Nonlinear dielectric response of antiferroelectric liquid crystals in the smectic phaseY. Kimura, H. Isono and R. Hayakawa
Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan email@example.com
(Received 19 April 2002 and Received in final form 23 July 2002 / Published online: 22 November 2002)
Nonlinear dielectric response of antiferroelectric liquid crystals has been studied in the smectic C * (SmC *) phase. The linear dielectric spectrum shows a single relaxation of Debye type and its relaxation frequency is as high as one hundred kHz. The profile of the third-order nonlinear dielectric spectrum varies in complex fashion with temperature. In the vicinity of the SmA-SmC * phase transition, experimentally obtained nonlinear spectra are well described by those calculated with phenomenological theory of Landau type. The soft mode of the SmC * phase shows critical slowing-down near the transition temperature. In the lower-temperature region of the SmC * phase, the contribution from the soft mode of the SmC * phase reduces and the other relaxation mode with Debye-type spectrum appears at several hundred Hz in the nonlinear spectrum. The appearance of this low-frequency mode suggests that the cooperative fluctuation of directors over long range exists in the SmC * phase.
77.22.Gm - Dielectric loss and relaxation.
77.84.-s - Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials.
64.70.Md - Transitions in liquid crystals.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002