A possible new phase of antagonistic nematogens in a disorienting field

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.

4 pages, 2 figures. Accepted for publication in PRL