Topological excitations in a two-dimensional spin system with high spin s≥1

We construct a class of topological excitations of a mean field in a two-dimensional spin system represented by a quantum Heisenberg model with high powers of the exchange interaction. The quantum model is associated with a classical model (the continuous classical analogue) based on a Landau-Lifshitz-like equation, which describes large-scale fluctuations of the mean field. On the other hand, the classical model in the case of spin s is a Hamiltonian system on a coadjoint orbit of the unitary group SU(2s+1). We construct a class of mean-field configurations that can be interpreted as topological excitations because they have fixed topological charges. Such excitations change their shapes and grow, conserving energy.