Tuning of the Magnetic Damping Parameter by Varying Cr Composition in Fe_1-xCr_x Alloy

We investigate the magnetic damping parameter of Fe_1-xCr_x thin films using the time-resolved magneto-optical Kerr effect technique. It is demonstrated that the overall effective damping parameter is enhanced with the increasing Cr concentration. The effective damping at high field \alpha_0 is found to be significantly enhanced when increasing the Cr concentration with the \alpha_0=0.159 in the Fe_45Cr_55 enhanced by 562% compared with that of \alpha_0=0.024 in the pure Fe film. This study provides a new approach of controlling the effective damping parameter with a desired magnitude via varying Cr composition.