Magnetically controlled double-twist director configuration of lyotropic chromonic liquid crystals in cylinders: Energetics, topological defects, and instability

TL;DR

This study investigates how magnetic fields influence the double-twist configuration of lyotropic chromonic liquid crystals in cylinders, revealing energetics, defect structures, and an instability that enables controlled manipulation of these configurations.

Contribution

It introduces a new director field model explaining magnetic field-induced transitions, defect structures, and symmetry-breaking instability in lyotropic chromonic liquid crystals.

Findings

Magnetic fields induce a transition in the twist profile of the DT configuration.

Cataloging of three types of topological defects between DT domains.

Identification of a symmetry-breaking instability at high field strengths.

Abstract

We study experimentally how the double-twist (DT) configuration of cylindrically confined lyotropic chromonic liquid crystals (LCLCs) responds to axial magnetic fields. Our director field model unveils the energetics behind the magnetic field-induced transition in the twist profile of the DT configuration. Additionally, we catalog three different types of topological defects -- residing between the DT domains of opposite handedness -- before and after the field application, and propose a new director field model for the defect with a ring disclination. Lastly, we report a symmetry-breaking instability occurring when the field strength exceeds a critical value, suggesting an eccentric DT director field model that reproduces a helix-like optical texture. Our systematic investigation not only enhances our understanding of LCLC energetics but also provides potential for precise control over DT configurations.