Two-Dimensional Inversion Asymmetric Topological Insulators in Functionalized III-Bi Bilayers

TL;DR

This paper predicts new inversion asymmetric topological insulators in functionalized III-Bi bilayers with large, room-temperature-stable band gaps, confirmed by first-principles calculations, promising for spintronic applications.

Contribution

The study introduces a series of novel IATIs with large band gaps exceeding 0.6 eV, including some up to 1 eV, confirmed by first-principles calculations, expanding the known materials for topological insulators.

Findings

Large bulk band gaps above room temperature

Intrinsic nontrivial topological band order in most materials

Remarkable Rashba spin splitting due to asymmetric structures

Abstract

The search for inversion asymmetric topological insulators (IATIs) persists as an effect for realizing new topological phenomena. However, so for only a few IATIs have been discovered and there is no IATI exhibiting a large band gap exceeding 0.6 eV. Using first-principles calculations, we predict a series of new IATIs in saturated Group III-Bi bilayers. We show that all these IATIs preserve extraordinary large bulk band gaps which are well above room-temperature, allowing for viable applications in room-temperature spintronic devices. More importantly, most of these systems display large bulk band gaps that far exceed 0.6 eV and, part of them even are up to ~1 eV, which are larger than any IATIs ever reported. The nontrivial topological situation in these systems is confirmed by the identified band inversion of the band structures and an explicit demonstration of the topological edge states. Interestingly, the nontrivial band order characteristics are intrinsic to most of these materials and are not subject to spin-orbit coupling. Owning to their asymmetric structures, remarkable Rashba spin splitting is produced in both the valence and conduction bands of these systems. These predictions strongly revive these new systems as excellent candidates for IATI-based novel applications.