HZB Newsroom
- Spintronics: A new path to room temperature swirling spin texturesA team at HZB has investigated a new, simple method at BESSY II that can be used to create stable radial magnetic vortices in magnetic thin films.
- Neutron experiment at BER II reveals new spin phase in quantum materialsNew states of order can arise in quantum magnetic materials under magnetic fields. An international team has now gained new insights into these special states of matter through experiments at the Berlin neutron source BER II and its High-Field Magnet. BER II served science until the end of 2019 and has since been shut down. Results from data at BER II are still being published.
- Spintronics: X-ray microscopy unravels the nature of domain wallsMagnetic skyrmions are tiny vortices of magnetic spin textures. In principle, materials with skyrmions could be used as spintronic devices, for example as very fast and energy-efficient data storage devices. But at the moment it is still difficult to control and manipulate skyrmions at room temperature. A new study at BESSY II analyses the formation of skyrmions in ferrimagnetic thin films of dysprosium and cobalt in real time and with high spatial resolution. This is an important step towards characterising suitable materials with skyrmions more precisely in the future.
- Spintronics at BESSY II: Domain walls in magnetic nanowiresMagnetic domains walls are known to be a source of electrical resistance due to the difficulty for transport electron spins to follow their magnetic texture. This phenomenon holds potential for utilization in spintronic devices, where the electrical resistance can vary based on the presence or absence of a domain wall. A particularly intriguing class of materials are half metals such as La2/3Sr1/3MnO3 (LSMO) which present full spin polarization, allowing their exploitation in spintronic devices. Still the resistance of a single domain wall in half metals remained unknown. Now a team from Spain, France and Germany has generated a single domain wall on a LSMO nanowire and measured resistance changes 20 times larger than for a normal ferromagnet such as Cobalt.
- Catherine Dubourdieu receives ERC Advanced GrantProf. Dr. Catherine Dubourdieu heads the Institute “Functional Oxides for Energy-Efficient Information Technology” at HZB and is Professor at the Physical and Theoretical Chemistry division at Freie Universität Berlin. The physicist and materials scientist specialises in nanometre-sized functional oxides and their applications in information technologies. She has now been awarded a prestigious ERC Advanced Grant for her research project “LUCIOLE”, which aims at combining ferroelectric polar textures with conventional silicon technologies.
- Scientists Develop New Technique to Image Fluctuations in MaterialsA team of scientists, led by researchers from the Max Born Institute in Berlin and Helmholtz-Zentrum Berlin in Germany and from Brookhaven National Laboratory and the Massachusetts Institute of Technology in the United States has developed a revolutionary new method for capturing high-resolution images of fluctuations in materials at the nanoscale using powerful X-ray sources. The technique, which they call Coherent Correlation Imaging (CCI), allows for the creation of sharp, detailed movies without damaging the sample by excessive radiation. By using an algorithm to detect patterns in underexposed images, CCI opens paths to previously inaccessible information. The team demonstrated CCI on samples made of thin magnetic layers, and their results have been published in Nature.
- Spintronics: A new tool at BESSY II for chirality investigationsInformation on complex magnetic structures is crucial to understand and develop spintronic materials. Now, a new instrument named ALICE II is available at BESSY II. It allows magnetic X-ray scattering in reciprocal space using a new large area detector. A team at HZB and Technical University Munich has demonstrated the performance of ALICE II by analysing helical and conical magnetic states of an archetypal single crystal skyrmion host. ALICE II is now available for guest users at BESSY II.
- Dynamics in one-dimensional spin chains newly elucidatedNeutron scattering is considered the method of choice for investigating magnetic structures and excitations in quantum materials. Now, for the first time, the evaluation of measurement data from the 2000s with new methods has provided much deeper insights into a model system – the 1D Heisenberg spin chains. A new toolbox is available for elucidating future quantum materials has been achieved.
