Canted Spin Texture and Quantum Spin Hall Effect in WTe2

TL;DR

This paper reports a novel quantum spin Hall phase in monolayer WTe2 featuring a canted spin texture and quantized spin Hall conductivity, revealing unique spin polarization properties of topological edge states.

Contribution

It introduces the discovery of a canted spin texture and quantized spin Hall effect in monolayer WTe2, based on large-scale quantum simulations and first-principles modeling.

Findings

Canted spin texture in the yz plane influences boundary state spin polarization.

Quantized spin Hall conductivity of 2e^2/h with a specific spin axis.

Potential for manipulating spin in topological materials through experimental design.

Abstract

We report an unconventional quantum spin Hall phase in the monolayer T$_\text{d}$-WTe$_2$, which exhibits hitherto unknown features in other topological materials. The low-symmetry of the structure induces a canted spin texture in the $yz$ plane, which dictates the spin polarization of topologically protected boundary states. Additionally, the spin Hall conductivity gets quantized ($2e^2/h$) with a spin quantization axis parallel to the canting direction. These findings are based on large-scale quantum simulations of the spin Hall conductivity tensor and nonlocal resistances in multi-probe geometries using a realistic tight-binding model elaborated from first-principle methods. The observation of this canted quantum spin Hall effect, related to the formation of topological edge states with nontrivial spin polarization, demands for specific experimental design and suggests interesting alternatives for manipulating spin information in topological materials.