Polar distortions in hydrogen bonded organic ferroelectrics

TL;DR

This study uses ab-initio methods to analyze the microscopic mechanisms of polarization in two organic ferroelectric crystals, revealing significant polarization values and suggesting potential for discovering new organic ferroelectrics.

Contribution

It provides a detailed microscopic analysis of polarization mechanisms in two organic ferroelectric crystals using distortion-mode analysis.

Findings

CBDC polarization: 14.3 μC/cm²

PhMDA polarization: 7.0 μC/cm²

Potential for discovering new organic ferroelectrics

Abstract

Although ferroelectric compounds containing hydrogen bonds were among the first to be discovered, organic ferroelectrics are relatively rare. The discovery of high polarization at room temperature in croconic acid [Nature \textbf{463}, 789 (2010)] has led to a renewed interest in organic ferroelectrics. We present an ab-initio study of two ferroelectric organic molecular crystals, 1-cyclobutene-1,2-dicarboxylic acid (CBDC) and 2-phenylmalondialdehyde (PhMDA). By using a distortion-mode analysis we shed light on the microscopic mechanisms contributing to the polarization, which we find to be as large as 14.3 and 7.0\,$\mu$C/cm$^{2}$ for CBDC and PhMDA respectively. These results suggest that it may be fruitful to search among known but poorly characterized organic compounds for organic ferroelectrics with enhanced polar properties suitable for device applications.