Sources of Anisotropy in Amorphous Magnetic Thin Film

Macroscopic magnetic anisotropy is induced in the amorphous rare earthtransition metal alloys such as TB-Fe when they are prepared by vapor deposition processes. The role of the vapor deposition process in producing the structural anisotropy which underlies the magnetic anisotropy has been explored and results compared with proposed models. It was shown that the anisotropy is independent of the state of stress in the film during the growth, and does not depend on film thickness, results inconsistent with recently-proposed models. Most significantly, the anisotropy was shown to be induced by a thermally- activated growth process. This process was hypothesized to involve rearrangement of local adatom configurations into energetically-favorable orientations which minimize surface energy during growth, a process analogous to the frequently- observed crystallographic texturing of polycrystalline thin film. The anisotropy vanishes upon subsequent annealing of the films, emphasizing the critical role of the surface during growth.