Magneto-optical Kerr effects on Co-Ag granular films

The magneto-optical Kerr effects on Co-Ag granular films annealed at 100°C, 250°C, 400°C, 500°C were studied. The optical constants, the complex dielectric function and magneto-optical Kerr parameters were measured at room temperature. For the sample Co₆Ag₉₄, the strong Kerr effect enhancement is observed around the Ag plasma edge. With the annealing temperature increasing, the values of the Kerr rotation θ_k increase, the enhanced peaks appear in the Kerr rotation and the peak positions are shifted toward the low photon energy region. As the Co composition x increases, the Kerr effect enhancement is weakened and disappears when x>50 at. %. From the analysis of the experiment data, it is concluded that the magneto-optical Kerr effect enhancement is due to the presence of the Ag plasma edge.