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

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(x2-y2) and O 2p(sigma) orbitals. The d(x2-y2) pairing correlation is found to rum into an increasing function of the repulsion U-d within the d orbitals or the d-p level offset Delta epsilon, where the normalized correlation grows with the system size. We have detected this in both the charge-transfer and Mott-Hubbard regimes upon entering the strong-correlation region (U-d or Delta epsilon > bare bandwidth).