In-plane magnetic field-driven symmetry breaking in topological insulator-based three-terminal junctions

TL;DR

This study reveals how an in-plane magnetic field influences the symmetry and current steering in topological insulator nanoribbon three-terminal junctions, highlighting its potential for topoelectronic device control.

Contribution

It demonstrates the orbital effect of in-plane magnetic fields on topological surface states in nanoribbon junctions, showing controllable current steering and symmetry breaking.

Findings

Magnetic field causes current steering towards specific terminals.

Orbital effects trap phase-coherent states, breaking symmetry.

In-plane magnetic field acts as a topoelectric switch.

Abstract

Topological surface states of three-dimensional topological insulator nanoribbons and their distinct magnetoconductance properties are promising for topoelectronic applications and topological quantum computation. A crucial building block for nanoribbon-based circuits are three-terminal junctions. While the transport of topological surface states on a planar boundary is not directly affected by an in-plane magnetic field, the orbital effect cannot be neglected when the surface states are confined to the boundary of a nanoribbon geometry. Here, we report on the magnetotransport properties of such three-terminal junctions. We observe a dependence of the current on the in-plane magnetic field, with a distinct steering pattern of the surface state current towards a preferred output terminal for different magnetic field orientations. We demonstrate that this steering effect originates from the orbital effect, trapping the phase-coherent surface states in the different legs of the junction on opposite sides of the nanoribbon and breaking the left-right symmetry of the transmission across the junction. The reported magnetotransport properties demonstrate that an in-plane magnetic field is not only relevant but also very useful for the characterization and manipulation of transport in three-dimensional topological insulator nanoribbon-based junctions and circuits, acting as a topoelectric current switch.