Direct observation of anisotropic interparticle forces in nematic colloids with optical tweezers

Interparticle forces in a nematic liquid-crystal colloid have been directly observed by the dual beam laser trapping method with pN sensitivity. We introduce two different types of spatial distributions of forces, detected between the particles accompanied by hyperbolic hedgehog defects. These force distributions lead to specific particle arrangements, which are both stabilized by the balance of the orientational stress field of nematics. On the basis of these results, we propose novel artificial construction for multiparticle regular arrangements.