Telephone-cord instabilities in thin smectic capillaries

Area of Science:

• Condensed Matter Physics
• Materials Science
• Soft Matter Physics

Background:

• Telephone-cord patterns, a novel instability, have been observed in smectic liquid-crystal capillaries.
• Understanding the physical mechanisms driving these complex structures is crucial for materials science and physics.

Purpose of the Study:

• To analyze the factors inducing telephone-cord patterns in smectic liquid-crystal capillaries.
• To investigate the role of chiral pitch, bending stress, and spontaneous polarization in capillary shape transitions.

Main Methods:

• Theoretical analysis of free energy minimization in liquid-crystal phases.
• Modeling of capillary shape under various physical conditions, including spontaneous polarization and molecular tilt.

Main Results:

• A nonzero chiral cholesteric pitch favors the Smectic-A* to Smectic-C* transition in linear capillaries.
• Neither cholesteric pitch nor bending stress alone can induce capillary curvature.
• Spontaneous polarization is identified as the key factor for the telephone-cord instability, leading to nonzero capillary curvature in the Sm-A* phase.
• In the Sm-C* phase, molecular tilt and spontaneous polarization together induce a helicoidal capillary shape with curvature and torsion.

Conclusions:

• Spontaneous polarization is the essential driver for telephone-cord instability in liquid-crystal capillaries.
• The Sm-A* phase exhibits planar capillary shapes with curvature due to spontaneous polarization.
• The Sm-C* phase displays helicoidal capillary shapes, characterized by curvature and torsion, resulting from the interplay of molecular tilt and spontaneous polarization.