Low frequency dielectric response in the smectic C* phase of a FLC mixture.

Experimental studies of the dielectric response of a ferroelectric liquid crystal (FLC) mixture having low spontaneous polarization at different temperature and frequency have been done in smectic C* (Sm-C*) phase. The dielectric measurement were carried out on homogeneously aligned samples. In the Sm-C* phase the temperature dependent dielectric contribution of the Goldstone mode has been measured using two cells of thicknesses of 20 mu m and 100 mu m. Dielectric strength and corresponding relaxation frequencies are determined. From the experimental results it has been observed that the variation of dielectric strength and relaxation frequency with temperature are similar for the two cell, but the dielectric strength obtained for 20 mu m cell is higher than that obtained for 100 mu m cell at all temperatures. On the other hand the temperature dependence of relaxation frequency for both 20 mu m and 100 mu m cell is almost the same. The mean field coupling coefficients between tilt and polarization are obtained from a fit of extended microscopic model for the interpretation of experimental results. The Goldstone mode rotational viscosity has been calculated from dielectric data. ?he results have been discussed.