Coexistence of superconductivity and antiferromagnetism in a bilayer t-J model

We examine the coexistence of superconductivity and antiferromagnetism in a bilayer t-J model using variational Monte Carlo method. The variational wave function considered describes antiferromagnetic, superconducting and a coexisting phase of these two orders depending on the variational parameters. We find that superconductivity coexists with antiferromagnetism upto ∼14% hole concentration. Beyond this upto ∼34% hole concentration the pure d-wave superconducting phase is found to be the stable state. The superconducting correlations, calculated for both the coexisting and the pure superconducting state, are found to be enhanced in the coexisting phase as compared to that in the d-wave superconducting state. (author)