The electrostatic polarization of ferroelectric liquid crystals: A new interpretation of the triangle-wave technique

Abstract

We show that the electrostatic polarization measured in ferroelectric liquid crystals using the standard triangle-wave technique is not the total polarization of the sample, but rather a specific nonlinear component of the total polarization. We present a Landau theory to calculate this nonlinear component explicitly. In the high-temperature limit, above the smectic-A–smectic-C* phase transition, the theory predicts that the observed polarization scales as E3/(T−TAC)4, where T is the temperature and E the applied electric field. In the low-temperature limit, the observed polarization approaches the total polarization. These theoretical predictions are consistent with experimental measurements.