Pairing Correlations on t-U-J Ladders

TL;DR

This paper investigates how pairing correlations in t-U-J two-leg ladder models are enhanced by additional interactions, revealing insights into charge transfer effects relevant to cuprate superconductors.

Contribution

It demonstrates that adding a nearest-neighbor exchange interaction J enhances pairing correlations in t-U-J ladders compared to traditional models.

Findings

Pairing correlations are significantly enhanced by the exchange interaction J.

Enhanced pairing correlates with increased pair-binding energy and mobility.

Charge transfer nature plays a key role in pairing enhancement.

Abstract

Pairing correlations on generalized t-U-J two-leg ladders are reported. We find that the pairing correlations on the usual t-U Hubbard ladder are significantly enhanced by the addition of a nearest-neighbor exchange interaction J. Likewise, these correlations are also enhanced for the t-J model when the onsite Coulomb interaction is reduced from infinity. Moreover, the pairing correlations are larger on a t-U-J ladder than on a t-Jeff ladder in which Jeff has been adjusted so that the two models have the same spin gap at half-filling. This enhancement of the pairing correlations is associated with an increase in the pair-binding energy and the pair mobility in the t-U-J model and point to the importance of the charge transfer nature of the cuprate systems.