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

• The magnetization dynamics of MBE-grown Fe/GaAs film is studied by TR-MOKE.
• The magnetization damping of Fe/GaAs is studied at different temperature and fields.
• The intrinsic Gilbert damping constant is extracted at higher external magnetic fields.
• The spin-flip scattering and the two-magnon scattering dominated the damping process.

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.