Bistable nematic azimuthal alignment induced by anchoring competition

We present a novel method to obtain bistable azimuthal anchoring conditions for nematic liquid crystals. The line control of the anchoring strengths of two independent planar surface anchoring attractors, perpendicular to each other, induces controlled surface transitions that give bistability. The independent anchoring sources are obtained by means of a composite surface made with a film of photopolymer on an anisotropic SiO layer. A phenomenological model, based on anchoring competition between the two orienting layers, is developed to describe the surface bistability. (C) 1998 American Institute of Physics.