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 n<^>(0) is between 0 degrees and approximate to 70 degrees and repel when 75 degrees less than or similar to theta <= 90 degrees. The particles aggregate in chains directed at approximate to 30 degrees to n<^>(0) and, at higher concentrations, form complex kinetically trapped structures.