- Rhombohedral graphite as a model for quantum magnetismGraphene is an extremely exciting material. Now a graphene variant shows another talent: rhombohedral graphite made of several layers slightly offset from each other could enlighten the hidden physics in quantum magnets.
- New road towards spin-polarised currentsThe transition metal dichalcogenide (TMD) series are a family of promising candidate materials for spintronics. A study at lightsource BESSY II has unveiled that in one of those materials even simple linear polarised light is sufficient to selectively manipulate spins of different orientations. This result provides an entirely new route for the generation of spin-polarised currents and is a milestone for the development of spintronic and opto-spintronic devices.
- Professorship at the University of Augsburg for Felix BüttnerFelix Büttner has led a junior research group at HZB. Now he has accepted a call to the University of Augsburg. As head of a joint research group, he will continue his studies of magnetic skyrmions at BESSY II.
- Humboldt Fellow Alexander Gray comes to HZBAlexander Gray from Temple University in Philadelphia, USA, is working with HZB physicist Florian Kronast to investigate novel 2D quantum materials at BESSY II. With the fellowship from the Alexander von Humboldt Foundation, he can now deepen this cooperation. At BESSY II, he wants to further develop depth-resolved X-ray microscopic and spectroscopic methods in order to investigate 2D quantum materials and devices for new information technologies even more thoroughly.
- Buckyballs on gold are less exotic than grapheneC60 molecules on a gold substrate appear more complex than their graphene counterparts, but have much more ordinary electronic properties. This is now shown by measurements with ARPES at BESSY II and detailed calculations.
- Spintronics: Giant Rashba semiconductors show unconventional dynamics with potential applicationsGermanium telluride is a strong candidate for use in functional spintronic devices due to its giant Rashba-effect. Now, scientists at HZB have discovered another intriguing phenomenon in GeTe by studying the electronic response to thermal excitation of the samples. To their surprise, the subsequent relaxation proceeded fundamentally different to that of conventional semimetals. By delicately controlling the fine details of the underlying electronic structure, new functionalities of this class of materials could be conceived.
- Thermal insulation for quantum technologiesNew energy-efficient IT components often only operate stably at extremely low temperatures. Therefore, very good thermal insulation of such elements is crucial, which requires the development of materials with extremely low thermal conductivity. A team at HZB has now used a novel sintering process to produce nanoporous silicon aluminium samples in which pores and nanocrystallites impede the transport of heat and thus drastically reduce thermal conductivity. The researchers have developed a model for predicting the thermal conductivity, which was confirmed using experimental data on the microstructure of the samples and their thermal conductivity. Thus, for the first time, a method is available for the targeted development of complex porous materials with ultra-low thermal conductivity.
- Fermi Arcs in an Antiferromagnet detected at BESSY IIAn international cooperation has analysed samples of NdBi crystals which display interesting magnetic properties. In their experiments including measurements at BESSY II they could find evidence for so called Fermi arcs in the antiferromagnetic state of the sample at low temperatures. This observation is not yet explained by existing theoretical ideas and opens up exciting possibilities to make use of these kind of materials for innovative information technologies based on the electron spin rather than the charge.
- "We can be proud that it worked out": BESSY and the Transregio-SFB on ultrafast spin dynamics
Collaborative Research projects as “Sonderforschungsbereiche” funded by Deutsche Forschungsgemeinschaft enable universities to build up their own research capacities. In the Transregio Sonderforschungsbereich 227 Ultrafast Spin Dynamic, the Freie Universität Berlin and the University in Halle-Wittenberg have also included HZB as a partner. The slicing facility of BESSY II plays a central role in this collaboration. With excellent results from the first phase, the Transregio-SFB 227 has completed its first interim review and is now preparing for the challenges ahead. A conversation with the two HZB physicists Niko Pontius and Christian Schüßler-Langeheine about the importance of such funding programmes for the research field.
