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

Area of Science:

• Soft Matter Physics
• Colloidal Science
• Liquid Crystal Physics

Background:

• Confined liquid crystals exhibit topological defects.
• External constraints and topology influence these defects.
• Understanding these structures is key in materials science.

Purpose of the Study:

• To explore the intrinsic structure of smectic colloidal layers under topological constraints.
• To investigate the interplay between entropy and imposed topology.
• To characterize defect structures in confined liquid crystals.

Main Methods:

• Real-space microscopy of thermal colloidal rods.
• Fundamental-measure-based density functional theory (DFT) for hard anisotropic bodies.
• Particle-resolved analysis.

Main Results:

• Discovery of competing states in annular confinement.
• Identification of nontrivial defect structures: laminar states, smectic domains, and edge dislocations.
• Observation of Shubnikov states, analogous to type-II superconductors.
• Quantitative agreement between experimental and theoretical results.

Conclusions:

• The interplay of entropy and topology dictates the structure of confined smectic colloidal layers.
• Annular confinement leads to diverse and complex defect patterns.
• The findings provide a fundamental understanding of topological defects in soft matter systems.