HZB Newsroom

Sear results - Keyword: spintronics

  • Science Highlight
    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.


  • <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
    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.


  • <p>Ultracold atoms in an optical lattice have been considered for quantum simulation.</p>
    Science Highlight
    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>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
    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.


  • <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
    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.


  • <p>At quantum physics atoms, molecules or photons are used to store information.</p>
    Science Highlight
    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.


  • <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
    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>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
    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>Prof. Dr. Johannes Reuther works at the Freie Universit&auml;t Berlin and the HZB.</p>
    Freie Universität Berlin appointed Johannes Reuther as W2 professor

    On April 6, 2020 Freie Universität Berlin appointed Johannes Reuther to the joint W2 professorship "Theory of Novel Quantum Materials”. The physicist will conduct research at both Helmholtz-Zentrum Berlin (HZB) and Freie Universität Berlin. The joint appointment will build a bridge between experimental and theoretical 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
    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>Felix B&uuml;ttner has set up a holography chamber at Brookhaven National Laboratory.</p>
    New Helmholtz Young Investigator Group at HZB
    Dr. Felix Büttner will establish a Helmholtz Young Investigator Group (YIG) on topological solitons at the HZB beginning in March 2020. Topological solitons occur in magnetic quantum materials and can contribute to extremely energy-efficient switching processes. Büttner wants to develop a new imaging technique at BESSY II to study these quasi-particles. [...]
  • Science Highlight
    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 Russian-German Laboratory operating its own beamline at BESSY II.</p>
    New instrument at BESSY II commences user operation
    A new instrument became available to the users of BESSY II on Oct. 28, 2019. The new beamline and apparatus for spin- and angular-resolved photoemission in the Russian-German Laboratory at BESSY II have successfully completed their test phase. They facilitate precise measurements of the electron band structure and spin of different material classes such as topological insulators and magnetic sandwich structures, as well as novel perovskite-based solar-cell materials. A photoelectron microscope has also been developed which is particularly important for nanoscopic structures.


  • <p>The illustration demonstrates skyrmions in one of their Eigen modes (clockwise).</p>
    Science Highlight
    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>View into the experimental hall of BESSY II at HZB, Berlin.</p>
    Physicists develop "time machine" for materials research

    Researchers from Martin Luther University Halle-Wittenberg (MLU), Freie Universität Berlin and Technische Universität München will develop fast electronics for data acquisition at BESSY II. It will make it possible to record the signal of all X-ray flashes generated during the experiment. This will enable researchers to evaluate the data more extensively - even retrospectively. The Federal Ministry of Education and Research (BMBF) is funding the project with two million euros. [...]

