Novel defect structures in a strongly confined liquid-crystalline blue phase

Area of Science:

• Materials Science
• Condensed Matter Physics
• Liquid Crystals

Background:

• Blue phases (BPs) are intermediate phases of chiral liquid crystals between the chiral nematic and chiral smectic phases.
• Strong confinement and surface anchoring significantly influence the self-assembly and structure of liquid crystalline materials.
• Topological defects, such as disclination lines, play a crucial role in defining the macroscopic properties of liquid crystals.

Purpose of the Study:

• To numerically investigate novel structures in strongly confined blue phase I (BP I) liquid crystals.
• To characterize the configurations of topological disclination lines within these confined systems.
• To explore the impact of system thickness and homeotropic surface anchoring on BP I structures.

Main Methods:

• Numerical simulation using a phenomenological description of liquid crystals.
• Modeling of strongly confined BP I with system thickness comparable to the bulk unit cell dimension.
• Application of homeotropic boundary conditions on confining surfaces.

Main Results:

• Identification of novel BP I structures with unique topological disclination line arrangements.
• Observation of an array of double-helix disclination lines associated with an orthorhombic lattice of double-twist cylinders.
• Discovery of two parallel arrays of winding disclination lines oriented nearly perpendicularly.

Conclusions:

• Strong confinement and homeotropic anchoring induce complex and novel topological structures in BP I.
• The identified structures, including double-helix disclinations and double-twist cylinders, offer new insights into defect formation in confined liquid crystals.
• These findings contribute to the fundamental understanding of liquid crystal phase behavior under geometric constraints.