Disorder effects of vacancies on the electronic transport properties of realistic topological insulators nanoribbons: the case of bismuthene

TL;DR

This study investigates how vacancies affect the electronic transport in realistic bismuthene nanoribbons, revealing that topological protection can be compromised by disorder, especially in narrow ribbons, impacting their potential for spintronics.

Contribution

It provides a detailed analysis of vacancy-induced disorder effects on topological insulator nanoribbons using advanced computational methods, highlighting size-dependent robustness.

Findings

Vacancies induce localized states that disrupt topological edge protection.

Narrow nanoribbons are more susceptible to disorder effects.

Topological protection remains more robust in wider nanoribbons but can still break down at moderate disorder levels.

Abstract

The robustness of topological materials against disorder and defects is presumed but has not been demonstrated explicitly in realistic systems. In this work, we use state-of-the-art density functional theory and recursive nonequilibrium Green's functions methods to study the effect of disorder in the electronic transport of long nanoribbons, up to 157 nm, as a function of vacancy concentration. In narrow nanoribbons, even for small vacancy concentrations, defect-like localized states give rise to hybridization between the edge states erasing topological protection and enabling backscattering events. We show that the topological protection is more robust for wide nanoribbons, but surprisingly it breaks down at moderate structural disorder. Our study helps to establish some bounds on defective bismuthene nanoribbons as promising candidates for spintronic applications.