Vortexlike topological defects in nematic colloids: chiral colloidal dimers and 2D crystals

Phys Rev Lett. 2009 Sep 18;103(12):127801. doi: 10.1103/PhysRevLett.103.127801. Epub 2009 Sep 15.

Abstract

We show that chiral ordering of the underlying complex fluid strongly influences defect formation and colloidal interactions. Nonsingular defect loops with a topological charge -2 are observed, with a cross section identical to hyperbolic vortices in magnetic systems. These loops are binding spontaneously formed pairs of colloidal particles and dimers, which are chiral objects. Chiral dimer-dimer interaction weakly depends on the chirality of dimers and leads to the assembly of 2D nematic colloidal crystals of pure or "mixed" chirality, intercalated with a lattice of nonsingular vortexlike defects.