Strong coupling superconductivity, pseudogap and Mott transition

TL;DR

This paper investigates the complex relationship between superconductivity, pseudogap phenomena, and Mott transitions in layered materials using advanced theoretical models, revealing how these states influence each other and affect observable properties.

Contribution

The study provides a unified theoretical framework for understanding the interplay of superconductivity, pseudogap, and Mott transition in the two-dimensional Hubbard model.

Findings

Superconductivity emerges near the Mott insulator at both half filling and doping.

Superconductivity can eliminate the first-order transition between pseudogap and overdoped metal.

The dynamical mean-field $T_c$ does not scale with the order parameter in the presence of a pseudogap.

Abstract

An intricate interplay between superconductivity, pseudogap and Mott transition, either bandwidth driven or doping driven, occurs in materials. Layered organic conductors and cuprates offer two prime examples. We provide a unified perspective of this interplay in the two-dimensional Hubbard model within cellular dynamical mean-field theory on a $2\times 2$ plaquette and using the continuous-time quantum Monte Carlo method as impurity solver. Both at half filling and at finite doping, the metallic normal state close to the Mott insulator is unstable to d-wave superconductivity. Superconductivity can destroy the first-order transition that separates the pseudogap phase from the overdoped metal, yet that normal state transition leaves its marks on the dynamic properties of the superconducting phase. For example, as a function of doping one finds a rapid change in the particle-hole asymmetry of the superconducting density of states. In the doped Mott insulator, the dynamical mean-field superconducting transition temperature $T_c^d$ does not scale with the order parameter when there is a normal-state pseudogap. $T_c^d$ corresponds to the local pair formation temperature observed in tunneling experiments and is distinct from the pseudogap temperature.