Natural oxide formation on cobalt investigated with the magneto-optical Kerr effect

We have studied the magneto-optical Kerr effect (MOKE) of air-annealed Co thin films. Structural investigations reveal the formation of a double layered Co oxide (fcc Co/sub 3/O/sub 4/)/Co metal structure. MOKE spectra, measured in the photon energy range 0.8/spl les/E/sub ph//spl les/5.5 eV, show characteristic changes as a function of the annealing time and temperature. In particular, we observe the occurrence of resonance type enhancements with peak Kerr rotations of /spl theta//sub K/=-5.5 deg. The experimental spectra can be quantitatively reproduced using bilayer optical stack calculations.