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

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.

Structural and electronic properties of realistic two-dimensional amorphous topological insulators

“…The experimental band gap of Bi supported by SiC(0001) surface is 0.67 eV and hosts a topologically non-trivial band structure with one of the largest reported topological band gaps [38]. The robustness of flat bismuthene is such that it withstands ∼ 17% of vacancy concentration while retaining its topological features, this threshold depends on the energy gap and spin-orbit coupling (SOC) strength [28,39].…”