PHYSICAL ASPECTS OF ELECTROOPTIC PROPERTIES OF SMECTIC LIQUID-CRYSTALS

We present an Effective Internal Field Model for the antiferroelectric (AF) to field induced ferroelectric (FF) transition of smectic C-A. T his model attributes the fast dynamics and high threshold fields of th is transition to the large magnitudes of its in-plane polarization. We conclude that propagating fingers observed in the vicinity of the AF <-> FF threshold field can only be observed in holding fields where th ere are metastable states. We argue that this is because relaxation ti mes for antiferroelectric liquid crystals (AFLCs) are too fast (simila r to mu s) for front propagation of stable states into unstable ones. The model is also used to interpret the decrease in threshold field wh en smectic C is added to C-A.