Depletion interactions in lyotropic nematics

A theoretical study of depletion interactions between pairs of small, globular colloids dispersed in a lyotropic nematic of hard, rodlike particles is presented. We find that both the strength and range of the interaction crucially depends on the configuration of the spheres relative to the nematic director, and on their size. The interaction is significantly stronger parallel than perpendicular to the director, explaining the emergence of stringlike aggregates observed in experiment.