Quantum Monte Carlo evidence for superconductivity in the three-band Hubbard model in two dimensions

Abstract

A possibility of the electronic origin of the high-temperature superconductivity in cuprates is probed with the quantum Monte Carlo method by revisiting the three-band Hubbard model comprising Cu$3d_{x^2-y^2}$ and O$2p_σ$ orbitals. The $d_{x^2-y^2}$ pairing correlation is found to turn into an increasing function of the repulsion $U_d$ within the $d$ orbitals or the $d$-$p$ level off-set $Δ\varepsilon$, where the correlation grows with the system size. % and is long-ranged as also seen from a real-space analysis. We have detected this in both the charge-transfer and Mott-Hubbard regimes upon entering the strong-correlation region ($U_d$ or $Δ\varepsilon >$ bare band width).

8 pages, revtex, 5 figures available on request from kuroki@izanagi.phys.s.u-tokyo.ac.jp , replaced because we have added reference [4] (R.T. Scalettar et.al. Phys. Rev. B 44, 770 (1991)) in our manuscript