抄録
We measured the nonlinear dielectric response of antiferroelectric liquid crystals in the SmCA and SmCa phase. In the SmCA phase, the spectrum of the third-order nonlinear permittivity ε3 shows a Debye-type relaxation and is ascribed to the coupling between dielectric anisotropy and electric field (antiferroelectric Goldstone mode). In the SmCa phase, the spectrum of ε3 shows a complicated form and is explained by the Landau-type phenomenological free-energy which is recently suggested by Bourny et al. This spectrum is mainly composed of the spectrum due to the ferroelectric soft mode and that of Debye-type due to the soft mode inducing the SmCα phase.
