Collective dielectric processes at the transition temperature of the Sm-C* and Sm-A* phase in a ferroelectric liquid crystal

An anomalous dielectric relaxation process, called the partially unwound helical mode (p-UHM), is a collective dielectric process apart from the well known Goldstone and soft mode process; it is studied in the smectic C* (Sm-C*) phase and at the transition temperature of the Sm-C*-Sm-A* phase in the ferroelectric liquid crystal (FLC) material. To avoid the surface effect, a thick cell of 40 mu m thickness was prepared with highly rubbed surfaces of the ITO substrates. It has been observed that the dielectric properties in Sm-C* and at the T-c temperature are dominated by the p-UHM process which is dependent on an applied oscillating field in the Sm-C* phase. The probing ac and dc bias field dependences of all these collective dielectric processes have been reported in the Sm-C* and Sm-A* phases of FLC materials