Superconductivity in the Two-Band Hubbard Model in Infinite D: an Exact Diagonalization Study

TL;DR

This paper uses an exact diagonalization approach to study the infinite-dimensional two-band Hubbard model, revealing superconducting instabilities relevant to high-temperature superconductors and providing detailed thermodynamic insights.

Contribution

It introduces an essentially exact diagonalization method for the infinite-D two-band Hubbard model, offering high-resolution thermodynamic calculations and identifying superconducting instabilities.

Findings

Normal state becomes unstable to singlet superconductivity at low doping.

Evidence of triplet superconductivity instability at high doping.

Method provides detailed thermodynamic properties beyond Monte Carlo capabilities.

Abstract

We apply an exact diagonalization method to the the infinite-D two-band Hubbard model. The method is essentially exact for the calculation of thermodynamic properties for all but the smallest frequencies and yields a resolution unavailable in Monte Carlo calculations. We establish the instability of the normal state with respect to singlet superconductivity at small frequencies at small doping, the regime of relevance for High-$T_c$ superconductors. We also present evidence for the existence of an instability towards triplet superconductivity in the large doping regime $n \sim 2$.