Stress and Magnetic Anisotropy in Thin Permalloy Films

Abstract

A UNIAXIAL magnetic anisotropy is observed in thin nickel–iron films which have been deposited, in the presence of a uniform magnetic field, on to a heated glass substrate supported in vacuum. Macdonald¹ and Finegan and Hoffman² have reported that both nickel and iron films can be in a state of anisotropic stress. Nickel, for example, can contain an anisotropic planar compression of about 5 × 10⁸ dynes/ cm.². Such an anisotropic stress, if present in the nickel–iron films, could contribute to the magnetic anisotropy both directly through the magnetostriction, and indirectly through stress-induced iron-pair directional ordering, as suggested by Zener³. Several authors^4–6 have used such stresses in explaining, at least in part, the magnetic anisotropy of thin nickel–iron films. However, no direction observations of the stress in evaporated nickel–iron films have been reported.