Appearance of Antiferromagnetism and Superconductivity in Superconducting Cuprates

TL;DR

This paper models superconducting cuprates using an extended Hubbard model, demonstrating how antiferromagnetism and d-wave superconductivity coexist and evolve with doping, aligning with experimental observations.

Contribution

It introduces a combined Hartree-Fock and coherent potential approximation approach to describe antiferromagnetism and superconductivity in cuprates, accounting for hopping interactions and doping effects.

Findings

Band expansion shifts superconductivity away from half-filling

Model reproduces rapid disappearance of antiferromagnetism with doping

Applicable to electron-doped cuprate compounds

Abstract

We represent the superconducting ceramic compounds by the single band extended Hubbard model. We solve this model for the simultaneous presence of antiferromagnetism and the d-wave superconductivity in the Hartree-Fock (H-F) and in the coherent potential (CP) approximation, which is applied to the on-site Coulomb repulsion U. The hopping interaction used in addition to the Coulomb repulsion causes rapid expansion of the band at carrier concentrations departing from unity. This expansion shifts the d-wave superconductivity away from the half filled point reducing its occupation range approximately to the experimental range in the YBaCuO compound. The CP approximation used for the Coulomb repulsion is justified by the large ratio of Coulomb repulsion to the effective width of perturbed density of states being reduced by the hopping interaction. Fast disappearance of antiferromagnetism observed experimentally is supported by the relatively large value of the total width of unperturbed density of states. It is shown that our model is capable of describing the electron doped compounds as well.