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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
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Landau theory for smectic-A-hexatic-B coexistence in smectic films
E I Kats1, V V Lebedev1,2, E S Pikina1,3
1Landau Institute for Theoretical Physics, RAS, 142432, Chernogolovka, Moscow region, Russia.
Physical Review. E
|October 3, 2019
Summary
We explain the smectic-A-hexatic-B phase coexistence in free-standing films. Surface hexatic order reduces the coexistence range with decreasing film thickness, disappearing at a critical thickness.
Area of Science:
- Soft matter physics
- Liquid crystal theory
Background:
- Experimental observation of smectic-A-hexatic-B equilibrium phase coexistence in free-standing smectic films.
- The phenomenon occurs within a finite-temperature range and presents theoretical peculiarities.
Purpose of the Study:
- To theoretically explain the observed phase coexistence.
- To quantitatively describe the phenomenon using Landau phase transitions theory.
- To investigate the role of film thickness and surface effects.
Main Methods:
- Application of Landau phase transitions theory.
- Assumption of the film state being close to a tricritical point.
- Analysis of the impact of surface hexatic order on phase coexistence.
Main Results:
- The surface hexatic order diminishes the phase coexistence range as film thickness decreases.
- The coexistence range shrinks to zero at a minimal film thickness (L_c).
- Universal laws for the temperature width of the coexistence range were established.
Conclusions:
- The developed theory quantitatively describes the smectic-A-hexatic-B phase coexistence.
- The theory aligns with existing experimental data.
- The findings provide insights into the behavior of liquid crystal films near critical points.
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