Influence of growth temperature on magneto-transport properties of Fe3Ge thin film on GaAs (100)

Fe3Ge thin films with cubic structure have been grown on GaAs (100) substrates at 100, 300, and 500 degrees C by molecular beam epitaxy (MBE). Metallic behavior of the films was confirmed by temperature dependence of resistivity. All films grown at 100, 300, and 500 degrees C showed negative magnetoresistance (MR). However, the MR curve's shapes changed with growth temperature. The strong anomalous Hall effect was observed in the thin film grown at 300 degrees C while it is very weak in the thin film grown at 100 degrees C. The modification from positive to negative Hall signal above 150 K in the thin film grown at 500 degrees C indicates a competition between positive charge (holes) and negative charge (electrons) which could be related to the spin-orbit coupling between Fe3Ge and Fe3Ge2 phases. The thin film grown at 300 degrees C, which clearly shows magneto-transport properties was selected for M-H measurements. A soft ferromagnetic behavior with saturation magnetization of 580 emu/cm3 was observed in temperature range from 20 K to 400 K.