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Updated: Apr 29, 2026
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High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
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Twist transition of nematic hyperbolic hedgehogs
Richard James1, Jun-ichi Fukuda2
1Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568, Japan and Department of Electronic & Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom.
Summary
Investigating hyperbolic hedgehogs in liquid crystals reveals that differing splay and bend moduli shift twist transitions. Increased confinement can inhibit these transitions, a property shared with radial hedgehogs.
Area of Science:
- Soft Matter Physics
- Liquid Crystal Science
- Complex Fluid Dynamics
Background:
- Nematic liquid crystals exhibit topological defects, such as hedgehogs, which influence material properties.
- The stability of these defects, particularly under confinement, is crucial for understanding liquid crystal behavior.
- Previous work established methodologies for analyzing hedgehog stability in confined geometries.
Purpose of the Study:
- To investigate the stability of hyperbolic hedgehogs in nematic liquid crystals against twist transitions.
- To extend existing methodologies to analyze the influence of differing elastic moduli on defect stability.
- To explore the effect of confinement on preventing twist transitions in hyperbolic hedgehogs.
Main Methods:
- Extended the methodology of Rüdinger and Stark (1999) for analyzing defect stability.
- Modeled a hyperbolic hedgehog confined between two concentric spheres.
- Analyzed the impact of differing splay (k11) and bend (k33) elastic moduli on molecular orientation and liquid crystal deformation.
Main Results:
- Deviations from ideal hyperbolic hedgehog orientation occur when splay and bend moduli differ, leading to splay-bend deformations.
- These deformations significantly alter the transition point, especially when the ratio k11/k33 is small.
- Increased confinement effectively inhibits the twist transition, a behavior consistent with radial hedgehogs.
Conclusions:
- The stability of hyperbolic hedgehogs is sensitive to the ratio of splay to bend elastic moduli.
- Confinement is a key factor in controlling the twist transition of hyperbolic defects.
- The stability analysis accurately predicts the twist transition of hyperbolic defects associated with particles.
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