Fluctuation-induced interactions in nematics with disordered anchoring energy

Area of Science:

• Physics
• Materials Science
• Surface Science

Background:

• Nematic liquid crystals exhibit unique anisotropic properties.
• Confinement between surfaces can induce novel physical phenomena.
• Surface anchoring conditions critically influence liquid crystal behavior.

Purpose of the Study:

• To investigate fluctuation-induced (pseudo-Casimir) interactions in nematic liquid-crystalline films.
• To analyze the impact of chemically disordered surface anchoring on these interactions.
• To understand how surface disorder modifies the effective anchoring parameter and interaction force.

Main Methods:

• Utilizing a saddle-point approximation to calculate the free energy of interaction.
• Modeling one surface with strong homeotropic anchoring and the other with annealed disorder in anchoring energies.
• Comparing interaction forces with and without disordered surface anchoring.

Main Results:

• Disordered surface anchoring leads to a renormalization of the effective surface anchoring parameter.
• This renormalization causes quantitative and qualitative changes in the pseudo-Casimir interaction force.
• A sign change in the interaction force is observed at intermediate inter-surface separations due to disorder.

Conclusions:

• Chemically disordered surfaces fundamentally alter confinement-induced forces in liquid crystals.
• The pseudo-Casimir interaction is highly sensitive to the statistical properties of surface anchoring.
• Understanding these effects is crucial for designing devices utilizing liquid crystal confinement.