Abstract
Temperature and bias electric field-dependent dielectric behaviour of an antiferroelectric liquid crystal compound was investigated in the frequency range 1 Hz to 10 MHz. The investigated compound possessed paraelectric (SmA*) and antiferroelectric () phases, in addition to a monotropic hexatic antiferroelectric smectic (
) phase. The dielectric study showed the presence of a soft mode in the SmA* phase. In the
phase, two weak relaxation modes were observed for a planar orientation of molecules. These two modes were related to antiferroelectric ordering and the helical structure of the
phase. Two modes, related to the hexatic order of the
phase, were also observed and characterized in terms of bond-orientational order and coupling to the molecular tilt direction. With respect to non-collective modes, rotation around the short axis of molecules was detected in the SmA* and
phases for a homeotropic alignment.