Professorship at the University of Augsburg for Felix Büttner
Prof. Dr. Felix Büttner has been called at the University Augsburg. He heads now a joint research group at HZB. © Uni Augsburg
Felix 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.
Felix Büttner has been leading a junior research group at HZB since the beginning of 2020, funded by the Young Investigator Grant of the Helmholtz Association. In spring 2022, he was awarded the Walter Schottky Prize of the German Physical Society for his pioneering achievements in the field of magnetic skyrmions. Since July, he holds a professorship at the Institute of Physics, University Augsburg.
Felix Büttner studied in Göttingen and received his doctorate in 2013 for his work at the interface of magnetism and X-ray physics. After a stint in industry at Daimler AG, he worked as a postdoctoral researcher at the Massachusetts Institute of Technology from 2015-2020.
Prof. Dr. Büttner investigates nanotextures in magnetic thin-film materials and drives the development of ultrahigh-resolution X-ray microscopy techniques. The aim is to understand the particle-like dynamics of such topological textures and to prepare their application in information technology.
Under a cooperation agreement between the University of Augsburg and HZB, Büttner will work one day a week at HZB, where he runs laboratories in Wannsee and carries out measurements at BESSY II. His research group will remain in full size.
- Magnetic imaging: Micro-flowers increase the local magnetic fieldMaterials with magnetic nanostructures have many potential applications such as in spintronics. To explore such materials, nanoscale magnetic-sensitive imaging techniques are very useful, but up to now only weak magnetic fields could be applied during the imaging process. Now an international collaboration led by Dr. Sergio Valencia, HZB, has developed an approach that overcomes this limitation. The team designed tiny magnetic flux concentrators (MFCs), into which the sample is placed. The geometry of the MFCs resembles a flower with a number of petals which focus the applied magnetic field into its center. This greatly expands the magnetic field range available during imaging, and so the range of magnetic systems that can be investigated. The micro-flowers, enhancing magnetic fields locally, can find application in different nanometric magnetic microscopy techniques.
- CIGS-perovskite tandem cell achieves record efficiency of 25.5 %A Berlin-based team from HZB and Center for the Science of Materials Berlin (CSMB) at the Humboldt-Universität zu Berlin has set a new record for a tandem solar cell. Using a combination of a CIGS semiconductor layer and perovskite, along with several optimised intermediate layers, they were able to convert 25.5% of sunlight into electrical energy. The previous record for this combination of materials and this size of cell stood at 24.6%. The new record has been certified and is visible in the prestigious Solar Cell Efficiency Tables (the "Green Tables"), which serve as the definitive ledger for the global photovoltaic community.
- Disorder creates new properties in compound semiconductorsAn international research team has demonstrated that the intrinsic disorder of the compound semiconductor CuInSnS₄ can be exploited to influence its optical properties. While the atomic vibrations also sense the local disorder, their response is averaged over many different local environments and therefore appear isotropic, as expected for a cubic crystal. In contrast, the optical excitations, known as excitons, are much more sensitive to the local arrangement of atoms. Surprisingly, they show a direction-dependent optical response even though the average crystal structure is cubic. These findings shed new light on the relationship between disorder and material properties, opening up new options for targeted 'disorder engineering' in optoelectronic and photocatalytic devices.