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

最近的fs时间尺度上的实验揭示了不寻常的淬灭机制的磁性多层膜系统，这暗示了伴随着退磁过程的空间分量。这是目前解释的超快自旋扩散过程通过磁性材料和跨界面产生超快自旋相关的运输过程。我们想研究这样的磁界面，使用软X射线和XUV辐射反射几何。这种散射几何形状允许映射出磁性多层系统的界面和表面的电荷和自旋密度分布，并识别对自旋系统的变化特别敏感的倒易空间中的位置。使用XFELs在XUV制度，我们要测量时间分辨的自旋和电荷分布的演变与超短红外激光脉冲照射后的界面结构。实验将研究界面结构中超快自旋扩散过程的细节。反射率产生的垂直自旋密度分布的细节，而漫散射通道允许按照磁相关长度平行于界面的深度分辨的方式。 因此，我们希望绘制出完整的可用Q空间的磁性多层膜系统的照射后，与超短激光脉冲，并遵循相应的自旋密度分布的空间和时间的演变。结果将提供独特的见解的物理自旋扩散和输运过程中的磁界面结构。

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.