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Abstract
Electroconvection is a classical example of pattern-forming phenomena in liquid crystals, typically observed in nematics with negative dielectric and positive conductivity anisotropies. This article focuses on how electroconvection in the homeotropic geometry differs from that in planar alignment. The influence of an additional magnetic field on the pattern characteristics and on secondary instabilities (the normal roll–abnormal roll transition) is discussed. The homeotropic alignment offers unique possibilities also for studying defect motion. Basic characteristics of some patterns of large wavelength are presented and compared with those of the classical Carr–Helfrich structures. Finally, electroconvection in substances with negative conductivity anisotropy is addressed.
Acknowledgements
Fruitful discussions with L. Kramer, W. Pesch, A. G. Rossberg, S. Kai, Y. Hidaka, J.-H. Huh and T. Tóth Katona are gratefully acknowledged. This work was partially supported by the Hungarian Research Grants OTKA T 037336, M 041888 and NKFP-128/6 as well as by the EU Research Training Network PHYNECS. N.É. is grateful to the hospitality provided by the Ewing Christian College, Allahabad, within the framework of a bilateral exchange project of the Indian National Science Academy and the Hungarian Academy of Sciences.