Nonlinear Dielectric Measurements of Antiferroelectric Liquid Crystals

Abstract

We have measured the linear and the third-order dielectric constants of an antiferroelectric liquid crystal MHPOBC and mixtures of R and S-enantiomers. In the optically pure and nearly pure samples with the SmCα* phase, the third-order dielectric constant discontinuously increases at the transition point from SmA to SmCα*, while the linear dielectric constant is continuous with a small change of the slope in its temperature dependence. These behaviors were well explained by the Landau theory. The optical purity dependence of the Curie constant was also investigated. The Curie constant slightly decreases as the optical purity is reduced, as predicted by the Landau theory.