Strongly Correlated Superconductivity and Pseudogap Phase near a multi-band Mott Insulator

TL;DR

This paper demonstrates how strong electron correlations near a Mott transition can enhance superconductivity, revealing a complex phase diagram with pseudogap, non-Fermi-liquid, and superconducting states similar to cuprates, using dynamical mean field theory.

Contribution

It introduces a two-orbital Hubbard model with inverted Hund's rules and shows how strong correlations promote superconductivity near a Mott insulator, highlighting the role of local spin-singlet configurations.

Findings

Superconductivity is enhanced near the Mott transition.

A pseudogap non-Fermi-liquid metal phase appears close to the insulator.

The superconducting state has a larger Drude weight than the normal state.

Abstract

Near a Mott transition, strong electron correlations may enhance Cooper pairing. This is demonstrated in the Dynamical Mean Field Theory solution of a twofold-orbital degenerate Hubbard model with inverted Hund's rules on-site exchange, which favors local spin-singlet configurations. Close to the Mott insulator, which is a local version of a valence bond insulator, a pseudogap non-Fermi-liquid metal, a superconductor, and a normal metal appear, in striking similarity with the physics of the cuprates. The strongly correlated superconducting state has a larger Drude weight than the corresponding normal state. The role of the impurity Kondo problem is underscored.