Dielectric Relaxation Behavior of Ferroelectric Smectic-A Phase in Dimeric Molecules

Abstract

The dielectric relaxation behavior is investigated in the ferroelectric smectic-A phase, which is a mixture of schiff base dimeric molecules with different alkyl chain lengths. The ferroelectric smectic-A phase shows the Goldstone mode due to its high dielectric strength (relative permittivity excluding the contribution of ion diffusion in the low frequency region). The dielectric strength increases dramatically with increasing the cell thickness. By applying the DC bias fields, the Goldstone mode of the ferroelectric smectic-A phase is quenched, and this phenomenon is explained by the suppression of the dipoles' fluctuation due to the DC bias fields. The Goldstone mode and the high frequency mode of the SmAP_F phase follow the standard Arrhenius equation in the vicinity of the phase transition with the isotropic phase.