Control of the skyrmion Hall angle by introducing ultrathin layers into Ta/CoFeB/MgO

Abstract In a Ta/CoFeB/MgO system where skyrmions were driven by spin–orbit torque (SOT), we demonstrated that the skyrmion Hall angle and SOT efficiency can be controlled by inserting an ultrathin layer at the Ta/CoFeB interface. It was confirmed by magneto-optical Kerr effect microscopy that the skyrmion Hall angle was increased and decreased by inserting the ultrathin layers, 0.2 nm Pt or 0.2 nm W, at the interface of Ta/CoFeB, respectively. Furthermore, we found that the damping-like torques determining the SOT efficiencies were decreased from 0.030 to 0.023 by inserting 0.2 nm Pt and enhanced to 0.050 by inserting 0.2 nm W. Interface engineering, such as an insertion layer, is a promising approach that enables the control of the Dzyaloshinskii–Moriya interaction and the SOT efficiency required for skyrmion devices.