Dynamics of the Goldstone mode near the point of polarization sign reversal in ferroelectric liquid crystal–aerosil mixtures

Abstract

Dielectric spectroscopy was used to study the influence of random disorder in aerosil–ferroelectric liquid crystal dispersions on the dynamics of the Goldstone mode near the point of polarization sign reversal and the relaxation rate and dielectric strength of the collective modes. In general, the dielectric strength and the relaxation frequency of the Goldstone mode decrease, in comparison with the bulk, with increasing aerosil density near a point of polarization sign reversal. However, the characteristic frequency of the Goldstone mode varies with silica density in an opposite manner on each side of this point. This can be explained as a different sensitivity on the spatial confinement of different molecular conformers above and below the point of polarization sign reversal. The experimental results of temperature and frequency dependence of the complex dielectric constant are compared with predictions of the generalized Landau model for ferroelectric liquid crystals.

Acknowledgments

This work has been supported by the National Fund for Scientific Research Flanders, Belgium (FWO, project G.0246.02). S.A.R. acknowledges the receipt of a senior postdoctoral fellowship from the Research Council of K.U.Leuven.