2017

Dirac Spin-Orbit Torques and Charge Pumping at the Surface of Topological Insulators

Dirac Spin-Orbit Torques and Charge Pumping at the Surface of Topological Insulators
P.B. Ndiaye, C.A. Akosa, M.H. Fischer, A. Vaezi, E.-A. Kim, and A. Manchon
Phys. Rev. B 96, 014408 (2017)​​
P.B. Ndiaye, C.A. Akosa, M.H. Fischer, A. Vaezi, E.-A. Kim, A. Manchon
.
2017
​We address the nature of spin-orbit torques at the magnetic surfaces of topological insulators using the linear-response theory. We find that the so-called Dirac torques in such systems possess a different symmetry compared to their Rashba counterpart, as well as a high anisotropy as a function of the magnetization direction. In particular, the damping torque vanishes when the magnetization lies in the plane of the topological-insulator surface. We also show that the Onsager reciprocal of the spin-orbit torque, the charge pumping, induces an enhanced anisotropic damping. Via a macrospin model, we numerically demonstrate that these features have important consequences in terms of magnetization switching.