Electrohydrodynamic convection in a homeotropically aligned nematic sample

H. Richter, A. Buka, and I. Rehberg
Phys. Rev. E 51, 5886 – Published 1 June 1995
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Abstract

Different features of electroconvection patterns at threshold in a homeotropically aligned nematic sample are studied as a function of the driving frequency and the conductivity of the sample. The primary instability is the bend Fréedericksz transition that spontaneously breaks the rotational symmetry. The director orientation is optically determined in the Fréedericksz distorted state. Stationary normal and oblique convection rolls appear as a secondary instability. A complex time dependence of the pattern at low frequencies involving a reorientation of the rolls together with the underlying director configuration is observed as predicted by theory. For low conductivity samples a transition to traveling waves is detected and the Hopf frequency is measured as a function of the driving frequency for samples with different conductivities.

  • Received 25 January 1995

DOI:https://doi.org/10.1103/PhysRevE.51.5886

©1995 American Physical Society

Authors & Affiliations

H. Richter

  • Physikalisches Institut, Universität Bayreuth D-95440 Bayreuth, Germany

A. Buka

  • Research Institute for Solid State Physics, H-1525 Budapest P.O. Box 49, Hungary

I. Rehberg

  • Otto-von-Guericke-Universität, Institut für Experimentelle Physik, Postfach 4120, D-39016 Magdeburg, Germany

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Issue

Vol. 51, Iss. 6 — June 1995

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