Observation of topological Hall torque exerted on a domain wall in the ferromagnetic oxide SrRuO(3)

In a ferromagnetic Weyl metal SrRuO(3), a large effective magnetic field H(eff) exerted on a magnetic domain wall (DW) by current has been reported. We show that the ratio of H(eff) to current density exhibits nonmonotonic temperature dependence and surpasses those of conventional spin-transfer torques and spin-orbit torques. This enhancement is described well by topological Hall torque (THT), which is exerted on a DW by Weyl electrons emerging around Weyl points when an electric field is applied across the DW. The ratio of the H(eff) arising from the THT to current density is over one order of magnitude higher than that originating from spin-transfer torques and spin-orbit torques reported in metallic systems, showing that the THT may provide a better way for energy-efficient manipulation of magnetization in spintronics devices.