Spin-Orbit Torque in Structures With Magnetization-Compensated MnGa/Co2MnSi Bilayer

We have systematically investigated the spin-orbit torque (SOT)-induced effective magnetic field in a structure consisting of a Ta heavy metal layer and an antiferromagnetically coupled Mn1.8Ga1/Co2MnSi (CMS) bilayer around the magnetization compensation point by varying CMS film thickness. The efficiency of SOT generation takes the maximum around the compensation point, and it is approximately six times as large compared with that in the devices with a MnGa single structure. The enhancement of SOT efficiency can be explained mainly by the reduction in saturation magnetic moment around the compensation point. Moreover, a significant enhancement of the effective spin Hall angle was observed around the compensation point because of the inversion of the magnetization configuration before and after the compensation point

Spin-orbit torque induced magnetization switching for an ultrathin MnGa/Co2MnSi bilayer

We investigated spin-orbit torque (SOT) induced magnetization switching and SOT efficiency for Mn1.8Ga1.0 (MnGa) single layers and MnGa/Co2MnSi (CMS) bilayers. Magnetization measurements showed that ultrathin MnGa and CMS were antiferromagnetically coupled to each other with clear perpendicular magnetization. SOT-induced magnetization switching was observed for both MnGa/CMS/Ta and MnGa/Ta stacks, and the switching current was reduced by a half in the MnGa/CMS/Ta stack. Examination of SOT acting on the domain walls revealed that the effective magnetic field originating from the SOT was approximately five times stronger in the MnGa/CMS/Ta stack than in the MnGa/Ta stack. These results indicate that the MnGa/CMS bilayer structure is effective in enhancing the efficiency of SOT generation

Magnetic properties and spin-orbit-torque-induced magnetization switching in Ta/MnGa grown on Cr and NiAl buffer layers

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 H-in along the channel direction. Clear asymmetric magnetization switching with respect to the polarity of I and H-in 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. (C) 2019 Author(s)