EPITAXIAL MNGA/NIGA MAGNETIC MULTILAYERS ON GAAS

We have grown a new class of epitaxial metallic multilayers consisting of ultrathin ferromagnetic tetragonal MnGa and nonmagnetic (CsCl-type) NiGa on (001) GaAs substrates by molecular beam epitaxy. Reflection high energy electron diffraction and cross-sectional transmission electron microscopy analyses show that MnGa/NiGa multilayers with atomically abrupt interfaces are formed with the expected epitaxial orientations, and, in particular, that the c-axis of the tetragonal structure of the MnGa film is aligned perpendicular to the substrate. Perpendicular magnetization of the MnGa/NiGa multilayers was evidenced by both vibrating sample magnetometer and extraordinary Hall effect measurements at room temperature, with higher values (M(r) = 267-302 emu/cm3) of remanent magnetization than those of previously reported MnGa and MnAl thin films. The capability of growing this new class of materials will allow a new degree of artificial materials design on semiconductor substrates.