Electric field induced tricritical point in chiral polarized liquid crystals

We present a Landau theory of the transition between a uniformly polarized smectic C phase and a distorted smectic C* phase in the presence of an electric field parallel to the layers. The field-temperature (E-T) phase diagram is shown to exhibit a tricritical point (Et, T t). The values of Et, Tt are expressed in terms of observable macroscopic properties of the material.