Amplitude and phase fluctuation modes in the smectic Cα* phase of an antiferroelectric compound

Dielectric measurements have been carried out on the chiral smectic C-alpha (SmC alpha*) phase of a MHPOBC analogous compound. Two relaxation modes have been observed in this phase for planar orientation of the molecules. One process has been observed at frequency lower than that of the soft mode of the chiral smectic A (SmA*) phase. This relaxation process is connected with the helicity of the SmC alpha* phase. In the high-frequency region, another relaxation process has been observed in the SmC alpha* phase for which bias field dependence is similar to that of the soft mode at the SmA*-SmC* phase transition. The experimental observations are in agreement with a recently proposed dielectric theory for the SmC alpha* phase and theoretical dielectric results obtained by numerical simulations. Thus, we report here experimental verification of two theoretically predicted dielectric modes in the SmC alpha* phase.