Structures and orientational transitions in thin films of tilted hexatic smectics

TL;DR

This paper investigates structural and orientational phase transitions in thin smectic-C to hexatic liquid crystal films, revealing all known structures for a single material and interpreting modulated patterns through Landau theory.

Contribution

It provides the first comprehensive observation of all known structures in a single material during phase transitions, and explains modulated stripe patterns via geometric frustration and Landau theory.

Findings

All known structures observed in one material during phase transition

Unusual modulated stripe patterns with doubled period

Interpretation of patterns through Landau phenomenological theory

Abstract

We present detailed systematic studies of structural transformations in thin liquid crystal films with the smectic-C to hexatic phase transition. For the first time all possible structures reported in the literature are observed for one material (5 O.6) at the variation of temperature and thickness. In unusual modulated structures the equilibrium period of stripes is twice with respect to the domain size. We interpret these patterns in the frame work of phenomenological Landau type theory, as equilibrium phenomena produced by a natural geometric frustration in a system having spontaneous splay distortion.