LAUSR

Abstract Magnetization dynamics of Co2FeSi full Heusler alloy films have been investigated by time-resolved magneto-optical Kerr effect (TR-MOKE). For the samples grown at a substrate temperature (Ts) lower than 350 °C, an obvious dual frequency phenomenon is found in the TR-MOKE signals due to the coexistence of a strong main precession mode and a weak additional mode. The amplitude of the additional high frequency mode decreases and becomes undetectable with increasing Ts. On the contrary, the magnetic damping parameter α0 measured at the highest external field of H = 15kOe is as low as 0.004 for low Ts samples, it rises abruptly at Ts > 350 °C and even reaches 0.023 at Ts = 480 °C in spite of the improved atomic ordering. We attribute the greatly increased magnetic damping to the enhanced two-magnon scattering occurred at grain-grain boundaries. This study provides a comprehensive insight into the spin precession and magnetic damping behaviors of Heusler alloy films, which will be helpful for developing high frequency spintronic devices.