Magnetization dynamics and Gilbert damping in a hybrid Fe/GaAs heterostructure

In this paper, we studied the ultrafast magnetization dynamics and damping process in a hybrid epitaxial Fe/GaAs structure by using time-resolved magneto-optical measurements over various temperatures. The phenomenological Gilbert damping constant depended strongly on both the direction and strength of the applied magnetic field. The damping process was revealed to be dominated by incoherent spin-flip scattering, with involvement of the Fe/GaAs interfacial defects mediated two-magnon scattering. The intrinsic damping parameter was extracted at sufficiently high magnetic fields (or magnetization precession frequencies). Our results allow for better understanding of magnetization relaxation of Fe/GaAs heterostructure for its potential application in novel spintronic devices.