XRMS

Xrms, short for X-ray resonant magnetic scattering, is a technique used to study magnetic order in materials by exploiting the resonant enhancement of X-ray scattering near an absorption edge. It is element-specific and sensitive to the orientation of magnetic moments, which makes it useful for determining magnetic structures in crystals, thin films, and interfaces.

Principle: When the incident X-ray energy is tuned near an absorption edge, the atomic scattering factor contains magnetic terms that depend on the magnetic moment. Using polarized X-rays and scanning energy, momentum transfer, and polarization, one can separate magnetic scattering from charge scattering and extract information about the direction and magnitude of the magnetization on specific elements.

Experiment: XRMS measurements are typically performed at synchrotron facilities. The sample is illuminated with polarized X-rays and the scattered intensity is detected as a function of scattering angle, photon energy around the edge, and polarization state. Geometry choices (surface-sensitive vs bulk-sensitive) and detector setup allow access to magnetic diffraction peaks or reflectivity from thin films and multilayers.

Applications: XRMS is widely used to determine magnetic structures in ferromagnets, antiferromagnets, and ferrimagnets, as well as to study magnetic order in thin films, multilayers, and interfaces. Its element specificity enables selective probing of different constituents in compounds and multilayer stacks, and it can be combined with temperature and field control to study phase transitions and spin textures.

Relation and history: XRMS is related to resonant elastic X-ray scattering (REXS) and to X-ray magnetic circular/linear dichroism techniques such as XMCD. It began to be developed in the late 1980s and 1990s as synchrotron sources and polarization control improved.