Semi-soft Nematic Elastomers and Nematics in Crossed Electric and Magnetic Fields

TL;DR

This paper investigates semi-soft elastic behavior in nematic elastomers under crossed electric and magnetic fields, linking it to a biaxial phase and analyzing phase diagrams through a minimal and generalized models.

Contribution

It establishes a connection between semi-soft elasticity and biaxial phases in nematic elastomers using a minimal model and explores the robustness of this behavior beyond the model.

Findings

Semi-soft elasticity is associated with a biaxial phase.

Semi-soft behavior persists into the supercritical regime.

Similar results are found in generalized models.

Abstract

Nematic elastomers with a locked-in anisotropy direction exhibit semi-soft elastic response characterized by a plateau in the stress-strain curve in which stress does not change with strain. We calculate the global phase diagram for a minimal model, which is equivalent to one describing a nematic in crossed electric and magnetic fields, and show that semi-soft behavior is associated with a broken symmetry biaxial phase and that it persists well into the supercritical regime. We also consider generalizations beyond the minimal model and find similar results.