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 →rₚ is less than 3 particle diameters. The particles attract when the angle θ between →rₚ and the uniform far-field director ^n₀ is between 0^∘{} and ≈70^∘ and repel when 75^∘θ≤90^∘. The particles aggregate in chains directed at ≈30^∘ to ^n₀ and, at higher concentrations, form complex kinetically trapped structures.