Robustness of spin-polarized edge states in a two-dimensional topological semimetal without inversion symmetry

TL;DR

This paper investigates the robustness of edge states in two-dimensional Weyl semimetals lacking inversion symmetry, finding they are more resilient to vacancies than graphene due to spin effects.

Contribution

It provides a comparative analysis showing that 2D Weyl semimetal edge states are more robust than graphene edge states, highlighting the role of spin in this robustness.

Findings

Edge states in 2D Weyl semimetals are more robust against vacancies than in graphene.

Spin degree of freedom enhances the robustness of edge states.

Comparison clarifies differences in edge state stability between topological semimetals and graphene.

Abstract

Three-dimensional topological gapless phases have attracted significant attention due to their unique electronic properties. A flagship example are Weyl semimetals, which require breaking time-reversal or inversion symmetry. In two dimensions, the dimensionality reduction requires imposing an additional symmetry, thereby weakening the phase. Like its three-dimensional counterpart, these two-dimensional Weyl semimetals present edge states directly related to Weyl nodes. The direct comparison with the edge states in zigzag-like terminated graphene ribbons is unavoidable, offering the question of how robust these states are and their differences. Here we benchmark the robustness of the edge states in two-dimensional Weyl semimetals without inversion symmetry with those present in zigzag graphene ribbons. Our results show that, despite having a similar electronic band structure, the edge states of two-dimensional Weyl semimetal are more robust against vacancies than graphene ribbons. We attribute this enhanced robustness to a crucial role of the spin degree of freedom in the former case