have found evidence that double layers of graphene have a property that may let them conduct current completely without resistance. They probed the bandstructure at BESSY II with extremely high resolution ARPES and could identify a flat area at a surprising location. [...]
  • <p>Doped Diamond Foam. </p>
    Science Highlight
    18.10.2018
    Nanodiamonds as photocatalysts
    Diamond nanomaterials are considered hot candidates for low-cost photocatalysts. They can be activated by light and can then accelerate certain reactions between water and CO2 and produce carbon-neutral "solar fuels". The EU project DIACAT has now doped such diamond materials with boron and shown at BESSY II how this could significantly improve the photocatalytic properties. [...]
  • <p>The STM image shows blue phosphorus on a gold substrate. The calculated atomic positions of the slightly elevated P atoms are shown in blue, the lower lying ones in white. Groups of six elevated P atoms appear as triangles. </p>
<p><strong> </strong></p>
    Science Highlight
    15.10.2018
    Blue phosphorus - mapped and measured for the first time
    Until recently, the existence of "blue" phosphorus was pure theory: Now an HZB team was able to examine samples of blue phosphorus at BESSY II for the first time and confirm via mapping of their electronic band structure that this is actually this exotic phosphorus modification. Blue phosphorus is an interesting candidate for new optoelectronic devices. The results have been published in Nano Letters. [...]
  • <p>Shown are the magnetic fluxlines inside a superconducting sample of lead in two different directions. The scale bar is 5 mm. </p>
    Science Highlight
    02.10.2018
    Neutrons scan magnetic fields inside samples
    With a newly developed neutron tomography technique, an HZB team has been able to map for the first time magnetic field lines inside materials at the BER II research reactor. Tensorial neutron tomography promises new insights into superconductors, battery electrodes, and other energy-related materials. [...]
  • <p>Principle of a silicon singlet fission solar cell with incorporated organic crystalls<br /></p>
    Science Highlight
    02.10.2018
    HZB researchers boost the efficiency of silicon solar cells
    The efficiency of a solar cell is one of its most important parameters. It indicates what percentage of the solar energy radiated into the cell is converted into electrical energy. The theoretical limit for silicon solar cells is 29.3 percent due to physical material properties. In the journal Materials Horizons, researchers from Helmholtz-Zentrum Berlin (HZB) and international colleagues describe how this limit can be abolished. The trick: they incorporate layers of organic molecules into the solar cell. These layers utilise a quantum mechanical process known as singlet exciton fission to split certain energetic light (green and blue photons) in such a way that the electrical current of the solar cell can double in that energy range. [...]
  • <p>The computer simulation shows how the electromagnetic field is distributed in the silicon layer with hole pattern after excitation with a laser. Here, stripes with local field maxima are formed, so that quantum dots shine particularly strongly. Picture. C. Barth/HZB</p>
    Science Highlight
    28.09.2018
    Machine learning helps improving photonic applications
    Photonic nanostructures can be used for many applications, not just in solar cells, but also in optical sensors for cancer markers or other biomolecules, for example. A team at HZB using computer simulations and machine learning has now shown how the design of such nanostructures can be selectively optimised. The results are published in Communications Physics. [...]
  • <p>Monthly news from HZB - via email newsletter.</p>
    Science Highlight
    24.09.2018
    Newsletter and Highlightreport
    Exactly twenty years ago, BESSY II went into operation. In the current September newsletter, which we are sending out this week, we present the anniversary website, report on the new highlight report 2017 and on successes in technology transfer. Have you already registered for the newsletter? Here is the registration link. [...]
  • <p>The nanostructure for capturing light is imprinted on silicon oxide (blue) and then "levelled" with titanium oxide (green). The result is an optically rough but smooth layer on which crystalline silicon can be grown.</p>
    Science Highlight
    17.09.2018
    Patented nanostructure for solar cells: Rough optics, smooth surface
    Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem. [...]
  • <p>The laser pulse (red) generates heat in the thin-film system. The physical mechanisms by which the heat is distributed can be analysed by temporally resolved X-ray diffraction experiments. </p>
    Science Highlight
    21.08.2018
    Future information technologies: nanoscale heat transport under the microscope
    A team of researchers from the Helmholtz-Zentrum Berlin (HZB) and the University of Potsdam has investigated heat transport in a model system comprising nanometre-thin metallic and magnetic layers. Similar systems are candidates for future high-efficiency data storage devices that can be locally heated and rewritten by laser pulses (Heat-Assisted Magnetic Recording). Measurements taken with extremely short X-ray pulses have now shown that the heat is distributed a hundred times slower than expected in the model system. The results are published in Nature Communications. [...]
  • <p>Granules of aluminium (grey) become a metallic foam when heated.The tompgraphies document the evolution of pores with time. </p>
    Science Highlight
    08.08.2018
    World record: Fastest 3D tomographic images at BESSY II
    An HZB team has developed an ingenious precision rotary table at the EDDI beamline at BESSY II and combined it with particularly fast optics. This enabled them to document the formation of pores in grains of metal during foaming processes at 25 tomographic images per second - a world record. [...]
  • <p>The analysed perovskite cell has a surface of 1 cm<sup>2</sup>. Credit. Uni Potsdam</p>
    Science Highlight
    01.08.2018
    Insight into loss processes in perovskite solar cells enables efficiency improvements
    In perovskite solar cells, charge carriers are mainly lost through recombination occurring at interface defect sites. In contrast, recombination at defect sites within the perovskite layer does not limit the performance of the solar cells at present. Teams from the University of Potsdam and the Helmholtz-Zentrum Berlin (HZB) were able to reach this interesting conclusion through extremely accurate quantitative measurements on 1 cm2 perovskite cells using photoluminescence. Their results contribute to improving  perovskite solar cells and have now been published in Nature Energy. [...]
  • <p>Manganese compounds also play a role as catalysts in photosynthesis. </p>
    Science Highlight
    31.07.2018
    Insight into catalysis through novel study of X-ray absorption spectroscopy
    An international team has made a breakthrough at BESSY II. For the first time, they succeeded in investigating electronic states of a transition metal in detail and drawing reliable conclusions on their catalytic effect from the data. These results are helpful for the development of future applications of catalytic transition-metal systems. The work has now been published in Chemical Science, the Open Access journal of the Royal Society of Chemistry. [...]
  • <div class="ce__subline ce__subline--black font--h7">&Uuml;bergabe der Technologieberichte an den parlamentarischen Staatssekret&auml;r Thomas Barei&szlig; (BMWi) durch Prof. Dr.-Ing. Manfred Fischedick und Dr. Peter Viebahn, (Wuppertal Institut) sowie Prof. Dr. Martin Wietschel (Fraunhofer ISI) und Juri Horst (IZES gGmbH). Quelle: Susanne Eriksson/BMWi</div>
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    Science Highlight
    26.07.2018
    Wissenstransfer: Neues Standardwerk zu Energietechnologien in Deutschland
    Vertreter des Wuppertal Instituts haben dem Bundesministerium für Wirtschaft und Energie (BMWi) einen mehrbändigen Bericht zu Energietechnologien übergeben. Dabei haben Experten aus dem HZB-Institut PVcomB am Themenfeld Photovoltaik mitgewirkt. Im Herbst verabschiedet die Bundesregierung das neue 7. Energieforschungsprogramm (EFP). Der Bericht liefert eine wissenschaftliche Basis für die Entwicklung des Programms. [...]
  • <p>With this experiment, the team could observe how magnetic order is changed by sudden heat.</p>
    Science Highlight
    16.07.2018
    Future information technology: Microscopic insight into processes when magnets suddenly heat up
    Magnetic solids can demagnetize upon heating. Despite decades of research, it has so far been unclear how this process works in detail. Now, for the first time, an international group has observed in a step-by-step manner how sudden heating affects the magnetic order of a ferrimagnetic insulator. The result: The magnetic order changes on two time scales. The first process is surprisingly fast and takes only one picosecond, while the second process takes 100,000 times longer. This insight could help to increase the switching speed in magnetic storage media by at least a factor of 1000.  The work is published in Science Advances. [...]
  • <p>The transparent anti-corrosion layer contains Rhodium nanoparticles as a catalyst. Credit ACS Energy Letters.</p>
    Science Highlight
    05.07.2018
    New world record for direct solar water-splitting efficiency
    Hydrogen will play a central role as a storage medium in sustainable energy systems. An international team of researchers has now succeeded in raising the efficiency of producing hydrogen from direct solar water-splitting to a record 19 per cent. They did so by combining a tandem solar cell of III-V semiconductors with a catalyst of rhodium nanoparticles and a crystalline titanium dioxide coating. Teams from the California Institute of Technology, the University of Cambridge, Technische Universität Ilmenau, and the Fraunhofer Institute for Solar Energy Systems ISE participated in the development work. One part of the experiments took place at the Institute for Solar Fuels in the Helmholtz-Zentrum Berlin. [...]
  • Science Highlight
    22.06.2018
    Silicon heterojunction solar cell with a certified 23.1 % energy conversion efficiency
    After further optimization of the baseline process for industrial silicon heterojunction (SHJ) solar cells, the accredited metrology lab ISFH CalTeC now certified an efficiency of 23.1 % for a 4 cm² solar cell. This performance is among the best in the world and demonstrates the leading role of HZB in this technology in Germany and Europe. [...]
  • <p>Perovskite-based tandem solar cells can achieve now efficiencies better than 25%.</p>
    Science Highlight
    14.06.2018
    Perovskite-silicon solar cell research collaboration hits 25.2% efficiency
    A 1 cm2 perovskite silicon tandem solar cell achieves an independently certified efficiency of 25.2 %. This was presented this week at an international conference in Hawaii, USA. The cell was developed jointly by HZB, Oxford University and Oxford PV - The Perovskite CompanyTM. [...]
  • <p>Fossils like this 250 million year old skull of a lystrosaurus can be examined very carefully by neutron tomography. </p>
    Science Highlight
    05.06.2018
    Neutron tomography: Insights into the interior of teeth, root balls, batteries, and fuel cells
    A team of researchers at Helmholtz-Zentrum Berlin (HZB) and European Spallation Source (ESS) has now published a comprehensive overview of neutron-based imaging processes in the renowned journal Materials Today (impact factor 21.6). The authors report on the latest developments in neutron tomography, illustrating the possible applications using examples of this non-destructive method. Neutron tomography has facilitated breakthroughs in so diverse areas such as art history, battery research, dentistry, energy materials, industrial research, magnetism, palaeobiology and plant physiology. [...]
  • <p>First author is the mathematician Sibylle Bergmann, whose PhD work is funded by MiCo. </p>
    Science Highlight
    17.05.2018
    Helmholtz Virtual Institute MiCo: Article selected as journal highlight for 2017
    The Helmholtz Virtual Institute MiCo offers a platform through which the Helmholtz-Zentrum Berlin conducts joint research with universities and other partners on the topic of microstructures for thin-film solar cells. The journal Modelling and Simulation in Materials Science and Engineering recently selected an article produced through MiCo as the highlight of those published by the journal during 2017. [...]
  • <p>Laser light for writing and erasing information &ndash; a strong laser pulse disrupts the arrangement of atoms in an alloy and creates magnetic structures (left). A second, weaker, laser pulse allows the atoms to return to their original lattice sites (right). </p>
    Science Highlight
    18.04.2018
    Writing and deleting magnets with lasers
    Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia in Charlottesville, USA have found a way to write and delete magnets in an alloy using a laser beam – a surprising effect. The reversibility of the process opens up new possibilities in the fields of material processing, optical technology, and data storage. [...]
