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

摘要

We report on the crystal growth as well as the structural and magnetic properties of Bi_(0.8)Sb_(0.2) topological insulator (TI)/Mn_xGa_(1-) _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 Mn_xGa_(1-) _x thin films on Bi_(0.8)Sb_(0.2) with the crystallographic orientation of Bi_(0.8)Sb_(0.2)(001)[110]//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 Mn_xGa_(1-) _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/Mn_xGa_(1-) _x bi-layer system is promising for perpendicular magnetization switching using the giant spin Hall effect in TIs.