Damping Constants of Ni-Fe and Ni-Co Alloy Thin Films

Abstract

Gilbert's damping constants, $alpha$ , of Ni-Fe and Ni-Co thin films are determined by Q-band ferromagnetic resonance (FMR) analysis. $alpha$ is calculated from the resonance width of the FMR spectrum. $alpha$ of Ni $_85$ Fe $_15$ film is found to be 0.0034, which is one-fourth of those of Ni film $(alpha =0.013)$ and Co $(alpha =0.013)$ . $alpha$ of the Ni $_100 - x$ Co $_ x$ specimens increases with decreasing the Co concentration from 100 to 68 at%, and the $alpha$ value of Ni $_32$ Co $_68$ film has the maximum value of 0.0021. The $alpha$ values of the Ni-Co specimens are nearly the same as those of the Co-Cr-Ta and the Co-Cr-Pt.