Microscopic Theory of Electrically Induced Spin Torques in Magnetic Weyl Semimetals

We theoretically study current- and charge-induced spin torques in magnetic Weyl semimetals (WSMs). In magnetic WSMs, a topologically nontrivial band structure mediates the anomalous coupling between magnetization and transport, making WSMs preferable for spintronics systems. In this study, we determine all current-induced spin torques including spin-orbit torque and spin-transfer torque, up to the first order with respect to spatial and temporal derivatives and electrical currents. We also calculate the charge-induced spin torque microscopically. We find that the charge-induced spin torque originates from the chiral anomaly due to the correspondence between spin operators and axial current operators in our model.