Nematic colloids entangled by topological defects
Colloids in complex fluids is a current hot topic at Ljubljana university and in soft matter physics in general. The cover of a recent issue of the Soft Matter journal features Nematic colloids entangled by topological defects, a paper published by Miha Ravnik and Slobodan Žumer.
Assembly of colloidal particles in nematic liquid crystals is governed by the symmetry of building blocks and type of defects in the liquid crystalline orientation. Particles in a nematic act as nucleation sites for topological defect structures that are homotopic to point defects. The tendency for a minimal deformation free energy and topological constraints limit possible defect configurations to extended and localized defect loops. We report on a recently discovered colloidal binding, where particles are entangled by disclination loops. Nematic braids formed by such disclinations stabilize multi-particle objects and entrap particles in a complex manner. Observed binding potentials are highly anisotropic showing string-like behavior.