Formation of bct structure and high magnetic anisotropy in Fe-Co films with added V and C elements

A high amount of 0-20 at.% of C was added into an Fe-Co-V film by sputtering method, and the crystal structure transformed from body-centered cubic (bcc) to face-centered cubic (fcc) through body-centered tetragonal (bct) structure. In the Fe-Co without V, with increasing C content, the crystal structure changed discontinuously from bcc to fcc not through bct structure. On the other hand, in the Fe-Co with added 10 at.% of V, a single bct phase with the axial ratio c/a of ~1.2 formed in samples with added 5-10at.% of C. The saturation magnetization of these samples (Fe-Co-V-C) were approximately 1200-1500 kA/m and the uniaxial magnetic anisotropy constants were approximately 10
⁶
J/m
³
.