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Field-driven crossover from attractive-to-repulsive Casimir-like force in smectic films
1Departamento de Física, Universidade Federal de Alagoas, 57072-970 Maceió-AL, Brazil.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 17, 2004
Summary
External fields significantly alter liquid crystal behavior. This study reveals how ordering fields modify thermal Casimir forces in smectic films, showing a crossover from repulsion to attraction with increasing thickness.
Area of Science:
- Condensed Matter Physics
- Soft Matter Physics
Background:
- External fields influence the dynamics of strongly correlated fluids like liquid crystals.
- Understanding these effects is crucial for predicting material behavior under various conditions.
Purpose of the Study:
- To compute the fluctuation-induced force in a smectic liquid-crystal film subjected to an external ordering field.
- To analyze the thermal Casimir interaction energy for asymmetrically anchored films.
Main Methods:
- Utilized a harmonic functional integral approach.
- Calculated the force between surfaces of a smectic liquid-crystal film.
Main Results:
- Demonstrated that the thermal Casimir interaction energy exhibits a universal form for asymmetrically anchored films.
- Observed a crossover from repulsive to attractive interactions as film thickness increases.
Conclusions:
- External ordering fields can fundamentally change the nature of surface interactions in liquid crystals.
- The findings may be relevant for understanding nematic-smectic wetting transitions.