Defect-populated configurations in nematic solid tori and cylinders

Abstract

We make toroidal droplets of nematic liquid crystal and explore the defect-populated stable configurations that appear after heating to the isotropic phase and cooling back to the nematic phase. These configurations, as confirmed by simulations, are made of defect pairs where the positive/negative defect is located in the region of maximum positive/negative Gaussian curvature. Moreover, we demonstrate through experiments and simulations that these defect pairs also appear and are stable in cylinders, which have zero Gaussian curvature, highlighting the crucial role of bulk nematic elasticity in stabilizing these structures.