  • <p class="Default">The picture shows the typical arrangement of cations in a kesterite type structure. In the background the crystal structure is shown, a unit cell is highlighted. </p>
    Science Highlight
    29.03.2018
    Kesterite solar cells: germanium promises better opto-electronic properties than tin
    Specific changes in the composition of kesterite-type semiconductors make it possible to improve their suitability as absorber layers in solar cells. As a team at the Helmholtz-Zentrum Berlin showed, this is particularly true for kesterites in which tin was replaced by germanium. The scientists examined the samples using neutron diffraction at BER II and other methods. The work was selected for the cover of the journal CrystEngComm. [...]
  • <p>A synchrotron source point image of a bending magnet of the Twin Orbit modus. The second orbit closes after three revolution and is winding around the standard orbit at the center.</p>
    Science Highlight
    15.03.2018
    Twin Orbit operation successfully tested at BESSY II
    The first “Twin Orbit User Test week” at BESSY II in February 2018 was a big success and can be considered as an important step towards real user operation. Physicists at Helmholtz-Zentrum Berlin have been able to store two separate electron beams in one storage ring. The twin orbit operation mode can serve users with different needs of the time structure of the photon pulses simultaneously and offers elegant options regarding the future project BESSY VSR. [...]
  • <p>PCN nanolayers under sunlight can split water. </p>
    Science Highlight
    28.02.2018
    Solar–to-hydrogen conversion: nanostructuring increases efficiency of metal-free photocatalysts by factor eleven
    Polymeric carbon nitrides exhibit a catalytic effect in sunlight that can be used for the production of hydrogen from solar energy. However, the efficiency of these metal-free catalysts is extremely low. A team at the Tianjin University in China, in collaboration with a group at the Helmholtz-Zentrum Berlin, has increased the catalytic efficiency of these polymeric carbon nitrides by a factor eleven through a simple process resulting in a larger surface area. The paper was published in the journal Energy & Environmental Science. [...]
  • <p>The GaAs nanocrystal has been deposited on top of a silicon germanium needle, as shown by this SEM-image. The rhombic facets have been colored artificially. </p>
    Science Highlight
    22.02.2018
    Luminescent nano-architectures of gallium arsenide
    A team at the HZB has succeeded in growing nanocrystals of gallium arsenide on tiny columns of silicon and germanium. This enables extremely efficient optoelectronic components for important frequency ranges to be realised on silicon chips. [...]
  • <p>Pencil, paper and co-polymer varnish are sufficient for a thermoelectrical device. </p>
    Science Highlight
    16.02.2018
    Hidden talents: Converting heat into electricity with pencil and paper
    Thermoelectric materials can use thermal differences to generate electricity. Now there is an inexpensive and environmentally friendly way of producing them with the simplest of components: a normal pencil, photocopy paper, and conductive paint are sufficient to convert a temperature difference into electricity via the thermoelectric effect. This has now been demonstrated by a team at the Helmholtz-Zentrum Berlin. [...]
  • <p>Sketch of the stripe order: The charge stripes, which are superconducting, are shown in blue. Reprinted with modifications from Physical Review Letters.</p>
    Science Highlight
    09.02.2018
    User research at BER II: New insights into high-temperature superconductors
    After 30 years of research, there are still many unsolved puzzles about high-temperature superconductors - among them is the magnetic “stripe order” found in some cuprate superconductors. A Danish research team has taken a closer look at these stripes, using high-resolution neutron scattering at the spectrometers FLEXX (HZB) and ThALES (ILL, Grenoble). Their results, now published in Physical Review Letters, challenge the common understanding of stripe order, and may contribute to unveil the true nature  of high-temperature superconductivity. [...]
  • <p>Electrons with differing energies are emitted along various crystal axes in the interior of the sample as well as from the surface. These can be measured with the angular-resolved photoemission station (ARPES) at BESSY II. Left image shows the sample temperature at 25 K, right at only 1 K. The energy distribution of the conducting and valence band electrons can be derived from these data. The surface remains conductive at very low temperature (1 K). </p>
    Science Highlight
    06.02.2018
    40-year controversy in solid-state physics resolved
    An international team at BESSY II headed by Prof. Oliver Rader has shown that the puzzling properties of samarium hexaboride do not stem from the material being a topological insulator, as it had been proposed to be. Theoretical and initial experimental work had previously indicated that this material, which becomes a Kondo insulator at very low temperatures, also possessed the properties of a topological insulator. The team has now published a compelling alternative explanation in Nature Communications, however. [...]
  • <p>The new building block (left, red outline) comprises two modified starting molecules connected to each other by a silver atom (blue). This leads to complex, semiregular tessellations (right, microscope image). </p>
    Science Highlight
    23.01.2018
    User experiment at BESSY II: Complex tessellations, extraordinary materials
    Simple organic molecules form complex materials through self-organization [...]
  • <p class="MsoNoSpacing">SEM-images of the different perovskite solar cell architectures, left with planar interface, right with mesoporous interface. Images are coloured: metal oxide (light blue), interface (red), perovskite (brown), hole conducting layer (dark blue), topped with contact (gold).  Scale bar is 200 nm. </p>
<p> </p>
    Science Highlight
    18.01.2018
    Perovskite solar cells: mesoporous interface mitigates the impact of defects
    The nominal cell operating life of perovskite solar cells is strongly influenced by their inner architecture.This was shown by two scientists at the Helmholtz-Zentrum Berlin and the Technical University of Munich. They combined experiments with numerical simulations in order to explain this observation. [...]
  • <p>Simplified cross-section of a perovskite solar cell: the perovskite layer does not cover the entire surface, but instead exhibits holes. The scientists could show that a protective layer is being built up which prevents short circuits.</p>
    Science Highlight
    15.01.2018
    Perovskite solar cells: perfection not required!
    Experiments at BESSY II reveal why even inhomogeneous perovskite films are highly functional  [...]
  • <p>Backscattered electron micrograph of kesterite powder. Grey grains are attributed to CZTSe. Black background is the epoxy matrix. </p>
    Science Highlight
    07.12.2017
    Solar energy: Defects in Kesterite semiconductors studied using neutrons
    A research team at the HZB has precisely characterised for the first time the various types of defects in kesterite semiconductors. They achieved this with the help of neutron scattering at the BER II research reactor and at Oak Ridge National Laboratory in the USA. The findings point to a means of guided optimisation for kesterite solar cells. [...]
  • <p>The MultiFLEXX detector. <em><br /></em></p>
    Science Highlight
    01.12.2017
    Neutron spectroscopy: new detector module MultiFLEXX increases count rate tenfold
    The triple axis spectrometer FLEXX at BER II provides a new detector module for user service. It measures many angles and multiple energy transfers simultaneously and thus increases the amount of data measured per hour by about a factor of ten. This enables neutron users to make optimal use of their beam time. [...]
  • <p>The illustration shows how photons break the dimers into the individual organometallic molecules again, which then effectively n-dope the organic semiconductor. </p>
    Science Highlight
    23.11.2017
    Light facilitates “impossible“ n-doping of organic semiconductors
    Applications as light-emitting diodes and solar cells [...]
  • <p>A short laser pulse pertubates magnetic order in dysprosium. This happens much faster if the sample had a antiferromagnetic order (left) compared to ferromagnetic order (right). </p>
    Science Highlight
    06.11.2017
    Future IT: Antiferromagnetic dysprosium reveals magnetic switching with less energy
    HZB scientists have identified a mechanism with which it may be possible to develop a form of magnetic storage that is faster and more energy-efficient. They compared how different forms of magnetic ordering in the rare-earth metal named dysprosium react to a short laser pulse. They discovered that the magnetic orientation can be altered much faster and with considerably less energy if the magnetic moments of the individual atoms do not all point in the same direction (ferromagnetism), but instead point are rotated against each other (anti-ferromagnetism). The study was published in Physical Review letters on 6. November 2017 and on the cover of the print edition. [...]
  • Science Highlight
    02.11.2017
    New magazine “lichtblick” is out: Select articles can be read in English on the website
    Some artikels from our magazine lichtblick are available in English: You can find these articles here: http://hz-b.de/lichtblick-en [...]
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<p>Additional spots appear on the neutron detector starting at a magnetic field strength of 23 Tesla that reveal the new magnetic order in the crystal. </p>
<p> </p>
<p> </p>
    Science Highlight
    19.10.2017
    High Field Magnet at BER II: Insight into a hidden order
    A specific uranium compound has puzzled researchers for thirty years. Although the crystal structure is simple, no one understands exactly what is happening once it is cooled below a certain temperature. Apparently, a “hidden order” emerges,  whose nature is completely unknown.Now physicists have characterised this hidden order state more precisely and studied it on a microscopic scale. To accomplish this, they utilised the High-Field Magnet at the HZB that permits neutron experiments to be conducted under conditions of extremely high magnetic fields. [...]
  • <p>The Bismut doping is enhanced from 0% (left) to 2.2% (right). Measurements at BESSY II show that this leads to increased bandgaps. </p>
    Science Highlight
    17.10.2017
    Missing link between new topological phases of matter discovered
    HZB-Physicists at BESSY II have investigated a class of materials that exhibit characteristics of topological insulators. During these studies they discovered a transition between two different topological phases, one of which is ferroelectric, meaning a phase in the material that exhibits spontaneous electric polarisation and can be reversed by an external electric field. This could also lead to new applications such as switching between differing conductivities. [...]
  • <p>Sketch of the Photosystem II. </p>
    Science Highlight
    30.09.2017
    Novel soft X-ray spectrometer enables individual steps of photosynthetic water oxidation to be observed
    HZB scientists have developed a novel spectrometer at BESSY II that enables researchers to obtain detailed insights about catalytic processes in metalloenzymes. Their international collaboration was successful in delineating individual steps in the catalytic oxidation of water to dioxygen in photosystem II. They published their study in the journal Structural Dynamics. Photosystem II is a part of the of photosynthetic electron transport chain, a process that is responsible for the conversion of solar energy to chemical energy in plants, algae and cyanobacteria. [...]
  • <p>Scanning Tunneling Microscopy shows the regular corrugation pattern of graphene over clusters of gold.</p>
    Science Highlight
    18.09.2017
    The miracle material graphene: convex as a chesterfield
    Graphene possesses extreme properties and can be utilised in many ways. Even the spins of graphene can be controlled through use of a trick. This had already been demonstrated by a HZB team some time ago: the physicists applied a layer of graphene onto a nickel substrate and introduced atoms of gold in between (intercalation). The scientists now show why this has such a dramatic influence on the spins in a paper published in 2D Materials. As a result, graphene can also be considered as a material for future information technologies that are based on processing spins as units of information. [...]
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    Science Highlight
    28.08.2017
    Solar hydrogen production by artificial leafs:
    Scientists analysed how a special treatment improves cheap metal oxide photoelectrodes [...]
  • <p>Schematic of experimental setup for PEEM, the laser optics integrated sample holder and the sample.</p>
    Science Highlight
    25.08.2017
    Optical control of magnetic memory – new insights into fundamental mechanisms
    A research team at Helmholtz-Zentrum Berlin (HZB) has shown for the first time how laser modulation of magnetic properties in materials is influenced by thermal effects and how the process occurs under moderate experimental parameters. At the same time, the scientists discovered a previously unknown dependence on the thickness of the magnetic layer. This is an important clue for our theoretical understanding of optically controlled magnetic data storage media. The findings are published today in the journal Scientific Reports. [...]
  • <p>Sketch of an yolk-shell-type nanoreactor: reactands A and B diffuse through the shell and react to C at the catalytically active nanoparticle (yellow). </p>
    Science Highlight
    04.08.2017
    New model for bimolecular reactions in nanoreactors
    Theoretical physicists have devised a mathematical model of two different molecules reacting within so called nanoreactors that act as catalysts. They gained surprising new insights as to what factors promote reactions and how to control and select them. The model is relevant for a wide range of research fields, from biophysics to energy materials. [...]
