Pairing Correlations in a Generalized Hubbard Model for the Cuprates

TL;DR

This study uses numerical methods to analyze pairing correlations in a generalized Hubbard model for cuprates, revealing enhanced vertex contributions and superconductivity with different symmetries depending on doping levels.

Contribution

It introduces a generalized Hubbard model with correlated hopping and demonstrates its impact on pairing correlations and superconductivity in cuprates.

Findings

Vertex contributions to pairing are significantly enhanced.

Superconductivity appears in d-wave channel at moderate doping.

s-wave superconductivity occurs at high doping and small U.

Abstract

Using numerical diagonalization of a 4x4 cluster, we calculate on-site s, extended s and d pairing correlation functions (PCF) in an effective generalized Hubbard model for the cuprates, with nearest-neighbor correlated hopping and next nearest-neighbor hopping t'. The vertex contributions (VC) to the PCF are significantly enhanced, relative to the t-t'-U model. The behavior of the PCF and their VC, and signatures of anomalous flux quantization, indicate superconductivity in the d-wave channel for moderate doping and in the s-wave channel for high doping and small U.