A Magnetic and Structural Investigation of the Composition Dependance of the Local Order in Amorphous Tb-Fe.

The properties of ferrimagnetic amorphous Tb-Fe prepared by magnetron cosputtering over a range of composition from 9 to 40 at.%Tb have been extensively examined. No sign of crystallinity is found for any of these samples by transmission electron microscopy or X-ray diffraction. The gross properties such as saturation moment and Curie temperature are well-behaved over this entire range. However, the magnetic anisotropy, which is an extremely sensitive probe of local structure, exhibits a relatively abrupt transition at 22 at.%Tb, the magnetic compensation composition. No change in such properties as anisotropy is expected to occur at the magnetic compensation composition, and indeed results to be described below suggest that this coincidence is indeed simply accidental. Deposition parameters are varied in an attempt to understand the unexpected transition in the local structural order.