d-wave pairing in the doped static charge-density-wave state on a two-dimensional square lattice

The extended Hubbard model with nearest-neighbor (NN) Coulomb repulsion is used to study superconductivity in a static charge-density-wave (CDW) state . It is found that the doped carriers form a large Fermi surface and are co ndensed into the d(xy)-wave superconducting state from the root 2 x root 2 CDW state stabilized by the NN Coulomb repulsion. The superconductivity coe xisting with a CDW order observed in YBa2Cu3O7-delta [S. Kramer and M. Mehr ing, Phys. Rev. Lett. 83, 396 (1999)] together with the superconductivity o f Pr2-xCexCuO4-y [M. Brinkmann, H. Bach, and K. Westerholt, Physica C 292, 104 (1997)] may be important examples of this pairing mechanism.