title: Dependence of interparticle force on temperature and cell thickness in nematic colloids.
abstract: We have experimentally studied the interparticle force between two particles accompanied by hyperbolic hedgehog defects in a nematic liquid crystal. The force F was measured with dual-beam optical tweezers at various temperatures and in cells with various thicknesses. In a thick cell, the dependence of F on the interparticle distance R obtained at different temperatures can be scaled to a universal curve of F∝R^(-4) for R>3a , where a is the radius of a particle. The effective elastic constant evaluated from F is found to be in good agreement with splay constant of the nematic liquid crystal. In a thin cell, the magnitude of F decreases and the dependence of F on R becomes short-ranged as the thickness of a cell, L , decreases. The reduced force curves, FL(4) against R/L , at different L are found to be scaled to a single theoretical curve which has been proposed recently.
authors.affiliation: Department of Physics, Kyushu University, Higashi-ku, Fukuoka, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Kondo
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Iwashita
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kimura