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Controlling topological textures of umbilics using spatiotemporal magnetic fields
Nina Kravets1, Gregorio Gonzalez-Cortes1, Etienne Brasselet1
1Université de Bordeaux, CNRS, Laboratoire Ondes et Matière d'Aquitaine, F-33400, Talence, France. nina.kravets@u-bordeaux.fr.
Soft Matter
|November 13, 2025
Summary
Researchers controlled topological defects in liquid crystals using structured magnetic fields. This method allows for reconfigurable generation of specific defect textures, offering new ways to structure soft materials.
Area of Science:
- Soft matter physics
- Liquid crystal science
- Topological defect manipulation
Background:
- Topological defects in liquid crystals are a key area of soft matter research.
- Controlling defect generation and evolution is crucial for applications.
Purpose of the Study:
- To demonstrate control over the generation of umbilic defect textures in nematic liquid crystals.
- To utilize spatiotemporally structured magnetic fields for defect manipulation.
Main Methods:
- Employing an array of four permanent magnets to generate a structured magnetic field.
- Analyzing the liquid crystal's orientational response to magnetic torque.
- Deriving a 2D amplitude equation from Frank-Oseen free energy for quantitative description.
Main Results:
- Achieved reconfigurable generation of textures with central umbilics (topological charge ±1).
- Experimental observations qualitatively supported by magnetic field analysis.
- Developed a quantitative model predicting the morphogenesis of liquid crystal topological textures.
Conclusions:
- Symmetry-guided field-orientation coupling enables deterministic control of topological defects.
- This spatiotemporal approach offers novel routes for structuring anisotropic soft materials.
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