  • <p>The new german russian undulator beamline at BESSY II</p>
    German Russian collaboration further strengthened at HZB
    HZB physicist Jaime Sánchez-Barriga establishes a "Helmholtz-RSF Joint Research Group". Over the next three years he will receive additional funding from the Helmholtz Association and the Russian Science Foundation (RSF) to investigate magnetic quantum materials for future information technologies with partners from the Lomonosov State University in Moscow. In particular, the funding should also enable the exchange and training of young scientists. [...]
  • <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
    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>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
    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>Shown are the magnetic fluxlines inside a superconducting sample of lead in two different directions. The scale bar is 5 mm. </p>
    Science Highlight
    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>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
    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>With this experiment, the team could observe how magnetic order is changed by sudden heat.</p>
    Science Highlight
    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>Fossils like this 250 million year old skull of a lystrosaurus can be examined very carefully by neutron tomography. </p>
    Science Highlight
    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>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
    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>Dr. Nele Thielemann-K&uuml;hn was awarded the Innomag Dissertation Award 2018.</p>
    HZB scientist got the dissertation prize at the spring conference of the Deutsche Physikalische Gesellschaft
    Dr. Nele Thielemann-Kühn was awarded the dissertation prize of the magnetism research group at the spring conference of the Deutsche Physikalische Gesellschaft (German physical society/DPG) in Berlin. The prize is awarded for outstanding research in the field of magnetism.  [...]
  • <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
    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>Professor Catherine Dubourdieu is head of the HZB Institute Functional thin film oxides for energy efficient future IT. </p>
    HZB researcher Catherine Dubourdieu appointed full professor at Freie Universität Berlin
    Catherine Dubourdieu has become a full professor at the Freie Universität Berlin commencing December 2017. The Freie Universität Berlin is one of eleven German elite universities in the German Universities Excellence Initiative. Her position will be that of W3-S, which enables her to continue her research at the Helmholtz-Zentrum Berlin (HZB) in joint role. The physicist is an expert in the field of functional metal oxides that are interesting candidates for future information technologies. [...]
  • <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
    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. [...]
  • <p></p>
<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
    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>Schematic of experimental setup for PEEM, the laser optics integrated sample holder and the sample.</p>
    Science Highlight
    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>Kickoff with a meeting on 19 June 2017:  Prof. Borisenko, Dr. Rienks, Prof. B&uuml;chner (all IFW), the leader of the Young Investigator Group Dr. Fedorov; Dr. Varykhalov and apl. Prof. Rader (both HZB) (from left to right). </p>
    Kickoff for Joint Lab with IFW Dresden
    The Leibniz Institute for Solid State and Materials Research Dresden (IFW) and Helmholtz-Zentrum Berlin (HZB) have created a Joint Lab for “functional quantum materials” and under its umbrella a Young Investigator Group. [...]
  • <p>This optical zone melting furnace is producing large single crystals. </p>
    New at Campus Wannsee: CoreLab Quantum Materials
    Helmholtz-Zentrum Berlin has expanded its series of CoreLabs for energy materials research. In addition to the five established CoreLabs, it has now set up a CoreLab for Quantum Materials. A research team from the HZB Institute for Quantum Phenomena in New Materials is responsible for the CoreLab and its modern equipment. The CoreLab is also open to experimenters from other research institutes.  [...]
  • <p>A magnetic field pulse switches the initial vortex state to &ldquo;onion state&rdquo; with two walls. In the subsequent magnetic snapshots the domain wall motion is shown. After 58 ns both walls meet and annihilate, thus completing the switching process into the opposite sense of rotation. </p>
    Green IT: New switching process in non-volatile spintronics devices
    Physicists achieved a robust and reliable magnetization switching process by domain wall displacement without any applied fields. The effect is observed in tiny asymmetric permalloy rings and may pave the way to extremely efficient new memory devices. The results have been published in Physical Review Applied, highlighted as an Editors' Suggestion.
  • <p>Gerrit G&uuml;nther und Veronka Grzymek help Zhilun Lu with the experiment.</p>
    NEAT starts user operation
    The newly built time of flight spectrometre NEAT has welcomed its first users: Jie Ma from Shanghai Jiao Tong University and his colleague Zhilun Lu examined magnetic excitations in crystalline samples and enjoyed fast data rate and high flexibility of instrumental configurations. NEAT team is now looking forward to further new studies and user experiments!      [...]
  • <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
    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
    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>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
    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>More than 100 experts did gather at the international conference "Dynamic Pathways in Multidimensional Landscapes", which was held in September in Berlin.</p>
    VI-Conference "Dynamic Pathways in Multidimensional Landscapes 2016"
    Near the museum island, in the heart of Berlin, the International Conference "Dynamic Pathways in Multidimensional Landscapes 2016" has taken place last week. More than 100 international experts met at the Magnus-Haus of the German Physical Society from 12 -16 September 2016. [...]
  • <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
    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
    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 nanostructured membrane has a honeycomb pattern with nanoholes of 68 nm in diameter. The nanoholes pin down the magnetic domains.</p>
    Science Highlight
    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>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
    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
    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>The magnetic structure of LiFePO<sub>4</sub></p>
    Anomalous magnetic structure and spin dynamics in magnetoelectric LiFePO4
    A team at HZB has recently unraveled intricate details of the magnetic structure and dynamics of the magnetoelectric compound LiFePO4.Such materials currently find use in sensors but there are promising perspectives for magnetoelectrics to be applied in data storage and spintronic devices as well. [...]
  • <p>The hedgehog-configuration of the spins and the Fermi-Level is shown. Illustration Thomas Splettst&ouml;&szlig;er/HZB</p>
    Science Highlight
    Spins in Graphene with a Hedgehog Texture
    HZB researchers demonstrate a fundamental property of the electron spin in graphene [...]
  • <p>Mapping of the captured magnetisation domains (right, red-blue patterns) in a sample 20 nanometres thick that had been wound in two layers into a tube. The tube has a diameter of 5 microns and a height of 50 microns. </p>
    New technique enables magnetic patterns to be mapped in 3D
    An international collaboration has succeeded in using synchrotron light to detect and record the complex 3D magnetisation in wound magnetic layers. This technique could be important in the development of devices that are highly sensitive to magnetic fields, such as in medical diagnostics for example. Their results are published now in Nature Communications. [...]
