Electric field effects of dielectric and ferroelectric properties in chiral smectic liquid crystal dobambc

Applied field dependence of static dielectric constant, and also dc bias field dependence of high frequency dielectric constant from 1 MHz to 100 MHz are measured in the helicoidal smectic C phase of ferroelectric liquid crystal (+)DOBAMBC. A very low characteristic threshold field, which may be thought as a coerceive field of Goldstone mode, E = 3.8 × 10−3 V/cm (at 82°C) was found in the static dielectric constant measurement by lock in amp and thermal noise method. The high frequency dielectric constant is temperature independent above from 10 MHz. A lucid ⊊ -E hysteresis loop by dc bias field E and its critical behaviour in 50 MHz region are observed.