Filaments in the twist-grain-boundary smectic-A phase

Area of Science:

• Materials Science
• Condensed Matter Physics
• Liquid Crystals

Background:

• The twist-grain-boundary smectic-A (TGBA) phase exhibits complex filament textures.
• Understanding the formation and structure of these filaments is crucial for liquid crystal display technology.
• Existing models do not fully capture the observed filament morphology and surface nucleation.

Purpose of the Study:

• To propose a novel model for TGBA phase filaments nucleating on a sample surface.
• To explain the helical structure of filaments formed by finite blocks of smectic layers.
• To describe the inclination of filament axes relative to surface molecular anchoring.

Main Methods:

• Development of a theoretical model based on finite blocks of parallel smectic layers.
• Incorporation of dislocation loops surrounding these blocks.
• Analysis of filament structure near the sample surface and axis inclination.
• Estimation of compression modulus using anchoring energy and critical field data.

Main Results:

• The proposed model successfully describes TGBA filament formation from the homeotropic smectic-A phase.
• The model accounts for the helical structure within filaments and their surface nucleation.
• It explains the observed inclination of filament axes relative to the easy anchoring direction.
• Compression modulus was estimated from experimental parameters.

Conclusions:

• The developed model provides a comprehensive framework for understanding TGBA phase filament structures.
• This model is applicable to TGBA filament formation in diverse chiral liquid crystalline compounds.
• The study offers insights into the relationship between molecular anchoring, phase structure, and material properties.