  • <p>Sequential tomography of a lupin root (yellowish green) after deuterated water (D<sub>2</sub>O) was introduced from below. The rising water front (H<sub>2</sub>O, dark blue) is displaced by the D<sub>2</sub>O from below over the course of time. The complete sequence can be viewed as a video. Created by Christian T&ouml;tzke &copy; University of Potsdam</p>
    Science Highlight
    25.07.2017
    User research at BER II: Lupin roots observed in the act of catching water from soil – so far too quick for 3D views
    Lupins not only produce colourful blossoms but also nutritious beans rich in proteins. Just how these plants draw water approaching their roots in soil has now for the first time been observed in three dimensions by a University of Potsdam team at the HZB-BER II neutron source in Berlin. To accomplish this, they worked with the HZB imaging group to improve the temporal resolution of neutron tomography more than onehundred-fold so that a detailed 3D image was generated every ten seconds. This ultrafast neutron tomography is generally suitable as well for analyses of dynamic processes in porous materials. [...]
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<p>Scanning electron micrographs show a 10-micron planar deposition. The constituting silver crystals are about 100 nanometres in size. </p>
<p></p>
    Science Highlight
    24.07.2017
    Writing with the electron beam: now in silver
    For the first time an international team realized direct writing of silver nanostructures using an electron beam applied to a substrate. Silver nanostructures have the potential to concentrate visible light at the nanoscale. Potential applications include sensor design to detect extremely small traces of specific molecules, as well as devices for optical information processing. [...]
  • Science Highlight
    19.07.2017
    Modern, concise and informative: HZB presents itself
    A information brochure, illustrated throughout with a fusion of photos and sketches, serves as the new business card of HZB. In concise and understandable language, it describes the centre’s most important research focuses, introduces the large-scale facilities and laboratories, and shows why HZB is an internationally attractive place to work. [...]
  • <p>Klaus Habicht analyses materials also with the help of neutron resonance spin-echo spectroscopy, a method, he helped to develop further.  </p>
    Science Highlight
    19.06.2017
    HZB researcher receives university-level teaching credential (Habilitation)
    Dr. Klaus Habicht has successfully completed the university-level teaching accreditation process in the Faculty of Mathematics and Natural Sciences at the University of Potsdam and received his official university-level teaching qualification for the physics of condensed matter. Habicht has conducted numerous lectures and seminars at the University of Potsdam since 2011, in particular in solid-state physics and methods in neutron research. He heads the Department of Methods for Characterisation of Transport Phenomenon in Energy Materials at the HZB. [...]
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<p></p>
<p>One example from the paper: <em>operando</em> radiography (A)- (C) shows how sulphur compounds (black features) are deposited on the carbon cathode (gray) of a lithium-sulphur cell during charging and discharging.</p>
    Science Highlight
    01.06.2017
    HZB paper appears in special anniversary edition of the Journal of Physics D: Applied Physics
    A paper on X-ray tomography of various types of batteries has been published as a highlight in the exclusive special edition of the Journal of Physics D: Applied Physics. Two groups at the HZB along with a team from Justus Liebig University in Giessen, Germany, contributed to the article. [...]
  • <p>The data show band gaps and efficiency levels of various perovskite materials. The efficiency levels for high band gaps fall due to undesired halide segregation effects. </p>
    Science Highlight
    30.05.2017
    Trends and pathways to high-efficiency perovskite solar cells
    Perovskite  solar cells have been the big surprise over the last while: inside of only a few years, their efficiency level has been increased from just under 10 % to fully 22 %. There has never been such rapid progress in a new material for solar cells. Scientists around the world are therefore working on this new class of materials. Eva Unger and Steve Albrecht from Helmholtz-Zentrum Berlin (HZB) have evaluated trends in the advancement of perovskite materials in an invited review article in Journal of Materials Chemistry A. They point out what opportunities exist for advancing this class of materials, combining them with other semiconductors, and where limitations lie.  [...]
  • <p>The porous structure of the nanoparticles is visible under the electron microscope. <strong><a href="http://onlinelibrary.wiley.com/doi/10.1002/adfm.201701176/abstract;jsessionid=F0393DC7BB4AAE76B24CFD675C8CC430.f03t04   " class="Extern">adfm.201701176</a></strong></p>
    Science Highlight
    17.05.2017
    Better cathode materials for Lithium-Sulphur-Batteries
    A team at the Helmholtz-Zentrum Berlin (HZB) has for the first time fabricated a nanomaterial made from nanoparticles of a titanium oxide compound (Ti4O7) that is characterised by an extremely large surface area, and tested it as a cathode material in lithium-sulphur batteries. The highly porous nanomaterial possesses high storage capacity that remains nearly constant over many charging cycles. [...]
  • <p>Nanodiamonds have been modified by attaching different molecules. </p>
    Science Highlight
    26.04.2017
    Nanodiamonds as energy materials: tuning the functionalities
    An international team has shed light onto interactions between nanodiamonds and water molecules. Experiments at synchrotron sources showed how hydrogenated groups on nanodiamond surfaces change the network of hydrogen bonds in the aqueous environment and may potentially influence the catalytic properties of nanodiamonds, for instance for the production of solar fuels from CO2 and light. [...]
  • <p>The experimental data show, how a light pulse dissociates a hydrogen nucleus from the nitrogen atom without destroying important bonds within the molecule. </p>
    Science Highlight
    07.04.2017
    Proton transfer: Researcher find mecanism to protect biomolecules against light induced damage
    A team at the Helmholtz-Zentrum Berlin (HZB) together with researchers in Sweden and the USA has analysed a mecanism which protects biomolecules such as the DNA against damage by light. They observed how the energy of incoming photons can be absorbed by the molecule without destroying important bonds. The experiments took place at the Linac Coherent Light Source (LCLS) free-electron laser in California as well as the BESSY II synchrotron source at the HZB in Berlin, where with resonant inelastic X-ray-diffraction a very sensitive method is available. [...]
  • <p>Chromium enhances the current density which is directly related to catalytic activity. </p>
    Science Highlight
    23.03.2017
    Finding and understanding low cost catalysts: it all comes down to the iron
    A team has investigated more than one hundred iron-nickel catalysts containing various admixtures of chromium. At BESSY II, they also analysed the configurations of the electrons in the individual elements. The team showed that an increasing proportion of chromium primarily influences the energy levels of the iron electrons, which are important for the catalytic effect. The results of this high-throughput study will assist the knowledge-based search for better specific catalysts. [...]
  • <p>Nanostructures trap the light, shows this illustration on the cover in  Advanced Optical Materials. </p>
    Science Highlight
    14.03.2017
    How to increase efficiencies of ultrathin CIGSe solar cells
    Nanoparticles at the back help harvesting the light. [...]
  • <p>Robert Seidel leads the Young Investigator Group Operando Interfacial Photochemistry. </p>
    Science Highlight
    09.03.2017
    Highly sensitive method for detecting ion pairs in aqueous solution developed

    Scientists of the Helmholtz-Zentrum Berlin, Freie Universität Berlin, Universität Heidelberg, and the University of Chemistry and Technology Prague have empirically detected a very specialised type of electron transfer in an aqueous salt solution, one which had only been predicted theoretically up to now. Based on these results, they now expect to have an extremely sensitive method for detecting ion pairs in solutions.

    [...]

  • <p>PFIA-molecules self-orient with their hydrophobic backbones outside (black lines) and their hydrophilic side-chains inside, in order to form nanometer sized water channels. Each side-chain possesses two docking points (red and yellow circles) for hydrogen ions (H+).  These are acidic groups, shown in the magnifying glass. </p>
    Science Highlight
    19.12.2016
    Fuel cells with PFIA-membranes:
  • <p>Diatomic nickel ions (gray) are captured at cryogenic temperatures in an RF ion trap; cold helium gas (blue) serves to dissipate the heat. The magnetic field orients the ions. </p>
<p> </p>
    Science Highlight
    28.11.2016
    A new record at BESSY II: ten million ions in an ion trap cooled for the first time to 7.4 K
    Magnetic ground states spectroscopically ascertained
    [...]
  • <p>The x-ray reflectitivityof the Mo/Si multilayer mirror is changed via a time delayed laserpulse. </p>
    Science Highlight
    14.11.2016
    Methods at BESSY II: Versatile cross-correlator for ultrafast X-ray experiments
    Particularly in the soft X-ray range experimentalists are lacking a broadband method to correlate ultrashort X-ray and laser pulses in space and time. Only recently, a team from Helmholtz-Zentrum Berlin and the University of Potsdam was able to achieve this by utilizing a standard molybdenum-silicon (Mo/Si) multilayer mirror at the FemtoSpeX facility at BESSY II. They use femtosecond laser pulses to modulate the multilayer period under the Bragg condition on a sub-picosecond up to nanosecond timescale which in turn strongly affects the mirror’s X-ray reflectivity. The presented Mo/Si cross-correlator works for the soft up to the hard X-ray regime as well as for a broad range of laser pump wavelengths (mid-IR to UV) and renders this technique as an easy to implement and versatile timing tool for various synchrotron- and lab-based pump-probe experiments. The results are published in the journal of "Structural Dynamics". [...]
  • <p>A pump pulse promotes the molecule's electrons to an excited state and with probe pulses the binding energy of the excited electrons can be measured. However, pump-probe laser experiments are only feasible under ultra-high vacuum.</p>
    Science Highlight
    19.10.2016
    Methodology advance at HZB: ionic liquids simplify laser experiments on liquid samples
    An HZB team has developed a new approach to conduct photoemission spectroscopy of molecules in solution. This has been difficult up to now because the sample needed to be situated in vacuum – but liquids evaporate. The work has now demonstrated it is feasible to replace the solvent with an ionic liquid of low vapor pressure, which does not perturb the sample characteristics.  This allows the molecules to be excited with a laser pulse and to record the behaviour of the excited energy states. It provides insight into the physical and chemical processes of novel liquid energy materials that might be employed in organic solar cells or catalysts, for instance. [...]
  • <p>X-PEEM images show the orientation of magnetic domains in the permalloy film overlaid on the superconducting dot (dashed square) before (left image) and after the write process (right image). In this sample the domains (arrows, right image) are reorientied in a monopole pattern. </p>
    Science Highlight
    10.10.2016
    Future Information Technologies: New combinations of materials for producing magnetic monopoles
    An international collaboration at BESSY II has discovered a new method to inscribe exotic magnetic patterns such as magnetic monopoles into thin ferromagnetic films. Such unconventional orientation of magnetic domains might open a new path for the design of energy efficient data storage. The new materials system consists of regular arrays of superconducting YBaCuO-dots covered with an extremely thin permalloy film. A shortly applied external magnetic field leads to the creation of supercurrents within the superconducting dots. These currents produce a complex magnetic field pattern, which is inscribed into the permalloy film above. The results are published in Advanced Science. [...]
  • <p>SEM &ndash; model of a metallic nano-network with periodic arrangement ( left) and visual representation of a fractal pattern (right). </p>
    Science Highlight
    27.09.2016
    Nanotechnology for energy materials: Electrodes like leaf veins
    Nano-sized metallic wires are attracting increasing attention as conductive elements for manufacturing transparent electrodes, which are employed in solar cells and touch screen panels. In addition to high electric conductivity, excellent optical transmittance is one of the important parameters for an electrode in photovoltaic applications. An international team headed by HZB scientist Prof. Michael Giersig has recently demonstrated for these applications that networks of metallic mesh possessing fractal-like nano-features surpass other metallic networks in utility. These findings have now been published in the most recent edition of the renowned journal Nature Communications. [...]
