Applications of resonant x-ray scattering

The performances of modern synchrotron x-ray sources (degree of polarization and energy tunability) have led to a large variety of experiments that were formerly considered as impossible due to the inherent weakness of the expected signal. In this presentation, we concentrate on two particular aspects of importance for the study of magnetism: the origin of multi-q magnetic structures and the existence of induced magnetic moments. These two problems can be tackled with the help of resonant and non-resonant x-ray scattering methods through the polarization dependence of the scattering amplitude. The nature of magnetic induced moments can be traced by tuning the photon energy to absorption edges of nominally nonmagnetic atoms and by studying the polarization dependence of the resonant intensities. Similarly, the existence of multi-q magnetic structures can be assessed by monitoring the polarization of intensities scattered at forbidden positions in reciprocal space.