The Goldstone mode in ferroelectric liquid crystals A non-linear dielectric loss process

Abstract

The dielectrically observed Goldstone mode in ferroelectric liquid crystals is shown to have, beside the well-known DC bias field dependence, a strong AC field dependence of the dielectric loss. This non-linearity arises at AC field strengths > 100 V/cm already in the materials which we have studied. It is maximal at the frequency of maximum loss of the Goldstone mode and levels off at frequencies far enough apart. Thus attempts to analyse the Goldstone mode within the framework of the linear response theory are not applicable in general, but are restricted to sufficiently small AC fields.