Eur. Phys. J. E 3, 123-130
Surface electric-field-induced instabilities in a homeotropically oriented nematic liquid crystal sample
H.A. Pereira - L.R. Evangelista
Departamento de Física, Universidade Estadual de Maringá,
Avenida Colombo 5790, 87020-900 Maringá, Paraná, Brazil
luiz.evangelista@cybertelecom.com.br
Received 4 November 1999 and Received in final form 4 April 2000
Abstract
The effect of a surface electric field produced by ionic
adsorption on the molecular orientation of a nematic liquid
crystal sample is analyzed. The eigenvalue problem for a
semi-infinite medium is analytically solved both for strong and
weak anchoring situations. The threshold instabilities are
numerically determined and it is shown that the homeotropic
pattern can be destabilized also in the situation of strong
anchoring. The dependence of the threshold field on the anchoring
strength and on the surface polarization is determined by taking
into account also the coupling of the quadrupolar component of the
flexoelectric coefficient with the field gradient.
PACS
61.30.-v Liquid crystals -
61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order -
64.70.Md Transitions in liquid crystals
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
