Dielectric versus optical response of chevron ferroelectric liquid crystals

Abstract

Dielectric and optical methods to investigate the response of surface‐stabilized ferroelectric liquid crystals (SSFLCs) of the chevron structure are examined and compared in the case of the azimuthal mode of collective relaxation processes. It is found that the variation of an effective (averaged over the chevron cell volume) dielectric permittivity tensor under the influence of a weak alternating external electric field is approximately equivalent to the transformation of this tensor as a consequence of the rotation of the laboratory frame around the axis perpendicular to the smectic plane about a small angle. Then, using an analytic solution of the equation of motion describing the azimuthal rotation of molecules, it is shown that both of the analysed approaches to calculate and measure the response of SSFLCs yield consistent results for these rotational dynamic processes. This allows the calculation of the spontaneous polarization of the unit volume of chevron slabs, provided that the pretilted azimuthal angle (in the absence of an applied electric field) within the smectic plane is known.