EPITAXIAL FERROMAGNETIC MNAS THIN-FILMS GROWN BY MOLECULAR-BEAM EPITAXY ON GAAS - STRUCTURE AND MAGNETIC-PROPERTIES

We have studied structural and magnetic properties of epitaxial MnAs thin films with various thicknesses (L=1.0-200 nm) on GaAs substrates. The MnAs thin films were grown at 200-250°C on an As-rich disordered c(4×4) (001) GaAs surface by molecular-beam epitaxy (MBE). The growth direction of the MnAs was found to be along the [1̄100] axis of the hexagonal unit cell. X-ray spectra of the MnAs at room temperature have two peaks, indicating that the present MBE-grown MnAs films consist of the hexagonal ferromagnetic phase and orthorhombic paramagnetic phase. Magnetization measurements revealed that the MnAs thin films have perfectly square hysteresis characteristics with relatively high remnant magnetization Mr=300-567 emu/cm3 and low coercive field Hc=65-926 Oe, compared with those of epitaxial MnGa and MnAl thin films reported previously.