Magnetic Properties of Sputtered Co-Ni/Cr Multilayer Films

Multilayer films consisting of 70 at% Co-30 at% Ni alloy and Cr were prepared by dc magnetron sputtering. The number of (Co-Ni/Cr) bilayers and the ratio of the thicknesses of the Co-Ni and Cr layers were varied, while the total Co-Ni thickness was maintained at 900 Ã…. Appropriate combinations of the number of bilayers and the thickness ratio serve to improve both the coercive force and the squareness ratio of the films without an appreciable decrease in saturation magnetization. The change in saturation magnetization can be explained in terms of interdiffusion near Co-Ni/Cr interfaces. The change in the coercive force of multilayer films, the value of which is determined by the coercive force of the first Co-Ni/Cr bilayer, is controlled by the thickness of the Co-Ni layers.