Particle-resolved topological defects of smectic colloidal liquid crystals in extreme confinement

• Published in: Nature communications 2021-01, Vol.12 (1), p.623-623, Article 623
• Main Authors: Wittmann, René, Cortes, Louis B. G., Löwen, Hartmut, Aarts, Dirk G. A. L.
• Format: Article
• Language: English
• Subjects: 639/766/530/2795; 639/766/94; Colloids; Confinement; Crystal defects; Crystal structure; Crystals; Density functional theory; Edge dislocations; Entropy; Humanities and Social Sciences; Light microscopy; Liquid crystals; Microscopy; multidisciplinary; Optical microscopy; Science; Science (multidisciplinary); Superconductors; Topology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-20842-5

Confined samples of liquid crystals are characterized by a variety of topological defects and can be exposed to external constraints such as extreme confinements with nontrivial topology. Here we explore the intrinsic structure of smectic colloidal layers dictated by the interplay between entropy and an imposed external topology. Considering an annular confinement as a basic example, a plethora of competing states is found with nontrivial defect structures ranging from laminar states to multiple smectic domains and arrays of edge dislocations, which we refer to as Shubnikov states in formal analogy to the characteristic of type-II superconductors. Our particle-resolved results, gained by a combination of real-space microscopy of thermal colloidal rods and fundamental-measure-based density functional theory of hard anisotropic bodies, agree on a quantitative level. Colloidal rod-like mesogens make the study of liquid crystal structures available to simple optical microscopy. Wittmann et al. study topological defects in smectic phases under annular confinement and reveal a remarkable, quantitative agreement with a theoretic density functional description.