Growth and characterization of MnGa thin films with perpendicular magnetic anisotropy on BiSb topological insulator

We report on the crystal growth as well as the structural and magnetic properties of Bi0.8Sb0.2 topological insulator (TI)/MnxGa1-x bi-layers grown on GaAs(111) A substrates by molecular beam epitaxy. By optimizing the growth conditions and Mn composition, we were able to grow MnxGa1-x thin films on Bi0.8Sb0.2 with the crystallographic orientation of Bi0.8Sb0.2(001)[1 (1) over bar 0]//MnGa (001)[ 100]. Using magnetic circular dichroism (MCD) spectroscopy, we detected both the L1(0) phase (x < 0.6) and the D0(22) phase (x > 0.6) of MnxGa1-x. For 0.50 <= x <= 0.55, we obtained ferromagnetic L1(0)-MnGa thin films with clear perpendicular magnetic anisotropy, which were confirmed by MCD hysteresis, anomalous Hall effect as well as superconducting quantum interference device measurements. Our results show that the BiSb/MnxGa1-x bi-layer system is promising for perpendicular magnetization switching using the giant spin Hall effect in TIs. Published by AIP Publishing.