  • <p>The newly developed expert system was used to analyse 364 data sets of a specidfic protein crystal, soaked in different fragments.  </p>
    Science Highlight
    26.09.2016
    Advancing methodology at BESSY II: Automated evaluation speeds up the search for new active substance
    The macromolecular crystallography (MX) beamlines at the BESSY II X-ray source are specially designed to highly automated structural analyses of protein crystals. With up to now more than 2000 solved structures of protein molecules, these beamlines are by far the most productive ones in Germany and are in vigorous demand by groups from either an academic and industrial research area. Now teams from HZB and Philipps-Universität Marburg in Germany have automated the evaluation of data records as well. The newly developed expert system identifies small molecule fragments bound to proteins in the raw X-ray diffraction data. These fragments represent suitable starting points for the development of an active substance. Using a series of 364 samples, the collaborating partners demonstrated that the expert system works reliably and can speed up the search for a suitable active agents. [...]
  • <p>Cover: WILEY-VCH&nbsp;</p>
    Science Highlight
    15.09.2016
    Manual of characterisation techniques for thin-film solar cells published with the involvement of HZB researchers
    In August 2016, the second, enlarged edition of the reference book "Advanced Characterization Techniques for Thin-Film Solar Cells" appeared from renowned publisher WILEY-VCH. Co-editor is HZB researcher Dr. Daniel Abou-Ras. A total of eleven authors from HZB wrote chapters for this reference. It provides a comprehensive overview of many characterisation and modelling techniques that can be employed for solar cell materials and components. [...]
  • <p>A section from the crystal lattice of Calcium-chromium oxide showing how the spins are subject to conflicting demands. In this ball-and-stick model, the green and red sticks connecting the atoms (grey and black balls) represent ferromagnetic interactions while the blue sticks represent anti-ferromagnetic interactions. </p>
    Science Highlight
    25.07.2016
    Novel state of matter: Observation of a quantum spin liquid
    A novel and rare state of matter known as a quantum spin liquid has been empirically demonstrated in a monocrystal of the compound calcium-chromium oxide by team at HZB. What is remarkable about this discovery is that according to conventional understanding, a quantum spin liquid should not be possible in this material. A theoretical explanation for these observations has now also been developed. This work deepens our knowledge of condensed matter and might also be important for future developments in quantum information. The results have just been published in Nature Physics. [...]
  • <p>BFO has a perovskite crystal structure.</p>
    Science Highlight
    22.06.2016
    New effect on laser induced switching for higher data densities
    An international collaboration has now demonstrated a completely new approach to increase data density in storage media. They used ultra-short laser pulses to trigger a phase transition in the ferromagnetic material BaFeO3 (BFO). Experiments at the Femtospex facility at BESSY II of Helmholtz-Zentrum Berlin showed that by inducing this phase transition, magnetic domains can be easily manipulated. These magnetic domains are otherwise very stable and therefore suited for long-time data storage. The results have been published in Phys. Rev. Letters now. [...]
  • <p>The illustration shows how iodine (purple) is embedded between the organic layer and the metal, thus reducing adhesion. </p>
    Science Highlight
    22.06.2016
    User Community Science: Soft decoupling of organic molecules on metal
    An international team has discovered an elegant way to decouple organic nanosheets grown on metal surfaces. After iodine intercalation, measurements at the synchrotron source BESSY II of Helmholtz-Zentrum Berlin (HZB) showed that a network of organic molecules behaved almost as it was free-standing. The strong influence of the metal on the network was reduced. This opens up new ways to transfer organic nanostructures from metal surfaces onto more suitable substrates for molecular electronics.  The results have been published in “Angewandte Chemie”. [...]
  • <p>The model illustrates how the gold atoms sit under the graphene. <br /><br /></p>
    Science Highlight
    16.06.2016
    Progress in the application of spin effects in graphene: from the metal to the semiconductor world
    Graphene on silicon carbide could be an interesting candidate for future spintronik components. Squeezing gold atoms between the semiconducting substrate and graphene does enhance spin-orbit interaction at hot spots and shows ways to controll the spins. First results at BESSY II are now published in Applied Physics Letters. [...]
  • <p>The nanostructured membrane has a honeycomb pattern with nanoholes of 68 nm in diameter. The nanoholes pin down the magnetic domains.</p>
    Science Highlight
    14.06.2016
    Spintronics: Resetting the future of Heat Assisted Magnetic Recording
    A HZB team has examined thin films of Dysprosium-Cobalt sputtered onto a nanostructured membrane at BESSY II. They showed that new patterns of magnetization could be written in a quick and easy manner after warming the sample to only 80 °Celsius, which is a much lower temperature as compared to conventional Heat Assisted Magnetic Recording systems. This paves the way to fast and energy efficient ultrahigh density data storage. The results are published now in the new journal Physical Review Applied. [...]
  • <p><span>Dentin's biological structure: tubules and mineral nanoparticles embedded in a network of collagen fibers. Image</span>: Jean-Baptiste Forien, &copy; <span>Charit&eacute;</span> &ndash; Universit&auml;tsmedizin Berlin</p>
    Science Highlight
    02.06.2016
    User research at BESSY II: nanostructures in human teeth

    Dentin is one of the most durable biological materials in the human body. Researchers from Charité–Universitätsmedizin Berlin were able to show that the reason for this can be traced to its nanostructures and specifically to the interactions between the organic and inorganic components. Measurements performed at BESSYII, the Helmholtz-Zentrum Berlin's synchrotron radiation source, showed that it is the mechanical coupling between the collagen protein fibers and mineral nanoparticles which renders dentin capable of withstanding extreme forces. Results from this research have been recently published in the journal Chemistry of Materials. [...]
  • <p>Combining the results from radiative and non-radiative relaxation processes enabled a complete picture of the filled and unfilled energy levels to be obtained. </p>
    Science Highlight
    11.05.2016
    Ferrous chemistry in aqueous solution unravelled
    An HZB team has combined two different analytical methods at the BESSY II synchrotron source in order to extract more information about the chemistry of transition-metal compounds in solution. These kinds of compounds can act as catalysts to promote desirable reactions in energy materials, but their behaviour has not been completely understood thus far.  The team demonstrated how a detailed picture of the electronic states can be ascertained by systematically comparing all of the interactive electronic processes in a simple system of aqueous iron(II).  The results have now been published in Scientific Reports, the open access journal from Nature Group publishing. [...]
  • <p>The illustration depicts the characteristic spin orientation (arrows) of electrons in a topological insulator (below). Using an initial circular polarised laser pulse, the spins are excited and point up or down. This can be proven by a second linearly polarised laser pulse (above).</p>
    Science Highlight
    29.04.2016
    Spintronics for future information technologies: spin currents in topological insulators controlled
    An international team headed by HZB researcher Jaime Sánchez-Barriga has shown how spin-polarised currents can be initiated in a controlled manner within samples of topological insulator material. In addition, they were able to manipulate the orientation of the spins of these currents. They thereby demonstrated that this class of materials is suitable for data processing based on spin. The work has been published in the renowned periodical Physical Review B and was selected as “Editor’s Suggestion” article. [...]
  • <p>The data (photon energies over time) show defects (lower signal) which disappear after 120 minutes. This happens at the transition from the copper-poor phase to the copper-rich one.</p>
    Science Highlight
    21.04.2016
    Thin-film solar cells: how defects appear and disappear in CIGSe-cells
    Concentration of copper plays a crucial role

    An international collaboration of German, Israeli, and British teams has investigated the deposition of thin chalcopyrite layers. They were able to observe specific defects as these formed during deposition and under what conditions they self-healed using the BESSY II X-ray source at the Helmholtz Zentrum Berlin. The results of their research provide clues to optimising fabrication processes and have now been published in Energy & Environmental Science. [...]

  • <p>Illustration of the initial charge transfer step in a dye sensitized solar cell. A photon from the sun is absorbed and excites the dye molecule. Subsequently, an electron can is injected into the ZnO-Layer where it can be trapped by so called interface-states. </p>
    Science Highlight
    13.04.2016
    Riddle of missing efficiency in zinc oxide-based dye-sensitised solar cells solved.
    To convert solar energy into electricity or solar fuels, you need specialised systems of materials such as those consisting of organic and inorganic thin films. Processes at the junction of these films play a decisive role in converting the solar energy. Now a team at HZB headed by Prof. Emad Aziz has used ultra-short laser pulses and observed for the first time directly how boundary states form between the organic dye molecules and a zinc-oxide semiconductor layer, temporarily trapping the charge carriers. This explains why zinc-oxide (ZnO) dye-sensitised solar cells have not yet met expectations. The results evolved from collaboration between Monash University (Australia) and Joint Lab partners Helmholtz Zentrum Berlin (HZB) and the Freie Universität Berlin (FU Berlin). They have now been published online by Nature in the open access magazine Scientific Reports. [...]
  • <p>The three-dimensional structural network of the ultra-porous and flexible material called DUT-49 can store large amounts of methane. &copy; TU Dresden, Prof. AC1</p>
    Science Highlight
    08.04.2016
    Energy storage materials under pressure
    Surprising discovery at BESSY II: the adsorption capacity of MOFs does not rise automatically with increasing pressure [...]
  • <p>The illustration shows the structure of the sample: n-doped silicon layer (black), a thin silicon oxide layer (gray), an intermediate layer (yellow) and finally the protective layer (brown) to which the catalysing particles are applied. The acidic water is shown in green. </p>
    Science Highlight
    21.03.2016
    Solar fuels:a refined protective layer for the “artificial leaf”
    A team at the HZB Institute for Solar Fuels has developed a process for providing sensitive semiconductors for solar water splitting (“artificial leaves”) with an organic, transparent protective layer. The extremely thin protective layer made of carbon chains is stable, conductive, and covered with catalysing nanoparticles of metal oxides. These accelerate the splitting of water when irradiated by light. The team was able to produce a hybrid silicon-based photoanode structure that evolves oxygen at current densities above 15 mA/cm2. The results have now been published in Advanced Energy Materials.

    [...]

  • <p>The team could observe for the first time with RIXS how the formation of hydrogen bonds does change C=O bonds in aceton molecules. </p>
    Science Highlight
    16.03.2016
    Measuring chemistry: local fingerprint of hydrogen bonding captured in experiments
    A team from Helmholtz-Zentrum Berlin has been able for the first time to measure how new bonds influence molecules: they have reconstructed the “energy landscape” of acetone molecules using measurement data from the Swiss Light Source (SLS) of the Paul Scherrer Institut, and thereby empirically established the formation of hydrogen bonds between acetone and chloroform molecules. The results have been published in Nature Scientific Reports and assist in understanding fundamental phenomena of chemistry. [...]
  • <p>In pure bismuth-selenide (left) no bandgap is found. With the addition of magnetic manganese (4%; 8%), a band gap (dashed line) arises, and electrical conductivity disappears. This effect shows even at room temperature and contrary to expectation, has nothing to do with the magnetism of the manganese,  which shows up only below 10 K (minus 263 Celsius). </p>
    Science Highlight
    19.02.2016
    Topological insulators: Magnetism is not causing loss of conductivity
    If topological insulators are doped with impurities that possess magnetic properties, they lose their conductivity. Yet contrary to what has been assumed thus far, it is not the magnetism that leads to this. This has been shown by recent experiments with BESSY II at HZB. The results are now published in Nature Communications. Understanding these effects is crucial for applications of topological insulators in information technology. [...]
  • <p>Sketch of the structure of both metal oxide layers. Interesting new properties can arise at the interface. </p>
    Science Highlight
    04.02.2016
    Metal Oxide Sandwiches: New option to manipulate properties of interfaces
    A Franco-German cooperation has investigated a sandwich system of transition metal oxides at BESSY II. The scientists discovered a new option to control properties of the interface between the two layers, for instance the amount of charge transferred from one layer to the other or the emergence of ferromagnetism.  Their insights might help to create new properties at the interface, not present in the primary materials, maybe even novel forms of High Tc superconductivity. [...]
