Electronic confinement of surface states in a topological insulator nanowire

TL;DR

This paper investigates how to control electronic surface states in topological insulator nanowires using geometric constrictions, magnetic flux, and electrostatic gates to create and manipulate quantum dots.

Contribution

It introduces a nanowire design with constrictions that form quantum dots and demonstrates control of electronic transport via magnetic flux and gating.

Findings

Confinement of surface states can be achieved with nanowire constrictions.

Magnetic flux and gates effectively tune quantum dot spectra.

Transport properties are controllable via external magnetic and electric fields.

Abstract

We analyze the confinement of electronic surface states in a model of a topological insulator nanowire. Spin-momentum locking in the surface states reduces unwanted backscattering in the presence of non-magnetic disorder and is known to counteract localization for certain values of magnetic flux threading the wire. We show that intentional backscattering can be induced for a range of conditions in the presence of a nanowire constriction. We propose a geometry for a nanowire that involves two constrictions and show that these regions form effective barriers that allow for the formation of a quantum dot. We analyze the zero-temperature non-interacting electronic transport through the device using the Landauer-B\"{u}ttiker approach and show how externally applied magnetic flux parallel to the nanowire and electrostatic gates can be used to control the spectrum of the quantum dot and the electronic transport through the surface states of the model device.