Statistical Mechanics of Splay Flexoelectricity in Nematic Liquid Crystals

TL;DR

This paper introduces a lattice model for splay flexoelectricity in nematic liquid crystals, revealing phase transitions and the statistical nature of flexoelectric effects through simulations and mean-field analysis.

Contribution

It develops a novel lattice model capturing flexoelectricity in nematic liquid crystals and analyzes phase behavior and flexoelectric effects near phase transitions.

Findings

Large splay flexoelectric effect in the nematic phase

Flexoelectricity diverges near the polar phase transition

Flexoelectricity is linked to the onset of polar order

Abstract

We develop a lattice model for the splay flexoelectric effect in nematic liquid crystals. In this model, each lattice site has a spin representing the local molecular orientation, and the interaction between neighboring spins represents pear-shaped molecules with shape polarity. We perform Monte Carlo simulations and mean-field calculations to find the behavior as a function of interaction parameters, temperature, and applied electric field. The resulting phase diagram has three phases: isotropic, nematic, and polar. In the nematic phase, there is a large splay flexoelectric effect, which diverges as the system approaches the transition to the polar phase. These results show that flexoelectricity is a statistical phenomenon associated with the onset of polar order.