We investigate the magnetic properties and spin-orbit-torque-induced (SOT-induced) magnetization switching in Ta/MnGa/Cr and Ta/MnGa/NiAl structures. Out-of-plane hysteresis loops for the Ta/MnGa/Cr (NiAl) structures are skewed (square). In-plane currents I are applied to Hall devices made of structures exposed to in-plane magnetic fields Hin along the channel direction. Clear asymmetric magnetization switching with respect to the polarity of I and Hin is detected for the Ta/MnGa/NiAl device. Similar asymmetric magnetization switching is observed for the Ta/MnGa/Cr device, although the magnetization is partially switched regardless of the polarity of I and Hin. These results suggest that an in-plane magnetization component opposite to Hin is present in the Cr-buffer structure and that the formation of such a component is suppressed in the NiAl-buffer structure.
