Element-specific magnetization dynamics of complex magnetic systems probed by ultrafast magneto-optical spectroscopy

The vision to manipulate and control magnetism with light is driven on the one hand by fundamental questions of direct and indirect photon-spin interactions, and on the other hand by the necessity to cope with ever growing data volumes, requiring radically new approaches on how to write, read and process information. Here, we present two complementary experimental geometries to access the element-specific magnetization dynamics of complex magnetic systems via ultrafast magneto-optical spectroscopy in the extreme ultraviolet spectral range. First, we employ linearly polarized radiation of a free electron laser facility to demonstrate decoupled dynamics of the two sublattices of an FeGd alloy, a prerequisite for all-optical magnetization switching. Second, we use circularly polarized radiation generated in a laboratory-based high harmonic generation setup to show optical inter-site spin transfer in a CoPt alloy, a mechanism which only very recently has been predicted to mediate ultrafast metamagnetic phase transitions. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Experience with MCP-based Photon Detector at FLASH2

We present recent experimental results on statistical measurements of amplification process in FLASH2 SASE FEL. Micro-channel plate (MCP) detector is used for precise measurements of the radiation pulse energy. DAQ based software is used for cross-correlation of the SASE FEL performance and electron beam jitters. Analysis of machine jitters essential for SASE FEL operation has been performed. Application of gating strategy with measured machine parameters allows us to isolate machine jitters from fundamental SASE fluctuations. Subsequent application of statistical techniques for characterization of SASE FEL radiation allows to derive such important quantities as gain length, saturation length, radiation pulse duration, coherence time, and degree of transverse coherence

The Evolution of the DOOCS C++ Code Base

This contribution traces the development of DESY's control system DOOCS from its origins in 1992 to its current state as the backbone of the European XFEL and FLASH accelerators and of the future Petra IV light source. Some details of the continual modernization and refactoring efforts on the 1.5 million line C++ code base are highlighted

Element-Specific Magnetization Dynamics of Complex Magnetic Systems Probed by Ultrafast Magneto-Optical Spectroscopy

The vision to manipulate and control magnetism with light is driven on the one hand by fundamental questions of direct and indirect photon-spin interactions, and on the other hand by the necessity to cope with ever growing data volumes, requiring radically new approaches on how to write, read and process information. Here, we present two complementary experimental geometries to access the element-specific magnetization dynamics of complex magnetic systems via ultrafast magneto-optical spectroscopy in the extreme ultraviolet spectral range. First, we employ linearly polarized radiation of a free electron laser facility to demonstrate decoupled dynamics of the two sublattices of an FeGd alloy, a prerequisite for all-optical magnetization switching. Second, we use circularly polarized radiation generated in a laboratory-based high harmonic generation setup to show optical inter-site spin transfer in a CoPt alloy, a mechanism which only very recently has been predicted to mediate ultrafast metamagnetic phase transitions