Critical behavior in an electric-field-induced anchoring transition in a liquid crystal.

We report an anchoring transition of a liquid crystal under the influence of an electric field (E field) in the vicinity of a first-order anchoring transition (ATr) temperature showing bistable homeotropic (H) and planar (P) states. By means of polarizing microscopy combined with retardation and switching and dielectric measurements, three important observations were made: (1) The anchoring transition from H to P driven by an E field is first order with a threshold E-field strength, which decreases with increasing temperature; (2) the thickness of the H layer that is to be converted to the P orientation increases toward ATr temperature T(ATr); and (3) the temperature dependence of both parameters is well described by a power law.