Carl-Ramsauer-Award for excellent dissertation
Dr. Raphael Jay has received this year's Carl-Ramsauer-Prize of the German Physical Society of Berlin. © Max Threlfall
Dr. Raphael Jay has received this year's Carl-Ramsauer-Prize of the German Physical Society of Berlin (DPGzB). The prize honours outstanding dissertations in physics and related fields and will be awarded during a festive colloquium on 18 November 2020 in the Magnus-Haus.
Dr. Raphael Jay studied ultrafast charge transfer dynamics in iron complexes during his doctorate at the University of Potsdam under the supervision of Prof. Alexander Föhlisch. In the context of the EDAX project at BESSY II, he carried out measurements with ultra-short X-ray pulses, whereby the experimental infrastructure was also used for measurements at the Free Electron Laser LCLS in Stanford.
The complex measurement results were analysed within the HZB Virtual Institute "Dynamic Pathways in multimensional Landscapes" in collaboration with Stockholm University. In future, this type of experiment will also be possible at the European XFEL in Hamburg, which was developed in parallel within the EDAX project. Raphael Jay is now continuing his scientific work at the University of Uppsala.
- BESSY II: New sample environment allows glimpse into thermocatalytic processesA novel measurement cell allows, for the first time, soft and hard X-ray investigations under high pressures of up to 20 bar and temperatures of up to 400°C. This provides new insights into thermocatalytic processes, such as the Fischer-Tropsch synthesis for producing synthetic fuels. The development of the measurement cell is considered a significant achievement within the Care-O-Sene project.
- 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.
- 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.