Elasticity-mediated self-organization and colloidal interactions of solid spheres with tangential anchoring in a nematic liquid crystal.

Using laser tweezers, we study colloidal interactions of solid microspheres in the nematic bulk caused by elastic distortions around the particles with tangential surface anchoring. The interactions overcome the Brownian motion when the interparticle separation r-->p is less than 3 particle diameters. The particles attract when the angle theta between r-->p and the uniform far-field director n0 is between 0 degrees and approximately 70 degrees and repel when 75 degrees <or approximately theta<or=90 degrees. The particles aggregate in chains directed at approximately 30 degrees to n0 and, at higher concentrations, form complex kinetically trapped structures.