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Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
Smectic order, pinning, and phase transition in a smectic-liquid-crystal cell with a random substrate
1Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
Summary
This study reveals that smectic liquid crystals on heterogeneous surfaces form a stable smectic glass state. A novel model explains the temperature-controlled phase transition between weakly and strongly pinned states, matching experimental data.
Area of Science:
- Condensed matter physics
- Soft matter physics
- Materials science
Background:
- Smectic liquid crystals exhibit complex ordering influenced by surface interactions.
- Heterogeneous substrates introduce random pinning, affecting bulk material properties.
- Understanding these effects is crucial for applications in displays and sensors.
Purpose of the Study:
- To investigate smectic liquid-crystal order on substrates with random positional and orientational pinning.
- To develop a theoretical model for predicting the behavior of smectic states under such conditions.
- To explain experimental observations using a new theoretical framework.
Main Methods:
- Development of a minimal random elastic model for smectic systems.
- Analysis of the stability of the smectic state on heterogeneous substrates.
- Computation of substrate-driven distortions and domain size statistics.
- Investigation of phase transitions in the smectic glass state.
Main Results:
- The smectic state in thick cells with heterogeneous substrates is unstable at long scales.
- A stable smectic glass state emerges for weak random pinning.
- A three-dimensional temperature-controlled phase transition occurs between weakly and strongly pinned smectic glass states.
- The model predicts domain size and distortions consistent with experimental observations.
Conclusions:
- The proposed random elastic model accurately describes smectic liquid-crystal behavior on heterogeneous substrates.
- The findings provide a theoretical basis for the observed smectic glass states and phase transitions.
- The study offers a plausible explanation for experimental results obtained via polarized light microscopy and X-ray scattering.
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