Field-induced behaviors near the smectic-A-smectic-C-alpha* phase transition of an antiferroelectric liquid crystal - art. no. 021703

We have experimentally and theoretically investigated the electric-field ef fect on the smectic-A-smectic-C-alpha* phase transition of an antiferroelec tric liquid crystal4-(1-methyl-heptyloxycarbonyl)phenyl 4'-octylcarbonyloxy biphenil-4-carboxylate. From the microscopic observations under electric fi elds and the measurements of the D-E hysteresis loop and apparent tilt angl e, the E (electric field)-T (temperature) phase diagram was established, in which a tricritical point was found. From the dielectric measurements unde r de electric fields, a soft mode inducing the transition was observed. Fur thermore, we have developed a phenomenological theory under de fields to an alyze the experimental results. The origin of the soft mode observed under fields was clarified and the temperature dependence of the relaxation frequ ency was obtained by the analyses.