Magnetic circular dichroism inL3-resonant soft-x-ray inelastic scattering of disordered Fe-Co alloys

We discuss the information given by dichroism measurements in soft-x-ray resonant scattering from magnetic systems with particular reference to experimental results on disordered ${\mathrm{Fe}}_{\mathrm{x}}$ ${\mathrm{Co}}_{1\mathrm{-}\mathrm{x}}$ alloys (x=0.05–0.9). We show how to recover the scattering cross sections from the raw data and we introduce the emission dichroism correlating with the difference between occupied valence states with opposite spin. We obtain direct evidence of the filling of Fe majority states upon dilution and of the dominant Fe minority states at ${\mathrm{E}}_{\mathrm{f}}$ (bcc structure); this is even more evident in Co due to the greater d-state occupation. The potential and limitations of this spectroscopic technique are illustrated.