X-Ray Imaging of Magnetic Structures

The characterization of nanoscale magnetic structures, their static properties, and fast spin dynamics with polarized soft X-rays has become an indispensable analytical tool due to the unique features of those probes. The spectroscopic magnetic response serves as a fingerprint of the specimen and can give quantitative information on element-specific spin and orbital magnetic moments. Images of magnetic domain structures at a spatial resolution down to nearly 10 nm, ultimately in all three dimensions, can be obtained with various X-ray microscopy techniques and can further be combined with stroboscopic pump-probe schemes to image the spin dynamics of spin structures, such as the motion of domain walls in nanowires or the vortex core dynamics in micropatterned magnetic elements. Next generation sources of polarized soft X-rays such as X-ray free electron lasers or high-harmonic generation laser sources hold the promise to provide nanometer spatial and femtosecond time resolution, enabling to address thus fundamental magnetic length and time scales in magnetism. This paper reviews the various X-ray imaging techniques using polarized soft X-rays by summarizing their characteristic features, recent achievements, and current limitations as well as future opportunities. A brief overview on other magnetic imaging techniques are given to set magnetic X-ray imaging techniques into context.