The growth and magnetic properties of Fe on (4×6)GaAs and S-(2×1)GaAs have been studied. Fe depositions were carried out onto the substrates held at room temperature using an e-beam evaporator. During the deposition, the ambient pressure was maintained at 10^-10 Torr. The results of reflection high-energy electron diffraction and electron-energy-loss spectroscopy showed that bcc-Fe band structures construct at different thicknesses between the two substrates, i.e. 2.8 for (4×6)GaAs and 7 for S-(2×1)GaAs. By magneto-optic Kerr effect measurements, strong uniaxial magnetic anisotropy was obtained for ultrathin Fe films, and two jumps in the hysteresis loops were observed for thicker Fe films. The calculations of the hysteresis shape indicated that two-jump behavior appears under coexistence of uniaxial and cubic anisotropy, and that the Fe film on S-(2×1)GaAs has stronger uniaxial anisotropy. The differences in properties between the two substrates were explained by the segregation of S that stabilizes the initial adsorption structure of Fe atoms on S-(2×1)GaAs.

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