Thickness Effect on Magnetostriction of Fe and Fe$_{98}$ B$_{2}$ Thin Films

摘要

Film thickness effect on saturation magnetostriction of Fe and Fe$_{98}$B$_{2}$ thin films has been investigated in relation to the film strain. Saturation magnetostriction varies from $-4times 10^{-6}$ to $+3times 10^{-6}$ with decreasing the film thickness from 40 to 10 nm, changing the sign at around 15 nm for both the Fe and the Fe $_{98}$B $_{2}$ films. The saturation magnetostrictions of Fe$_{98}$B$_{2}$ films of 7 and 5 nm thicknesses are $+10times 10^{-6}$ and $+17times 10^{-6}$, respectively. XRD patterns observed for these films show only the bcc(110) reflection, which indicates that the films consist of oriented nanocrystals with bcc structure. The lattice spacing, $d_{{rm bcc}(110)}$, increases with decreasing the film thickness from 20 to 10 nm for both films. With decreasing the film thicknesses, both magnetostriction and strain increase. These experimental results support the theoretical study which suggests a strain effect on magnetostriction.