Excitation fluence dependence of spin-wave dynamics and intrinsic Gilbert damping in epitaxial Co2FeAl film

Abstract

Spin wave dynamics and transient reflectivity measurement in Co2FeAl film are studied under different excitation fluences by the time resolved pump-probe experiment with the external field applied normal to the film. We found that the excitation fluence has only a slight influence on the frequency of the spin wave, but greatly modulates the lifetime and intrinsic Gilbert damping. The lifetime of spin wave decreases but that of coherent acoustic phonon increases with increasing excitation fluence. The enhancement of electron-phonon scattering with increasing excitation fluence is proven to the dominant origin of the enhancement of the intrinsic Gilbert damping.