d-Wave Pairing in an Ensemble of Spin Polaron Quasiparticles in the Spin-Fermion Model of the Electronic Structure of the CuO2 Plane

TL;DR

This paper demonstrates that strong coupling in the CuO2 plane leads to d-wave pairing of spin polaron quasiparticles, aligning well with experimental phase diagrams.

Contribution

It introduces a novel mechanism for d-wave pairing driven by spin-polaron interactions in the spin-fermion model of cuprates.

Findings

Effective attraction between spin polarons due to exchange interaction.

Formation of Cooper pairs with d-wave symmetry.

Phase diagram matches experimental data.

Abstract

It is demonstrated for the first time that the strong coupling between spin moments of copper ions and oxygen holes, which arises upon hybridazation mixing of two hole subsystems in the Emery model, not only affects the formation of spin polaron quasiparticles but also ensures effective attraction between them via the exchange interaction. This results in the Cooper instability with d-wave pairing in a 2D ensemble of spin polaron quasiparticles. The T-x-phase diagram obtained using this approach agrees well with the available experimental data.