Mixed Phases for the t-J Model

We study the competition between non-magnetic (dimer or flux) states and short-range antiferromagnetically ordered RVB states in the t-J model and present a finite temperature phase diagram. We show that, for a wide range of temperatures and dopings, the stable phase results to be a state in which both the flux and the RVB parameters are nonzero. PACS: 71.27, 74.20. In this paper we want to extend the analysis of the phase diagram of the t-J model on a square lattice, started by some of the authors in ref. [1], where only the so called non-magnetic states (such as the dimer and the flux phase) were considered. Our starting point is the t-J Hamiltonian, as originally proposed in [2]: H = tδ ∑