Flexoelectric effect in biaxial nematics

TL;DR

This paper develops a statistical theory to analyze the flexoelectric effect in biaxial nematic liquid crystals, revealing temperature-dependent behaviors and coefficient splitting at phase transitions.

Contribution

It introduces a theoretical framework for understanding flexoelectric coefficients and elastic constants in biaxial nematics, including their splitting at phase transitions.

Findings

Splitting of Meyer FE coefficients at the uniaxial-biaxial transition

Temperature dependence of order parameters and elastic constants

Correlation between FE coefficient splitting and elastic constant ordering

Abstract

The flexoelectric (FE) effect provides a linear coupling between electric polarization and orientational deformation in liquid crystals. It influences many electrooptical phenomena and it is used in some bistable nematic devices. A statistical theory of dipole FE polarization in biaxial nematic liquid crystals is used to calculate temperature dependence of order parameters, elastic constants, and FE coefficients. The splitting of the two Meyer FE coefficients and the appearance of new FE coefficients is obtained at the uniaxial-biaxial nematic transition. The ordering of the splited FE coefficients corresponds to the ordering of the splited elastic constants.