Robust Helical Edge Transport in Quantum Spin Hall Quantum Wells

TL;DR

This paper demonstrates that buried Dirac points in certain quantum wells lead to robust edge states in quantum spin Hall systems, maintaining near-quantized conductance even under strong magnetic fields, supported by theoretical and simulation analyses.

Contribution

It reveals that buried Dirac points in InAs/GaSb and HgTe/CdTe quantum wells enhance edge state robustness against magnetic fields, a novel insight into topological protection mechanisms.

Findings

Edge states remain nearly quantized under strong magnetic fields.

Buried Dirac points are identified in specific quantum wells.

Simulations align with recent experimental observations.

Abstract

We show that burying of the Dirac point in semiconductor-based quantum-spin-Hall systems can generate unexpected robustness of edge states to magnetic fields. A detailed ${\bf k\cdot p}$ band-structure analysis reveals that InAs/GaSb and HgTe/CdTe quantum wells exhibit such buried Dirac points. By simulating transport in a disordered system described within an effective model, we further demonstrate that buried Dirac points yield nearly quantized edge conduction out to large magnetic fields, consistent with recent experiments.