Abstract
Dielectric properties in ferroelectric and antiferroelectric liquid crystals which show isotropic (Iso.)→chiral smectic C (SmC*) and Iso.→chiral smectic CA (SmCA*) phase transitions have been studied. In the ferroelectric liquid crystal with the Iso.-SmC* phase sequence, two dielectric relaxations are observed under dc bias voltage. One appears around 700 kHz in frequency and is attributed to the soft mode. The other is related to the contribution of the Goldstone mode whose relaxation frequency is increased by the application of bias voltage. The antiferroelectric liquid crystal with the Iso.-SmCA* phase sequence also has two relaxations in the SmCA* phase. One originates from the molecular rotation around the short molecular axis and the other may correspond to the soft mode.