Periodic structures induced by director reorientation in the lyotropic nematic phase of disodium cromoglycate–water

Abstract

A nonequilibrium periodic structure is induced by a magnetic field H applied to an aligned lyotropic uniaxial nematic phase of disodium cromoglycate–water. A series of parallel lines perpendicular to H represents boundaries between 180° out-of-phase regions of director reorientation. The distance between the lines decreases with increasing H. The line spacing is also directly proportional to thickness of the sample (in a limited range of thickness), and a secondary periodicity, consisting of nodes in these lines, is observed in thicker samples. An extension of a theoretical model by Guyon et al. is used to qualitatively interpret the abovementioned dependencies.