Quantum spin- two-dimensional XXZ model: an alternative quantum renormalization-group approach

We study the phase diagram of the two-dimensional quantum spin- anisotropic Heisenberg model. We adapt a renormalization-group approach to treat this quantum model, and an analysis on low temperatures is presented and compared with the exact results in the isotropic limit, obtained from the Mermin–Wagner theorem. We comment on extensions of the procedure to treat antiferromagnetic models, for and .