Wave Structures in Nematic Layers

Abstract

Wave structures have been observed in thin nematic layers of 4–4′-n−pentylcyanobiphenyl. This compound is nematic between 22 and 35°C. The wave structures are observed in transverse-field cells. In this geometry, the electric field (produced by an in-plane electrode structure) and the viewing direction are perpendicular. The wave structure occurs at the interface between electrically and surface oriented regions of the layer. Layer thickness was varied between 2.5 and 42 microns. The wavelength of the structure was found to vary from 15 to 280 microns depending on layer thickness and temperature. The conditions of voltage, frequency and temperature which promote the formation of the wave structure are discussed. The wave structure occurs in the dielectric regime of the electrical deformation.