THEORETICAL-STUDY OF THE X-RAY DICHROISM OF 5D-IMPURITY ATOMS DISSOLVED IN FERROMAGNETIC FE

Recent measurements of the X-ray absorption at the L-edges of 5d-impurity atoms dissolved in ferromagnetic Fe resulted in a very pronounced dependence of the corresponding absorption spectra on the helicity of the radiation. Because the physical origin of this X-ray dichroism is the subtle interplay of spin-polarization and spin-orbit coupling, a satisfying description of the phenomenon has to treat spin-magnetism and relativistic effects on the same level. The spin-polarized relativistic Korringa-Kohn-Rostoker-Green's function method of band structure calculation provides a very sound, parameter-free basis for such a description. We have adopted this approach to calculate the electronic structure and from this the absorption spectra of 5d-impurities dissolved in ferromagnetic Fe. The results of our calculations are in very satisfying agreement with experiment and permit a detailed discussion of the observed spectra and their dependence on the polarization of the X-ray radiation. © 1989.