  • <p>These samples with precise proportions of nickel and copper were produced via an improved preparation procedure. Photo: M. Tovar/HZB</p>
    Crystal structure and magnetism – new insight into the fundamentals of solid state physics
    HZB team decodes relationship between magnetic interactions and the distortions in crystal structure within a geometrically “frustrated” spinel system [...]
  • <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
    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><strong>Frostige Wissenschaften:</strong> Experimente mit fl&uuml;ssigem Stickstoff</p>
    Eine lange Nacht geballtes Wissen tanken
    Führungen an der Neutronenquelle, Experimente zur Energie für Groß und Klein, Licht-Show und vieles mehr [...]
  • <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
    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>Dichromium: both chromium atoms "share" the  12 valence electrons which leads to a multible bond. </p>
    Science Highlight
    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>
    Science Highlight
    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>180 scientists listened to the lectures. <span>The aim of the dialogue is to identify future scientific fields as well as expectations, needs and requirements</span> for BESSY II.</p>
    BESSY II – From Pico to Femto – time resolved studies at BESSY II
    180 scientists attended the workshop on time resolved studies
  • <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
    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>Hard disc from space: the Pallasite meteorite, studied by Harrison, contains information about the early solar system.<br /><em></em></p>
    Science Highlight
    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>A general view of the VEKMAG end-station. The vector magnet chamber (grey) is supported by a hexapod frame. Below the magnet  one can distinguish the detector chamber (green) and  in the forward direction the deposition chamber (dark grey) is displayed. The beam quality is monitored by a diagnostic chamber (yellow) positioned in front of the magnet chamber. </p>
    “VEKMAG” at BESSY II creates 3D magnetic fields in samples
    Together with HZB, teams from the Universität Regensburg, from the Freie Universität Berlin and from  the  Ruhr Universität Bochum have jointly set up a unique measurement station at BESSY II: a vector electromagnet consisting of three mutually perpendicular Helmholtz coils which enables  setting the local magnetic field at the sample position  to any orientation desired. The first measurements of magnetic materials, spin systems, and nanostructured magnetic samples are scheduled for early 2015. [...]
  • <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
    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>HZB-scientists Karsten Holldack, Alexander Schnegg and Joscha Nehrkorn at the BESSY II Beamline.</p>
    Science Highlight
    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>Aus dem Technikum</p>
    Hochfeldmagnet sucht Neutronenleiter
    Am Freitag, den 12. Dezember 2014 fand der Umzug des Hochfeldmagneten an seinen endgültigen Aufstellungsort in der Neutronenleiterhalle statt. Eine Spezialfirma für Maschinentransporte bugsierte den über 25 Tonnen schweren Stahlkoloss aus dem HFM-Technikum heraus und setzte ihn in Bewegung. [...]
  • <p>In january 2014, the HFM was just delivered to HZB.  </p>
    26 tesla! High field magnet exceeds everyone’s expectations
    It’s done! The high field magnet is consistently producing magnetic fields of approx. 26 tesla and staying at this value over extended periods of time. And all this in spite of the fact that 26 tesla exceeds the original 25-tesla goal; in other words, the magnet turns out to be even stronger than anyone had hoped for. On Thursday afternoon, October 16, 2014, Dr. Peter Smeibidl who heads the HFM’s team of eight was able to report on their success and thank everyone involved with setting up the complex high field magnet with its own cooling systems and 4-megawatt power supply. [...]
  • <p>Im ehemaligen Plenarsaal der Bundesregierung in Bonn finden die Vort&auml;ge statt.</p>
    Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten in Bonn
    Das HZB ist mit eigenem Stand, Vortrag und Postern präsent auf der Deutschen Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten (SNI). Die dreitägige Veranstaltung findet vom 21. bis 23.09. im ehemaligen Plenarsaal der Bundesregierung im heutigen World Conference Centers in Bonn statt. [...]
  • <p>Outstanding researchers took part in the &ldquo;New Trends in Topological Insulators 2014&rdquo; - workshop.</p>
    Leading scientists on topological insulators met in Berlin
    From July 7-10, 150 researchers met in Berlin to discuss recent findings in the field of topological insulators. [...]
  • News
    Invitation: Reception Final Assembly of HFM
    Six years full of hard work with planning and constructing the High-Field Magnet for Helmholtz-Zentrum Berlin we are proud to inform you that the final assembly is now complete. [...]
  • News
    Magnetic switch gets closer to application
    Scientists from Paris, Newcastle and Helmholtz-Zentrum Berlin have been able to switch on and off robust ferromagnetism close to room temperature by using low electric fields. Their results are inspiring for future applications in low-power spintronics, for instance in fast, efficient and nonvolatile data storage technologies. [...]
  • News
    High field magnet for neutron scattering has made its way to Italy
    After five years of manufacture, the superconducting spool for the new high field magnet for neutron scattering finally took off from Atlanta, USA, inside the belly of an MD-11F Lufthansa cargo plane on October 9, 2013, at 3:00 am EST. The plane landed in the cargo area at Frankfurt Airport promptly at 6:21 pm that same day. Following German customs clearance, the magnet was subsequently transferred to Italy by truck where, on Friday, October 11, it arrived in Chivasso/Turin. [...]
  • A scanning electron micrograph of a w=500&#8201;nm wide and 30&#8201;nm thick permalloy ring with radius r=2&#8201;&#956;m overlayed with a scanning transmission X-ray microscopy (STXM) image showing the in-plane magnetic contrast.
    Domain walls as new information storage
    Domain wall motion imaging: at high speeds, material defects no longer play a role [...]
  • <p>Prof. Dr. Alan Tennant.</p>
    Prof. Dr. Alan Tennant has accepted a new position
    Prof. Dr. Alan Tennant has been selected as the new Chief Scientist for the Neutron Sciences Directorate, at Oak Ridge National Laboratory. He will start in his new capacity there in November 2013. “We are proud to have had Alan Tennant working with us for these last nine years”, says Professor Anke Kaysser-Pyzalla, scientific director of the Helmholtz-Zentrum Berlin (HZB). [...]
  • Dr. Anup Kumar Bera from the department of Quantum Phenomena in Novel Materials convinced the committee with his poster about  ‘Haldane chains’.
    International Conference in Neutron Scattering: HZB-contributions awarded
    More than 800 participants had gathered for the International Conference in Neutron Scattering, held during 8-12 July 2013 in Edinburgh, to discuss advances in neutron research and the advancement of the neutron scattering instruments and techniques. A committee selected sixteen outstanding posters from the 650 poster presentations, two of these from HZB scientists. [...]
  • Scanning electron microscopy image of the sample corresponding to a top view on the nanopillar structure.
    Shedding light on magnetoelectric coupling
    Effect opens up new possibilities for digital data storage [...]
  • <p>Magnet islands: Scanning electron micrograph from a regularly arranged square lattice of magnetic islands. The researchers created the islands using electron beam lithography &copy; modifiziert nach / modified from Physical Review Letters</p>
    RUB physicists let magnetic dipoles interact on the nanoscale for the first time
    “Of great technical interest for future hard disk drives”

