One-dimensional helical transport in topological insulator nanowire interferometers

TL;DR

This paper reports the experimental observation of a topologically protected one-dimensional helical electron mode in topological insulator nanowires, demonstrating robustness against disorder and dependence on magnetic flux, advancing nanoscale topological physics and device applications.

Contribution

It provides the first direct observation of a 1D helical mode in topological insulator nanowires at specific magnetic flux values, highlighting topological protection and flux dependence.

Findings

Observation of 1D helical mode at half magnetic flux quantum

Robustness of the mode against disorder

Fragility under perpendicular magnetic field

Abstract

The discovery of three-dimensional (3D) topological insulators opens a gateway to generate unusual phases and particles made of the helical surface electrons, proposing new applications using unusual spin nature. Demonstration of the helical electron transport is a crucial step to both physics and device applications of topological insulators. Topological insulator nanowires, of which spin-textured surface electrons form 1D band manipulated by enclosed magnetic flux, offer a unique nanoscale platform to realize quantum transport of spin-momentum locking nature. Here, we report an observation of a topologically protected 1D mode of surface electrons in topological insulator nanowires existing at only two values of half magnetic quantum flux ($\pm$h/2e) due to a spin Berry's phase ($\pi$). The helical 1D mode is robust against disorder but fragile against a perpendicular magnetic field breaking time-reversal-symmetry. This result demonstrates a device with robust and easily accessible 1D helical electronic states from 3D topological insulators, a unique nanoscale electronic system to study topological phenomena.