The linear and third-order nonlinear dielectric constants of the antiferroelectric liquid crystal 4-(1-trifluoromethyl-pheptyloxycarbonyl) phenyl [Formula Presented]-octyloxybiphenyl-4-carboxylate were experimentally studied in its smectic-A (Sm-A) and smectic-[Formula Presented] (Sm-[Formula Presented]) phases. Both dielectric constants showed a critical behavior near the Sm-A–Sm-[Formula Presented] phase transition corresponding to the softening of ferroelectric soft mode and the increase of the fluctuation in the tilt direction. In the Sm-[Formula Presented] phase, no relaxation was observed in the linear spectrum, but the third-order nonlinear dielectric spectrum showed a Debye-type relaxation with a relaxation frequency of a few kHz corresponding to the Goldstone mode in the Sm-[Formula Presented] phase. This nonlinear response was theoretically analyzed and ascribed to a field-induced biaxiality, i.e., the deformation of the helical structure due to a coupling between the dielectric anisotropy and the electric field. The temperature dependence of the nonlinear spectrum was also discussed.
|Number of pages
|Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
|Published - 1996
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Statistical and Nonlinear Physics
- Statistics and Probability