Angular and Magnitude Dispersion of the Anisotropy in Magnetic Films

Abstract

A physical model for the angular and magnitude dispersion of the anisotropy of magnetic films has been investigated. It is based on the effect of anisotropic strain on a microscopic scale acting on magnetostrictive material. If the strain-induced anisotropy component Hks is less than the intrinsic unstrained value Hko the following results are obtained: (1) Regions with highest and lowest local Hk values are unskewed. Regions with maximum skew have approximately average Hk. (2) Although local skew α and the resultant anisotropy Hk are not uniquely related since each depends on both direction and magnitude of applied stress, their maximum values for a composite film having isotropic strain on a macroscopic scale are related by; αmax=(1/2) arcsin (Hk max−Hko)/Hko. The following measurements have been taken which tend to support the theory. (1) The angular distribution function has been found to be Gaussian using a measurement technique for which the angle can be read with ±0.1°. (2) The broadening of the Stoner-Wohlfarth switching threshold depends on both angular and magnitude variations. A machine calculation was performed to give this broadening as a function of ασ and Hkσ, the standard deviation of the angular and magnitude distributions, respectively. Using a measured ασ=1.0° the best fit gave Hkσ=0.1 H̄k, which agrees with theory within a factor of three. The data showed that the Hk distribution is not completely symmetric but has approximately 10% of the film with Hk>2Hko. Measurements of angular dispersion as a function of applied stress for films of known chemical inhomogeneity yield results an order of magnitude below those calculated, using the model described. This is thought to represent the ``stiffening'' effect of magnetostatic and exchange interactions.

Structure and magnetic properties of etched NiFeCo films

“…The initial thickness of the films d, was between 200 and 1000 A. Chemical etching was carried out in a 1% aqueous solution of sulphuric acid a t a temperature of (20 4 1) "C. The coercive force H , was measured from the hysteresis loop ; the anisotropy field H , was found by improved Kobelev technique [4], and the angular dispersion ago by the Crowther technique [5]. The effect of etching upon the surface relief of the film was studied with the help of transmission and scanning electron microscopy and the method of replicas.…”

Study of the effect of the deposition rate and seed layers on structure and magnetic properties of magnetron sputtered FeNi films

“…In addition, voids and nonmagnetic inclusions could be a source of angular dispersion of anisotropy. When the magnetization veers around these imperfections the angular dispersion increases [23].…”

“…Angular dispersion of magnetic anisotropy was estimated using the hysteresis method [23]. These measurements were carried out on samples with dimensions of 1 cm × 1 cm.…”

How to give a sense to senseless vectors in plane

“…and by a phase a given by: tan2a = -is 1 sin2a 1 +.K 2 sin2a 2 t cos 2a j +K 2 cos 2a 2 (1) (2) It is easy to see that the result of the addition ft = K t + K 2 in the senseless vectors set is independent of the chosen origin of phases.…”

“…Some authors [2][3][4][5] have studied theoretically and tested experimentally the addition law of uniaxial magnetic anisotropies mixed in a measurement plane. This law coincides with the formal one presented here for the addition of 'senseless' vectors in plane.…”