    Physicists at the Ruhr-Universität Bochum (RUB) have found out how tiny islands of magnetic material align themselves when sorted on a regular lattice - by measurements at BESSY II. Contrary to expectations, the north and south poles of the magnetic islands did not arrange themselves in a zigzag pattern, but in chains. “The understanding of the driving interactions is of great technological interest for future hard disk drives, which are composed of small magnetic islands”, says Prof. Dr. Hartmut Zabel of the Chair of Experimental Physics / Solid State Physics at the RUB. Together with Dr. Akin Ünal, Dr. Sergio Valencia and Dr. Florian Kronast from the Helmholtz-Zentrum in Berlin, Bochum’s researchers report in the journal “Physical Review Letters”.


    Read the full text in the press release of RUB:


  • An ultrafast spin current triggers the emission of Terahertz-Radiation.
    Ultrafast Spin Manipulation at THz frequencies
    The demands for ever increasing speed of information storage and data processing have triggered an intense search for finding the ultimately fast ways to manipulate spins in a magnetic medium. In this context, the use of femtosecond light pulses – the fastest man-made event - with photon energies ranging from X-rays (as used for instance at the HZB femto-slicing facility) to THz spectral range proved to be an indispensable tool in ultrafast spin and magnetization dynamics studies. [...]
  • News
    Demagnetization by rapid spin transport

    The fact that an ultrashort laser pulse is capable of demagnetizing a ferromagnetic layer in a jiffy has been well-known since approximately 1996. What we don't yet understand, however, is how exactly this demagnetization works. Now, physicist Dr. Andrea Eschenlohr and her colleagues at the Helmholtz Centre Berlin and Uppsala University in Sweden have shown that it turns out not to be the light pulse itself that prompts demagnetization. [...]

  • Nachricht
    Neue deutsch-russische Forschungsgruppe zu Topologischen Isolatoren

    Der HZB-Physiker Dr. Andrei Varykhalov war mit seinem Antrag auf Förderung einer „Helmholtz-Russia Joint Research Group“ erfolgreich. Mit diesem Programm fördert die Helmholtz-Gemeinschaft seit 2006 zusammen mit der „Russian Foundation for Basic Research“ Kooperationen zwischen deutschen und russischen Wissenschaftlern. Partner auf russischer Seite ist die Chemikerin Prof. Dr. Lada V. Yashina von der Moskauer Staatsuniversität. [...]

