Graphene nanoribbons subject to gentle bends

TL;DR

This paper investigates how gentle bends in graphene nanoribbons affect their electronic properties, revealing significant changes in energy gaps that are crucial for their electronic applications.

Contribution

It provides the first detailed analysis of the electromechanical effects of gentle bending on both armchair and zigzag graphene nanoribbons.

Findings

Gentle bends cause significant energy gap variations in armchair ribbons.

Bends can open sizeable energy gaps in zigzag ribbons without magnetism.

Bending effects are important for electronic measurements of supported ribbons.

Abstract

Since graphene nanoribbons are thin and flimsy, they need support. Support gives firm ground for applications, and adhesion holds ribbons flat, although not necessarily straight: ribbons with high aspect ratio are prone to bend. The effects of bending on ribbons' electronic properties, however, are unknown. Therefore, this article examines the electromechanics of planar and gently bent graphene nanoribbons. Simulations with density-functional tight-binding and revised periodic boundary conditions show that gentle bends in armchair ribbons can cause significant widening or narrowing of energy gaps. Moreover, in zigzag ribbons sizeable energy gaps can be opened due to axial symmetry breaking, even without magnetism. These results infer that, in the electronic measurements of supported ribbons, such bends must be heeded.