Goldstone Mode Relaxation in the Ferroelectric Phases of 8OSI

Abstract

Abstract The ferroelectric properties of the Sm C*, Sm I*, Sm J* and Sm K* phases of 4-(2-methylbutyl)-phenyl-4′-(octyloxy)-(l,l′)-biphenyl-carboxylate (80SI) have been studied by dielectric spectroscopy. We observed the bias field dependence of the Goldstone mode and a weak low frequency molecular relaxation. The Sm C* and Sm I* phases showed a composed absorption peak with a critical frequency of ca. 1 kHz. In the highly ordered Sm J* phase there is only a weak absorption peak at about 0.8 kHz. In the Sm K* phase no Goldstone mode has been detected, but only a contribution coming from a molecular relaxation process. The Goldstone mode could be suppressed by an electrical field of about 30 kV/cm. The study of the Goldstone mode was performed in the presence of an aligning magnetic field of 1.2 T parallel to the helix and also without magnetic field. It was found that a magnetic field of 1.2 T is sufficient to reduce the Goldstone mode dielectric increment by about 50%. The fits of the Cole-Cole function ...