Theoretical calculation of x-ray magnetic circular dichroism spectra for Gd/Cu multilayers at the Cu K edge

To explain the remarkable oscillations observed in the x-ray magnetic circular dichroic absorption spectra from Gd/Cu multilayers at the Cu K edge, ab initio calculations have been made using the fully relativistic Korringa-Kohn-Rostoker formalism including the spin-orbit coupling. The result reproduces well the oscillatory profiles in the near-edge region, but the peaks and valleys do not correspond to those in the difference density of states [Formula: see text] for the unoccupied Cu 4p band above the Fermi level. We find small spin and orbital moments on the interfacial Cu sites, which decay towards the core of the Cu layer. Surprisingly, neither the spin nor the orbital moments die out on the Cu sites four atomic layers away from the Co interface. This extended polarization is ascribed to the hybridization of the Cu 4p and the Gd 5d states. The accuracy of the calculation is supported by the near-bulk spin and orbital moments found on the Gd sites away from the interface.