Soft Magnetic Properties of Highly Resistive Co-Al-N Alloy Films

The effects of the Al and N content on the structure and properties of Co_.95Fe_.05-Al-N films prepared by rf reactive magnetron sputtering using (N₂+Ar) gas were studied. TEM observations revealed that nitrided films are composed of heterogeneous phases with a very fine network structure. It was found that the properties of films are determined mainly by the combination of the Al and N concentrations. The coercivity of films containing more than 10 at% Al decreases with increasing N content, even when the film thickness is more than 2 μm. A steep increase in the electrical resistivity and a slight decrease in the magnetization of films containing more than 15 at% Al were observed during the initial increase in the N concentration, and both electrical resistivity and magnetization decreased rapidly when the N concentration was the same as that of Al. These anomalies are attributed to intergranular materials, indicating the presence in these films of a phase rich in Al and N.