Dynamic Critical Behavior of the Heisenberg Model with Strong Easy Plane   Anisotropy
  The dynamic critical behavior of the Heisenberg model with a strong anisotropy of the exchange constant in the z direction is investigated. The main features of the time evolution of this model are revealed. The static and dynamic critical behavior of planar magnetic models is shown to be described well by the Heisenberg model with strong easy plane anisotropy. 
V. A. Mutailamov, A. K. Murtazaev
cond-mat.stat-mech