- From Dublin to Berlin as a Humboldt Research FellowDr. Katarzyna Siewierska joins the group of Prof. Alexander Föhlisch as a postdoctoral Humboldt Research fellow. She has earned her PhD at Trinity College in Dublin, Ireland, and plans in the next two years to explore the electronic structure and spin dynamics of half-metallic thin films at BESSY II. Understanding these spintronic materials better may pave the way for more energy efficient data storage technologies.
- Green information technologies: Superconductivity meets SpintronicsSuperconducting coupling between two regions separated by a one micron wide ferromagnetic compound has been proved by an international team. This macroscopic quantum effect, known as Josephson effect, generates an electrical current within the ferromagnetic compound made of superconducting Cooper-pairs. Magnetic imaging of the ferromagnetic region at BESSY II has contributed to demonstrate that the spin of the electrons forming the Cooper pairs are equal. These results pave the way for low-power consumption superconducting spintronic-applications where spin-polarized currents can be protected by quantum coherence.
- Neutron data help to reveal “spooky” entanglement in quantum magnetsUsing data from the British neutron source ISIS from the year 2000, research teams have now demonstrated the viability of a “quantum entanglement witness” capable of proving the presence of entanglement between magnetic particles, or spins, in a quantum material. A team from HZB led by Prof. Bella Lake was also involved in the analysis.
- Walter-Schottky-Award for Felix BüttnerThe Walter Schottky Prize honours outstanding work by young physicists in solid-state research. For 2022, the award goes to HZB physicist Dr Felix Büttner for his groundbreaking achievements in the field of magnetic skyrmions.
- 20 Years Russian-German Joint Laboratory at BESSY IITo mark its 20th anniversary, the Russian-German Laboratory at the BESSY II storage ring for synchrotron radiation in Berlin is organising an online workshop on 18 and 19 November. Scientists will discuss the future perspectives of Russian-German cooperation as well as innovative projects and new goals of the laboratory.
- Spintronics: Exotic ferromagnetic order in two-dimensionsAn international team has detected at HZB's vector magnet facility VEKMAG an unusual ferromagnetic property in a two-dimensional system, known as “easy-plane anisotropy”. This could foster new energy efficient information technologies based on spintronics for data storage, among other things. The team has published its results in the renowned journal Science.
- Ultrafast magnetism: heating magnets, freezing timeMagnetic solids can be demagnetized quickly with a short laser pulse, and there are already so-called HAMR (Heat Assisted Magnetic Recording) memories on the market that function according to this principle. However, the microscopic mechanisms of ultrafast demagnetization remain unclear. Now, a team at HZB has developed a new method at BESSY II to quantify one of these mechanisms and applied it to the rare-earth element Gadolinium, whose magnetic properties are caused by electrons on both the 4f and the 5d shells. This study is completing a series of experiments done by the team on Nickel, Iron-Nickel Alloys. Understanding these mechanisms is useful for developing ultrafast data storage devices.
- A sharp look into tiny ferroelectric crystalsWhat happens to ferroelectric materials when their dimensions are greatly reduced? A team of researchers at HZB has now been able to show how this question can be answered in a detailed way.
- Disorder brings out quantum physical talentsQuantum effects are most noticeable at extremely low temperatures, which limits their usefulness for technical applications. Thin films of MnSb2Te4, however, show new talents due to a small excess of manganese. Apparently, the resulting disorder provides spectacular properties: The material proves to be a topological insulator and is ferromagnetic up to comparatively high temperatures of 50 Kelvin, measurements at BESSY II show. This makes this class of material suitable for quantum bits, but also for spintronics in general or applications in high-precision metrology.
- Future information technologies: Topological materials for ultrafast spintronicsA team led by HZB physicist Dr. Jaime Sánchez-Barriga has gained new insights into the ultrafast response of topological states of matter to femtosecond laser excitation. Using time- and spin-resolved methods at BESSY II, the physicists explored how, after optical excitation, the complex interplay in the behavior of excited electrons in the bulk and on the surface results in unusual spin dynamics. The work is an important step on the way to spintronic devices based on topological materials for ultrafast information processing.
- World's first video recording of a space-time crystalA 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.
