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Chiral condensed matter systems, such as liquid crystals and magnets, exhibit a host of spatially localized topological structures that emerge from the medium’s tendency to twist and its competition with confinement and field coupling effects. We show that the strength of perpendicular surface boundary conditions can be used to control the structure and topology of solitonic and other localized field configurations. By combining numerical modeling and threedimensional imaging of the director field, we reveal structural stability diagrams and intertransformation of twisted walls and fingers, torons and skyrmions and their crystalline organizations upon changing boundary conditions. Our findings provide a recipe for controllably realizing skyrmions, torons and hybrid solitonic structures possessing features of both of them, which will aid in fundamental explorations and technological uses of such topological solitons. Moreover, with limited examples, we discuss how similar principles can be systematically used to tune stability of twisted walls versus cholesteric fingers and hopfions versus skyrmions, torons and twistions.
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Multiple Twisted Chiral Nematic Structures in Cylindrical Confinement
We study theoretically and numerically chirality and saddle-splay elastic constant (K_24) enabled stability of multiple-twist-like nematic liquid crystal (LC) structures in cylindrical confinement. We focus on the so-called radially-z-twisted (RZT) and radially-twisted (RT) configurations, which simultaneously exhibit twists in different spatial directions. We express free energies of the structures in terms of dimensionless wave vectors, which characterise the structures and play the role of order parameters. The impact of different confinement anchoring conditions is explored. A simple Landau-type analysis provides insight into how different model parameters influence the stability of structures. We determine conditions for which the structures are stable in chiral and also nonchiral LCs. In particular, we find that the RZT structure could exhibit macroscopic chirality inversion on varying the relevant parameters. This phenomenon could be exploited for measurements of K_24.
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- Award ID(s):
- 1901797
- PAR ID:
- 10168391
- Date Published:
- Journal Name:
- Crystals
- ISSN:
- 1742-0970
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/cryst10070576
