Magneto-optical response of twisted nematic cells

Abstract

We construct a theoretical model for a thermotropic ferronematic (magnetic liquid crystal colloid) in an asymmetric twisted nematic cell, subject to in-plane magnetic fields. At low colloidal concentrations, the nematic director is unchanged by strong fields, the magnetic director principally responds to its coupling to, and the suspension density peaks sharply where and are co-aligned. At higher concentrations feedback between and aligns over a significant part of the cell, and the suspension divides into a region where is parallel toH, and a region where it is not. We also make calculations of the optical properties of this cell