Non-Standard Electroconvection in a Bent Core Nematic

David B. Wiant ,Jim T. Gleeson ,Nandor Eber 2,Katalin Fodor-Csorba 3,Antal Jakli 4,Tibor Toth-Katona 4

kent state u., phys. dept.
kent state phys.
2research institute for solid state physics and optics, hungarian acad. of sciences
3institute for solid state physics and optics, hungarian acad. of sciences
4lci, kent state u.

We characterize three non-standard electrohydrodynamic instabilities in nematic liquid crystals composed of bent core molecules. In addition to their shape, another important attribute of this material is that the anisotropy in the electrical conductivity changes sign as the frequency of the applied electric field changes. These instabilities do not appear to fit within the standard model for electroconvection. The first instability creates a pattern with stripes parallel to the initial director orientation, with a wavelength about equal to the separation of the cell plates. The next is the previously reported prewavy instability. The third instability is optically and dynamically identical to the prewavy instability, but is distinguished by different threshold behavior.


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