Regensburg 2004 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.81: Poster

Donnerstag, 11. März 2004, 16:00–18:00, Poster D

The corkscrew instability in a nematic liquid crystal — •Alberto de Lozar, Wolfgang Schoepf, Lorenz Kramer, and Ingo Rehberg — Universitaet Bayreuth

A liquid crystal with slightly positive dielectric anisotropy is investigated in the planar configuration. This system allows for competition between electroconvection and the homogeneous Frèedericksz transition, leading to a rather complicated bifurcation scenario. We report measurements of a novel instability leading to the No-dqcorkscrewNo-dq pattern. This state is closely connected to the Frèedericksz state as it manifests itself as a regular modulation along a Frèedericksz 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, wavelenght and relaxation time. Its wavelenght 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.