Dynamically Stable Topological Phase of Arsenene

Gul Rahman,Víctor M García-Suárez,Asad Mahmood

doi:10.1038/s41598-019-44444-4

Gul Rahman, Víctor M García-Suárez + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-44444-4

Copy DOI

Abstract

First-principles calculations based on density functional theory (DFT) are used to investigate the electronic structures and topological phase transition of arsenene under tensile and compressive strains. Buckling in arsenene strongly depends on compressive/tensile strain. The phonons band structures reveal that arsenene is dynamically stable up to 18% tensile strain and the frequency gap between the optical and acoustic branches decreases with strain. The electronic band structures show the direct bandgap decreases with tensile strain and then closes at 13% strain followed by band inversion. With spin-orbit coupling (SOC), the 14% strain-assisted topological insulator phase of arsenene is mainly governed by the p-orbitals. The SOC calculated bandgap is about 43 meV. No imaginary frequency in the phonons is observed in the topological phase of arsenene. The dynamically stable topological phase is accessed through Z2 topological invariant ν using the analysis of the parity of the wave functions at the time-reversal invariant momentum points. The calculated ν is shown to be 1, implying that arsenene is a topological insulator which can be a candidate material for nanoelectronic devices.

Highlights

Since the discovery of graphene[1,2,3,4], much attention has been devoted to discover new two-dimensional (2D) materials due to their exceptional properties such as high electrical conductivity, mechanical strength, band tunability etc
We note that this last point, which is essential to determine the feasibility of applications based on this material, has not been addressed in many previous studies of topological insulators (TIs) or, in general, in studies of electronic phase transitions.To address this technologically important issue, we used first-principles calculations based on density functional theory (DFT) to show that strain can induce a TI state in arsenene
The biaxial tensile strain was applied by fixing the lattice constant to a series of values larger than that of the equilibrium state and optimizing the atomic coordinates for each case

Summary

Introduction

Since the discovery of graphene[1,2,3,4], much attention has been devoted to discover new two-dimensional (2D) materials due to their exceptional properties such as high electrical conductivity, mechanical strength, band tunability etc. Semimetal–semiconductor and indirect–direct band gap transitions can be driven by applying biaxial strain and electric fields perpendicular to the plane of arsenene[14] This material can be passivated with hydrogens (hydrogenated arsenene) and becomes quasi-planar with a magnetic ground state[15]. The main purpose of the present work is to address the dynamic stability of arsenene under strain and to investigate whether the strain driven TI phase of arsenene is dynamically stable or not We note that this last point, which is essential to determine the feasibility of applications based on this material, has not been addressed in many previous studies of TI or, in general, in studies of electronic phase transitions.To address this technologically important issue, we used first-principles calculations based on density functional theory (DFT) to show that strain can induce a TI state in arsenene. The phonon calculations demonstrate that the strain driven TI state is dynamically stable, implying that arsenene can be a candidate material for QSH devices

Objectives

Methods

Results