Observation of phason dispersion in a ferroelectric liquid crystal by light scattering

Abstract
The phason dispersion relation has been measured in the smectic-C* phase of the ferroelectric liquid crystal p-decyloxybenzylidene-p’-omino-2-methylbutyl cinnamate (DOBAMBC) together with the temperature dependence of the phason and amplitudon excitations, by optical mixing spectroscopy. The overdamped phason was found to be nearly gapless in contrast to crystalline incommensurate systems where the modulation wave is pinned by frozen defects. A theory of light scattering by phasons and amplitudons in ferroelectric liquid crystals has been developed.