  • Magnetic force microscope image of a 10 by 10 micron sample<br />showing the magnetic domains' labyrinthine structure.<br />
    X-ray laser FLASH uncovers fast demagnetization process
    With the help of free-electron laser FLASH at the Helmholtz Research Centre DESY, an international team of researchers has recently described a most surprising effect that can result in faster demagnetization in ferromagnetic materials. This effect could be key to the continued miniaturization and acceleration of magnetic storage. Now, Prof. Dr. Stefan Eisebitt of the Helmholtz Zentrum Berlin (HZB) and TU Berlin and his team have published their findings in the current issue of the scientific journal Nature Communications (DOI 10.1038/ ncomms2108). [...]
  • <p> <a href="http://www.helmholtz-berlin.de/pubbin/news_datei?did=4689">&#9654;<strong> Video-Interview</strong> with Alan Tennant (6 min, MP4, 122.6 MB) </a> </p>
<p> <a href="http://www.helmholtz-berlin.de/pubbin/news_datei?did=4692">&#9654;<strong> Video-Interview</strong> with Alan Tennant (11 min, MP4, 206.9 MB) </a> </p>
    Prof. Alan Tennant has won the Europhysics Prize, Europe’s foremost prize for condensed matter physics
    Tennant was honored for the experimental observation of magnetic monopoles using neutron scattering at the Berlin research reactor BER II. He shares the 2012 prize with 5 other scientists “for the prediction and experimental observation of magnetic monopoles in spin ice.” The price is endowed with 12.000 Euro and will be presented at the forthcoming EPS CMD General Conference in Edinburgh on 5th September. It is awarded once every two years for a recent work in the area of physics of condensed matter which, in the opinion of the Society's selection committee, represents scientific excellence. [...]
  • News
    Researchers find spins acting like real bar magnets in a new material
    An international team of researchers from Switzerland, Great Britain and Germany has discovered an excellent new material for studying the behaviour of spins. The researchers have shown that the spins in the colourless salt of chemical formula LiErF4 behave like real bar magnets. They also managed to switch on and off the magnetic properties of the material using quantum mechanics. HZB scientists supported the research team from the Laboratory for Quantum Magnetism (Switzerland) and the London Centre for Nanotechnology on their measurements. The results are published in the journal Science (DOI: 10.1126/science.1221878). [...]
  • <p>Fig.: Spectra of one-third atomic layer iron on bismuth selenide.<br />Bisecting lines indicate the material's surface state. The figure's top<br />and bottom portions are symmetric to each other due to time reversal<br />symmetry, &gt;which also protects the point of intersection.<br /></p>
    In topological insulator debate, scientists document mate-rials' high-level surface state stability
    Following scientists' announcement, new class of materials stakes its claim to holding the key to computer technology's future. [...]
  • <p>A pictorial view of the coupling mechanism between hard and<br />soft ferrimagnetic alloys with perpendicular magnetization.<br /></p>
    Resetting the future of MRAM
    Helmholtz-Zentrum Berlin developed a magnetic valve that novel electronic devices can be realistic [...]
  • <p>The topping-out ceremony and relaying of the foundation<br />stone for the NEAT building were celebrated at the beginning<br />of December</p>
    Important Milestones Celebrated for the Neutron Instrument NEAT II
    Around 100 guests attended the NEAT building’s topping-out ceremony / The experimental capabilities at NEAT II were discussed among other topics at the Workshop on Neutron Spectroscopy in the Terahertz Range [...]
  • Synchrotron Radiation Source BESSY II
    Tiny, Tailored Magnets - CeNIDE Researchers Publish in “Nature Communications”
    Nanomagnets are used in many places nowadays, from medicine to data storage. Sometimes they have to be strong and and sometimes they have to be weak. Researchers from the Center for Nanointegration (CeNIDE) at University of Duisburg-Essen (UDE) have found out just how to produce these tiny magnets with highly specific properties, and have published their results. [...]
  •  HZB staff scientist Florin Radu checks the BaTiO3 sample<br />alignment in the ALICE diffractometer.
    Locating the Elusive
    HZB scientists observe how a material at room temperature exhibits a unique property – a „multiferroic“ material with potential uses for cheap and quick data storage. [...]
  • <p>Ein Datenpunkt &auml;ndert die Polarisierung:<br /> Der Probenausschnitt zeigt die Magnetisierung,<br /> w&auml;hrend sie sich von oben nach unten umkehrt.</p>
    Nutzerexperiment bei BESSY-II: Ein schneller Schalter für Magnetnadeln
    Wissenschaftler aus aller Welt kommen ans HZB, um die beiden Großgeräte – die Synchrotronstrahlungsquelle in Adlershof und den Forschungsreaktor in Wannsee – für ihre Untersuchungen zu nutzen. Doch bevor es mit den Messungen losgehen kann, müssen die Forscher Anträge einreichen, die ein international besetztes Gremium begutachtet. Dieser Aufwand wird betrieben, um für die aussichtsreichsten wissenschaftlichen Ideen Messzeit zur Verfügung zu stellen. Nicht selten führen sie zu herausragenden Publikationen. Ein aktuelles Beispiel ist ein Nutzerexperiment, das am Speicherring BESSY II von dem Team von Dr. Hermann Stoll vom Max-Planck-Institut für Intelligente Systeme (ehemals Max-Planck-Institut für Metallforschung) zusammen mit Kollegen aus Gent und Regensburg durchgeführt wurde. [...]
  • Top, centre: While the magnetization of gadolinium (red arrow)<br />has not yet changed, the magnetization of iron (blue arrow)<br />has already reversed.<br />Large <br />reversal, while the X-ray pulse (blue) measures it.<br />
    Ultra-Fast Magnetic Reversal Observed
    A newly discovered magnetic phenomenon could accelerate data storage by several orders of magnitude. [...]
  • <p>Boundaries of magnetic domains can be computer imaged<br />in three dimensions.<br /></p>
    Imaging with neutrons: Magnetic domains shown for the first time in 3D
    So far, it has only been possible to image magnetic domains in two dimensions. Now, for the first time, Scientists at Helmholtz-Zentrum Berlin (HZB) have managed to create three-dimensional images of these domains deep within magnetic materials. [...]
  • News
    Many Roads lead to Superconductivity

    HZB-Scientists discovered a unique feature of Superconductivity [...]

  • Nachricht
    Ein schneller Blick auf komplexe Ordnung
    Grundlagenforschung zu magnetischen Ordnungsphänomenen in Festkörpern ist eine der Hauptforschungsrichtungen am HZB, bei denen die Kombination von Neutronen- und Röntgenstreuung eine herausragende Rolle spielt. Materialien mit komplexen magnetischen Strukturen wie z.B. antiferromagnetische Halbleiter lassen sich mit solchen Methoden untersuchen. Hier ordnen sich unterhalb einer bestimmten Temperatur die magnetischen Momente in atomaren Schichten mit alternierender Magnetisierungsrichtung an. Dies führt zu magnetischen Beugungsreflexen, die auch mit Neutronen beobachtet werden können. Röntgenstreuung als komplementäre Methode kann zusätzlich eine hohe Ortsauflösung und, in Kombination mit ultrakurzen Röntgenpulsen, eine sehr hohe Zeitauflösung erreichen. Dies ermöglicht nun die Untersuchung der bisher nicht zugänglichen magnetischen Dynamik solcher komplexer Strukturen. [...]
  • <p>Christian Stamm at BESSY II-beamline for femtoslicing</p>
    First the orbit, then the spin
    Novel storage materials of the future will be made out of magnetic films. Researchers at HZB are the first to find out just how fast magnetic particles can be controlled. [...]
  • News
    X-rays shed light on magnets

    A new test method developed in Berlin could soon find its way into textbooks. It makes thick, compact magnetic materials accessible, as well as materials used in spintronics and semiconductor technology.

  • News
    Data at the end of the Tunnel

    Electric control of aligned Spins improves Computer Memory [...]

