Epitaxial MnGa/NiGa magnetic multilayers on GaAs

Abstract

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.