Spiral vortices in a 2D ferromagnet
  We present a study of a new class of exact solutions having a form of spiral vortices for an isotropic two-dimensional Heisenberg ferromagnet using a continuum theory and direct numerical simulations of the spin system on a square lattice. We find their features issued from the conservation laws and describe their interaction. Reasons behind the formation of the proper spin configurations on a square lattice are investigated. 
A.B. Borisov, I.G. Bostrem, A.S. Ovchinnikov