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Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
Reentrant orthogonal smectic-A phase below a tilted smectic-C phase in a chiral compound
Vladimíra Novotná1, Milada Glogarová, Miroslav Kašpar
1Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, CZ-182 21 Prague 8, Czech Republic. novotna@fzu.cz
Summary
A chiral liquid crystal exhibits a reentrant orthogonal smectic-A phase below the smectic-C phase. This finding, confirmed by layer spacing, is explained by mean field theory and temperature-dependent coefficients.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Physical Chemistry
Background:
- Chiral liquid crystals exhibit complex phase behaviors.
- Smectic phases, particularly smectic-A and smectic-C, are well-studied liquid crystalline phases.
- Reentrant phase transitions, where a phase reappears at lower temperatures, are intriguing phenomena.
Purpose of the Study:
- To establish and characterize a reentrant orthogonal smectic-A phase in a chiral liquid crystalline compound.
- To investigate the structural properties, specifically layer spacing, of the observed smectic phases.
- To provide a theoretical explanation for the reentrant behavior using mean field theory.
Main Methods:
- Synthesis and characterization of a chiral liquid crystalline compound.
- Temperature-dependent X-ray diffraction to measure layer spacing.
- Analysis using mean field free energy calculations.
Main Results:
- A reentrant orthogonal smectic-A phase was successfully established below the tilted smectic-C phase.
- Temperature evolution of layer spacing confirmed a monolayer structure in both the upper and reentrant smectic-A phases.
- Mean field free energy calculations, incorporating non-monotonous temperature dependence of coefficients, explained the reentrancy.
Conclusions:
- The study confirms the existence of a reentrant orthogonal smectic-A phase in chiral liquid crystals.
- Monolayer structures are maintained in both smectic-A phases, indicating robust molecular ordering.
- Mean field theory provides a valid framework for understanding the complex reentrant phenomenon in these materials.
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