Topological Phase Diagram of BiTeX–Graphene Hybrid Structures

Zoltán Tajkov,László Oroszlány,János Koltai,Dávid Visontai

doi:10.3390/app9204330

Zoltán Tajkov, László Oroszlány + Show 2 more

Open Access

https://doi.org/10.3390/app9204330

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Journal: Applied sciences	Publication Date: Oct 15, 2019
Citations: 3	License type: CC BY 4.0

Affiliation: Eötvös Loránd University

Abstract

Combining graphene with other novel layered materials is a possible way for engineering the band structure of charge carriers. Strong spin-orbit coupling in BiTeX compounds and the recent fabrication of a single layer of BiTeI points towards a feasible experimental realization of a Kane–Mele phase in graphene-based heterostructures. Here, we theoretically demonstrate the tunability of the topological phase of hybrid systems built from graphene and BiTeX (X = I, Br, Cl) layers by uniaxial in-plane tensile and out-of plane compressive strain. We show that structural stress inherently present in fabricated samples could induce a topological phase transition, thus turning the sample in a novel experimental realization of a time reversal invariant topological insulator.

Highlights

After the first successful isolation of graphene in 2004, graphene has proved to be an excellent template material with outstanding mechanical properties for revolutionary applications [1]
As we claimed in our previous work, the single sided heterostructures of BiTeX and graphene under appropriate conditions are topological insulators, we showed evidence for only the BiTeBr–graphene structure [22]
In this manuscript we investigate in details the phase diagram of the BiTeCl–graphene and BiTeI–graphene systems in the level of density functional theory calculations, as well as the BiTeBr–graphene structure

Summary

Introduction

After the first successful isolation of graphene in 2004, graphene has proved to be an excellent template material with outstanding mechanical properties for revolutionary applications [1]. Due to the small atomic weight of the carbon atoms building up the graphene lattice, the effect of spin-orbit coupling (SOC) on the electronic band structure is negligible [2]. There has recently been a strong push to find ways to enhance spin-orbit coupling in graphene [3] in order to enable spintronics applications [4]. Introducing curvature in the graphene sheet enhances the effect of the spin-orbit interaction up to ≈17 meV in realistic situations [5]. It has been shown that impurities influence the SOC in a positive way and can amplify its strength up to ≈7 meV [2]

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