Perpendicular anisotropy in rare earth-transition metal amorphous films prepared by dual ion beam sputtering

The effect of resputtering on perpendicular magnetic anisotropy has been investigated for amorphous Gd-Co, Gd-Fe, Tb-Co and Tb-Fe films using a dual ion beam sputtering system. In Tb-Co and Tb-Fe films, perpendicular anisotropy increases remarkably owing to resputtering, while in Gd-Co and Gd-Fe films, it changes only through compositional change caused by resputtering. It is likely that the different behaviors between two cases are due to the fact that Tb is anisotropic and Gd is isotropic atom. However, its mechanism is not clear.