Spin waves in skyrmionic structures with various topological charges

Abstract

Equilibrium properties and localised magnon excitations are investigated in topologically distinct skyrmionic textures. The observed shape of the structures and their orientation on the lattice is explained based on their vorticities and the symmetry of the crystal. The transformation between different textures and their annihilation as a function of magnetic field is understood based on the energy differences between them. The angular momentum spin-wave eigenmodes characteristic of cylindrically symmetric structures are combined in the distorted spin configurations, leading to avoided crossings in the magnon spectrum. The susceptibility of the skyrmionic textures to homogeneous external fields is calculated, revealing that a high number of modes become detectable due to the hybridization between the angular momentum eigenmodes. These findings should contribute to the observation of spin waves in distorted skyrmionic structures via experiments and numerical simulations, widening the range of their possible applications in magnonic devices.

Skyrmion-antiskyrmion droplets in a chiral ferromagnet

“…Textures with skyrmion and antiskyrmion parts ("chimera skyrmions"), similar to the ones reported here, have been found numerically and studied in Refs. [14,17,18] within a model with frustrated isotropic exchange interaction and DM interaction. Related to our droplet are also the Q = 0 magnetic bubbles reported in Ref.…”