The influence of stress and heat treatment on the magnetization of TbDyFe films

Amorphous (Tb_0.3Dy_0.7)₄₃Fe₅₇ films were prepared by DC magnetron sputtering. After annealing at 400 °C for 1 h, a small amount of (Tb, Dy)Fe₂ crystal grain precipitated from the amorphous film. The magnetization in the as-deposited film and the film treated at 200 °C is nearly isotropic. After treatment at 300 and 400 °C, the films showed anisotropic magnetization with the easy axis parallel to the film surface. For the as-deposited films, stress applied to the films makes it magnetize slightly. Annealed below 200 °C, the coercivity of the films did not change. After 300 °C heat treatment, the coercivity, H_c, reduced because of the release of stress in the film. For the films with 400 °C heat treatment, H_c increased because partial crystallization occurred in the film.