- Future Information Technologies: Germanium telluride's hidden properties at the nanoscale revealedGermanium 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.
- Modelling shows which quantum systems are suitable for quantum simulationsA 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).
- Mathematical tool helps calculate properties of quantum materials more quicklyMany 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.
- Robust high-performance data storage through magnetic anisotropyThe 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.
- Future information technologies: 3D Quantum Spin Liquid revealedQuantum 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.
- New interaction between light and matter discovered at BESSY IIA 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.
- 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.
- BESSY II: Ultra-fast switching of helicity of circularly polarized light pulsesAt 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.
- New Helmholtz Young Investigator Group at HZBDr. 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.
- Topological materials for information technology offer lossless transmission of signalsNew 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.
- New instrument at BESSY II commences user operationA 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.
- Dynamic pattern of Skyrmions observedTiny 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).
- 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.
- Spintronics by “straintronics”: Superferromagnetism with electric-field induced strainData 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.
- Neutrons scan magnetic fields inside samplesWith 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.
- Future information technologies: nanoscale heat transport under the microscopeA 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.
- Future information technology: Microscopic insight into processes when magnets suddenly heat upMagnetic 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.
- Neutron tomography: Insights into the interior of teeth, root balls, batteries, and fuel cellsA 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.
- Writing and deleting magnets with lasersScientists 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.
- HZB scientist got the dissertation prize at the spring conference of the Deutsche Physikalische GesellschaftDr. 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.
- User research at BER II: New insights into high-temperature superconductorsAfter 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.
- HZB researcher Catherine Dubourdieu appointed full professor at Freie Universität BerlinCatherine 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.
- Future IT: Antiferromagnetic dysprosium reveals magnetic switching with less energyHZB 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.
- High Field Magnet at BER II: Insight into a hidden orderA 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.
- Optical control of magnetic memory – new insights into fundamental mechanismsA 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.
- Kickoff for Joint Lab with IFW DresdenThe 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.
- New at Campus Wannsee: CoreLab Quantum MaterialsHelmholtz-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.
- Green IT: New switching process in non-volatile spintronics devicesPhysicists 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.
- NEAT starts user operationThe 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!
- A new record at BESSY II: ten million ions in an ion trap cooled for the first time to 7.4 KMagnetic ground states spectroscopically ascertained
- Methods at BESSY II: Versatile cross-correlator for ultrafast X-ray experimentsParticularly 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".
- Future Information Technologies: New combinations of materials for producing magnetic monopolesAn 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.
- 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.
- Novel state of matter: Observation of a quantum spin liquidA 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.
- New effect on laser induced switching for higher data densitiesAn 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.
- Spintronics: Resetting the future of Heat Assisted Magnetic RecordingA 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.
- Topological insulators: Magnetism is not causing loss of conductivityIf 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.
- Metal Oxide Sandwiches: New option to manipulate properties of interfacesA 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.
- Anomalous magnetic structure and spin dynamics in magnetoelectric LiFePO4A 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.
- Spins in Graphene with a Hedgehog TextureHZB researchers demonstrate a fundamental property of the electron spin in graphene
- New technique enables magnetic patterns to be mapped in 3DAn 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.
- Crystal structure and magnetism – new insight into the fundamentals of solid state physicsHZB team decodes relationship between magnetic interactions and the distortions in crystal structure within a geometrically “frustrated” spinel system
- Emergence of a “devil’s staircase” in a spin-valve systemA 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.
- Eine lange Nacht geballtes Wissen tankenFührungen an der Neutronenquelle, Experimente zur Energie für Groß und Klein, Licht-Show und vieles mehr
- New options for spintronic devices: Switching between 1 and 0 with low voltageScientists 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.
- Stretch and relax! – Losing one electron switches magnetism on in dichromiumAn 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.
- Insight into inner magnetic layersMeasurements at BESSY II have shown how spin filters forming within magnetic sandwiches influence tunnel magnetoresistance – results that can help in designing spintronic components.
