Commensurate and Incommensurate Structures in a Nonequilibrium System

Abstract

A layer of nematic liquid crystal that has undergone an electrohydrodynamic instability (and contains nonequilibrium structures with period ${l}_{0}$) is subjected to a spatially periodic electric field with periodicity ${l}_{1}$. The competition between these two length scales is found to result in novel ordered phases similar to those found in equilibrium condensed-matter systems. A simple model is proposed that accounts for most of the observations.