Novel surface-induced modulated texture in thick nematic samples

A novel macroscopic stripe texture has been observed in thick homeotropic nematic cells by polarizing microscopy. The stripes involve a splay-bend deformation of the nematic director. They are stable in a temperature range of about 2 degreesC and are localized at the nematic-substrate interface. The observed phenomena are explained, within a phenomenological model, as a result of linear terms of the deformation tensor entering the interfacial-layer free energy. When the surface elastic constants are strong enough, the modulated texture can occur if the anchoring energy is lower than a critical value of similar to10(-6) J/m(2).