LOW-ENERGY EFFECTIVE REPRESENTATION OF THE PROJECTED BCS HAMILTONIAN CLOSE TO HALF FILLING

It has recently been shown (K. Park, Phys. Rev. Lett. 95, 027001 (2005)) that the ground state of the t-J model at half filling is entirely equivalent to the ground state of the Gutzwiller-projected Bardeen-Cooper-Schrieffer (BCS) Hamiltonian with strong pairing. Here we extend this result to finite doping. We show that in the immediate vicinity of half filling the projected 2D BCS Hamiltonian with strong pairing still develops the antiferromagnetically (AF) ordered ground state.