Current-driven dynamics of spin textures on a surface of topological insulators*

The application of topological properties has attracted research interest to more efficiently manipulate magnetization. For instance, at the interface of the topological insulator and the ferromagnetic insulator, the electrical control of magnetic textures, magnetization switching induced by electric current, and spin-charge conversion have been intensely studied theoretically and experimentally.
In this talk, we present analytical expressions of the spin-transfer torques on a surface of the magnetic topological insulator by including the higher-order contributions of momentum, k2-term and the hexagonal warping. We obtain six different types of the spin-transfer torque including both the field-like and the damping-like torques; the four of them appear only when the higher-order momentum contributions are included. In addition, we discuss the dynamics of magnetic skyrmions driven by the spin-transfer torques on the surface of the topological insulator. Unlike the skyrmion dynamics in conventional metals, we find that the dynamics significantly depends on the internal structure of magnetic textures.