  • <p>Nano-island of graphene in which iron-nitrogen complexes are embedded. The FeN<sub>4</sub> complexes (shown in orange) are catalytically active. </p>
    Science Highlight
    27.01.2016
    An alternative to platinum: iron-nitrogen compounds as catalysts in graphene
    Teams at HZB and TU Darmstadt have produced a cost-effective catalyst material for fuel cells using a new preparation process which they analysed in detail. It consists of iron-nitrogen complexes embedded in tiny islands of graphene only a few nanometres in diameter. It is only the FeN4 centres that provide the excellent catalytic efficiency – approaching that of platinum. The results are interesting for solar fuels research as well and have been published in the Journal of the American Chemical Society. [...]
  • <p>Flexible CIGS module. Photo </p>
    Science Highlight
    26.01.2016
    The solar technologies race: thin-film photovoltaics are catching up
    ZSW and HZB present current data – with new    opportunities for Europe’s solar industry [...]
  • <p>Vertical cut through a quadrupole magnet: Black: Field distribution at a fixed vertical distance to the midplane. Magenta: Electron trajectories for various initial coordinates. </p>
    Science Highlight
    20.01.2016
    A Fast Way of Electron Orbit Simulation in Complex Magnetic Fields
    The design  of  advanced synchrotron radiation sources requires precise  algorithms  for the  simulation of electron trajectories in  complex magnetic fields. However, multi-parameter studies can  be very time consuming. Now, a team of the HZB has developed a new algorithm which significantly reduces the computation time.  This approach is now published in the renowned journal “Physical Review Special Topics Accelerator & Beams”. [...]
  • <p>Sketch of the tandem cell. </p>
    Science Highlight
    07.01.2016
    Optimum band gap for hybrid silicon/perovskite tandem solar cell
    Tandem solar cells based on silicon and perovskites have raised high hopes for future high efficiency solar modules.  A team led by perovskite solar cell pioneer Henry Snaith at the University of Oxford has now shown, with contributions by Bernd Rech and Lars Korte of the Helmholtz-Zentrum Berlin, that an ultimate efficiency of 30% should be attainable with such tandem cells. They discovered a structurally stable perovskite composition with its band gap tuned to an optimum value of 1.75 eV. The results have been published in "Science". [...]
  • <p>Composite Raman intensity-distribution map on a polycrystalline CuInSe<sub>2</sub> thin film.</p>
    Science Highlight
    18.12.2015
    Alternative method for the representation of microstructures in polycrystalline materials
    Also Raman microspectroscopy in an optical microscope provides the means to determine local crystal orientations of polycrystalline materials over large sample areas. This method can be used alternatively to electron backscatter diffraction in a scanning electron microscope. It was shown by a team from Helmholtz-Zentrum Berlin and the Federal Institute for Materials Research and Testing (BAM) that both characterization techniques result in similar orientation distribution maps on areas of several hundreds of square micrometers. [...]
  • <p>x-ray diffraction on pure 4T, colored for chrismas reasons. </p>
    Science Highlight
    14.12.2015
    Doped organic semiconductors explored
    Organic semiconductor materials are already being employed today in solar cells and organic LEDs (OLEDs) amongst others. Until now, however, little was known about how the doping molecules are integrated into the chemical structure of organic semiconductors. The Molecular Systems Joint Research Team of the Helmholtz-Zentrum Berlin and Humboldt-Universität zu Berlin at BESSY II have now analysed this with surprising results. The molecules are not necessarily uniformly dispersed in the host lattice, as it is usual with inorganic semiconductors, but instead form what are known as co-crystallites. The doped organic semiconductor consists of a matrix of undoped crystallites in which such “mixed crystallites” are embedded. It is this very species that takes over the role as the actually doping molecule. The results were published in Nature Communications.
    [...]
  • <p>Nanostructures of silicon shown in scanning electron microscope image. The diameter of the nanocolumns is 570 nm. By comparison, the nanocones taper from their upper diameter of 940 nm down to 360 nm at their base. </p>
    Science Highlight
    26.11.2015
    Whispering gallery modes in Silicon nanocones intensify luminescence
    Silicon, a semiconducting material, reveals new talents when reduced to nanoscopic dimensions. A joint team at the HZB Institute of Nanoarchitectures for Energy Conversion and the Max Planck Institute for the Science of Light (MPL) has demonstrated this. Silicon nanocones generate 200 times as much infrared luminescence as comparably sized nanocolumns when excited by visible light. Modelling and experimental results show that due to their geometry, cones are able to sustain what is referred to as whispering gallery modes at infrared wavelengths which can intensify the silicon luminescence. New applications are conceivable, including silicon-based nanolasers. [...]
  • <p>A cross section through the tandem cell is shown by this SEM-image. </p>
    Science Highlight
    28.10.2015
    Monolithic perovskite/silicon tandem solar cell achieves record efficiency
    Teams from the Helmholtz-Zentrum Berlin and École Polytechnique Fédérale de Lausanne, Switzerland, have been the first to successfully combine a silicon heterojunction solar cell with a perovskite solar cell monolithically into a tandem device. The hybrid tandem cell showed an efficiency of 18 per cent. That is the highest currently reported value for this type of device architecture. There are even prospects for the efficiency to reach as much as 30 per cent. [...]
  • <p>The SiO<sub>2</sub> nanoparticles (black) have been imprinted directly on the Molybdenum substrate (purple) which corresponds to the back contact of the solar cell. On top of this structured substrate the ultrathin CIGSe layer (red) was grown at HZB, and subsequently all the other layers and contacts needed for the solar cell. Since all layers are extremely thin, even the top layer is showing deformations according to the pattern of the nanoparticles.  </p>
    Science Highlight
    15.10.2015
    Scientists demonstrate how to improve ultrathin CIGSe solar cells by nanoparticles
    CIGSe solar cells  are made of a thin chalcopyrite layer consisting of Copper, Indium, Gallium and Selenium and can reach high efficiencies. Since Indium is becoming scarce and expensive, it is interesting to reduce the active CIGSe layer, which however decreases the efficiency quite strongly.  Now, scientists at Helmholtz-Zentrum Berlin have produced high quality ultrathin CIGSe layers and increased their efficiency by an array of tiny nanoparticles between the back contact and the active layer. [...]
  • <p>The perovskite film (black, 200-300 nm) is covered by Spiro.OMeTAD, Graphene with gold contact at one edge, a glass substrate and an amorphous/crystalline silicon solar cell. </p>
    Science Highlight
    02.10.2015
    Graphene as a front contact for silicon-perovskite tandem solar cells
    HZB team develops elegant process for coating fragile perovskite layers with graphene for the first time. Subsequent measurements show that the graphene layer is an ideal front contact in several respects. [...]
  • <p>New efficiency record: This small device is able to convert 14 percent of the incoming solar energy into hydrogen. </p>
    Science Highlight
    15.09.2015
    Hydrogen from sunlight: new efficiency record for artificial photosynthesis
    An international team has now succeeded in considerably increasing the efficiency for direct solar water splitting. They are using a tandem solar cell whose surfaces have been selectively modified. The new record value is 14 % and thus considerably above the previous record of 12.4 % held by the National Renewable Energy Laboratory (NREL) in the USA, broken now for the first time in 17 years. Researchers from the Institute for Solar Fuels at the Helmholtz-Zentrum Berlin, TU Ilmenau, the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg and the California Institute of Technology (Caltech) participated in the collaboration. The results have been published in Nature Communications. [...]
  • <p>Sara J&auml;ckle has demonstrated the formation of a pn-heterojunction at the interface between an organic contact and n-doped silicon. Photo</p>
    Science Highlight
    17.08.2015
    Charge transport in hybrid silicon solar cells
    An HZB team headed by Prof. Silke Christiansen has made a surprising discovery about hybrid organic/inorganic solar cells. Contrary to expectations, a diode composed of the conductive organic PEDOT:PSS and an n-type silicon absorber material behaves more like a pn junction between two semiconductors than like a metal-semiconductor contact (Schottky diode). Their results have now been published in the Nature journal Scientific Reports and could point the way toward improvements in hybrid solar cells. [...]
  • <p>Manuela G&ouml;belt is evaluating SEM-images to calculate the local degree of networking. Photo: Bj&ouml;rn Hoffmann.</p>
    Science Highlight
    31.07.2015
    Transparent, electrically conductive network of encapsulated silver nanowires – a novel electrode for optoelectronics
    A team headed by Prof. Silke Christiansen has developed a transparent electrode with high electrical conductivity for solar cells and other optoelectronic components – that uses minimal amounts of material. It consists of a random network of silver nanowires that is coated with aluminium-doped zinc oxide. The novel electrode requires about 70 times less silver than conventional silver grid electrodes, but possesses comparable electrical conductivity. [...]
  • <p>The hedgehog-configuration of the spins and the Fermi-Level is shown. Illustration Thomas Splettst&ouml;&szlig;er/HZB</p>
    Science Highlight
    27.07.2015
    Spins in Graphene with a Hedgehog Texture
    HZB researchers demonstrate a fundamental property of the electron spin in graphene [...]
  • <p>X-ray spectroscopies have shown a higher chlorine concentration near the perovskite/TiO<sub>2</sub> interface than throughout the rest of the perovskite film. </p>
    Science Highlight
    10.07.2015
    Depletion and enrichment of chlorine in perovskites observed
    X-ray spectroscopy at BESSY II reveals inhomogenous distribution of chlorine in a special class of perovskite materials. The discovery could help to enhance efficiencies of perovskite thin film solar cells by controlled processing to optimize the chlorine distribution. [...]
  • <p>Hexagonal single crystal of SrCo<sub>6</sub>O<sub>11</sub>, with a sample diameter of approximately 0,2 millimetres.</p>
    Science Highlight
    01.07.2015
    Emergence of a “devil’s staircase” in a spin-valve system
    A Japanese-German team observes at BESSY II how spins form unusual magnetic structures in a complex cobalt oxide single crystal. Such a material offers new perspectives for spintronic applications. [...]
  • <p>The illustration shows how maleimide compounds bind to the graphene surface. The graphene monolayer lies on a thin film of silicon nitride (red) that in turn is on a quartz microbalance (blue) and can be subjected to a potential via a gold contact (yellow).<br /><br />Illustration: Marc Gluba/HZB</p>
    Science Highlight
    24.06.2015
    Towards graphene biosensors
    For the first time, a team of scientists has succeeded in precisely measuring and controlling the thickness of an organic compound that has been bound to a graphene layer. This might enable graphene to be used as a sensitive detector for biological molecules in the future. [...]
  • <p>Illustration of the complex biostructure of dentin: the dental tubuli (yellow hollow cylinders, diameters appr. 1 micrometer) are surrounded by layers of mineralized collagen fibers (brown rods). The tiny mineral nanoparticles are embedded in the mesh of collagen fibers and not visible here. </p>
    Science Highlight
    10.06.2015
    Strong teeth: Nanostructures under stress make teeth crack resistant
    Human teeth have to serve for a lifetime, despite being subjected to huge forces. But the high failure resistance of dentin in teeth is not fully understood. An interdisciplinary team led by scientists of Charité – Universitätsmedizin Berlin has now analyzed the complex structure of dentin. At the synchrotron sources BESSY II at HZB, Berlin, Germany, and the European Synchrotron Radiation Facility ESRF, Grenoble, France, they could reveal that the mineral particles are precompressed. The internal stress works against crack propagation and increases resistance of the biostructure. [...]