  • <p></p>
    Golden ratio discovered in a quantum world
    Researchers from the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB), in cooperation with colleagues from Oxford and Bristol Universities, as well as the Rutherford Appleton Laboratory, UK, have for the first time observed a nanoscale symmetry hidden in solid state matter. They have measured the signatures of a symmetry showing the same attributes as the golden ratio famous from art and architecture. The research team is publishing these findings in Science on the 8. January. [...]
  • Prof. A. Föhlisch und Dr. E. Suljoti bei der Arbeit an der<br>Undulatorbeamline UE52-PGM bei BESSY II.
    Wie Kreisel auf atomarer Ebene miteinander wechselwirken
    Die Wechselwirkungen zwischen Elektronen und dem Atomgerüst in einem Festkörper sind die Grundlage von Materialeigenschaften, die eine zunehmend wichtige technologische Rolle spielen. Dazu gehört zum Beispiel das schnelle Schalten magnetischer Medien, wie es etwa für die Speicherung von Daten auf Computerfestplatten erforderlich ist.  Diesen Vorgang untersuchen und optimieren Wissenschaftler derzeit im Labor anhand der ultraschnellen Demagnetisierung von ferromagnetischen Schichtsystemen. Um solche Materialsysteme weiter optimieren zu können, müssen Wissenschaftler die Wechselwirkung zwischen Elektronen und Atomgitter detailliert verstehen. Forscher die am Helmholtz-Zentrum Berlin (HZB) und der Universität Hamburg tätig sind, haben nun einen wichtigen Teilprozess der Wechselwirkung der Elektronen mit den so genannten Phononen, den Quasiteilchen der atomaren Gitterschwingung, aufgeklärt. Dabei konnten sie zeigen, wie und vor allem mit welcher Effizienz Elektronen eine ihrer fundamentalsten Eigenschaften, den so genannten Drehimpuls, mit den Phononen austauschen können. Ihre Ergebnisse hat das Team um Professor Alexander Föhlisch, Leiter des HZB-Instituts für „Methoden und Instrumentierung der Synchrotronstrahlung“, und Professor Wilfried Wurth von der Universität Hamburg jetzt in der Fachzeitschrift „Physical Review Letters“ publiziert. Den Nachweis und die Quantifizierung dieses Effekts führten das Team an einem klassischen Modellsystem durch, dessen physikalische Eigenschaften sehr genau bekannt sind: Silizium. An der Synchrotronstrahlungsquelle BESSY II des HZB bestrahlten sie Siliziumkristalle mit Röntgenstrahlung und maßen dann hochpräzise die Energie der an der Probe gestreuten Lichtteilchen, der Photonen. Die Analyse der Ergebnisse dieser auch als resonante inelastische Röntgenstreuung bezeichneten Methode erlaubte es nun, die Wahrscheinlichkeit eines sogenannten Drehimpulstransfers zwischen Phonon und Elektron genau zu bestimmen. Der Effekt ist klein - in Silizium etwa 50 Mal kleiner als die bekannte dominierende klassische Elektronen-Phononen Wechselwirkung, bei der kein Drehimpuls übertragen werden kann –, weil die Phononen nur in seltenen ausgewählten Situationen zu einem Drehimpulsübertrag in der Lage sind. Die zur genauen Vermessung notwendige Sensitivität erreichten die Wissenschaftler durch die Kopplung der „Hamburg Inelastic X-ray scattering station“ (HIXSS) mit der hochbrillanten Synchrotronstrahlung des Speicherrings BESSY II. „Das Resultat unserer Messung ist ein wichtiger Baustein auf dem Weg zu einem besseren Verständnis der komplizierten Kopplungen zwischen Atomgitter und den drei wichtigen Eigenschaften der Elektronen – dem Spin, dem Bahndrehimpuls und der Ladung“, sagt Alexander Föhlisch: „Technologisch bedeutsame Materialeigenschaften wie schnelle Magnetisierungsprozesse können wir somit besser erklären.“ Um diese Untersuchungen zukünftig in idealer Weise am Helmholtz-Zentrum Berlin zu ermöglichen, befindet sich der neue RICXS Messplatz am Speicherring BESSY II im Aufbau. Zukünftig wird dort resonante inelastische Röntgenstreuung hoher Energie und Impulsauflösung bei höchster Transmission durchgeführt werden. Mehr dazu in der Originalveroeffentlichung: M. Beye, F. Hennies, M. Deppe, E. Suljoti, M. Nagasono, W. Wurth, A. Foehlisch, Dynamics of Electron-Phonon Scattering: Crystal- and Angular-Momentum Transfer Probed by Resonant Inelastic X-Ray Scattering, Phys. Rev. Lett. 103 (2009), 237401. [...]
  • Nachricht
    MAXYMUS - Neue Einsichten mit Röntgenblitzen

    Das derzeit modernste Rasterröntgenmikroskop wird vom Stuttgarter Max-Planck-Institut für Metallforschung am Helmholtz-Zentrum Berlin eingeweiht; Experten treffen sich zum Workshop über Röntgenmikroskopie Stuttgart/Berlin: Am 10. und 11. November weiht das Stuttgarter Max-Planck-Institut für Metallforschung (MPI-MF) im Rahmen des internationalen Workshops „New Frontiers in Soft X-Ray Microscopy“ feierlich sein neues Rasterröntgenmikroskop MAXYMUS an der Berliner Synchrotronstrahlungsquelle BESSY II ein. Unter der Schirmherrschaft von Professor Dr. Anke Rita Kaysser-Pyzalla, Wissenschaftliche Geschäftsführerin am Helmholtz-Zentrum Berlin (HZB), Professor Dr. Gisela Schütz, Direktorin der Abteilung „Moderne magnetische Materialien“ am MPI-MF und Dr. Brigitte Baretzky, Projektleiterin am MPI-MF treffen sich zahlreiche hochrangige Experten aus aller Welt, um über die neuesten Entwicklungen auf dem Gebiet der Röntgenmikroskopie zu diskutieren. [...]

