The critical behavior of the order parameter and susceptibility near smectic A-smectic C phase transition

The SmA-SmC phase transition in number of different Liquid Crystals has been investigated by electrooptic and dielectric techniques. The critical exponent beta was determined from the fitting of the temperature dependence of tilt angle and spontaneous polarization in SmC phase. The value of beta is found to be dependent on the fitting temperature range. The critical exponent gamma was determined from the temperature dependence of the electroclinic coefficient and dielectric intensity of the soft mode. For all studied substances the value of gamma is 1.32 +/- 0.03 supporting de Gennes' model for SmA-SmC transition.