Electroclinic effect at theA−Cphase change in a chiral smectic liquid crystal

When a smectic-A phase is composed of chiral molecules, it exhibits an electroclinic effect, i.e., a direct coupling of molecular tilt to applied field. The pretransitional behavior of the electroclinic effect in the A phase is used to study the critical behavior near the second-order, smectic-A---smectic-C phase transition. This behavior is measured by monitoring the change in birefringence of a sample as the electroclinic effect causes a tilt of the molecules. A large pretransitional effect is measured, and constants describing the critical behavior are determined.