Magnetooptic depth sensitivity in a simple ultrathin film structure

Polar magnetooptics (MO) is able to probe the magnetization depth profile in ultrathin magnetic film structures on a nanometer scale. This information can be deduced by modelling the MO effects in the considered layered medium when performing MO experiments with a compensator or changing the wavelength of the incident light beam. Spectroscopic MO measurements are then helpful for analysing this phenomenon in detail. The in-depth selectivity of MO effects for magnetization is demonstrated for a simple ultrathin film structure consisting of two magnetic Co layers with perpendicular anisotropy separated by a non-magnetic Au spacer layer. The individual magnetic contributions of the two Co layers may be observed directly when performing MO Kerr measurements at selected compensator phase shifts or photon energies. The experimental data are interpreted by MO calculations in both cases.