D-wave pairing in the two-dimensional Hubbard model with low filling

Douglas J. Scalapino

Andrey V. Chubukov, Jianping Lü

We show that for low and moderate fillings the ground state of the two-dimensional Hubbard model with positive-U and nearest-neighbor hopping is unstable with respect to d-wave pairing with dxy symmetry of the gap wave function: Δ∼sinkxsinky. The inclusion of the next-neighbor hopping may either suppress the pairing or change the symmetry of the superconducting state.

Thomas Pruschke, Thomas Maier, J. Keller +1 more

Andrey V. Chubukov, Jian Ping Lu

We show that for low and moderate fillings the ground state of the two-dimensional Hubbard model with positive-U and nearest-neighbor hopping is unstable with respect to d-wave pairing with ${\mathit{d}}_{\mathit{x}\mathit{y}}$ symmetry of the gap wave function: \ensuremath{\Delta}\ensuremath{\sim}sin${\mathit{k}}_{\mathit{x}}$sin${\mathit{k}}_{\mathit{y}}$. The inclusion of the next-neighbor hopping may either suppress the pairing or change the symmetry of the superconducting state.

Nikolay M. Plakida, V. Yu. Yushankhaï, Ihor V. Stasyuk

H. Q. Lin, J. E. Hirsch, Douglas J. Scalapino

We have studied the pair susceptibilities for all possible pair wave functions that fit on a two-dimensional (2D) eight-site Hubbard cluster by exact diagonalization of the Hamiltonian. Band fillings corresponding to four and six electrons were studied (two or four holes in the half-filled band) for a wide range of Hubbard interaction strengths and temperatures. Our results show that all pairing susceptibilities are suppressed by the Hubbard repulsion. We have also carried out perturbation-theory calculations which show that the leading-order ${U}^{2}$ contributions to the d-wave pair susceptibility suppresses d-wave pairing over a significant temperature range. These results are consistent with recent Monte Carlo results and provide further evidence suggesting that the 2D Hubbard model does not exhibit superconductivity.