Speaker
Description
Magnetic vortices and skyrmions are typically characterized by distinct topological invariants corresponding to elements of homotopy groups of different spaces. At the same time, intermediate forms of these states - merons - exist and are well studied. This term was introduced in the 1970s, and today an elementary magnetic meron is typically understood to be a planar vortex where the core is non-singular due to out-of-plane spins. In this talk, we show how to resolve the puzzling fractional topological charge postulate for merons, which has become standard practice in recent decades. Namely, we present a unified topological classification bringing together vortices, skyrmions, and merons [1]. In this classification, merons, as well as any combinations of them, correspond to elements of the homotopy group isomorphic to the free abelian group ℤ×ℤ. Additionally, we briefly discuss generalizations to cases where the homotopy group is no longer abelian and has exponential growth [1,2].
[1] F.N. Rybakov, O. Eriksson and N.S. Kiselev, Phys. Rev. B 111, 134417 (2025).
[2] F.N. Rybakov and O. Eriksson, arXiv:2205.15264 (2022).
