Domain Structure in the Nematic Freedericksz Transition

Abstract

In the course of experiments using the Freedericksz transition on a planar nematic film in a magnetic field perpendicular to the limiting plates, we have observed the transient existence of a periodic roll structure very similar to published observations by Carr, and apparently similar to Williams domains. The present paper develops a model based on the effect of the decrease of the effective viscosity in the presence of the back flow, induced by the rotation of n and taking place as a convective roll pattern. Direct observations and order of magnitude estimates of the wavelength of the roll and of the time constant for the development of the rolls agree with the model. We also addressed ourselves with the problem of distortion in an initially well aligned bulk material placed in a field perpendicular to n and find that inertia effects can also lead to a roll structure in the problem.