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Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
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Polarity sensitive electric responses in a twisted smectic-C liquid crystal
1Centre for Soft Matter Research, P.O. Box 1329, Jalahalli, Bangalore 560013, India.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 4, 2014
Summary
This study reveals two polarity-sensitive electrical responses in a twisted liquid crystal. These phenomena, involving director modulation and pattern shifts, are linked to flexoelectric polarization mechanisms.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Liquid Crystal Physics
Background:
- Achiral rodlike smectic-C liquid crystals exhibit complex electrical responses under low-frequency fields.
- The 90°-twisted configuration is crucial for observing specific electro-optic phenomena.
Purpose of the Study:
- To investigate and characterize two novel polarity-sensitive electrical responses in a specific liquid crystal configuration.
- To elucidate the underlying physical mechanisms, particularly the role of flexoelectric polarization.
Main Methods:
- Applying low-frequency (<1 Hz) square wave electric fields to a 90°-twisted achiral smectic-C liquid crystal.
- Observing and analyzing transient director modulation and periodic Fréedericksz pattern shifts.
- Utilizing electro-optic measurements and theoretical modeling.
Main Results:
- Identified a transient director modulation at polarity reversals, localized near the negative electrode.
- Observed a polarity-sensitive shift in the periodic Fréedericksz pattern, saturating at high fields.
- Associated these effects with the Carr-Helfrich mechanism and flexoelectric polarization.
Conclusions:
- The observed phenomena are attributed to flexoelectric polarization, enhanced by quadrupolar effects and director twist.
- The study provides insights into the electro-optic behavior of twisted liquid crystals and the role of flexoelectricity.
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