The influence of interface structure on the magneto-optical properties of Co/Pd multilayers

Magneto-optical Kerr effect (MOKE) spectra of Co/Pd multilayered structures (MLS), measured in the polar geometry over the spectral range 0.8-5.5 eV, are presented and compared to spectra obtained from ob initio band-structure calculations. It is shown that the MOKE spectra of the Co/Pd MLS calculated using the spin-polarized relativistic linear-muffin-tin-orbital method reproduce the experimental spectra only moderately well if ideal multilayer structures with sharp interfaces are assumed. Calculations of the magneto-optical (MO) response of MLS with imperfect interfaces modelled by introducing ordered compounds at the interface have also been performed. The results obtained reveal that the MOKE spectra of the Co/Pd MLS can be adequately reproduced using a model of limited interdiffusion within one or two atomic planes at the interface which results in the formation of a Pd-rich alloy. The role of the Pd spin polarization in the formation of the MO spectra as inferred from first-principles calculations is examined and discussed. Finally, the influence of thermal annealing on the MO properties of Co/Pd MLS is studied both experimentally and theoretically. The good agreement between the calculated spectra of the MLS and experimentally observed ones demonstrates the validity of the proposed models. The results obtained demonstrate the crucial role played by the interface microstructure in the formation of the MOKE spectra of the multilayered systems studied.