Dielectric properties in ferroelectric liquid crystal mixtures with ultrashort pitch

The dielectric propereties of smectic liquid crystal mixtures containing chiral dopants derived from trifluoromethylated pyranose were studied. In every mixture, a large dielectric response due to the Goldstone mode was observed, indicating the smectic C* phase, although two switching current peaks indicative of the smectic C-A* phase were observed in the mixtures with high dopant ratios. With increasing the chiral dopant ratio, the dielectric strength becomes smaller and the relaxation frequency becomes larger. This behavior was qualitatively explained by the chiral dopant ratio dependence of the spontaneous polarization and the helicoidal pitch. It was also found that a higher de bias field was required to suppress the Goldstone mode in the mixture with a higher dopant ratio, suggesting the helicoid-stabilized state.