Ab initio study of flexoelectricity in MXene monolayers

TL;DR

This study uses first-principles calculations to systematically analyze flexoelectricity in 126 MXene monolayers, revealing how composition and structure influence their flexoelectric coefficients.

Contribution

It provides the first comprehensive ab initio analysis of flexoelectric properties across a wide range of MXene monolayers, highlighting the role of transition metals and structural thickness.

Findings

Flexoelectric coefficients range from 0.19$e$ to 1.3$e$ across MXenes.

Nitride-based MXenes have larger coefficients than carbides.

Coefficients increase with thickness but decrease when normalized by bending modulus.

Abstract

We investigate flexoelectricity in MXene monolayers from first principles. Specifically, we compute the transverse flexoelectric coefficients of 126 MXene monolayers along their two principal directions using Kohn-Sham density functional theory. The values span a wide range from 0.19$e$ to 1.3$e$ and are nearly isotropic with respect to bending direction. The transition metal is found to play a significant role in the flexoelectric response, with nitride-based MXenes consistently displaying larger coefficients than their carbide counterparts. Moreover, the coefficients increase with structural thickness, but when normalized by the bending modulus, which is also computed for all 126 monolayers, they exhibit the opposite trend.