We discuss the director deformation inside a hybrid aligned nematic (HAN) cell, assuming that the surface interaction is of the (w/2) sin2 (φ - Φ) kind, and we suppose that the anchoring energy for homeotropic alignment is greater than the planar one. In the absence of an external electric field, we show that a critical thickness dc, below which the nematic liquid crystal (NLC) is undistorted, exists. Furthermore we investigate theoretically dc vs. the reduced electric field (E/Ec, where Ec is a threshold field depending upon the anchoring energies and the intrinsic constants of the NLC). The last analysis shows that there are two critical thicknesses dc(H) and dc(P): for d < dc(H) the sample is homeotropic (HOM), while for d > dc(P) it is planar (PLAN). Finally we point out that if the anchoring energies are the same on the upper and lower plates of the sample, the HAN-configuration is realizable only if E/Ec < 1.

Critical thickness of a hybrid aligned nematic liquid crystal cell / Barbero, Giovanni; R., Barberi. - In: JOURNAL DE PHYSIQUE. - ISSN 0302-0738. - 44:5(1983), pp. 609-616. [10.1051/jphys:01983004405060900]

Critical thickness of a hybrid aligned nematic liquid crystal cell

BARBERO, GIOVANNI;
1983

Abstract

We discuss the director deformation inside a hybrid aligned nematic (HAN) cell, assuming that the surface interaction is of the (w/2) sin2 (φ - Φ) kind, and we suppose that the anchoring energy for homeotropic alignment is greater than the planar one. In the absence of an external electric field, we show that a critical thickness dc, below which the nematic liquid crystal (NLC) is undistorted, exists. Furthermore we investigate theoretically dc vs. the reduced electric field (E/Ec, where Ec is a threshold field depending upon the anchoring energies and the intrinsic constants of the NLC). The last analysis shows that there are two critical thicknesses dc(H) and dc(P): for d < dc(H) the sample is homeotropic (HOM), while for d > dc(P) it is planar (PLAN). Finally we point out that if the anchoring energies are the same on the upper and lower plates of the sample, the HAN-configuration is realizable only if E/Ec < 1.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/1660786
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