Intrinsic Negative Poisson's Ratio for Single-Layer Graphene

TL;DR

This paper demonstrates that single-layer graphene intrinsically exhibits a negative Poisson's ratio due to its deformation mechanisms, which could lead to novel applications in materials science.

Contribution

It reveals the intrinsic NPR property of graphene and explains its origin through deformation pathways and energy considerations, independent of size and temperature.

Findings

Graphene exhibits an intrinsic negative Poisson's ratio.

The NPR arises from a competition between deformation pathways.

NPR becomes dominant above 6% strain due to energy favorability.

Abstract

Negative Poisson's ratio (NPR) materials have drawn significant interest because the enhanced toughness, shear resistance and vibration absorption that typically are seen in auxetic materials may enable a range of novel applications. In this work, we report that single-layer graphene exhibits an intrinsic NPR, which is robust and independent of its size and temperature. The NPR arises due to the interplay between two intrinsic deformation pathways (one with positive Poisson's ratio, the other with NPR), which correspond to the bond stretching and angle bending interactions in graphene. We propose an energy-based deformation pathway criteria, which predicts that the pathway with NPR has lower energy and thus becomes the dominant deformation mode when graphene is stretched by a strain above 6%, resulting in the NPR phenomenon.