Phase diagram of a generalized tJ model: renormalization group approach

A generalized t J Hamiltonian is analyzed within the framework of a quantum real space renormalization group. Besides the usual hopping (t), exchange (J) and chemical potential (μ) terms the Hamiltonian contains a nearest-neighbor charge interaction one and is invariant under the renormalization. The finite temperature phase diagram of the d = 2 and d = 3 model is calculated in the full range of the parameters. Our results show that many of the critical properties of the La and Y based high-Tc superconductors can be explained by the present model. (author)