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 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 Ni100-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.