  • Nachricht
    Orbital 2009 - internationaler Workshop am HZB
    Am 7. und 8. Oktober 2009 findet am Helmholtz-Zentrum Berlin am Standort Adlershof der Workshop "Orbital 2009" mit 95 Teilnehmern aus aller Welt statt. [...]
  • News
    Magnetic monopoles detected in a real magnet
    Researchers from the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) have, in cooperation with colleagues from Dresden (Germany), St. An-drews (UK), La Plata (Argentina) and Oxford (UK), for the first time observed magnetic monopoles and how they emerge in a real material. They publish this result in the journal Science within the Science Express web site on 3. September. Magnetic monopoles are hypothetical particles proposed by physicists that carry a single magnetic pole, either [...]
  • Nachricht
    Forscher sehen Molekulare Magneten in neuem Licht
    Erkenntnisse über Molekulare Magnete könnten künftig völlig neue Horizonte für eine neue Form der Datenspeicherung sowie der Spintronik (Elektronik mit Spins) auf der Basis einzelner Moleküle eröffnen. Eine Voraussetzung für die Verwirklichung solcher Anwendungen ist jedoch die Weiterentwicklung neuartiger Molekularer Magnete auf der Basis der genauen Kenntnis ihrer magnetischen Wechselwirkungsenergien. Alexander Schnegg und Kollegen vom HZB und der FU Berlin haben nun erstmals EPR (Elektronenparamagnetische Resonanz) Spektroskopie in Kombination mit kohärenter Synchrotron Strahlung verwendet, um die magnetischen Wechselwirkungen eines Molekularen Magneten, dem Molekül Mn12Ac, zu untersuchen. Ziel dieser Untersuchungen war die Vermessung einer besonderen quantenmechanischen Eigenschaft, dem Eigendrehimpuls (Spin). Spins richten sich ähnlich kleinen Stabmagneten in einem äußeren Magnetfeld aus und bestimmen so die Magnetisierung des Materials. Sie richten sich sowohl in einem von außen angelegten Feld, als auch an den Feldern im Inneren des Materials aus. Ändern lässt sich die Orientierung der Spins durch die Einstrahlung von Licht, wobei nur solche Lichtquanten Spinübergänge verursachen, deren Energie genau der Spinübergangsenergie entsprechen. In Molekülen verschwindet die Ausrichtung der Spins normalerweise wieder sobald das äußere Magnetfeld abgeschaltet wird. In einer kleinen, aber wichtigen Klasse von Molekülen sind die inneren Wechselwirkungen aber so stark, dass sie ein magnetisches Gedächtnis besitzen und ihre Magnetisierung auch nach Abschalten des Feldes behalten. Dies sind die Molekularen Magneten. Leider haben sie diese Eigenschaften bisher nur bei sehr tiefen Temperaturen nahe dem absoluten Nullpunkt. Um diese Eigenschaften weiter zu optimieren, um vielleicht einmal Molekulare Magneten bei Raumtemperatur einzusetzen zu können, sind vor allem Messverfahren wie das am HZB aufgebaute Experiment notwendig.  Bahnbrechend ist dabei die Kombination der Instrumentierung – zum einen die Anwendung von kohärenter Synchrotronstrahlung im TeraHertzbereich, verbunden mit einem sehr starken Magneten von 11 Tesla, und einem ultra hochauflösenden FTIR-Spektrometer. Mit dem am HZB verfügbaren so genannten low alpha Modus erreichten Schnegg und Kollegen eine 103-fach höhere Intensität im Vergleich zu klassischen Quellen. Damit ist es möglich, einen sehr breiten Frequenzbereich mit höchster Auflösung in wenigen Minuten abzufahren und somit zeitliche Änderungen magnetischer Eigenschaften festhalten zu können.  Aufgebaut wurde das Spektrometer im Rahmen des BMBF geförderten Netzwerkprojektes EPR-Solar, das es den Forschern am HZB erlaubt, mit Partnern an der FU Berlin, dem Max-Planck Institut für Eisenforschung, dem Forschungszentrum Jülich und der TU München dedizierte Methoden der EPR für den Einsatz in der Energieforschung zu entwickeln. Bisher mit so großem Erfolg, dass das BMBF ein weiteres weltweit einmaliges 263 GHz EPR-Spektrometer fördert, das Ende des Jahres ebenfalls in Adlershof in Betrieb genommen werden soll. [...]
  • <div class="bildlupe"></div>
<div class="InhaltSpalte Rechts"><a id="c237861" name="c237861"></a>
<p>Auf dem Bild schwebt der Dipolmagnet &uuml;ber einem gek&uuml;hlten Supraleiter, ein aus Yttrium- Barium-Kupferoxid (YBCO) bestehender keramischer Stoff.</p>
    Dreidimensionale Bildgebung- erstmalige Einblicke in Magnetfelder
    3D-Bilder werden nicht nur in der Medizin erzeugt, etwa mithilfe der Röntgen- oder Kernspinresonanztomographie. Auch Materialwissenschaftler blicken gern ins Innere eines Körpers. Forschern des Berliner Hahn-Meitner-Instituts (HMI) ist es nun in Kooperation mit der Technischen Fachhochschule Berlin (TFH) erstmals gelungen, Magnetfelder im Inneren von massiven, nicht transparenten Materialien dreidimensional darzustellen. Das berichten Nikolay Kardjilov und Kollegen in der aktuellen Ausgabe der Zeitschrift Nature Physics, die eine Online-Version als Highlight-Beitrag in dieser Woche vorab veröffentlicht. [...]
  • Nachricht
    Magnetische Fingerabdrücke im Fotostrom

