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

Yamanouchi, Michihiko*; Araki, Yasufumi; Sakai, Takaki*; Uemura, Tetsuya*; Ota, Hiromichi*; Ieda, Junichi

Science Advances (Internet), 8(15), p.eabl6192_1 - eabl6192_6, 2022/04

https://doi.org/10.1126/sciadv.abl6192

In a ferromagnetic Weyl metal SrRuO, a large effective magnetic field exerted on a magnetic domain wall (DW) by current has been reported. We show that the ratio of 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 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.

Anomalous temperature dependence of current-induced torques in CoFeB/MgO heterostructures with Ta-based underlayers

Kim, J.*; Sinha, J.*; Mitani, Seiji*; Hayashi, Masamitsu*; Takahashi, Saburo*; Maekawa, Sadamichi; Yamanouchi, Michihiko*; Ohno, Hideo*

Physical Review B, 89(17), p.174424_1 - 174424_8, 2014/05

https://doi.org/10.1103/PhysRevB.89.174424

We have studied the underlayer thickness and temperature dependencies of the current-induced effective field in CoFeB/MgO heterostructures with Ta-based underlayers. The underlayer thickness at which the effective field saturates is found to be different between the two orthogonal components of the effective field; i.e., the dampinglike term tends to saturate at a smaller underlayer thickness than the fieldlike term. For large underlayer thickness films in which the effective field saturates, we find that the measurement temperature significantly influences the size of the effective field. A striking difference is found in the temperature dependence of the two components: the dampinglike term decreases whereas the fieldlike term increases with increasing temperature. Using a simple spin diffusion-spin transfer model, we find that all of these results can be accounted for provided the real and imaginary parts of an effective spin mixing conductance are negative. These results imply that either spin transport in this system is different from conventional metallic interfaces or effects other than spin diffusion into the magnetic layer need to be taken into account in order to model the system accurately.

Temperature dependence of current-induced effective magnetic field acting on domain wall in SrRuO

Sakai, Takaki*; Yamanouchi, Michihiko*; Araki, Yasufumi; Uemura, Tetsuya*; Ota, Hiromichi*; Ieda, Junichi

no journal, ,