Linh Dang

Affiliation

University of Cologne

Title of work

Topological-insulator spin transistor

Authors

Linh Dang$^1$, Oliver Breunig$^1$, Zhiwei Wang$^{1*}$, Henry F. Legg$^2$, Yoichi Ando$^1$

$^1$Physics Institute II, University of Cologne, D-50937 Köln, Germany

$^2$Department of Physics, University of Basel, CH-4056 Basel, Switzerland

$^*$Present address: School of Physics, Beijing Institute of Technology, Beijing 100081, China

Abstract

A net spin polarization can be realized by injecting charge current into the spin-momentum-locked surface state of topological insulators (TIs). Due to the helical spin structure of this surface state, only one sign of spin polarization is expected from a fixed current direction. However, both signs that agree and disagree with this prediction have been observed in the past. Although the origin of the opposite sign is unclear, it suggests that the spin polarization can be switched from one sign to the other. In this talk, we present both signs of spin polarization in the same device and demonstrate the ability to switch between the two signs by electrostatic gating; which gives a proof of principle of a spin transistor based on TI. The complicated switching behaviour is explained by a minimal model taking in account the contribution of the topological surface state and trivial Rashba-split bands.