Dominant Excitonic Superconductivity in a Three-component Hubbard Chain

TL;DR

This paper investigates a one-dimensional three-component Hubbard model, revealing that excitonic mechanisms can mediate superconductivity from repulsive interactions, with density wave coexistence and analytical insights across coupling regimes.

Contribution

It introduces a novel excitonic mechanism for superconductivity in a three-component Hubbard chain, combining numerical and analytical approaches.

Findings

Cooper pairs emerge upon doping in the model.

Superconductivity is mediated by particle-hole fluctuations in a non-pairing component.

Multiple density waves and superconductivity coexist at different fillings.

Abstract

Understanding superconductivity emerging from repulsive fermions remains a major challenge in condensed matter physics. In this paper, we investigate the pairing tendencies in a one-dimensional, three component repulsive Hubbard model, using the density matrix renormalization group method. At half-filling, the system exhibits density wave ground state due to strong Hubbard repulsions. Upon doping, we find that Cooper pairs can emerge, whose fluctuations predominate the long-range physics in the system across a wide parameter range. The effective attractions between Cooper pairs are mediated by the particle-hole fluctuations in the third non-pairing component, resembling an excitonic mechanism of superconductivity. The coexistence of multiple density waves and superconductivity at different fermion fillings is explored. We also present an analytical study of the pairing mechanism in both weak and strong coupling limits. Our results provide a new perspective for understanding and exploring unconventional superconductivities in strongly correlated fermionic systems.