Influence of multiple reflection and optical interference on the magneto-optical properties of Co-Pt alloy films investigated by using the characteristic matrix method

The magneto-optical Kerr effect (MOKE) of a multilayered system was describ ed by using the characteristic matrix method based on the electromagnetic w ave theory. In addition 60 the multiple reflection and the optical interfer ence, a contribution from the plasma resonance absorption of a metallic lay er can be included in the formulation. As an example, we carried out a simu lation of the MOKE for Co0.25Pt0.75 alloy films with and without a Pt buffe r layer. It was found that the Kerr rotation and the read-out figure of mer it of a film directly deposited on a glass substrate were enhanced at a thi ckness below 40 nm owing to the multiple reflection and the optical interfe rence. This enhancement was more remarkable at long wavelengths when light was incident on the substrate side. However, the introduction of a Pt buffe r layer was not beneficial in improving the Kerr rotation and the figure of merit, although it promoted the perpendicular magnetic anisotropy of the f ilm, as reported. The simulated results for an alloy thickness beyond the p enetration depth of light agreed well with the experimental data for a prep ared "thick" alloy film.