In-plane anchoring energy in ferroelectric liquid crystals: Evidence for its existence and measurement

Direct evidence for the existence of an in-plane term in the anchoring energy of a ferroelectric liquid crystal (FLC) cell is provided. This energy term arises from the anisotropy of the interaction of the FLC with the rubbed surface. A method for the measurement of the in-plane anchoring energy based on the offset of the electro-optic hysteresis curve is proposed. Investigations of different surface conditions in the cells reveals that the in-plane energy depends on the manner in which the alignment layer is prepared. The dependence of the optical bistability properties on this energy term is also discussed.