Field- and Current-Induced Domain Wall Motion in Tb/Co Multilayers in the Presence of Spin-Orbit Coupling-Induced Torques

We have studied the field- and current-induced domain wall (DW) motion in perpendicularly magnetized Tb/Co multilayer wires with asymmetric interface structures. We found that both up/down and down/up walls of a domain move at the same velocity. In the current-induced case, the DWs were moved along the current flow, not electron flow. This can be attributed to spin-orbit torques induced by structural inversion asymmetry (SIA). In addition, the DW velocity was changed by inserting ultrathin Pt interlayers into the wire stack. These results suggest that the SIA of the wire is tunable by changing layered structures.