The corkscrew instability of a Fréedericksz domain wall in a nematic liquid crystal

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Muñoz, Alberto de Lózar ; Bock, Thomas ; Müller, Matthias ; Schöpf, Wolfgang ; Rehberg, Ingo:
The corkscrew instability of a Fréedericksz domain wall in a nematic liquid crystal.
In: New Journal of Physics. Bd. 5 (2003) . - no. 63.1-63.12.
ISSN 1367-2630
DOI der Verlagsversion: https://doi.org/10.1088/1367-2630/5/1/363

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Abstract

A liquid crystal with slightly positive dielectric anisotropy is investigated in the planar configuration. This system allows for competition between electroconvection and the homogeneous Fréedericksz transition, leading to a rather complicated bifurcation scenario. We report measurements of a novel instability leading to the "corkscrew" pattern. This state is closely connected to the Fréedericksz state as it manifests itself as a regular modulation along a Fréedericksz domain wall, although its frequency dependence indicates that electroconvection must play a crucial role. It can be understood in terms of a pitchfork bifurcation from a straight domain wall. Quantitative characterization is performed in terms of amplitude, wavelength and relaxation time. Its wavelength is of the order of the probe thickness, while its ondulation amplitude is an order of magnitude smaller. The relaxation time is comparable to the one obtained for electroconvection.