Multiple-scattering theory of magnetic x-ray circular dichroism

Abstract

Multiple-scattering theory is generalized to take into account the effects of spin-orbit interaction and spin polarization of the photoelectron that are at the origin of the magnetic x-ray circular dichroism (MXD) effect observed in x-ray-absorption spectra where the final state of the photoelectron is delocalized. The basic framework of this treatment is nonrelativistic and relativistic corrections are considered as perturbations. The multiple-scattering approach sheds light on various aspects of MXD spectra: the relation between ${\mathit{L}}_{\mathrm{II}}$- and ${\mathit{L}}_{\mathrm{III}}$-edge magnetic signals, the difference between K-edge and ${\mathit{L}}_{\mathrm{I}\mathrm{I},\mathrm{I}\mathrm{I}\mathrm{I}}$-edge spectra, and the analysis of spin-polarized extended x-ray-absorption fine structure. The equivalence between multiple-scattering and band-structure formalisms is used to show that useful information concerning the spin-polarized projected density of states of the photoabsorbing atom can be obtained from an analysis of MXD spectra.