Ferroelectric Ordering at Interface of Paraelectric Phase of Liquid Crystal and Solid Substrate in Confined Geometry

The interfacial molecular dynamics at the interface of solid substrate and paraelectric phase liquid crystal is investigated by dielectric spectroscopy in surface stabilized geometry of strongly and weakly rubbed cells. The material under study is ferroelectric liquid crystal (FLC) below the paraelectric phase. The studies are intended to explore the well-known surface stabilized memory effect in thin cells. The memory effect in weakly rubbed cells is long lasting than strongly rubbed cell. The studies near transition temperature (Tc) of ferroelectric (chiral smectic C) to paraelectric (chiral smectic A) phase is carried out. The molecular interface of FLC with substrate causes the phason mode to appear abnormally in paraelectric phase. The phason mode is the character of ferroelectric phase in liquid crystals. In strongly rubbed cell, the amplitude of phason mode is appeared just in ferroelectric phase only whereas in the weakly rubbed cells, the phason mode and soft mode are seen simultaneously at separate frequencies in paraelectric phase near Tc. The appearance of phason mode at the interface of FLC and solid substrate indicates towards the unusual ferroelectric molecular interface of FLC with substrate which is responsible for the longer duration memory effect in weakly rubbed cell.