Dielectric measurements of a new antiferroelectric liquid crystal
series exhibiting different phase sequences have been carried
out as a function of frequency from 10 Hz to 10 MHz. Structural
properties of SCα* and ferrielectric SCFI* phases were discussed
on the basis of the experimental results of temperature and dc
bias field dependencies of the dielectric modes. Besides the
soft mode observed around the SA−SCα* phase transition, a Goldstone
mode was detected in the SCα* phase indicating a helicoidal structure
with small pitch values. In agreement with a bilayer ordering
model, the dielectric absorption in the SCFI* phase was splitted
up into two contributions: one related to a Goldstone mode and
the other to an azimuthal antiphase mode.