Defect kinetics and dynamics of pattern coarsening in a two-dimensional smectic-A system

TL;DR

This study uses high-order Landau-de Gennes simulations to analyze defect dynamics during the coarsening of a 2D smectic-A phase, revealing defect interactions, movement mechanisms, and dislocation behaviors.

Contribution

It introduces a detailed simulation framework for defect kinetics in smectic-A systems, highlighting disclination interactions and the role of curvature walls in defect dynamics.

Findings

Disclination interactions dominate coarsening.

Dislocation emission and absorption facilitate defect movement.

Curvature walls connect disclinations and influence defect evolution.

Abstract

Two-dimensional simulations of the coarsening process of the isotropic/smectic-A phase transition are presented using a high-order Landau-de Gennes type free energy model. Defect annihilation laws for smectic disclinations, elementary dislocations, and total dislocation content are determined. The computed evolution of the orientational correlation length and disclination density is found to be in agreement with previous experimental observations showing that disclination interactions dominate the coarsening process. The mechanism of smectic disclination movement, limited by the absorption and emission of elementary dislocations, is found to be facilitated by curvature walls connecting interacting disclinations. At intermediate times in the coarsening process, split-core dislocation formation and interactions displaying an effective disclination quadrupole configuration are observed. This work provides the framework for further understanding of the formation and dynamics of the diverse set of curvature defects observed in smectic liquid crystals and other layered material systems.