Defects and interactions with the structures in ehd convection in nematic liquid crystals

Abstract

Convective structures in nematic liquid crystals subjected to electric field can be developed in extended geometries. They offer a wide set of situations for the study of defects. In particular the two main types of defects show respectively glide and climb motion. These defects analyzed by analogy with the defects in smectic-A layers correspond to a change of magnitude in the ratio of smectic-like elastic moduli (compression, curvature). The shape of the defects allows one to predict the structure that will appear for a higher stress. Therefore defects appear clearly as nuclei for the growing of structures of decreasing symmetry. Indeed we can show that these structures can be obtained from defects either by continuous slow process or through martensitic-like transformations.