Quantum Spin-Valley Hall Kink States: From Concept to Materials Design

TL;DR

This paper introduces a tunable platform for creating high-density quantum spin-valley Hall kink states in 2D topological insulators, with potential for room-temperature spin-valley electronic devices.

Contribution

It proposes a general method to realize and protect QSVHK states in 2D materials, supported by first-principles calculations and disorder robustness analysis.

Findings

QSVHK states are topologically protected by valley-inversion and time-reversal symmetries.

Conductance of QSVHK states remains quantized under nonmagnetic and magnetic disorder.

QSVHK states with a gap up to 287 meV can be realized in bismuthene through various engineering techniques.

Abstract

We propose a general and tunable platform to realize high-density arrays of quantum spin-valley Hall kink (QSVHK) states with spin-valley-momentum locking based on a two-dimensional hexagonal topological insulator. Through the analysis of Berry curvature and topological charge, the QSVHK states are found to be topologically protected by the valley-inversion and time-reversal symmetries. Remarkably, the conductance of QSVHK states remains quantized against either nonmagnetic or long-range magnetic disorder, verified by the Green function calculations. Based on first-principles results, we show that QSVHK states, protected with a gap up to 287 meV, can be realized in bismuthene by alloy engineering, surface functionalization, or electric field, supporting non-volatile applications of spin-valley filters, valves, and waveguides even at room temperature.