Unusual Thickness-Dependent Thermal Behavior and Anticlinic Coupling in Chiral Smectic Free-Standing Liquid-Crystal Films

We observe, in free-standing films of a chiral smectic liquid crystal, a series of discrete transitions in the relative orientation of the tilt of the interior and surface layers. These transitions include a remarkable reentrant synclinic-anticlinic-synclinic ordering sequence of the film surfaces in the presence of an electric field upon cooling. The profiles of the associated heat-capacity anomalies are found to be strongly thickness dependent and exhibit a novel crossover behavior in reduced dimensions. We measure the anticlinic coupling between tilted surface layers in the smectic- A phase.