An active hydroelastic liquid crystal phase of a fluttering ferroelectric nematic

TL;DR

This paper reports the discovery of an active ferroelectric nematic phase in liquid crystals driven by polarization flutter under AC electric fields, revealing nonequilibrium structures and flow-driven elasticity that differ from equilibrium states.

Contribution

It introduces a new active ferroelectric nematic phase characterized by nonequilibrium textures and flow-driven elasticity, expanding understanding of ferroelectric liquid crystal behaviors under electric fields.

Findings

Observation of polarization flutter inducing active nematic behavior.

Identification of nonequilibrium director splay and polarization alignment structures.

Evidence of flow-driven apparent elasticity dominating equilibrium elastic forces.

Abstract

Polarization flutter, produced by an applied AC electric field drives an equilibrium ferroelectric nematic ($\mathrm{N_F}$) liquid crystal (LC) through a transition into a dissipative active ferroelectric nematic state exhibiting strong elasto-hydrodynamic intermolecular interaction. In such a fluttering ferroelectric, the typical equilibrium $\mathrm{N_F}$ textural features adopted to reduce electrostatic energy, such as preferences for director bend, and alignment of polarization parallel to LC/air interfaces, are overcome, giving way to nonequilibrium conjugate structures in which director splay, and alignment of polarization normal to $\mathrm{N_F}$/air interfaces are preferred. Viewing the latter textures as those of an active nematic phase reveals that self-organization to reduce effective viscosity and resulting dissipation generates a flow-driven apparent nematic elasticity and interface structuring that dominates equilibrium LC elastic and surface forces.