SOFT MAGNETIC-PROPERTIES OF SPUTTERED CO-FE FILMS

This paper reports on the relationships between the crystal structure and the magnetic properties of Co-rich Co-Fe films prepared by rf diode sputtering in a mixed Ar and N2 gas atmosphere. The crystal structure changed from a bcc phase (110) preferred orientation to an fcc phase (100) preferred orientation while maintaining the nitrogen content in the film at less than 1 at. % as the N2 partial pressure increased to 3.8×10 -4 Torr. Corresponding to this change, the Bs, λs, and Hk values decreased from 21 kG, 2×10-5, and 20 Oe to 19 kG, 1×10-6, and 14 Oe, respectively, though the hard-axis Hc of about 3 Oe did not change. The nitrogen content in the film, the compressive internal stress, the resistivity, and the lattice constant for the fcc phase increased as the N 2 partial pressure increased from 3.8×10-4 Torr. Corresponding to these increases, Bs and Hc decreased while λs and Hk increased. It was found that Co-Fe films with an fcc phase (100) preferred orientation show good soft magnetic properties.