Magnetic Anisotropy Of Films Research Articles

A novel method for the measurement of crystal anisotropy in magnetic films

A method of using the transverse initial susceptibility to measure the magnetocrystalline anisotropy of single crystal films is reported. By using transverse magneto-optic effect no delicate suspensions or pick-up coils are required. Observations on a (100) oriented nickel film are described.

Switching of Thin Anisotropic Magnetic Films as a Function of the Rate and Amplitude of the Applied Field

The switching of thin anisotropic magnetic films by sinusoidal fields varying in frequency from 103 to 106 cps and having amplitudes up to 18 Oe has been studied and the results compared with both theory and previous pulse-field measurements. As the amplitude of the switching field is increased, it is concluded that the reversal mechanism changes from irreversible domain wall motion to nonuniform rotation of the magnetization, the point at which the transition occurs increasing with frequency. This conclusion is in disagreement with previously published work. A possible dependence of the switching coefficients on film thickness is also noted.

1250. Angular nd magnitude disperson of the anisotropy in Magnetic films: T. S. Crowther, J. Appl. Phys., 34 (3), March 1963, 580

1250. Angular nd magnitude disperson of the anisotropy in Magnetic films: T. S. Crowther, J. Appl. Phys., 34 (3), March 1963, 580

Angular and Magnitude Dispersion of the Anisotropy in Magnetic Films

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.

Fiber Texture and Magnetic Anisotropy in Evaporated Iron Films

The fiber texture and magnetic anisotropy of evaporated iron films have been studied as a function of film thickness. It is found that there are three textures present: [110], [111], and [221]. In thin films, the [111] texture is dominant. It is also found that the magnetic anisotropy is of the order of 2×104 ergs/cm3 for 350-A films and decreases with increasing thickness. On the basis of this experiment and information from earlier experiments, several theories of the origin of magnetic anisotropy in films are examined, and shown to be inadequate for iron films. A theory for the origin of the anisotropy is proposed, based primarily on the magnetic energy associated with an array of vacancy needles. These vacancy needles can also qualitatively explain the resistivity anisotropy and dichroism observed by other workers.