Effect of Si Composition on Static and Dynamic Magnetic Properties of FeSi Films

This article describes the effect of Si composition (x) on static and dynamic magnetic properties of 30 nm-thick FexSi(100-x) polycrystalline films (9.7 <= x <= 21.7). In the experiments, in-plane and out-of-plane effective damping constant (alpha//, alpha perpendicular to) were investigated by broadband ferromagnetic resonance (B-FMR). The difference between alpha// and alpha(perpendicular to) in Fe-Si films indicated that the damping constant was attributed to extrinsic damping for alpha//. Moreover, a simple relation between the saturation magnetostriction (lambda(s)) and the in-plane effective damping can be obtained for Fe-Si films. In the range of lambda(s) less than (2.59 +/- 0.05) x 10-5, alpha// slightly increased as x was decreased. Meanwhile, for lambda(s) more than (2.59 +/- 0.05) x 10-5, alpha// significantly increased as x was increased except x = 15.7. alpha// reached a minimum as lambda(s) was (2.59 +/- 0.05) x 10-5 for x = 13.7. These results demonstrate that the different behavior exhibited by alpha// depends on lambda(s).