X-ray Resonant Scattering and Holography with Application to Magnetization Dynamics

Abstract

We introduce resonant magnetic scattering using extreme ultraviolet radiation and soft X-rays. We discuss time-resolved studies of lateral magnetization dynamics in thin film systems with nanometre spatial resolution on ultrafast timescales based on classical ensemble-averaged reciprocal-space information provided by incoherent scattering. Moreover, we provide a formalism to expand the resonant atomic scattering factor into the corresponding charge and magnetic scattering amplitude components. We also examine the opportunities offered by interference-based approaches, which have only recently become available due to the development of short-pulse soft-X-ray sources with large coherent photon flux. Correlation analysis of speckle patterns and X-ray holography are discussed, with the latter currently being the only commonly used approach for sub-50 nm resolution magnetization imaging at free-electron X-ray lasers and high harmonic generation sources. We discuss pioneering work and examples of scattering-based experiments on magnetization dynamics, focusing predominantly on laser-induced lateral dynamics in thin films and multilayers on the femtosecond to nanosecond timescale. In addition to approaches providing temporal resolution via pump–probe experiments, we provide details on real-time imaging of magnetization dynamics in thermal equilibrium based on a combination of coherent X-ray scattering and holography.