Semi-Quantized Pumping and Spin-Orbit Torque in Topological Dirac Semimetals

We study the spin/charge transport phenomena and magnetization switching in a topological Dirac semimetal attached to a ferromagnetic insulator. Topological Dirac semimetals manifest a large inverse spin Hall effect when a spin current is pumped from the attached ferromagnetic insulator with a precessing magnetization, compared to conventional normal metals. We show that the induced charge current is semi-quantized because it originates to topological nature. We also show that an applied electric field in the topological Dirac semimetal generates the spin-orbit torque which reverses the magnetization in the ferromagnet.