Orientational order in two dimensions from competing interactions at different scales

TL;DR

This paper investigates how competing interactions at different scales induce orientational order in two-dimensional systems, revealing a transition into a phase with quasi-long-range order driven by fluctuations, extending the Brazovskii model.

Contribution

It introduces an extended Brazovskii model with nematic symmetry and demonstrates the isotropic-nematic transition belongs to the Kosterlitz-Thouless universality class.

Findings

Transition driven by fluctuations into a Kosterlitz-Thouless phase

Existence of a thermodynamic phase with orientational quasi-long-range order

Extension of the Brazovskii model to include nematic symmetry

Abstract

We discuss orientational order in two dimensions in the context of systems with competing isotropic interactions at different scales. We consider an extension of the Brazovskii model for stripe phases including explicitly quartic terms with nematic symmetry in the energy. We show that leading fluctuations of the mean field nematic solution drive the isotropic-nematic transition into the Kosterlitz-Thouless universality class, i.e. these systems have a thermodynamic phase with orientational quasi-long-range order.