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

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 Ni₈5Fe₁5film 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 Ni₁00 - xCo_ xspecimens increases with decreasing the Co concentration from 100 to 68 at%, and the$alpha$value of Ni₃2Co₆8film 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.