Generating and controlling spin-polarized currents induced by a quantum spin Hall antidot

TL;DR

This paper investigates an electrically controlled quantum spin Hall antidot in a topological insulator, demonstrating how to generate and manipulate spin-polarized currents through barrier asymmetry and bias voltage variations.

Contribution

It introduces a method to generate and control spin-polarized currents in a topological insulator device using simple electrical tuning of barrier asymmetry and bias.

Findings

Spin-polarized current can be generated and controlled electrically.

Asymmetry in barriers causes switching behavior of spin current.

The device operates effectively with or without electron interactions.

Abstract

We study an electrically controlled quantum spin Hall antidot embedded in a two-dimensional topological insulating bar. Helical edge states around the antidot and along the edges of the bar are tunnel coupled. The close connection between spin and chirality, typical of helical systems, allows to generate a spin-polarized current flowing across the bar. This current is studied as a function of the external voltages, by varying the asymmetry between the barriers. For asymmetric setups, a switching behavior of the spin current is observed as the bias is increased, both in the absence and in the presence of electron interactions. This device allows to generate and control the spin-polarized current by simple electrical means.