Phase diagram of the one-dimensional extended attractive Hubbard model for large nearest-neighbor repulsion

TL;DR

This paper analyzes the phase diagram of a one-dimensional extended attractive Hubbard model with large nearest-neighbor repulsion, revealing distinct phases including Luttinger liquids and phase separation, with implications for superconductivity.

Contribution

The authors derive an effective Hamiltonian for the model and map it onto solvable XXZ models, providing new insights into its quantum phases and correlations.

Findings

Identified two Luttinger liquid phases and phase separation regions.

Found dominant singlet superconducting correlations for certain parameters.

Results qualitatively agree with experimental observations in BaKBiO.

Abstract

We consider the extended Hubbard model with attractive on-site interaction U and nearest-neighbor repulsions V. We construct an effective Hamiltonian H_{eff} for hopping t<<V and arbitrary U<0. Retaining the most important terms, H_{eff} can be mapped onto two XXZ models, solved by the Bethe ansatz. The quantum phase diagram shows two Luttinger liquid phases and a region of phase separation between them. For density n<0.422 and U<-4, singlet superconducting correlations dominate at large distances. For some parameters, the results are in qualitative agreement with experiments in BaKBiO.