Vortices in the presence of a nonmagnetic atom impurity in 2D XY   ferromagnets
  Using a model of nonmagnetic impurity potential, we have examined the behavior of planar vortex solutions in the classical two-dimensional XY ferromagnets in the presence of a spin vacancy localized out of the vortex core. Our results show that a spinless atom impurity gives rise to an effective potential that repels the vortex structure. 
L. A. S. M\'ol, A. R. Pereira and A. S. T. Pires