Spin injection and helicity control of surface spin photocurrent in a three dimensional topological insulator

Y Q Huang,W M Chen,S M Wang,I A Buyanova,Y X Song

doi:10.1038/ncomms15401

Abstract

A three-dimensional (3D) topological insulator (TI) is a unique quantum phase of matter with exotic physical properties and promising spintronic applications. However, surface spin current in a common 3D TI remains difficult to control and the out-of-plane spin texture is largely unexplored. Here, by means of surface spin photocurrent in Bi2Te3 TI devices driven by circular polarized light, we identify the subtle effect of the spin texture of the topological surface state including the hexagonal warping term on the surface current. By exploring the out-of-plane spin texture, we demonstrate spin injection from GaAs to TI and its significant contribution to the surface current, which can be manipulated by an external magnetic field. These discoveries pave the way to not only intriguing new physics but also enriched spin functionalities by integrating TI with conventional semiconductors, such that spin-enabled optoelectronic devices may be fabricated in such hybrid structures.

Highlights

A three-dimensional (3D) topological insulator (TI) is a unique quantum phase of matter with exotic physical properties and promising spintronic applications
In a three-dimensional (3D) topological insulator (TI), a strong spin–orbit interaction and the time-reversal symmetry result in spin-momentum locking of the surface electrons[4,5,6], which leads to a unique spin texture unravelled by recent angle-resolved photoemission spectroscopy (ARPES) results[7,8,9,10]
To clarify the origin of the photocurrent, Ixpol and Iypol were measured as a function of the incident angle of the light and the results are shown in Fig. 1e–g for two TI devices (S1 and S2, described in Methods)

Summary

Introduction

A three-dimensional (3D) topological insulator (TI) is a unique quantum phase of matter with exotic physical properties and promising spintronic applications. Dyðor xÞ has a non-zero value under the optical excitation below the bandgap of GaAs EgGaAs, providing a direct proof for the out-of-plane spin texture and the hexagonal warping effect that wThasirdp,revDioyu 61⁄4slyjDoxvjerulonodkeerd in the the spin current measurements.

Results

Conclusion