Europhys. Lett.
Volume 61, Number 5, March 2003
Page(s) 646 - 652
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 February 2003
DOI: 10.1209/epl/i2003-00120-y
Europhys. Lett., 61 (5) , pp. 646-652 (2003)

Novel surface-induced modulated texture in thick nematic samples

I. Lelidis1 and G. Barbero2

1  Laboratoire de Physique de la Matière Condensée, Université de Picardie 33 rue Saint-Leu, 80039 Amiens, France
2  Dipartimento di Fisica del Politecnico e INFM Corso Duca degli Abruzzi 24, 10129 Torino, Italy

(Received 18 July 2002; accepted in final form 16 December 2002)

A novel macroscopic stripe texture has been observed in thick homeotropic nematic cells by polarizing microscopy. The stripes involve a splay-bend deformation of the nematic director. They are stable in a temperature range of about 2 $\un{{}^{\circ}C}$ and are localized at the nematic-substrate interface. The observed phenomena are explained, within a phenomenological model, as a result of linear terms of the deformation tensor entering the interfacial-layer free energy. When the surface elastic constants are strong enough, the modulated texture can occur if the anchoring energy is lower than a critical value of $\sim
10^{-6}$ $\un{J/m^{2}}$.

61.30.Hn - Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions.
68.08.-p - Liquid-solid interfaces.
75.70.Kw - Domain structure (including magnetic bubbles).

© EDP Sciences 2003