New instrument at BESSY II commences user operation
The Russian-German Laboratory operating its own beamline at BESSY II. © HZB/Michael Setzpfandt
The new measurement station will be available beginning at the next beamtime period. © HZB/Michael Setzpfandt
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.
The Russian-German Laboratory has existed at BESSY II for more than fifteen years, operating its own beamline for absorption and photoelectron spectroscopy. Now, in addition to the dipole beamline, lab members have also set up a powerful measurement station for spin- and angularly-resolved photoelectron spectroscopy and photoelectron microscopy on an undulator beamline. This measurement station was developed together with Technische Universität Dresden (TU Dresden) and Freie Universität Berlin through a German Federal Ministry of Education and Research (BMBF) grant. The measurement station along with Russian and German user-support teams will be available beginning at the next beamtime period.
International Workshop
Prof. Eckart Rühl of Freie Universität Berlin, chairman of the laboratory's steering committee, emphasises the strong ties with Russian colleagues. “In order to familiarise Russian research groups with the new opportunities offered by the instrument, we have launched the instrument as part of an international workshop”, explains Rühl. 26 researchers (seven women and nineteen men) from Russia, Germany, Spain, and Japan will report on their experiments over the two-day event.
Measuring spin-orbit interactions
“In recent years, spin-orbit interactions, i.e. the coupling of magnetic orientation to the direction of motion of electrons, has developed without pause to become a main research topic in solid-state physics. This was particularly due to the discovery of a new class of materials called topological insulators, which was honoured by the 2016 Nobel Prize in Physics“, explains Prof. Oliver Rader of the HZB, in whose department the new instrument is located. “This led to a sharp increase in international demand for experiments that can detect spin directly.” The current interest in stable two-dimensional solids might also contribute to this demand as well, for novel two-dimensional magnets such as CrI3 have been discovered in recent years.
Reception at the Russian Embassy
The great importance attached to the laboratory was exemplified by the participation of the Embassy of the Russian Federation: Alexander Rusinov, attaché for the Department of Education, Science, and Technology at the Embassy, gave the opening address, and the Federation Ambassador received the participants in the evening.
Partners of the collaboration:
The collaboration is being supported by Freie Universität Berlin, TU Dresden, TU Freiberg, and the Helmholtz-Zentrum Berlin on the German side, while from the Russian side by St. Petersburg State Univerisity, the Kurchatov Institute (Moscow), Ioffe Physical-Technical Institute of the Russian Academy of Sciences (Ioffe Institute, St. Petersburg), and the Shubnikov Institute of Crystallography (Moscow).
- 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.
- Fractons as information storage: Not yet quite tangible, but closeA new quasiparticle with interesting properties has appeared in solid-state physics - but so far only in the theoretical modelling of solids with certain magnetic properties. An international team from HZB and Freie Universität Berlin has now shown that, contrary to expectations, quantum fluctuations do not make the quasiparticle appear more clearly, but rather blur its signature.
- Graphene on titanium carbide triggers a novel phase transitionResearchers have discovered a Lifshitz-transition in TiC, driven by a graphene overlayer, at the photon source BESSY II. Their study sheds light on the exciting potential of 2D materials such as graphene and the effects they can have on neighboring materials through proximity interactions.