Independent Control of Spin-Orbit Torque

Since the discovery of current-induced domain wall motion (CIDWM), a lot of attention has been paid due to its promising applicability for memory device. In the CIDWM, the spin-orbit torque (SOT) and Dzyaloshinskii-Moriya interaction (DMI) are important for the efficiency and direction of the CIDWM. However, because these two parameters share the common origin of the spin-orbit coupling, it is hard to control just one independently of the other. If one can independently control one of these parameters, it is possible to freely control the movement of magnetic domain walls. Here we show the strategy to control the SOT independently of the DMI. Two groups (A and B) of samples are prepared for testing controllability of the SOT. We focus on the diverse materials in the group A and we focus on the thickness of material in the group B. In the group A, both SOT and DMI changed with the material choice. On the other hand, in the group B, only the SOT could be controlled independently of DMI by thickness adjustment.