  • <p>To obtain the 3D structure of the battery electrode on a micormeter scale, snchrotron tomography at BESSY II was used. </p>
    Science Highlight
    02.06.2015
    Realistic computer model of battery electrodes
    A research team has developed a new approach for more realistic computer models of battery electrodes. They combined images from synchrotron tomography that capture three-dimensional structure at micron resolution with those from an electron microscope that can even resolve nanometre-scale features over a small section. They were able to transfer these nano-features to areas beyond the section using a mathematical model. Properties and processes within battery electrodes can now be simulated highly realistically using this method. [...]
  • <p>A thin magnetic FeRh film is grown onto a ferroelastic BTO substrate with two different crystal domains a and c. At 0 Volt ferromagnetic domains (red-blue pattern) are observed above BTO a-domains, whereas above c-domains the net magnetization is zero. At 50 Volt all BTO domains are converted into c-domains, which switches off ferromagnetic domains in FeRh. </p>
    Science Highlight
    18.05.2015
    New options for spintronic devices: Switching between 1 and 0 with low voltage
    Scientists from Paris and Helmholtz-Zentrum Berlin have been able to switch ferromagnetic domains on and off with low voltage in a structure made of two different ferroic materials. The switching works slightly above room temperature. Their results, which are published online in  Scientific Reports, might inspire future applications in low-power spintronics, for instance for fast and efficient data storage. [...]
  • <p>A <a href="https://www.youtube.com/watch?v=gzrDtZkCwqc" class="Extern">short filmclip</a> demonstrates the production of the photocathode with ILGAR method.</p>
    Science Highlight
    13.05.2015
    Artificial photosynthesis: New, stable photocathode with great potential
    A team at the HZB Institute for Solar Fuels has developed a new composite photocathode for generating hydrogen with high quantum efficiency using sunlight. This enables solar energy to be stored chemically.The photocathode consists of a thin film of chalcopyrite produced by HZB/PVcomB coated with a newly developed thin film of photoresistant titanium dioxide containing platinum nanoparticles. This layer does not only protect the chalcopyrite thin film from corrosion, it additionally acts as a catalyst to speed-up the formation of hydrogen as well as being a novel photodiode itself that even shows photoelectric current density and voltage comparable to those of a chalcopyrite-based thin film solar cell. [...]
  • <p>Illustration of the working principle of inkjet printing. </p>
    Science Highlight
    06.05.2015
    Inkjet printing process for Kesterite solar cells
    A research team at HZB has developed an inkjet printing technology to produce kesterite thin film absorbers (CZTSSe). Based on the inkjet-printed absorbers, solar cells with total area conversion efficiency of up to 6.4 % have been achieved. Although this is lower than the efficiency records for this material class, the inkjet printing minimizes waste and has huge advantages for industrial production. [...]
  • <p></p>
<p class="MsoNormal"><span></span><span>The neutron images (left row) detect the distribution of liquids in this filled tooth, whereas the X-ray-CT shows the microstructure and pores in the material. A comparision of both images allows to see which pores are filled with liquids. </span></p>
    Science Highlight
    13.03.2015
    Neutrons and X-rays show how to prepare durable tooth cement
    There are many ways to mix cements for tooth fillings, but it can be difficult to tell which way works best. Now, a team of scientists from Copenhagen, Denmark, has come up with an answer: They used neutron imaging and x-ray-microtomography at HZB to analyze fillings with glass ionomere cements, prepared by different methods. Their results, now published in  Scientific Reports, demonstrate how much the order of mixing steps matters to obtain a nearly homogenous filling without large liquid-filled pores which reduce stability. [...]
  • <p></p>
<p>The scanning electron microscopies (SEM) show how regularly the funnels etched in a silicon substrate are arranged (left: the line segment = 5 microns; right: 1 micron). The funnels measure about 800 nanometres in diameter above and run down to about a hundred nanometres at the tip. </p>
    Science Highlight
    24.02.2015
    Learning by eye: silicon micro-funnels increase the efficiency of solar cells
    A biological structure in mammalian eyes has inspired a team headed by Silke Christiansen to design an inorganic counterpart for use in solar cells. With the help of conventional semiconductor processes, they etched micron-sized vertical funnels shoulder-to-shoulder in a silicon substrate. Using mathematical models and experiments, they tested how these kind of funnel arrays collect incident light and conduct it to the active layer of a silicon solar cell. Their result: this arrangement of funnels increases photo absorption by about 65% in a thin-film solar cell fitted with such an array and is reflected in considerably increased solar cell efficiency, among other improved parameters. [...]
  • <p>Dichromium: both chromium atoms "share" the  12 valence electrons which leads to a multible bond. </p>
    Science Highlight
    23.02.2015
    Stretch and relax! – Losing one electron switches magnetism on in dichromium
    An international team of scientists from Berlin, Freiburg and Fukuoka has provided the first direct experimental insight into the secret quantum life of dichromium. Whereas in its normal state the 12 valence electrons form a strong multiple bond between the two chromium atoms, removing only one electron changes the situation dramatically: 10 electrons localize and align their spins, thus resulting in ferromagnetic behavior of the dichromium-kation. The bonding is done by one electron only, resulting in a much weaker bond. The scientists used the unique Nanocluster Trap experimental station at the BESSY II synchrotron radiation source at Helmholtz-Zentrum Berlin and published their results in the Journal Angewandte Chemie. [...]
  • <p>The insulating LFO-layer in its normal state is antiferromagnetically ordered (AFM) and has no ferromagnetic domains. Due to the proximity to the ferromagnetic LSMO, ferromagnetic domains develop (white arrows) at the interface, pointing into the opposite direction of the LSMO-layer.</p>
<p></p>
    Science Highlight
    17.02.2015
    Insight into inner magnetic layers
    Measurements at BESSY II have shown how spin filters forming within magnetic sandwiches influence tunnel magnetoresistance – results that can help in designing spintronic components. [...]
  • <p>This illustrates a moment captured for the first time in experiments at SLAC National Accelerator Laboratory. The CO-molecule and oxygen-atoms are attached to the surface of a ruthenium catalyst. When hit with an optical laser pulse, the reactants vibrate and bump into each other and the carbon atom forms a transitional bond with the lone oxygen center. The resulting CO<sub>2</sub> detaches and floats away. </p>
    Science Highlight
    12.02.2015
    Details of a crucial reaction: Physicists uncover oxidation process of carbon monoxide on a ruthenium surface
    An international team has observed the elusive intermediates that form when carbon monoxide is oxidized on a hot ruthenium metal surface. They used ultrafast X-ray and optical laser pulses at the SLAC National Accelerator Laboratory, Menlo Park, California. The reaction between carbon monoxide and adsorbed oxygen atoms was initiated by heating the ruthenium surface with optical laser pulses. Directly afterwards, changes in the electronic structure of oxygen atoms were probed via X-ray absorption spectroscopy as they formed bonds with the carbon atoms.The observed transition states are consistent with density functional theory and quantum oscillator models. [...]
  • <p>F&uuml;r das Titelbild hat Teamleiter Peter Smeibidl seine Leute zum Klettern motiviert; die Ingenieure haben darin viel &Uuml;bung, denn beim Aufbau der gewaltigen Struktur m&uuml;ssen sie ohnehin &uuml;berall ran. Foto: Ingo Kniest/HZB</p>
    Science Highlight
    12.02.2015
    Forschungsmagazin „Sichtbar“: Große Forschung, interessante Leute, neue Perspektiven
    Auf dem Titelbild prangt ein echter Star: Der neue Hochfeldmagnet, umgeben und beklettert von den Physikerinnen und Experten, die in den letzten sieben Jahren am Aufbau dieses weltweit einzigartigen Großgeräts mitgearbeitet haben. Auch im Heft finden Sie Bilder und Geschichten aus der HZB-Forschung, die wir manchmal auch aus einer anderen Perspektive erzählen als sonst. [...]
  • <p>The local magnetisation is depicted by small arrows; a magnetic vortex is located in the centre. A brief current pulse through this nano-wire deflects the skyrmion  out of its rest position; it then moves back to its initial position on a spiral trajectory. This motion can be observed with the help of X-ray holography. The skyrmion and the spiral shape of its trajectory are represented schematically above the structure. </p>
    Science Highlight
    02.02.2015
    Spintronics: Dance of the nanovortices
    The trajectories of small magnetic entities referred to as skyrmions have been captured and recorded with the help of X-ray holography. Researchers gained new insight from the analysis of this motion: these nanoscale vortices possess mass. The discovery is published in Nature Physics 2 February 2015. [...]
  • <p>Nanodiamonds are tiny crystals only a few nanometres in size. Mohamed Sennour, MINES ParisTech.</p>
    Science Highlight
    28.01.2015
    Holes in valence bands of nanodiamonds discovered
    Researchers hope that their properties might be altered to permit nanodiamonds to be used as catalysts for generating hydrogen from sunlight [...]
  • <p>All about Kesterite-Solarcells, just published. </p>
    Science Highlight
    23.01.2015
    Just published: New book on CZTS-based thin film solar cells published
    In time at the start of the new year the book "Copper Zinc Tin Sulfide-based Thin Film Solar Cells" was published (Wiley, 2015, ed. by K. Ito), in which also scientists from the HZB are involved. Thomas Unold, Justus Just and Hans-Werner Schock provided the chapter "Coevaporation of CZTS Films and Solar Cells", Susan Schorr has contributed the chapter "Crystallographic Aspects of CZTS". [...]
  • <p>Hard disc from space: the Pallasite meteorite, studied by Harrison, contains information about the early solar system.<br /><em></em></p>
    Science Highlight
    22.01.2015
    Messages From Space
    Geologists from the University of Cambridge uncover hidden magnetic messages from the early solar system in meteorites measured at BESSY II. The team of scientists led by Dr. Richard Harrison has captured information stored inside tiny magnetic regions in meteorite samples using the PEEM-Beamline at BESSY II. [...]
  • <p>Artificial catalysts imitate natural photo-synthesis.<br />Image </p>
    Science Highlight
    21.01.2015
    The path to artificial photosynthesis
    HZB researchers describe efficient manganese catalyst capable of converting light to chemical energy [...]
  • <p><span class="imageCaption">Researchers at PSI spotted a curious black-and-white magnetic substructure on a five-by-five micrometre square &ndash; and were reminded of the stylised Batman logo. The black areas reveal where the magnetisation is pointing downwards, i.e. into the picture; the white ones where it is pointing upwards. <br /></span></p>
    Science Highlight
    12.01.2015
    Batman lights the way to compact data storage
    Researchers at the Paul Scherrer Institute (PSI) have succeeded in switching tiny, magnetic structures using laser light and tracking the change over time. In the process, a nanometre-sized area bizarrely reminiscent of the Batman logo appeared. The research results could render data storage on hard drives faster, more compact and more efficient. [...]
  • <p>The a-Si:H is deposited on a AZO-film that acts as a transparent front contact. A ITO-layer serves as rear contact. The organic sub-cell possesses a front contact made of a conductive polymer material (PEDOT) and a metallic rear contact.</p>
    Science Highlight
    12.01.2015
    Maximum efficiency, minimum materials and complexity
    Silicon-based thin-film solar cell with a supplementary organic layer can utilise infrared light as well [...]
  • <p>HZB-scientists Karsten Holldack, Alexander Schnegg and Joscha Nehrkorn at the BESSY II Beamline.</p>
    Science Highlight
    06.01.2015
    New light shed on electron spin flips
    Researchers from Berlin Joint EPR Lab at Helmholtz-Zentrum Berlin (HZB) and University of Washington (UW) derived a new set of equations that allows for calculating electron paramagnetic resonance (EPR) transition probabilities with arbitrary alignment and polarization of the exciting electromagnetic radiation. The validity of the equations could be demonstrated with a newly designed THz-EPR experiment at HZB’s storage ring BESSY II. This progress is relevant for a broad community of EPR users and is published in Physical Review Letters on January 6. 2015 (DOI 10.1103/PhysRevLett.114.010801). [...]
