The work reports on the mutual knotting of physical knots in the form of microscopic colloidal particles and the field knots in the molecular ordering field of nematic liquid crystal. Microscopic particle-knots are produced via laser two-photon photopolimerisation technique. Numerical modelling is used for characterisation of the structures in the nematic field, especially topological boojum defects and defect lines, which reveals an interesting interplay of knotted particle and field topologies. The research opens a new route for the self-assembly of topological superstructures and for modelling of other physical systems with similar topological characteristics. The paper was additionally highlighted with the Front Cover of Nature Materials issues and with a News and Views article by Prof. W.T.M. Irvine from the University of Chicago, who is one of the world leading experts on experimental topology of complex fields.
COBISS.SI-ID: 2630244
We demonstrate that quasicrystalline structures can be achieved in the form of Penrose tiling by assembling micro-platelets in the shape of pentagons within a thin layer of nematic fluid. The tiling is energetically stabilized with binding energies of typically several orders of magnitude higher than thermal energy and further allows for hierarchical substitution of individual pentagonal tiles with smaller tiles, which is interesting for the design of photonics at multiple frequency ranges.
COBISS.SI-ID: 2638948
Tunable photonic crystals based on blue phase colloids are shown where the birefringent profile generates the periodic variation of the dielectric permittivity. Multicomponent design of the material, where each components is orgnaised into a lattice with different symmetry, allows for conceptually diffeent tuning of the photonic bands, including local opening and closing of the photonic band gaps.
COBISS.SI-ID: 2701924