Continuous nematic anchoring transition due to surface-induced smectic order.

A continuous transition from tilted to homeotropic alignment at an interface is observed at a temperature T(a) for a nematic liquid crystal on cooling toward the nematic-smectic-A phase transition temperature. T(a) is found to depend on the treatment of the substrate. The behavior is examined theoretically in terms of a pair of competing easy axes (homeotropic and planar) and the tilt elasticity associated with the growth of surface-induced smectic order.