We demonstrate full control over the creation, manipulation and analysis of topological charges that are pinned to a microfibre in a nematic liquid crystal. Oppositely charged pairs are created through the Kibble–Zurek mechanism by applying a laser-induced local temperature quench in the presence of symmetry-breaking boundaries. The pairs are long-lived, oppositely charged rings or points that either attract and annihilate, or form a long-lived, charge-neutral loop made of two segments with a fractional topological charge.
COBISS.SI-ID: 2786916
In this article, we show how several abstract concepts manifest elegantly as observable and measurable features in nematic colloids with knotted disclination lines. Construction of medial graphs, surfaces, and Jones polynomials is showcased directly on experimental images, and adapted for the specific system of colloidal crystals in a twisted nematic cell. We discuss the correspondence between topological concepts and experimental observation, which is essential for building the bridge between mathematical and physical communities.
COBISS.SI-ID: 2787940
We observe that topological defects in nematic colloids are strongly influenced by the elasticity and onset of smectic layering across the nematic (N) to smectic-A (SmA) phase transition. When approaching the SmA phase from above, the nematic hyperbolic hedgehog defect that accompanies a spherical colloidal inclusion is transformed into a focal conic line in the SmA phase. This phase transformation has a strong influence on the pairwise colloidal interaction and is responsible for a structural transition of two-dimensional colloidal crystals. The pretransitional behavior of the point defect is supported by Landau–de Gennes Q-tensor modeling accounting for the increasing elastic anisotropy. The article was published at the time of this report, but hasn't been assigned the COBISS ID yet.