Thermal Stability of Compositionally Modulated Amorphous Nitride Alloy Films

Co-based amorphous alloy films composed of non-nitride and nitride layers were prepared by N₂ reactive sputtering. The layered films showed soft magnetic properties when the layer thickness was less than 300 Å. The saturation magnetization (4πM_s) was increased by nitriding. The 4πM_s of the non-nitride films in the present study was about 7400 G, and that of the layered films was about 8400 G. The layered structure changes into a compositionally modulated structure after annealing above 400°C, and the 4πM_s of films is thereby increased up to 11,300 G. The resulting compositionally modulated films are thermally stable and were found to have a high crystallization temperature (T_x > 600°C).