Sputtered FexCoyO100-x-yperpendicular magnetic films

Partialy oxidized iron based thin films FexCoyO100-x-y(x+y>50) prepared by rf sputtering are found to have a strong perpendicular magnetic anisotropy which overwhelms the shape anisotropy in a certain composition range. The magnetism of these films could be arise from long and thin metallic ferromagnetic phase precipitating between columnar structure of non-magnetic oxide matrix. In these films, the matrix phase is mainly FexO (x<1). FexO is a metastable phase, and decomposes into Fe and Fe3O4at temperature below 570°C, but sputtered FexCoyO100-x-yfilms are very stable below 150 °C and have a strong corrosion resistance against humidity and NaCl solution.