  • <p>Crystal structures of HgBa<sub>2</sub>CuO<sub>4</sub>+ and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6</sub>+</p>
    Science Highlight
    22.12.2014
    Universality of charge order in cuprate superconductors
    Charge order has been established in another class of cuprate superconductors, highlighting the importance of the phenomenon as a general property of these high-Tc materials. [...]
  • <p>The new organic material is able to &ldquo;add up&rdquo; low-energy photons (red) to yield higher-energy light (blue), which can then be harvested by the solar cell. </p>
    Science Highlight
    27.11.2014
    Organic layer adds light particles
    Solar cells can only use photons with energies above a specific threshold to generate electricity. A German-Australian research collaboration has now combined solar cells with an organic material which can “add up” low-energy photons to yield higher-energy light, which can then be harvested by the solar cell. In an invited review paper published in the prestigious journal Energy & Environmental Science the scientists give an overview on the fascinating phenomenon of photonic upconversion and report new results: The organic layers show less photo-degradation than suspected and may also be used for other optoelectronics applications. [...]
  • <p>Both figures display experimental data on the &ldquo;Dirac cone".</p>
    Science Highlight
    14.11.2014
    Warping in topological insulators
    Topological insulators are promising to develop into a material for lossless electricity and information transport. Now, Jaime Sánchez-Barriga and colleagues from HZB investigated for the first time whether the direction of motion of electrons in topological insulators affects their behavior. In their work they identified directions along which electrons are much more prone to scattering losses and cannot conduct as well. To explain their results, they included the spin of the electron and questioned an established theory. The results could push topological insulator research, especially when a future BESSY-VSR will be available to provide much shorter light pulses to study the dynamics of the electrons. Their investigation into the "warping" of topological insulators is published by Physical Review B and has been selected as "Editor's Suggestion". Only six percent of the articles  published there receive this sort of acclaim. [...]
  • <p>RIXS-spectroscopy is a powerful method to gain insights into molecular and electronic structures in complex samples, liquid or solid. HZB scientists now know even a bit better how to interpret the RIXS-spectra. </p>
    Science Highlight
    14.10.2014
    New light on the "Split Peak" in x-ray (RIXS) spectra of Alcohols
    New study from Helmholtz-Zentrum Berlin in the journal "Structural Dynamics" makes sense of mysterious spectra, paving way for RIXS spectroscopy probe dynamic electronic structure of complex liquids and materials [...]
  • Science Highlight
    06.10.2014
    Open Access: Webinar for Helmholtz Ph.D. students
    As part of the international Open Access Week 2014, a series of events around the World will help canvass and inform about open access to knowledge. [...]
  • Science Highlight
    29.09.2014
    Tage der Forschung in Adlershof
    Am 25. und 26. September fanden in Adlershof die jährlichen Tage der Forschung statt. Das HZB bot rund 90 Schülerinnen und Schülern in drei unterschiedlichen Programmpunkten einen Einblick in die Welt der Forschung. [...]
  • Science Highlight
    26.09.2014
    “Multi-spectra glasses” for scanning electron microscopy
    Reflection zone plates produced by HZB enable lighter elements in material samples to be precisely detected using scanning electron microscopy (SEM) by providing high resolution in the range of 50-1120 eV. [...]
  • Science Highlight
    26.09.2014
    German Society for Materials Science awards publication with HZB scientist as co-author

    At its annual conference on September 22, 2014, the German Society for Materials Science (DGM), presented the Werner Köster Award for best publication. The work, whose authors include HZB scientist Dr. Michael Tovar and which has been published in the International Journal of Materials Research, examines the catalytic effect of vanadium pentoxide in propene synthesis from propane using spectroscopic, microscopic, and radiographic methods. [...]

  • <p>Das Forschungsmagazin Sichtbar erscheint zweimal j&auml;hrlich.</p>
    Science Highlight
    10.09.2014
    Sichtbar: Das Forschungsmagazin aus dem HZB
    Die neue Sichtbar ist erschienen. Mit Interviews, Hintergrundberichten und Meldungen zeigt das Magazin, an welchen Fragen HZB-Forscherinnen und -Forscher arbeiten: Von neuen Solarzellen bis hin zu Mikrogelen, aus denen sich komplexe funktionale Materialien für medizinische Anwendungen komponieren lassen, zum Beispiel für eine effizientere Dialyse. [...]
  • Science Highlight
    22.08.2014
    Proteins: New class of materials discovered
    German-Chinese research team gleans seminal insights into protein crystalline frameworks at HZB's BESSY II [...]
  • Science Highlight
    11.08.2014
    Neuer „lichtblick“ online
    Ein Denkmal im Ehrenhof der Humboldt-Universität erinnert seit kurzem an Lise Meitner – das erste Denkmal für eine Wissenschaftlerin in Deutschland überhaupt. Über die außergewöhnliche Wissenschaftlerin und die Entstehung der Bronze berichten wir in der aktuellen Ausgabe der HZB-Mitarbeiterzeitung „lichtblick“, die jetzt auch online ist. [...]
  • <p>Cryogenic TEM micrograph of gold nanoparticles (Au-NP) in DES-solvent. Sputtering duration 300 s. Red circles show the different domains of self-assembled Au-NPs. The inset shows an enlarged image of one particular domain of self-assembled Au-NPs.<br /></p>
    Science Highlight
    04.08.2014
    Self-assembly of gold nanoparticles into small clusters
    Researchers at HZB in co-operation with Humboldt-Universität zu Berlin (HU, Berlin) have made an astonishing observation: they were investigating the formation of gold nanoparticles in a solvent and observed that the nanoparticles had not distributed themselves uniformly, but instead were self-assembled into small clusters. [...]
  • <p>Reconstructed energy-selective neutron tomography: Visualization of austenite and martensite distribution in torsion (two images to left) and tensile (image to the right) loading.<br /></p>
    Science Highlight
    31.07.2014
    Neutron Tomography technique reveals phase fractions of crystalline materials in 3-Dimensions
    Researchers at Helmholtz-Zentrum Berlin (HZB) and The University of Tennessee Knoxville (UTK) developed a novel method, based on energy-selective neutron imaging for visualization of crystalline phase distributions within the bulk of metallic samples. [...]
  • <p>Ammonium tungstate/PSS film surface:  (a) SEM picture before pyrolysis; (b &amp; c) SEM picture after pyrolysis. </p>
    Science Highlight
    01.07.2014
    Collecting light with artificial moth eyes
    Scientists at EMPA in Zürich and University of Basel have developed a photoelectrochemical cell, recreating a moth’s eye to drastically increase its light collecting efficiency. The cell is made of cheap raw materials – iron and tungsten oxide. Analyses at BESSY II have revealed which chemical processes are useful to facilitate the absorption of light. [...]
  • <p>SEM image of the membrane. </p>
    Science Highlight
    01.07.2014
    “Muscled skin”: Simple formulas describe complex behaviors
    HZB researchers help chemists understand polymeric "biomimetic" materials' mechanical properties [...]
  • <p>When inserting an ultrathin dielectric between metal electrode and organic semiconductor, charge carriers (shown here for a positively charged holes in red) are, counter intuitively, more efficiently extracted from their transport level (blue) in the organic to the Fermi level (black) in the metal than without the interlayer.</p>
    Science Highlight
    18.06.2014
    Electrostatics do the trick
    A simple model describes what happens between organic semiconductors and metals [...]
  • <p>These scanning electron micrographs show how accurately the three Fresnel zone plates were positioned above one another. 3D X-ray optics of this kind allow the resolutions and optical intensities to be considerably improved.</p>
    Science Highlight
    18.06.2014
    Sharper imaging using X-rays
    HZB team develops three-dimensional volume diffraction optics for X-rays [...]
  • <p>Die drei Vertreterinnen des&nbsp;<a href="http://hzbzlog.com/" class="Extern"> #HZBzlog</a> Sibylle Grunze, Ina Helms und Antonia R&ouml;tger (v.l.)</p>
    Science Highlight
    22.05.2014
    #HZBzlog gewinnt Deutschen Preis für Onlinekommunikation als beste Microsite
    Seit etwa vier Monaten ist das HZB-Zukunftslogbuch #HZBzlog mit seiner ungewöhnlichen Episodenstruktur online, und es findet immer mehr Fans. Die als Langzeitdokumentation angelegte Seite öffnet ein Fenster in die Forschung und gibt den Blick frei auf die Geschichten hinter den Kulissen. Täglich surfen zwischen 500 und 1.000 Menschen auf der Seite und warten gespannt auf neue lebendige Einträge rund um die großen Zukunftsprojekte am HZB. Vier Monate nach dem Start gewinnt das neue HZB-Portal nun den von der Deutschen Presseakademie herausgegebenen "Deutschen Preis für Onlinekommunikation" und ist auf dem besten Weg, ein Erfolg zu werden. [...]
  • <p><a href="https://www.helmholtz-berlin.de/media/media/aktuell/print//lichtblick/76/hzb_lichtblick_mai-2014_extern_web.pdf" class="Extern"><span class="Intern">Lichtblick zum Download</span></a></p>
    Science Highlight
    20.05.2014
    Neuer Lichtblick erschienen
    Am Campus Wannsee entstehen neue Labore für die Materialsynthese: In unserer Mitarbeiterzeitung "lichtblick" berichten wir erstmals über das neue Bauvorhaben, das Materialforscherinnen und -forscher anlocken soll. Die Labore werden benötigt, um erfolgreich neuartige Materialkonzepte für die Energieumwandlung und -speicherung zu charakterisieren. [...]
  • <p>Crystal structure of human MTH1 in complex with a key inhibitor.<br />Source: Stockholm University, Prof. Pal Stenmark.</p>
    Science Highlight
    08.04.2014
    A new concept for the treatment of cancer
    A team of researchers from five Swedish universities has identified a new way to treat cancer. They present their concept in the journal „Nature“. It is based on inhibiting a specific enzyme called MTH1. Cancer cells, unlike normal cells, need MTH1 to survive. Without this enzyme, oxidized nucleotides are incorporated into DNA, resulting in lethal DNA double-strand breaks in the cancer cells. The research group at Stockholm University has determined the structure of MTH1 based on diffraction measurements at HZB´s MX-beamline at BESSY II. These detailed structural studies are important for the development of efficient inhibitors targeting MTH1. [...]
  • <p>The picture shows the characteristic spin texture (arrows) in a topological insulator (bottom) and how it is either probed by circularly polarized light (top) or manipulated by it (middle). </p>
    Science Highlight
    27.03.2014
    Controlling electron spins by light
    Researchers of HZB manipulate the electron spin at the surface of topological insulators systematically by light [...]
  • <p></p>
<p></p>
    Science Highlight
    20.02.2014
    HZB-Zeitung "Lichtblick" erschienen
    Viele Menschen, die in einem Forschungszentrum arbeiten, bleiben unsichtbar. Sie sind Dienstleister für die Wissenschaftlerinnen und Wissenschaftler – oder machen, wie der Strahlenschutzexperte, Dr. Guido Buchert, das Forschen an den Großgeräten erst möglich. In dieser Ausgabe stellen wir seinen Berufsweg und sein höchst verantwortungsvolles Aufgabengebiet vor. [...]
  • <p>The image shows the three-dimensional reconstruction of an atom probe measurement. The &gamma; matrix (purple) can be seen surrounding the cuboidal &gamma;&rsquo; precipitates (green). Only a few nanometre-sized &gamma; platelets can be seen in the &gamma;&rsquo; precipitates. Atom probe tomography allows a site specific analysis of the structure at the atomic scale and reveals the chemical composition in measurements of individual areas. </p>
    Science Highlight
    14.01.2014
    What makes superalloys super - hierarchical microstructure of a superalloy
    Researchers have observed for the first time in detail how a hierarchical microstructure develops during heat treatment of a superalloy [...]
