On the origin of the perpendicular anisotropy in rare earth-transition metal amorphous films

The induced anisotropy in amorphous (Co₉₃Zr₇)_100−x(RE)_x films has been studied. The sputter deposition was performed in a magnetic field. For RE = Nd, Pr, Dy and Tb, the formation of a well-defined in-plane uniaxial anisotropy K_u is related to the single-ion anisotropy of RE atoms. When RE = Gd and Sm, a biaxial anisotropy develops, comprising K_u and a perpendicular anisotropy K_p. This magnetic structure is expected to be related to the simultaneous formation of two distinct local structural configurations when the deposition temperature is higher than the critical value.