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

Amorphous (Tb0.3Dy0.7)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, Hc, reduced because of the release of stress in the film. For the films with 400°C heat treatment, Hc increased because partial crystallization occurred in the film.