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TT: Fachverband Tiefe Temperaturen

TT 74: Topological Insulators

TT 74.7: Vortrag

Donnerstag, 21. März 2024, 16:45–17:00, H 3005

Topological-insulator spin transistor — •Linh T. Dang¹, Oliver Breunig¹, Zhiwei Wang^1,3, Henry F. Legg², and Yoichi Ando¹ — ¹Physics Institute II, University of Cologne, D-50937 Köln, Germany — ²Department of Physics, University of Basel, CH-4056 Basel, Switzerland — ³School of Physics, Beijing Institute of Technology, Beijing 100081, China

A net spin polarization can be induced 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 report our experiment in which we observed both signs of spin polarization in the same device at different back-gate voltages, which demonstrates the ability to switch between the two signs by electrostatic gating; which gives a proof of principle of a spin transistor based on TI [1]. We observed a complicated switching behaviour which can be explained by a minimal model taking into account the competing contributions of the topological surface state and trivial Rashba-split bands.

[1] L. T. Dang, O. Breunig, Z. Wang, H. F. Legg, Y. Ando, Phys. Rev. Appl. 20 (2023) 024065.

Keywords: Topological insulators; Spintronic; Spin transistor