A sweeping twist defect as a topological flagellum that drives colloid motion
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arXiv
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| Autores principales: | , , , , |
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| Formato: | Preprint |
| Publicado: |
2026
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| _version_ | 1866917531284930560 |
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| author | Zhang, Qi Xing Dore, Claire Rajabi, Mojtaba Steager, Edward B. Stebe, Kathleen J. |
| author_facet | Zhang, Qi Xing Dore, Claire Rajabi, Mojtaba Steager, Edward B. Stebe, Kathleen J. |
| contents | Nematic liquid crystals can dramatically reconfigure under dynamic forcing, providing exciting opportunities in active matter. Here, we study a hybrid disk colloid rotated by an external field which generates a dynamic companion topological defect. The disk moves faster when the defect sweeps across the disk's face. We identify the defect as a non-singular twist wall, characterize the twist energy landscape, and identify the sweeping motion as a topological instability. As the defect sweeps, it reverses the handedness of twist and lowers the free energy in the fluid in the gap above the disk. Landau-de Gennes modeling shows that the sweeping wall behaves as a propagating director texture: the director field is nearly stationary in the wall frame, while nematogens rotate locally as the wall passes. The nematogens' rotation generates a viscous stress on the surface of the disk that hastens its propulsion. Thus, the defect acts as a flagellum that powers colloid swimming, providing an example of a dissipative topological structure whose dynamics can be harnessed to perform useful work. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_25606 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | A sweeping twist defect as a topological flagellum that drives colloid motion Zhang, Qi Xing Dore, Claire Rajabi, Mojtaba Steager, Edward B. Stebe, Kathleen J. Soft Condensed Matter Nematic liquid crystals can dramatically reconfigure under dynamic forcing, providing exciting opportunities in active matter. Here, we study a hybrid disk colloid rotated by an external field which generates a dynamic companion topological defect. The disk moves faster when the defect sweeps across the disk's face. We identify the defect as a non-singular twist wall, characterize the twist energy landscape, and identify the sweeping motion as a topological instability. As the defect sweeps, it reverses the handedness of twist and lowers the free energy in the fluid in the gap above the disk. Landau-de Gennes modeling shows that the sweeping wall behaves as a propagating director texture: the director field is nearly stationary in the wall frame, while nematogens rotate locally as the wall passes. The nematogens' rotation generates a viscous stress on the surface of the disk that hastens its propulsion. Thus, the defect acts as a flagellum that powers colloid swimming, providing an example of a dissipative topological structure whose dynamics can be harnessed to perform useful work. |
| title | A sweeping twist defect as a topological flagellum that drives colloid motion |
| topic | Soft Condensed Matter |
| url | https://arxiv.org/abs/2605.25606 |