# New Group V Elemental Bilayers: A Tunable Structure Model with 4,6,8-atom Rings

## TL;DR

This paper introduces new 2D group V elemental bilayers with tunable structures and properties, revealing stable configurations with potential applications in nanodevices due to their semiconducting and topological features.

## Contribution

It proposes a series of stable, tunable group V bilayer structures with novel 4, 6, and 8-atom ring configurations, highlighting their electronic and topological properties.

## Key findings

- Sb and As bilayers are large-gap semiconductors.
- Bi bilayers exhibit nontrivial topological properties.
- Tuning ring ratios enhances band gaps and stability.

## Abstract

Two-dimensional (2D) group V elemental materials have attracted widespread attention due to their nonzero band gap while displaying high electron mobility. Using first-principles calculations, we propose a series of new elemental bilayers with group V elements (Bi, Sb, As). Our study reveals the dynamical stability of 4, 6, and 8-atom ring structures, demonstrating their possible coexistence in such bilayer systems. The proposed structures for Sb and As are large-gap semiconductors that are potentially interesting for applications in future nanodevices. The Bi structures have nontrivial topological properties with a large and direct nontrivial band gap. The nontrivial gap is shown to arise from a band inversion at the Brillouin zone center due to the strong intrinsic spin-orbit coupling (SOC) in Bi atoms. Moreover, we demonstrate the possibility to tune the properties of these materials by enhancing the ratio of 6-atom rings to 4 and 8-atom rings, which results in wider nontrivial band gaps and lower formation energies.