Theoretical study of the magnetic x-ray dichroism of Os, Ir, Pt, and Au impurities in Fe

The electronic structure of the 5d impurities Os, Ir, Pt, and Au in ferromagnetic Fe has been studied by the spin-polarized, relativistic version of the Korringa-Kohn-Rostoker Green’s-function method. This approach simultaneously treats spin polarization and spin-orbit coupling and naturally allows for a theoretical investigation of effects arising from an interplay of both. Here the polarization dependence of x-ray absorption (magnetic x-ray dichroism) is considered. For all the impurities studied, the agreement with recent experimental ${\mathit{L}}_2$ and ${\mathit{L}}_3$ absorption spectra is very satisfactory. For Pt in Fe, a decomposition of the spectra into various absorption channels is presented and the applicability of a simplified model is discussed that interprets the spectra in terms of a spin-polarized band structure alone.