Structural origins of magnetic anisotropy in sputtered amorphous Tb-Fe films

Using X-ray-absorption fine-structure measurements, clear evidence was obtained for structural anisotropy in amorphous sputter-deposited TbFe films exhibiting perpendicular magnetic anisotropy. Modeling of the data shows that perpendicular anisotropy in these films is associated with Fe--Fe and Tb--Tb pair correlations which are greater in plane and Tb--Fe correlations which are greater perpendicular to the film plane. Upon annealing at 300 deg C, the measured structural anisotropy disappears and the magnetic anisotropy decreases to a level consistent with magnetoelastic interactions between the film and substrate.