Slippery paraelectric transition metal dichalcogenide bilayers

TL;DR

This paper investigates the atomistic structure of paraelectric phases in transition metal dichalcogenide bilayers, revealing that their paraelectricity arises from dynamic averaging of opposing ferroelectric states requiring large-scale slip.

Contribution

It provides a detailed atomistic understanding of the paraelectric phase in transition metal dichalcogenide bilayers using molecular dynamics simulations.

Findings

Paraelectricity results from time-averaged opposing ferroelectric phases.

Large-area slip is necessary for polarization switching.

Numerical simulations reveal the atomistic configuration of the paraelectric phase.

Abstract

Traditional ferroelectrics undergo thermally-induced phase transitions whereby their structural symmetry increases. The associated higher-symmetry structure is dubbed {\em paraelectric}. Ferroelectric transition metal dichalcogenide bilayers have been recently shown to become paraelectric, but not much has been said of the atomistic configuration of such a phase. As discovered through numerical calculations that include molecular dynamics here, their paraelectricity can only be ascribed to a time average of ferroelectric phases with opposing intrinsic polarizations, whose switching requires macroscopically large areas to slip in unison.