Magnetic-mediated carrier, phonon and spin dynamics in the ferromagnetic semiconductor (In,Fe)Sb

We investigate the carrier, phonon and spin dynamics in the ferromagnetic semiconductor (In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^*(~40 K) and T^†(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modification in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^* and T^†, which not only illustrate the spin-related scatterings closely related to the long-range magnetic order but also reveal the D’yakonov Perel and Elliot-Yafet mechanisms dominating at temperatures below and above T^†, respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited (In,Fe)Sb.