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Topological defects are quasiparticles whose topological nature provides some stability against perturbations. Skyrmions, domain walls, dislocations in crystals, vortices in superconductors and superfluids, and strings and monopoles in liquid crystals are all examples of topological defects. The concept of topological defects is diverse, spanning from condensed matter to fields such as particle physics and cosmology.
Authors predict polar Bloch points with negative capacitance in tensile-strained ultrathin ferroelectric PbTiO3 film by phase-field simulations, observing their polarization structures by scanning transmission electron microscopic imaging.
Topological solitons are localized structures whose stability emerges from the topology of their spatial structure, hence they are usually independent of the temporal dimension. The authors construct topological magnetic solitons in space-time from periodically driven magnetic structures that can be externally controlled.
Previous measurements of FeSe0.45Te0.55 found one-dimensional (1D) defects that were interpretated as domain walls hosting propagating Majorana topological modes. Here, the authors reveal that these 1D defects correspond to sub-surface debris and show that the filling of the superconducting gap on these defects is topologically trivial.
Kekulé vortices in hexagonal lattices can host fractionalized charges at zero magnetic field, but have remained out of experimental reach. Here, the authors report a Kekulé vortex in the local density states of graphene around a chemisorbed hydrogen adatom.
The ferromagnet CrVI6 serves as a material platform to demonstrate the topological Kerr effect in two-dimensional magnets. This can be used to identify skyrmions by magneto-optical means.
The antiferromagnetic material haematite, named for its blood-red colour, hosts swirling spin vortices termed merons. The rotation sense of such antiferromagnetic vortices has now been imaged in real space.
A paper in Nature Nanotechnology reports the room-temperature generation and control of meron–antimeron pairs in an antiferromagnet by means of electrical pulses.
Liquid crystal defect structures with topology similar to a Möbius strip can rotate, translate and transform into one another under an applied electric field.