Mean-field study of the interplay between antiferromagnetism and d-wave superconductivity

The interplay between antiferromagnetism and d-wave superconductivity is st udied in a mean-field approximation for a generic microscopic Hamiltonian w ith short-range repulsion and near-neighbor attraction. In the presence of competing microscopic interactions, the phase boundaries of antiferromagnet ic apd superconducting states are significantly modified in some region of the doping-temperature plane. The transition between superconductivity and antiferromagnetism occurs through a phase where both order parameters coexi st with a third, dynamically generated, spin-tripler amplitude. This dynami cal generation of a new order parameter is not restricted to a system with antiferromagnetism and cl-wave superconductivity, but is a generic feature for fermionic Systems. The dynamically generated spin;triplet order paramet er is found to be robust to variations in the mean-field Hamiltonian.