Ferromagnetic resonance properties of Fe81-xNixGa19/Si(1 0 0) and Fe81-yNiyGa19/glass films

Abstract

Two series of Fe81 xNixGa19/Si(100) and Fe81 yNiyGa19/glass films, where x or y = 0-26, were made by the magnetron sputtering method. The film thickness (t(f)) was fixed at 100 nm. We have performed three kinds of experiments on these films: (i) the saturation magnetostriction (lambda(S)) measurement; (ii) the easy-axis and hard-axis magnetic hysteresis loop measurements; and (iii) the ferromagnetic resonance (FMR) experiment to find the resonance field (H-R) with an X-band cavity tuned at f(R) = 9.6 GHz. The natural resonance frequency, f(FMR), of the Kittel mode at zero external field (H = 0) is defined as f(FMR) (sic) nu[H(K)4-pi M-S](1/2), where gamma = 2 pi nu is the gyromagnetic ratio, H-K and 4 pi M-S are the uniaxial anisotropy field and saturation magnetization, and H-K << 4 pi M-S. The Gilbert damping constant, alpha, is calculated from the formula, alpha = [nu(Delta H)(S)]/(2f(R)), where (Delta H)(exp) = (Delta H)(S) + (Delta H)(A), (Delta H)(exp) is the half-width of the absorption peak around the resonance field H-R, (Delta H)(S) is the symmetric part of (Delta H)(exp), and (Delta H)(A) is the asymmetric part. The degree of asymmetry, (Delta H)(A)/(Delta H)(exp), is associated with the structural and/or magnetic inhomogeneities in the film. The main findings of this study are as follows: (A) f(FMR) tends to decrease, as x or y increases; (B) alpha decreases from 0.052 to 0.020 and then increases from 0.020 to 0.050, as x increases, and a decreases from 0.060 to 0.013 in general, as y increases; and (C) lambda(S) reaches a local maximum when x = 22. We conclude that the Fe59Ni22Ga19/glass film should be the most suitable for application in magneto-electric microwave devices. (C) 2013 Elsevier B.V. All rights reserved.