We study the phase diagram of a new model that exhibits a first order transition between s-wave superconducting and antiferromagnetic phases. The model, a generalized Hubbard model augmented with competing spin-spin and pair-pair interactions, was investigated using the projector Quantum Monte Carlo method. Upon varying the Hubbard U from attractive to repulsive we find a first order phase transition between superconducting and antiferromagnetic states.
@article{arxiv.cond-mat/0212244,
title = {Coexistence of s-wave Superconductivity and Antiferromagnetism},
author = {M. Feldbacher and F. F. Assaad and F. Hebert and G. G. Batrouni},
journal= {arXiv preprint arXiv:cond-mat/0212244},
year = {2009}
}