Origin of anisotropy inhomogeneity in thin permalloy films

Inhomogeneity of induced uniaxial anisotropy in evaporated Permalloy thin films is found to be divided roughly into two classes, namely, intrinsic and extrinsic inhomogeneities. The former, which is the short wavelength component of the anisotropy change and results in the magnetization ripple, is found to originate mainly from the randomly oriented magnetocrystalline anisotropy and the magnetoelastic anisotropy in crystallites. The latter, the long wavelength component of the anisotropy change, seems to result from the same origin as that of the skew. Annealing experiments of the intrinsic angular dispersion showed that the activation energy of the relaxation process was about 0.5 eV. This result suggests that the magnetoelastic anisotropy originates mostly from the stress due to divacancies and/or dislocations.