Theory of Glide Symmetry Protected Helical Edge States in WTe$_{2}$ Monolayer

TL;DR

This paper theoretically investigates the robustness and transport properties of helical edge states in large-gap WTe2 monolayers, revealing enhanced stability due to glide symmetry and disorder effects, with implications for topological electronics.

Contribution

It provides a detailed theoretical analysis of how edge termination, disorder, temperature, and interactions influence QSH edge states in WTe2 monolayers, highlighting the role of glide symmetry in protection.

Findings

Conductance quantization remains robust despite heavy disorder.

Moderate disorder can enhance conductance stability by localizing bulk states.

Edge state velocity and Luttinger parameters vary with chemical potential, indicating complex physics.

Abstract

Helical edge states in quantum spin Hall (QSH) materials are central building blocks of topological matter design and engineering. Despite their principal topological protection against elastic backscattering, the level of operational stability depends on manifold parameters such as the band gap of the given semiconductor system in the 'inverted' regime, temperature, disorder, and crystal orientation. We theoretically investigate electronic and transport properties of QSH edge states in large gap 1-T' WTe$_{2}$ monolayers. We explore the impact of edge termination, disorder, temperature, and interactions on experimentally addressable edge state observables, such as local density of states and conductance. We show that conductance quantization can remain surprisingly robust even for heavily disordered samples because of an anomalously small edge state decay length and additional protection related to the large direct gap allowed by glide symmetry. From the simulation of temperature-dependent resistance, we find that moderate disorder enhances the stability of conductance by localizing bulk states. We evaluate the edge state velocity and Luttinger liquid parameter as functions of the chemical potential, finding prospects for physics beyond linear helical Luttinger liquids in samples with ultra-clean and well-defined edges.