Anisotropic two-dimensional Heisenberg model studied by the Schwinger-boson Gutzwiller-projection method

A two-dimensional Heisenberg model with anisotropic couplings in the x and y directions (${\mathit{J}}_{\mathit{x}}$≠${\mathit{J}}_{\mathit{y}}$) is considered. The model is first solved in the Schwinger boson mean-field approximation. Then the solution is Gutzwiller projected to satisfy the local constraint that there is only one boson at each site. The energy and spin-spin correlation of the obtained wave function are calculated for systems with up to 20×20 sites by means of the variational Monte Carlo simulation. It is shown that the antiferromagnetic long-range order remains down to the one-dimensional limit.