Signatures of the quantum skyrmion Hall effect in the Bernevig-Hughes-Zhang model

TL;DR

This paper explores the quantum skyrmion Hall effect within the BHZ model, revealing phenomena akin to four-dimensional Chern insulators and connecting theoretical predictions with experimental observations of edge conduction in HgTe quantum wells.

Contribution

It demonstrates the presence of quantum skyrmion Hall effect signatures in the BHZ model, linking higher-dimensional topological phenomena with experimental edge conduction data.

Findings

Observation of boundary orbital angular momentum textures

Detection of gapless boundary modes robust against magnetic disorder

Correlation with experimental edge conduction in HgTe quantum wells

Abstract

Given recent discovery of the quantum skyrmion Hall effect, we re-examine the related canonical Bernevig-Hughes-Zhang (BHZ) model for the quantum spin Hall insulator. Within the framework of the quantum skyrmion Hall effect, isospin degree(s) of freedom of the BHZ model encode additional spatial dimensions. Consistent with this framework, we observe phenomena similar to those of the four dimensional Chern insulator, revealed by weakly breaking time-reversal symmetry. Bulk-boundary correspondence of these states includes real-space boundary orbital angular momentum textures and gapless boundary modes that are robust against magnetic disorder, consistent with compactified three dimensional boundary Weyl nodes (WN$_F$s) of the quantum skyrmion Hall effect. These theoretical findings are furthermore consistent with past experimental work reporting unexpected edge conduction in HgTe quantum wells under applied Zeeman and orbital magnetic fields. This past work is therefore potentially the first known experimental observation of signatures of the quantum skyrmion Hall effect beyond the quantum Hall effect.