DOI: 10.1140/epje/i2002-10087-y
Colloidal interactions in two-dimensional nematics
M. Tasinkevych1, N.M. Silvestre1, P. Patrício1, 2 and M.M. Telo da Gama11 Departamento de Física da Faculdade de Ciências and Centro de Física Teórica e Computacional, Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisboa Codex, Portugal
2 Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro 1, P-1949-014 Lisboa, Portugal
miko@cii.fc.ul.pt
(Received 1 October 2002 and Received in final form 12 November 2002 / Published online: 21 January 2003)
Abstract
The interaction between two disks immersed in a 2D nematic is
investigated
i) analytically using the tensor order parameter formalism for the
nematic configuration around isolated disks and
ii) numerically using finite-element methods with adaptive meshing
to minimize the corresponding Landau-
de Gennes free energy.
For strong homeotropic anchoring, each disk generates a pair of defects
with one-half topological charge responsible for the 2D quadrupolar
interaction between the disks at large distances.
At short distance, the position of the defects may change,
leading to unexpected complex interactions with the quadrupolar repulsive
interactions becoming attractive. This short-range attraction in all
directions is still anisotropic.
As the distance between the disks decreases, their preferred relative
orientation with respect to the far-field nematic director changes from
oblique to perpendicular.
77.84.Nh - Liquids, emulsions, and suspensions; liquid crystals.
61.30.Cz - Molecular and microscopic models and theories of liquid crystal structure.
61.30.Jf - Defects in liquid crystals.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002
