Film thickness dependence of magneto-optical and magnetic properties in Co/Pt and Co/Pd multilayers

Co/Pt and Co/Pd multilayers were prepared by two source dc‐magnetron sputtering. It was found that magneto‐optical and magnetic properties of the multilayers were affected by total film thickness. Kerr rotation angle of the films was remarkably enhanced at the film thickness below several hundred angstroms. The theoretical calculation clarified that the increase of Kerr rotation was due to optical interference and multiple reflection. The shape of Kerr loop also depends upon the film thickness and a perfect squareness is attained only at the ultrathin region. The improvement in the squareness of Kerr loop can be explained by the change in the domain structure from a stripe domain to a single domain. These behaviors at the ultrathin region in the multilayers are suitable for new magneto‐optical recording media.