J. Phys. II France
Volume 1, Numéro 7, July 1991
Page(s) 797 - 803
DOI: 10.1051/jp2:1991110
J. Phys. II France 1 (1991) 797-803

Dielectric method for determining the electrical critical field in ferroelectric liquid crystals

A. Levstik1, Z. Kutnjak1, B. Zeks1, S. Dumrongrattana2 and C. C. Huang2

1  J. Stefan Institute, University of Ljubljana, 61111 Ljubljana, Jamova 39, Yugoslavia
2  School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 U.S.A.

(Received 14 January 1991, accepted 27 March 1991)

Both the electrical field and the dielectric constant ( $\varepsilon_0 \Delta \varepsilon_{\rm G}$) associated with the Goldstone mode in the ferroelectric liquid crystals are related to the helical pitch. A direct relation between these two physical quantities is established. We have calculated the electrical critical field for both DOBAMBC and DOBA-1-MPC compound from the measured temperature variation of $\varepsilon_0 \Delta \varepsilon_{\rm G}$ and polarization without any adjustable parameter. Just below the transition temperature region, the results obtained agree qualitatively with the experimental data. Away from the transition temperature, there exist systematic deviations.

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