Field induced phase transition in smectic C (beta)* phase of antiferroelectric liquid crystals

Electric field dependence of complex dielectric constant and temperature dependence of switching current were measured in antiferroelectric liquid crystals for various optical purities. A two-step change in the dielectric constant of bias field and current peaks representing SmC (alpha)* phase were observed in high optical purity MHPOBC. A molecular orientational model to explain results of the two-step change is proposed. The first and the second decrease in the dielectric constant correspond to the reorientation to the ferroelectric and antiferroelectric orderings, respectively, and the two-step change in dielectric constant for electric field is related to the generation of antiferroelectric ordering in SmC (beta)* phase.