Describing the origin of uniaxial magnetic anisotropy (UMA) is generally
problematic in systems other than single crystals. We demonstrate an in-plane
UMA in amorphous CoFeB films on GaAs(001) which has the expected symmetry of
the interface anisotropy in ferromagnetic films on GaAs(001), but strength
which is independent of, rather than in inverse proportion to, the film
thickness. We show that this volume UMA is consistent with a bond-orientational
anisotropy, which propagates the interface-induced UMA through the thickness of
the amorphous film. It is explained how, in general, this mechanism may
describe the origin of in-plane UMAs in amorphous ferromagnetic films.Comment: 4 pages, 4 figure
