Isothermal annealing behavior of zero-magnetostrictive permalloy films II experimental

The relaxation process of the uniaxial anisotropy during isothermal magnetic annealing is studied in zero-magnetostrictive Permalloy films. The measurements were performed by creating the anisotropy under a dc magnetic field in isotropic films, which were deposited and stabilized in a rotating field at various temperatures up to about 350°C. It is found that the annealing property consists of two separate stages with different activation energies and frequency factors. The activation energy of each stage is found to distribute continuously in a narrow range. The mean value of the activation energy, the range of the distribution and the frequency factor are respectively 0.85 eV, ±0.15 eV, 10⁷sec^-1for the first stage, and 2.2 eV, ±0.13 eV, 10¹⁴sec^-1for the second stage. The fractional anisotropy of each stage varies depending on the stabilization treatment. However, the frequency factor of the first stage and the total anisotropy are nearly constant regardless of the stabilization. Agreeing quantitatively with a theory, the separation into two annealing stages can be explained on the basis whether the vacancies, on which the reorientation of the atom-pair orderings depends, are in excess or not.