- BESSY II – From Pico to Femto – time resolved studies at BESSY II180 scientists attended the workshop on time resolved studies
- Spintronics: Dance of the nanovorticesThe 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.
- Messages From SpaceGeologists 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.
- “VEKMAG” at BESSY II creates 3D magnetic fields in samplesTogether 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.
- Batman lights the way to compact data storageResearchers 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.
- New light shed on electron spin flipsResearchers 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).
- Hochfeldmagnet sucht NeutronenleiterAm 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.
- 26 tesla! High field magnet exceeds everyone’s expectationsIt’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.
- Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten in BonnDas 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.
- Leading scientists on topological insulators met in BerlinFrom July 7-10, 150 researchers met in Berlin to discuss recent findings in the field of topological insulators.
- Invitation: Reception Final Assembly of HFMSix 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.
- Magnetic switch gets closer to applicationScientists 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.
- High field magnet for neutron scattering has made its way to ItalyAfter 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.
- Domain walls as new information storageDomain wall motion imaging: at high speeds, material defects no longer play a role
- Prof. Dr. Alan Tennant has accepted a new positionProf. 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).
- International Conference in Neutron Scattering: HZB-contributions awardedMore 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.
- Shedding light on magnetoelectric couplingEffect opens up new possibilities for digital data storage
- 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:
- Ultrafast Spin Manipulation at THz frequenciesThe 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.
- 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.
- 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.
- X-ray laser FLASH uncovers fast demagnetization processWith 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).
- Prof. Alan Tennant has won the Europhysics Prize, Europe’s foremost prize for condensed matter physicsTennant 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.
- Researchers find spins acting like real bar magnets in a new materialAn 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).
- In topological insulator debate, scientists document mate-rials' high-level surface state stabilityFollowing scientists' announcement, new class of materials stakes its claim to holding the key to computer technology's future.
- Resetting the future of MRAMHelmholtz-Zentrum Berlin developed a magnetic valve that novel electronic devices can be realistic
- Important Milestones Celebrated for the Neutron Instrument NEAT IIAround 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
- 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.
- Locating the ElusiveHZB scientists observe how a material at room temperature exhibits a unique property – a „multiferroic“ material with potential uses for cheap and quick data storage.
- Nutzerexperiment bei BESSY-II: Ein schneller Schalter für MagnetnadelnWissenschaftler 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.
- Ultra-Fast Magnetic Reversal ObservedA newly discovered magnetic phenomenon could accelerate data storage by several orders of magnitude.
- Imaging with neutrons: Magnetic domains shown for the first time in 3DSo 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.
- Many Roads lead to Superconductivity
HZB-Scientists discovered a unique feature of Superconductivity
- Ein schneller Blick auf komplexe OrdnungGrundlagenforschung 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.
- First the orbit, then the spinNovel 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.
- 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.
- Data at the end of the Tunnel
Electric control of aligned Spins improves Computer Memory
- Golden ratio discovered in a quantum worldResearchers 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.
- Wie Kreisel auf atomarer Ebene miteinander wechselwirkenDie 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.
- 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.
- Orbital 2009 - internationaler Workshop am HZBAm 7. und 8. Oktober 2009 findet am Helmholtz-Zentrum Berlin am Standort Adlershof der Workshop "Orbital 2009" mit 95 Teilnehmern aus aller Welt statt.
- Magnetic monopoles detected in a real magnetResearchers 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
- Forscher sehen Molekulare Magneten in neuem LichtErkenntnisse 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.
- Dreidimensionale Bildgebung- erstmalige Einblicke in Magnetfelder3D-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.
- 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.
- Der weltweit stärkste Magnet für Neutronenexperimente wird in Berlin errichtetDer 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.
- Nanomuster bringen Strom unter Kontrolle: Natriumkobaltoxid als perfektes Material für Laptop-Batterien, als Kühlmittel oder SupraleiterRegelmäßige 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.
- 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.
- 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.
- 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.