    Wissenschaftlern des Hahn-Meitner-Instituts Berlin (HMI) sowie der Freien Universität (FU) Berlin ist ein außergewöhnlicher Einblick ins Innere von organischen Materialien gelungen. Die Physiker konnten im Fotostrom erstmals eine Quantensignatur magnetisch aktiver Zentren in einer molekularen Schicht beobachten. Daraus ergeben sich neue Möglichkeiten sowohl für das Ein- und Auslesen von Quanteninformationen in molekularen Spinquantencomputern als auch für ein verbessertes Verständnis von organischer Photovoltaik.  [...]

  • <p>Modell des Hochfeldmagneten im Ma&szlig;stab 1:5</p>
    Der weltweit stärkste Magnet für Neutronenexperimente wird in Berlin errichtet
    Der Kooperationsvertrag zwischen dem Hahn-Meitner-Institut Berlin (HMI) und dem National High Magnetic Field Laboratory (NHMFL) Tallahassee (Florida State University) zum Bau eines neuen Hochfeldmagneten ist unterzeichnet worden. Er wird der weltweit stärkste Magnet für Neutronenstreuexperimente. Von den Experimenten an dem Magneten erwarten Forscher neue Erkenntnisse zu Fragen aus der Physik, Chemie, Biologie und den Materialwissenschaften, unter anderem Beiträge zum Verständnis der Hochtemperatursupraleitung. [...]
  • <p>Anordnung der Natriumatome im Natriumkobaltoxid, wenn 80% der verf&uuml;gbaren Natriumpl&auml;tze besetzt sind. Die Farben Rot und Blau entsprechen den zwei m&ouml;glichen Positionen der Natriumatome.</p>
    Nanomuster bringen Strom unter Kontrolle: Natriumkobaltoxid als perfektes Material für Laptop-Batterien, als Kühlmittel oder Supraleiter
    Regelmäßige Muster aus Natriumatomen mit Strukturen im Nanometerbereich machen Natriumkobaltoxid zu einem perfekten Material für Laptop-Batterien, effiziente Kühlmittel oder Supraleiter – das berichten Wissenschaftler des Berliner Hahn-Meitner-Instituts, des CEA-Forschungszentrums in Saclay bei Paris und der Universität Liverpool in der neuesten Ausgabe des Wissenschaftsmagazins Nature. Dabei bestimmt die genaue Anordnung der Natriumatome die Eigenschaften des Materials, wobei das jeweilige Natriummuster sehr empfindlich von der Dichte an Natriumatomen abhängt. Diese ist mit chemischen Methoden leicht veränderbar, und man kann so aus einem anfangs metallischen Material einen Isolator und dann einen Supraleiter machen. Man bringt dazu das Material in eine elektrochemische Zelle und ändert die Spannung. [...]
  • Nachricht
    Stromsignal hinterlässt in Manganitkristall magnetische Spur

    Optische und kristallographische Experimente belegen erstmals, dass man magnetische Signale durch elektrische Felder erzeugen kann. Für die jetzt veröffentlichten Experimente („Magnetic phase control by an electric field“, Nature, 29. 7. 2004, 430 / 541-544) wurden Manganitkristalle (HoMnO3) mit hexagonaler Atomstruktur untersucht. [...]

  • Nachricht
    Bose-Einstein-Kondensat: Magnetfelder erzeugen ungewöhnlichen Materiezustand

    In einem Experiment am Hahn-Meitner-Institut in Berlin wurden zum ersten Mal die magnetischen Eigenschaften eines Kristalls für die Erzeugung eines Bose-Einstein-Kondensats genutzt. Dieser ungewöhnliche Materiezustand entstand, als der Kristall in ein starkes Magnetfeld von 14 Tesla gebracht wurde und konnte mit Hilfe von Neutronen aus dem Forschungsreaktor des Hahn-Meitner-Instituts nachgewiesen werden. Mit Magnetfeldern von bis zu 17 Tesla (mehr als das 200.000-fache des Erdmagnetfelds) bei Experimenten mit Neutronen stehen in Berlin weltweit einzigartige Forschungsmöglichkeiten zur Verfügung, die Voraussetzung für Erzeugung und Nachweis des Kondensats waren. [...]

  • Nachricht
    EU-Projekt zu exotischen Eigenschaften von Helium-3-Atomen

    Mit einer Förderung von rund einer Million Euro, verteilt über drei Jahre, startet am Hahn-Meitner-Institut ein internationales Grundlagenprojekt, das der weiteren Erforschung der faszinierenden exotischen Eigenschaften des Helium-3 Atoms gilt. Bei den erhofften Ergebnissen geht es sowohl um neue Modelle zur Theorie des Magnetismus als auch um universelle Mechanismen für die treibenden Kräfte sogenannter Phasenübergänge.