Thermotropic Biaxial Nematics: Spontaneous or Field-Stabilized?

TL;DR

This paper proposes a model for an intermediate nematic phase in bent-core liquid crystals, explaining experimental biaxiality through microscopic domains and their collective alignment under electric fields.

Contribution

It introduces a phenomenological theory describing the molecular order and phase transitions involving uniaxial, biaxial, and polar nematic phases in bent-core liquid crystals.

Findings

Microscopic biaxial domains explain observed biaxiality.

Electric fields induce macroscopic biaxial order.

Theoretical framework for phase transitions in bent-core nematics.

Abstract

An intermediate nematic phase is proposed for the interpretation of recent experimental results on phase biaxiality in bent-core nematics. The phase is macroscopically uniaxial but consists of microscopic biaxial, and possibly polar, domains. On applying an electric field the phase exhibits substantial macroscopic biaxial ordering resulting from the collective alignment of the domains. A phenomenological theory is developed for the molecular order in this phase and for its transitions to purely uniaxial and to spontaneously biaxial nematic phases.