A possible new phase of antagonistic nematogens in a disorienting field

TL;DR

This paper introduces a theoretical model predicting a new nematic phase, called N_{+4}, arising under a disorienting field in systems with antagonistic nematogenic molecules, expanding understanding of phase behavior in such materials.

Contribution

The study proposes a novel phase, N_{+4}, in a simple model of antagonistic nematogens under a disorienting field, highlighting new symmetry and phase transition phenomena.

Findings

Identification of a new N_{+4} phase invariant under 90° rotations

Coexistence of N_- and biaxial nematic phases at low fields

Prediction of phase behavior changes with increasing field strength

Abstract

A simple model is proposed for nematogenic molecules that favor perpendicular orientations as well as parallel ones. (Charged rods, for example, show this antagonistic tendency.) When a small disorienting field is applied along $z$, a low density phase $N_-$ of nematic order parameter $S_z<0$ coexists with a dense biaxial nematic $N_b$. (At zero field, $N_-$ becomes isotropic and $N_b$ uniaxial.) But at stronger fields, a new phase $N_{+4}$, invariant under $\pi/2$ rotations around the field axis, appears in between $N_-$ and $N_b$. Prospects for finding the $N_{+4}$ phase experimentally are briefly discussed.