Electric field induced order reconstruction in a nematic cell

Barberi, R. and Ciuchi, F. and Durand, G.E. and Iovane, M. and Sikharulidze, D. and Sonnet, A.M. and Virga, E.G. (2004) Electric field induced order reconstruction in a nematic cell. European Physical Journal E - Soft Matter, 13 (1). pp. 61-71. ISSN 1292-8941 (http://dx.doi.org/10.1140/epje/e2004-00040-5)

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Abstract

We have experimentally observed the biaxial switching between two topologically distinct textures of a nematic liquid crystal cell submitted to a strong electric field. The effect is deduced from optical and electrical measurements across the cell. Above a static threshold, a bulk order reconstruction is observed, where the final nematic orientation in the centre becomes perpendicular to its initial one, inducing a total change of orientation across the cell. Using short electric field pulses, a higher dynamical threshold is observed. These experiments are explained by a Landau-de Gennes-Khalatnikov model. The threshold implies the local exchange of two eigenvalues of the nematic order tensor through intermediate biaxial states. The onset of the effect in a thin splay-bend wall decreases the static threshold by almost an order of magnitude. The model explains reasonably well the static and dynamic measurements within the present description of nematic biaxiality.

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