DOI: 10.1140/epje/i2002-10116-y
Controlled nucleation of point defects on a disclination line near a free surface during smectic-A-to-nematic directional melting
J. Ignés-Mullol, L. Scurtu and P. OswaldLaboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon, Cedex 07, France jignes@qf.ub.es
(Received 1 October 2002 / Published online: 15 April 2003)
Abstract
A disclination line populated with point defects that break the
translational symmetry forms near a free nematic (N) interface in a confined
geometry. The disclination line is, however, absent in the smectic-A phase
(SmA). We use this fact to control the formation of point defect distributions
on a disclination line by directional melting of the SmA phase in a
temperature gradient. A threshold velocity (
) exists below which a
defect-free disclination line is formed. The frequency of nucleation of point
defects increases steadily for
and exhibits a remarkable
regularity. We derive an empirical scaling for
in terms of the
experimental tuning parameters. We propose a simple model that allows to
understand the formation of the point defects.
61.30.Jf - Defects in liquid crystals.
61.30.Pq - Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems.
64.70.Md - Transitions in liquid crystals.
61.30.Hn - Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003
