Strain-induced band gaps in bilayer graphene

TL;DR

This paper investigates how applying strain to bilayer graphene can induce and control band gaps, revealing mechanisms for strain-engineered electronic properties with potential experimental applications.

Contribution

It provides a detailed tight-binding analysis of strain effects on bilayer graphene's electronic structure, highlighting new ways to open and tune band gaps.

Findings

Perpendicular strain enhances A-B atom inequivalence and opens a band gap.

Perpendicular strain can induce linear dispersion near the K-point.

Lateral strain can create an indirect band gap in bilayer graphene.

Abstract

We present a tight-binding investigation of strained bilayer graphene within linear elasticity theory, focusing on the different environments experienced by the A and B carbon atoms of the different sublattices. We find that the inequivalence of the A and B atoms is enhanced by the application of perpendicular strain $\epsilon_{zz}$, which provides a physical mechanism for opening a band gap, most effectively obtained when pulling the two graphene layers apart. In addition, perpendicular strain introduces electron-hole asymmetry and can result in linear electronic dispersion near the K-point. When applying lateral strain to one layer and keeping the other layer fixed, we find the opening of an indirect band gap for small deformations. Our findings suggest experimental means for strain-engineered band gaps in bilayer graphene.