Phase Diagram of the Attractive Hubbard Model with Inhomogeneous Interactions

TL;DR

This paper maps the phase diagram of an inhomogeneous attractive Hubbard model using dynamical mean field theory, revealing regimes of non-BCS superconductivity relevant to various physical systems.

Contribution

It introduces a phase diagram for the inhomogeneous attractive Hubbard model considering three key parameters, highlighting conditions for non-BCS superconductivity.

Findings

Identification of non-BCS superconductivity regimes

Dependence of phases on interaction strength and active fraction

Relevance to real materials and cold atom systems

Abstract

The phase diagram of the attractive Hubbard model with spatially inhomogeneous interactions is obtained using a single site dynamical mean field theory like approach. The model is characterized by three parameters: the interaction strength, the active fraction (fraction of sites with the attractive interaction), and electron filling. The calculations indicate that in a parameter regime with intermediate values of interaction strength (compared to the bare bandwidth of the electrons), and intermediate values of the active fraction, "non-BCS" superconductivity is obtained. The results of this work are likely to be relevant to many systems with spatially inhomogeneous superconductivity such as strongly correlated oxides, systems with negative U centers, and, in future, cold atom optical lattices.