Topological defects in soft matter

Topology plays a crucial role in many branches of physics. One of the exciting and versatile systems for studying topological structure of matter are nematic liquid crystals and their colloidal composites, where singularities in nematic order parameter emerge as topological defects. Under constraints imposed by boundary conditions and different topologies of inserted colloids, distinct defects are formed, such as disclination lines, knots, links and particle-induced defect loops. We explore the structures of fields and defects, study their topological properties and how to manipulate them.

Selected papers

  • J. Pišljar, S. Ghosh, S. Turlapati, N. V. S. Rao, M. Škarabot, A. Mertelj, A. Petelin, A. Nych, M. Marinčič, A. Pusovnik, M. Ravnik, and I. Muševič, Blue phase III: Topological fluid of skyrmions, Phys. Rev. X 12, 011009 (2022). [Link] [PDF].

  • J.C. Everts and M. Ravnik, Ionically Charged Topological Defects in Nematic Fluids, Phys. Rev. X 11, 011054 (2021). [Link] [PDF].

  • M. Ravnik and J. C. Everts, Topological-Defect-Induced Surface Charge Heterogeneities in Nematic Electrolytes, Phys. Rev. Lett. 125, 037801 (2020). [Link] [PDF].

  • J. Polard, G. Posnjak, S. Čopar, I. Muševič, G. P. Alexander Point Defects, Topological Chirality, and Singularity Theory in Cholesteric Liquid-Crystal Droplets, Phys. Rev. X 9, 021004 (2019) [PDF].

  • D. S. Kim, S. Čopar, U. Tkalec, and D. K. Yoon, Mosaics of topological defects in micropatterned liquid crystal textures, Sci. Adv. 4, 11 (2018). [Abstract] [PDF].

  • G. Posnjak, S. Čopar and I. Muševič, Hidden topological constellations and polyvalent charges in chiral nematic droplets, Nat. Commun. 8, 14594 (2017). [Link] [PDF].

  • A. Martinez, M. Ravnik, B. Lucero, R. Visvanathan and S. Žumer, Mutually tangled colloidal knots and induced defect loops in nematic fields, Nat. Mater. 13, 3 (2014). [Link] [PDF].

  • D. Seč, S. Čopar and S. Žumer, Topological zoo of free-standing knots in confined chiral nematic fluids, Nat. Commun. 5, 3057 (2014). [Link] [PDF].

  • U.Tkalec, M. Ravnik, S. Čopar, S. Žumer and I. Muševič, Reconfigurable knots and links in chiral nematic colloids, Science 333, 6038 (2011). [Link] [PDF].