Superconductivity in the t-J model on the square lattice

Ehsan Khatami, Richard T. Scalettar, Rajiv R. P. Singh

Hong‐Chen Jiang

Katsunori Kubo

J. Samuel Millán, Luis Antonio Pérez, Chumín Wang

R. Zeyher, A. Greco

J. M. P. Carmelo

The Hubbard model on a square lattice is one of the most studied condensed-matter quantum problems.Here we find evidence that for intermediate $U/4t$ values and a hole-concentration range $x\in (x_c,x_*)$ the ground state of the Hubbard model on the square lattice perturbed by weak three-dimensional (3D) uniaxial anisotropy has long-range d-wave superconducting order. Here $t$ is the effective nearest-neighbor transfer integral and $U$ the effective on-site repulsion. The lower critical concentration $x_c$ involves the Ginzburg number Gi and is approximately given by $x_c\approx {\rm Gi}+x_0\approx 0.05$. Here $x_0