Controlling Energy Gap of Bilayer Graphene by Strain

TL;DR

This paper demonstrates that applying different homogeneous strains to each layer of bilayer graphene can mechanically induce and control an electronic energy gap, enabling pseudo-electromagnetic effects and potential device applications.

Contribution

It introduces a novel mechanical method to control the energy gap in bilayer graphene using strain-induced pseudo-scalar potentials, without external electronic sources.

Findings

Energy gap size can be tuned by adjusting strain strength and direction.

Strain induces pseudo-scalar potentials leading to transverse electric fields.

Method enables pseudo-electromagnetism and electromechanical device fabrication.

Abstract

Using the first principles calculations, we show that mechanically tunable electronic energy gap is realizable in bilayer graphene if different homogeneous strains are applied to the two layers. It is shown that the size of energy gap can be simply controlled by adjusting the strength and direction of these strains. We also show that the effect originates from the occurrence of strain-induced pseudo-scalar potentials in graphene. When homogeneous strains with different strengths are applied to each layer of bilayer graphene, transverse electric fields across the two layers can be generated without any external electronic sources, thereby opening an energy gap. The results demonstrate a simple mechanical method of realizing pseudo-electromagnetism in graphene and suggest a maneuverable approach to fabrication of electromechanical devices based on bilayer graphene.