Thick liquid crystalline cholesteric shells

TL;DR

This study numerically explores how shell thickness and chirality influence defect structures and phase transitions in thick cholesteric liquid crystal shells, revealing new defect arrangements and metastable states.

Contribution

It introduces a detailed numerical analysis of defect configurations in cholesteric shells, highlighting the effects of thickness and chirality on phase behavior and metastability.

Findings

Thickness-dependent transition from defect to defect-free states

Chirality stabilizes novel defect arrangements and blue phases

Metastable configurations can be achieved through elastic rearrangements

Abstract

We numerically investigate the phase behavior of thick shells of cholesteric liquid crystals with tangential anchoring at the shell boundary. For achiral liquid crystal, we demonstrate a thickness-dependent transition from a configuration featuring four disclination line connecting the inner and outer surfaces to a state free of defect in the bulk, where each surface is topologically isolated and features two boojums. Incorporating chirality stabilizes novel defect arrangements, including a mixed state combining boojums and disclination lines and blue phases at high chirality and we demonstrate that shell thickness strongly modulates these transitions. Finally, we exploit the metastability features of the observed phases to obtain an elastically induced rearrangement of the shell surfaces during a cholesteric hysteresis cycle, stabilizing an alternative configuration that minimizes the free energy at low chirality. Our work paves the way for exploring dynamic behaviors under external fields, mixed anchoring conditions, or active flows.