OBSERVATION OF AMPLITUDE MODE UNDER DC ELECTRIC FIELD IN SMECTIC-C α * PHASE

Linear and nonlinear dielectric spectroscopy under DC electric fields has been performed in the high temperature region of smectic-Cα* phase of an antiferroelectric liquid crystal 4-(1-methylheptyloxycarbonyl) phenyl 4-octylcarbonyloxybiphenyl-4-carboxylate (MHPOCBC) to obtain a deeper insight of dynamic properties. It is observed a softening of amplitude mode and ferroelectric mode with increasing the DC field close to the smectic-Cα*-smectic-A(C) phase boundary line. It was seen that the relaxation frequency of the amplitude mode obeys the Curie-Weiss law with respect to the applied electric field. Keywords: Dielectric relaxation, Nonlinear dielectric,MHPOCBC, DC field.