Stable nematic droplets with handles

TL;DR

This paper investigates the stabilization and complex nematic textures of droplets with handles, revealing persistent twisted configurations and defect structures influenced by saddle-splay elasticity and topological constraints.

Contribution

It introduces a method to stabilize nematic droplets with handles using yield-stress materials and uncovers novel defect and texture phenomena driven by saddle-splay effects.

Findings

Persistent twisted nematic configurations in droplets with tangential anchoring.

Spontaneous mirror symmetry breaking in toroidal droplets due to saddle-splay.

Presence of surface defects at handles minimizing elastic free energy.

Abstract

We stabilize nematic droplets with handles against surface-tension-driven instabilities using a yield-stress material as outer fluid and study the complex nematic textures and defect structures that result from the competition between topological constraints and the elasticity of the nematic liquid crystal. We uncover a surprisingly persistent twisted configuration of the nematic director inside the droplets when tangential anchoring is established at their boundaries, which we explain after considering the influence of saddle-splay on the elastic free energy. For toroidal droplets, we find that the saddle-splay energy screens the twisting energy resulting in a spontaneous breaking of mirror symmetry; the chiral twisted state persists for aspect ratios as large as ~20. For droplets with additional handles, we observe in experiments and computer simulations that there are two additional -1 surface defects per handle; these are located in regions with local saddle geometry to minimize the nematic distortions and hence the corresponding elastic free energy.