Detection of chiral domains and linear electro-optical response in planar-aligned cells of an achiral rod-like ferro-electric nematic liquid crystal

TL;DR

This paper reports the discovery of stable chiral domains in achiral rod-like ferroelectric nematic liquid crystals, induced by weak electric fields, revealing symmetry breaking and domain behavior in these phases.

Contribution

It demonstrates the formation and stability of chiral domains in achiral nematic phases under electric fields, a novel observation in ferroelectric liquid crystals.

Findings

Chiral domains are induced by weak electric fields in achiral nematic phases.

Domains of opposite chirality remain stable even after removing the field.

Domain size varies with temperature, especially near the nematic to ferroelectric transition.

Abstract

Chiral domains of opposite chirality are observed surprisingly in a nematic phase of an achiral rod-like liquid crystalline mesogen that shows ferroelectric nematic and antiferroelectric smectic phases. The observations of chiral domains of opposite chirality are enabled by application of a weak electric field across a planar-aligned cell. However once domains of opposite chirality are created, these stay permanently even if the field is removed. The observed phenomenon is due to the symmetry breaking of achiral mesogens of rod-shaped molecules. These domains are similarly observed in the Nx phase. However for temperatures close or in the NF, the size of domains is reduced significantly below the wavelength of visible light. There is either a single domain with dipole moments parallel to the surface or domains antiparallel in the NF phase, not possible to determine in this experiment.