Ferrielectricity in smectic-C* dechiralisation lines lattices

TL;DR

This paper develops a phenomenological Landau theory to describe ferrielectric phase transitions in smectic-C* dechiralisation line lattices, explaining experimental dielectric and optic anomalies and predicting new phases.

Contribution

It introduces a novel Landau model linking line positions to order parameters, capturing complex phase behavior and predicting limit phases in ferrielectric smectic systems.

Findings

Phase transition sequence SmA->SmC*->Ferri explained

Dielectric and optic anomalies accounted for by model

Prediction of new limit phases within the lattice

Abstract

Recent experiments probing a new ferroelectric liquid crystal (CLF08) confined in cells with planar alignment have shown dielectric and optic anomalies suggesting the onset of ferrielectric ordering within the surface lattice of dechiralisation lines. We present a phenomenological theory describing the corresponding phase transitions sequence SmA->SmC*->Ferri. Phase diagrams, thermodynamic, dielectric and optic properties are worked out and compared with experiments. The anomalies are related to the predicted tristability of the experimental cells under applied electric field. The order parameters of Landau theory are reinterpreted in terms of line positions, allowing the description of the entrance/exit lines behavior, and yielding the prediction and identification of new limit phases within a non-conventional Landau approach.