ANTIFERROMAGNETISM AND SUPERCONDUCTIVITY IN A 2-DIMENSIONAL HEISENBERG-MODEL - FURTHER-STUDIES ON POSSIBLE COEXISTENCE

The question of possible coexistence of antiferromagnetism (AF) and superconductivity (SC) is reexamined within the t-J model by using an improved mean-field treatment. The renormalization of the effective Hamiltonian and the symmetry of the order parameters are properly taken into account. Our calculations reconfirm the possible coexistence of AF and SC below critical doping concentrations c=0.04 and 0.06 for t/J=5 and 2.5, respectively, in good agreement with recent variational Monte Carlo results. This conclusion is consistent with the muon-spin-rotation data. Among pairings of various symmetries, the d-wave pairing has the lowest energy. © 1990 The American Physical Society.