Electric Field Effect on the SmA-SmC_α^* Phase Transition

Abstract

We have experimentally and theoretically investigated the electric field effect on the SmA-SmC_α phase transition of MHPOCBC. From the microscopic observations under electric fields and the measurements of D-E hysteresis loop and apparent tilt angle, the E (electric field)-T (temperature) phase diagram was established, in which a tricritical point was found. From the dielectric measurements under DC electric fields, a soft mode inducing the transition was observed. Furthermore, we have developed a phenomenological theory under DC fields to analyse the experimental results.