Soft Magnetic Properties and Microstructure of Co-Ta-N Films

Co-(0 to 15 at%) Ta-N sputtered films were studied in order to clarify the correlation between the structure, induced magnetic anisotropy, local anisotropy fluctuation, and soft magnetic properties. The results for electrical resistivity and film magnetostriction indicate that the temperature Tx1 at which Co crystallites are formed from an amorphous structure is lower than the temperature at which crystallites of Ta-nitrides are formed. The difference was 150°C for Co-15 at% Ta-N films. A large uniaxial magnetic anisotropy was induced at Tx1 by annealing in a magnetic field, and even after crystallization, a uniaxial anisotropy of magnitude 2×10³ erg/cc could be reversibly induced by annealing in a magnetic field.