Two-dimensional liquid crystalline growth within a phase-field-crystal model.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Crystallography

Background:

• The phase-field-crystal (PFC) model is a powerful tool for simulating materials at atomic scales.
• Understanding crystal growth dynamics is crucial for designing materials with desired properties.
• Liquid crystalline phases exhibit unique ordering and defect structures.

Purpose of the Study:

• To investigate the liquid crystalline growth of plastic triangular crystals (PTCs).
• To analyze the influence of different precursor phases (isotropic vs. columnar/smectic-A) on PTC shape.
• To characterize the formation and evolution of topological defects during PTC growth.

Main Methods:

• Simulation using a two-dimensional phase-field-crystal (PFC) model.
• Comparison of PTC equilibrium shapes grown from isotropic and columnar/smectic-A (CSA) phases.
• Analysis of topological defect structures, specifically disclinations, during growth.

Main Results:

• PTC shape in an isotropic phase resembles classical PFC models.
• PTC shape in CSA is influenced by stripe orientation, yielding irregular shapes (hexagonal, elliptical, octagonal, rectangular).
• Growth involves nucleation of +/- 1/2 disclination pairs, evolving into hexagonal cells with +1 vortices and satellite -1/2 disclinations.
• Orientational order lags behind positional order, creating a broad transition zone.

Conclusions:

• The precursor phase significantly alters PTC growth morphology and defect formation.
• The observed defect structures are characteristic of nematic liquid crystal ordering.
• The decoupling of orientational and positional order during growth has implications for understanding phase transitions in soft matter systems.