Filaments in the TGBA phase

TL;DR

This paper proposes a model for filaments in the TGBA phase of liquid crystals, explaining their structure, inclination, and formation based on smectic layer blocks and dislocation loops, applicable across compounds.

Contribution

It introduces a new model describing TGBA filament formation from homeotropic smectic A phase, incorporating dislocation loops and layer blocks, and estimates the compression modulus.

Findings

Model explains filament inclination relative to surface anchoring

Filament structure derived from smectic layer blocks and dislocation loops

Estimated compression modulus from filament parameters

Abstract

A model of filaments of the TGBA phase arising from the homeotropic smectic A phase and nucleating on the sample surface is proposed. The model is based on the concept of finite blocks of parallel smectic layers forming a helical structure. The blocks are surrounded by dislocation loops. The model describes the filament structure near the sample surface and explains the observed inclination of the filament axis with respect to the easy direction of the molecular anchoring on the surface. The model is based on the observations of filament textures of the TGBA phase in a new chiral liquid crystalline compound, but can be applied for forming of TGBA filaments in any compound. The compression modulus of the compound has been estimated using such parameters as anchoring energy, estimated from the field necessary to transform the structure into the homeotropic smectic A, and the observed filament width.