Poisson's Ratio of Layered Two-dimensional Crystals

TL;DR

This study uses first-principles calculations to explore the elastic properties of layered 2D materials, revealing diverse out-of-plane Poisson's ratios influenced by interlayer interactions and stacking, with implications for their elastic-electronic interplay.

Contribution

It provides the first comprehensive analysis of out-of-plane Poisson's ratios in multilayered 2D crystals, linking elastic behavior to stacking and interlayer interactions.

Findings

Out-of-plane Poisson's ratios are negative, near zero, and positive for graphene, h-BN, and MoS2.

In-plane Poisson's ratios are positive across all studied materials.

Interlayer interactions and stacking determine the sign of out-of-plane Poisson's ratios.

Abstract

We present first-principles calculations of elastic properties of multilayered two-dimensional crystals such as graphene, h-BN and 2H-MoS2 which shows that their Poisson's ratios along out-of-plane direction are negative, near zero and positive, respectively, spanning all possibilities for sign of the ratios. While the in-plane Poisson's ratios are all positive regardless of their disparate electronic and structural properties, the characteristic interlayer interactions as well as layer stacking structures are shown to determine the sign of their out-of-plane ratios. Thorough investigation of elastic properties as a function of the number of layers for each system is also provided, highlighting their intertwined nature between elastic and electronic properties.