Current-induced effective magnetic field acting on a domain wall in perpendicularly magnetized Pd/Co2MnGa

We investigated the current-induced effective magnetic field Heff acting on a domain wall (DW) under an in-plane magnetic field H// along the current direction in a perpendicularly magnetized heterostructure composed of a Pd and Weyl ferromagnet Co2MnGa (CMG) layer. Heff is equivalent to a perpendicular magnetic field to move the DW. The magnitude of Heff per current density had a local maximum with respect to H// and decreased at large |H//|. This relationship cannot be explained only by Heff originating from the conventional spin-orbit torque and/or orbit torque (SOT/OT). Assuming that the residual component of Heff excluding the contribution of SOT/OT originates from the conventional field-like spin-transfer torque, the lower bound of the nonadiabaticity parameter characterizing the torque, which is usually much less than 1, is estimated to be 1.9. These results suggest that unconventional and energy-efficient mechanisms are superposed on the SOT/OT in Pd/CMG.