Topo-electronic transitions in Sb(111) nanofilm: the interplay between quantum confinement and surface effect

TL;DR

This study uses first-principles calculations to reveal how Sb(111) nanofilms undergo multiple topological and electronic phase transitions as their thickness decreases, highlighting the interplay of quantum confinement and surface effects.

Contribution

It is the first to identify the quantum spin Hall phase in Sb(111) nanofilms within a specific thickness range, demonstrating novel topo-electronic phase transitions.

Findings

Transition from topological semimetal to insulator at 7.8 nm

Emergence of quantum spin Hall phase at 2.7 nm

Final transition to trivial semiconductor at 1.0 nm

Abstract

When the dimension of a solid structure is reduced, there will be two emerging effects, quantum confinement and surface effect, which dominate at nanoscale. Based on first-principles calculations, we demonstrate that due to an intriguing interplay between these two dominating effects, the topological and electronic (topo-electronic) properties of Sb (111) nanofilms undergo a series of transitions as a function of the reducing film thickness: transforming from a topological semimetal to a topological insulator at 7.8 nm (22 bilayer), then to a quantum spin hall (QSH) phase at 2.7 nm (8 bilayer), and finally to a normal (topological trivial) semiconductor at 1.0 nm (3 bilayer). Our theoretical findings for the first time identify the existence of the QSH in the Sb (111) nanofilms within a narrow range of thickness and suggest that the Sb (111) nanofilms provide an ideal test bed for experimental study of topo-electronic phase transitions.