Unidirectional magneto-transport of linearly dispersing topological edge states

TL;DR

This paper demonstrates that applying a magnetic field to quantum spin-Hall edge states in diffusive samples enhances their transport properties, inducing ballistic conduction and non-linear non-reciprocal currents, with potential experimental detection.

Contribution

It reveals how magnetic fields can transform diffusive topological edge states into ballistic regimes and induce non-reciprocal currents, advancing understanding of topological transport.

Findings

Magnetic field increases mean free path in diffusive samples.

Transition from diffusive to ballistic transport with Landauer-Buttiker conductance.

Emergence of non-linear non-reciprocal currents on edges.

Abstract

Quantum spin-Hall edges are envisaged as next-generation transistors, yet they exhibit dissipationless transport only over short distances. Here we show that in a diffusive sample, where charge puddles with odd spin cause back-scattering, a magnetic field drastically increases the mean free path and drives the system into the ballistic regime with a Landauer-Buttiker conductance. A strong non-linear non-reciprocal current emerges in the diffusive regime with opposite signs on each edge, and vanishes in the ballistic limit. We discuss its detection in state-of-the-art experiments.