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

A. Levstik; Z. Kutnjak; B. Zeks; S. Dumrongrattana; C. C. Huang

doi:doi:10.1051/jp2:1991110

Numéro		J. Phys. II France Volume 1, Numéro 7, July 1991


Page(s)		797 - 803
DOI		https://doi.org/10.1051/jp2:1991110

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)

Abstract
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.