Experimental and ab initio theoretical study of optical and magneto-optical properties of Co/Cu multilayers

The polar Kerr rotation and ellipticity spectra were measured in the spectral range 0.8-5.5 eV for a set of Co/Cu multilayered structures (MLS). The magneto-optical (MO) response of Co/Cu MLS being related to the sigma(xy)-part of the optical conductivity tensor was obtained from the Kerr spectra and tensor component sigma(xx), determined by spectroscopic ellipsometry. The self-consistent spin-polarized fully relativistic linear muffin-tin orbital method within the local spin-density approximation was used to calculate the electronic structure, optical, and MO properties of some model Co/Cu MLS. Good agreement between the measured and calculated optical and MO spectra is observed. The role of the spin-orbit coupling and exchange splitting at the Co and Cu sites, and the hybridization effects are examined and discussed. The spin-polarized Cu interface states appear to give a weak contribution to the sigma(xy)- and Kerr spectra whereas the latter ones are strongly influenced by the Cu-dominated optical spectra structure. The results obtained demonstrate that the MO properties of real large-period multilayered structures can be quantitatively predicted from first-principles band-structure calculations.