# Anisotropic mechanical and optical response and negative Poissons ratio in Mo2C nanomembranes revealed by first-principles simulations

## TL;DR

This study uses first-principles simulations to reveal that Mo2C nanomembranes exhibit anisotropic mechanical and optical responses, including negative Poisson's ratio and retained metallicity under strain, highlighting their potential in nanodevices.

## Contribution

First-principles density functional theory calculations uncover the anisotropic mechanical and optical properties of Mo2C nanomembranes, including negative Poisson's ratio and stable metallic behavior under strain.

## Key findings

- Mo2C sheets have negative Poisson's ratio (auxetic behavior).
- Dielectric function of Mo2C is anisotropic in different directions.
- Mo2C retains metallic properties under uniaxial strain.

## Abstract

Transition metal carbides include a wide variety of materials with attractive properties that are suitable for numerous and diverse applications. Most recent experimental advance could provide a path toward successful synthesis of large-area and high-quality ultrathin Mo2C membranes with superconducting properties. In the present study, we used first-principles density functional theory calculations to explore the mechanical and optical response of single-layer and free-standing Mo2C. Uniaxial tensile simulations along the armchair and zigzag directions were conducted and we found that while the elastic properties are close along various loading directions, nonlinear regimes in stress-strain curves are considerably different. We found that Mo2C sheets present negative Poisson's ratio and thus can be categorized as an auxetic material. Our simulations also reveal that Mo2C films retain their metallic electronic characteristic upon the uniaxial loading. We found that for Mo2C nanomembranes the dielectric function becomes anisotropic along in-plane and out-of plane directions. Our findings can be useful for the practical application of Mo2C sheets in nanodevices.

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Source: https://tomesphere.com/paper/1703.06786