Interparticle potential and drag coefficient in nematic colloids

Phys Rev Lett. 2006 May 26;96(20):207801. doi: 10.1103/PhysRevLett.96.207801. Epub 2006 May 23.

Abstract

Magneto-optic tweezers were used for measurements of liquid-crystal-mediated forces between spherical beads with tangential anchoring in thin nematic samples. Repulsive force, which results from the quadrupolar symmetry of defects around the immersed beads, decreases proportionally to 1/x6, with x being the bead separation. The velocity with which the particles are pushed apart also follows the same separation dependence. We thus find the effective drag coefficient gamma(eff) independent of x for surface-to-surface distances as small as 10% of the bead diameter.