Band gap opening by two-dimensional manifestation of Peierls instability in graphene

TL;DR

This paper demonstrates that band gap opening in graphene can be achieved through a two-dimensional Peierls-like distortion, specifically Kekule distortion, which breaks chiral symmetry and affects various graphene nanostructures.

Contribution

It introduces the concept of 2D Peierls distortion in graphene, linking band gap opening to chiral symmetry breaking and local hybridizations, expanding understanding of graphene's electronic properties.

Findings

Kekule distortion causes band gap opening in strained graphene.

Chiral symmetry breaking explains gap opening in nanoribbons and antidots.

2D Peierls transition is an extension of 1D metal-insulator transition.

Abstract

Using first-principles calculations of graphene having high-symmetry distortion or defects, we investigate band gap opening by chiral symmetry breaking, or intervalley mixing, in graphene and show an intuitive picture of understanding the gap opening in terms of local bonding and antibonding hybridizations. We identify that the gap opening by chiral symmetry breaking in honeycomb lattices is an ideal two-dimensional (2D) extension of the Peierls metal-insulator transition in 1D linear lattices. We show that the spontaneous Kekule distortion, a 2D version of the Peierls distortion, takes place in biaxially strained graphene, leading to structural failure. We also show that the gap opening in graphene antidots and armchair nanoribbons, which has been attributed usually to quantum confinement effects, can be understood with the chiral symmetry breaking.