X-ray specular and off-specular diffuse scattering of magnetic interface structures at XFEL sources - investigating ultrafast spin transport processes

• Applicants: Professor Dr. Christian Gutt; Professor Dr. Ullrich Pietsch
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 271933576

Recent experiments on fs time scales revealed unusual quenching mechanisms in magnetic multilayer systems, which hint towards a spatial component accompanying the demagnetization process. This is currently interpreted in terms of ultrafast spin-diffusion processes through magnetic materials and across interfaces yielding an ultrafast spin-dependent transport process. We want to study such magnetic interfaces using soft X-ray and XUV radiation in reflection geometry. This scattering geometry allows to map out the charge and spin density profiles of interfaces and surfaces of magnetic multilayer systems and to identify positions in reciprocal space being particular sensitive to changes in the spin-system. Using XFELs in the XUV regime we want to measure time resolved the evolution of spin and charge profiles across interface structures upon irradiation with an ultra-short IR laser pulse. The experiments shall investigate details of the ultrafast spin diffusion processes across interface structures. Reflectivity yields details of the perpendicular spin density profile while the diffuse scattering channels allow to follow magnetic correlation lengths parallel to the interface in a depth resolved manner. Thus we want to map out the full available Q-space of magnetic multilayer systems upon irradiation with an ultrashort laser pulse and follow the space and time evolution of the corresponding spin density profiles. The results will give unique insights into the physics of spin diffusion and transport processes across magnetic interface structures.

• DFG Programme: Research Grants