  • <p>The outline of the lizard serves as a test object, as well as the conventional test pattern, a section of a so called Siemens star. The lizard&rsquo;s tail and the converging rays of the Siemens star can be used to measure how well narrow lines will be reproduced in an image. With a diameter of six thousandths of a millimetre, the entire test object is about the size of a red blood cell. The smallest resolved structure has a width of 46 nanometres. </p>
    Science Highlight
    07.01.2014
    New holographic process uses image-stabilised X-ray camera
    A team headed by Stefan Eisebitt has developed a new X-ray holography method that will enable snap-shots of dynamic processes at highest spatial resolution. The efficiency of the new method is based on a X-ray focussing optics being firmly fixed to the object to be imaged. While this approach initially provides a blurry image, this can be focussed in the computer based on the hologram information. At the same time, the rigid connection between the object and the focussing optics elegantly solves the problem of vibration induced jitter that plays an enormous role at the nanometre scale. [...]
  • <p>Stripe order of charge carriers in Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+x</sub> [2]. The figure shows the structure with a period of approximately one nanometer (front) and the related diffraction pattern (back) obtained by a so-called Fourier transformation (Yazdani Lab, Princeton University).</p>
    Science Highlight
    19.12.2013
    Charge Order competes with superconductivity
    Today in Science Express: Charge carriers in cuprate high-Tc superconductors form nanostripes that suppress superconductivity, as shown by guest researchers from Princeton and Vancouver using synchrotron radiation at BESSY II [...]
  • Science Highlight
    13.11.2013
    HZB-Zeitung "lichtblick" erschienen
    In der aktuellen Ausgabe der Lichtblick stellen wir Ihnen Mitarbeiterinnen und Mitarbeiter aus dem HZB vor. Jessica Neumann leitet das Rechnungs- und Finanzwesen und stellt sicher, dass das HZB immer genug Geld auf dem Konto hat - eine herausfordernde Aufgabe, die Fingerspitzengefühl und Kommunikationsstärke erfordert. [...]
  • Science Highlight
    06.09.2013
    Now available: Highlights 2012 - the annual report with reseach highlights at HZB
    The Annual Report with research highlights is now available und could be downloaded. [...]
  • <p>Susan Schorr wird portr&auml;tiert.</p>
    Science Highlight
    23.08.2013
    Neue "lichtblick" erschienen
    Großes Interview mit der Geschäftsführung zur Zukunft des HZB [...]
  • <p>Researchers have documented how inelastic scattering can intelligently intensified so that a shift of frequency is observed.<br />&copy;HZB/E. Strickert</p>
    Science Highlight
    21.08.2013
    Researchers from HZB open a door for solid state physics
    Laser processes observed with X-rays on a solid [...]
  • This sketch demonstrates the principle of measurement which enables to address  atom-specific and state-dependent emission of photons. With the help of first principles theory the spectral features can be associated with molecular orbitals.
    Science Highlight
    21.08.2013
    Better insight into molecular interactions
    How exactly atoms and molecules in biochemical solutions or at solid-liquid interfaces do interact, is a question of great importance. Answers will provide insights at processes in catalysts, smart functional materials and even physiological processes in the body, which are essential for health. Until now, scientists could have a look at these interactions by methods of spectroscopy, but it was hard to distinguish the many different interactions, which take place simultaneously. [...]
  • <p>Polymer chain incorporation during formation of ideal PE-nanocrystals by catalytic insertion polymerization with a water-soluble Ni(II) catalyst. The amorphous layers covering both platelets act as the wheels of a pulley just changing the direction of the chains. A moderate raise of the temperature induces sufficient mobility that allows the chains to move within the crystal.</p>
    Science Highlight
    14.08.2013
    Ideal nanocrystal produced from bulk plastics
    Polyethylene is an inexpensive commodity plastic found in many household objects. Now, a consortium of researchers from Constance, Bayreuth, and Berlin has successfully used this plastic to synthesize the ideal polymer nanocrystal. The prerequisite was a new type of catalyst produced by Constance University researchers as well as a combination of unique analytic tools like those found at the Helmholtz Zentrum Berlin (HZB). The crystalline nanostructure, which gives the polymer its new properties, could prove of interest to production of new kinds of coatings. The scientists’ findings are being published in the Journal of the American Chemical Society’s current issue (DOI: 10.1021/ja4052334). [...]
  • As part of her doctoral work, Dr. Melanie Timpel was able to show just how strontium is able to refine modern-day lightweight alloys.
    Science Highlight
    08.08.2013
    Melanie Timpel receives Acta Student Award
    Dr. Melanie Timpel's submission to the journal Acta Materialia made her one of this year's recipients of the 2,000 dollar 2012 Acta Materialia Student Award. The award is considered a high distinction conferred upon up-and-coming scientists. The award ceremony is scheduled for October 28, 2013, as part of the Materials Science & Technology Conference (MS&T) in Montreal, Canada. [...]
  •  Optical laser flash (red) destroys the electronic order (blue) in magnetite and, within one trillionth of a second, switches the state of the material from insulating to conducting.
    Science Highlight
    29.07.2013
    Picosecond accurate slow-motion confirms oxide materials exhibit considerably faster switching properties than do semi-conductors
    As part of an international team of researchers, scientists at the Helmholtz Center Berlin (HZB) have observed the switching mechanism from a non-conducting to a conducting state in iron oxide (specifically, magnetite) with previously unrealized precision. This switching mechanism - which, in oxides, proceeds in two consecutive steps and which is thousands of times faster than it is in current transistors - is described in the current epub-ahead-of-print issue of the scientific journal Nature Materials (DOI: 10.1038/NMAT3718).   [...]
  • <p>Fundamental processes: Charge donation/backdonation in the [Fe(CO)5] model catalyst in solution was studiedby resonant inelastic X-ray scattering. This method can be used to selectively probe the electronic structure at each atom in the iron-carbonyl bond. </p>
    Science Highlight
    25.07.2013
    Watching catalysts at work – at the atomic scale
    Innovative combination of methods at HZB leads to fundamental insights in catalyst research [...]
  • <p>Polycrystalline film growth during coevaporation in real time using in situ X-ray diffraction and fluorescence analysis.</p>
    Science Highlight
    27.06.2013
    Watching solar cells grow
    For the first time, a team of researchers at the HZB led by Dr. Roland Mainz and Dr. Christian Kaufmann has managed to observe growth of high-efficiency chalcopyrite thin film solar cells in real time and to study the formation and degradation of defects that compromise efficiency. To this end, the scientists set up a novel measuring chamber at the Berlin electron storage ring BESSY II, which allows them to combine several different kinds of measuring techniques. Their results show during which process stages the growth can be accelerated and when additional time is required to reduce defects. Their work has now been published online in Advanced Energy Materials. [...]
  • <p>The colloids that were used for the model: particles, each with a diameter of approximately 150 nanometers, suspended in water. The solid nucleus consists of the plastic polystyrene, the surrounding shell of a thermosensitive poly(N-isopropyl-acrylamide) network. By lowering the temperature, each individual particle's volume - and, by definition, its packing density - can be increased. Photo: HZB/M. Siebenb&uuml;rger</p>
    Science Highlight
    28.05.2013
    Crystal-clear method for distinguishing between glass and fluids
    Many solids are produced from melting. Depending on how quickly they cool off, invariably, internal tensile stresses begin to build up. One example are Prince Rupert's Drops, or Dutch tears: you can hit their thick end with a hammer without breaking them while a slight pressure applied to their thin end is enough to shatter the entire tear. The properties of safety or even gorilla glass are determined to a large extent by their internal tensile stresses. However, until now, our understanding of the unique characteristics exhibited by the condition of the glass as compared with a tough molten mass was spotty at best. Now, a collaboration of several German and Cretian research teams has offered a surprisingly simple model to explain the difference between glass and molten materials. [...]
  • Science Highlight
    15.05.2013
    Zwei Humboldt-Stipendiaten forschen am HZB: In der neuen Lichtblick stellen wir Jan Heyda und Stefano Angioletti-Uberti vor
    Die Qualität des Alexander-von-Humboldt-Stipendiums ist weltweit anerkannt. Die Nachwuchswissenschaftler Stefano Angioletti-Uberti und Jan Heyda haben sich für dieses Stipendium entschieden, obwohl sie gleich mehrere Angebote für einen Forschungsaufenthalt im Ausland bekommen hatten. Beide forschen am HZB-Institut für Weiche und Funktionale Materialien bei Joachim Dzubiella. Sie interessieren sich für stimuli-responsive Polymaterialien. Wir stellen sie in der neuen Ausgabe der Lichtblick vor. [...]
  • <p></p>
    Science Highlight
    27.03.2013
    Magnetic fingerprints of interface defects in silicon solar cells detected
    Using a highly sensitive method of measurement, HZB physicists have managed to localize defects in amorphous/crystalline silicon heterojunction solar cells. Now, for the first time ever, using computer simulations at Paderborn University, the scientists were able to determine the defects' exact locations and assign them to certain structures within the interface between the amorphous and crystalline phases. [...]
  • <p>Die Kurven zeigen, wie sich mit zunehmender Dotierung in der halbleitenden Schicht das Transistorverhalten drastisch verbessert. Als Ursache machten die Forscher die Bildung leitf&auml;higer Perkolationspfade aus, die den Transport von Ladungen entlang des Transistorkanals erm&ouml;glichen.</p>
    Science Highlight
    13.03.2013
    Schwache Dotierung verbessert polymerbasierte Feldeffekttransistoren
    In der organischen Elektronik haben sich Mischsysteme, in denen halbleitende Makromoleküle in einer isolierenden Polymermatrix eingebettet sind, als besonders geeignet für die Herstellung von  Transistoren erwiesen. Bislang waren die Gründe dafür nicht genau bekannt. Nun konnten Wissenschaftler aus mehreren Forschungseinrichtungen die komplexe Morphologie dieser Mischsysteme aufklären und damit die elektronischen Eigenschaften erklären. [...]
  • <p>With the help of computer simulation, researchers have been<br />able to calculate the movements and forces between <br />water molecules (small, red-and-white dipoles), a ligand (shown in green),<br />and the protein molecule's water-repellant hollow pocket.</p>
    Science Highlight
    16.01.2013
    Water fluctuations mediate lock-and-key fit
    Without water, life as we know, it would not exist. Nearly every biological binding process that takes place within a cell requires the presence of an aqueous environment. Here, tiny molecules called ligands fit like "keys" into their matching "locks" - docking sites on larger protein molecules. This in turn activates signals or leads to the production of some other substance by the cell. But what was previously unclear, was the part water plays in all this. Is water merely a passive transport medium or does it perform other, more active jobs as well? Now, HZB's own Prof. Dr. Joachim Dzubiella and a team of physicists have looked for answers to this question using a computer simulated model system. In the process, they discovered that water is capable of actively influencing the docking speed of the ligand through subtle interactions with other molecules' unique geometry and surface topography. Their findings could become important in drug delivery. [...]
  • Science Highlight
    21.05.2008
    Towards imaging ultrafast evolution in a single shot

    Research carried out by BESSY scientists in collaboration with colleagues from SLAC and SOLEIL has been featured as Editors’ Choice in the Nov. 23 issue of the Science Magazine. In the Optics Letters article by W. F. Schlotter et al., multiplexed x-ray holograms generated simultaneously from many objects are presented. The feasibility of this approach implies that ultrafast pump-probe time sequences can be recorded with free electron x-ray lasers in this way. [...]