SUPERCONDUCTIVITY IN CORRELATED WAVEFUNCTIONS

We discuss variational approaches to the one band Hamiltonian in the projected subspace. This Hamiltonian has a kinetic energy term for charge degree of freedom and nearest neighbor antiferromagnetic spin-spin interactions. We show that the project d-wave BCS state (RVB-wavefunction) is a quantum spin liquid. This is done with results from numerical evaluation of the wavefunction, renormalized mean field theory and results from exact diagonalization of small systems. Off half-filling, this wavefunction leads to superconductivity with an order parameter which has d-symmetry.