Renormalization of the quasiparticle hopping integrals by spin interactions in layered copper oxides

TL;DR

This paper studies how spin interactions in layered copper oxides affect the movement of oxygen holes, revealing that magnetic correlations significantly reduce hopping parameters, aligning with experimental data.

Contribution

It demonstrates that spin interactions renormalize quasiparticle hopping integrals in cuprates, combining quantum chemical calculations with model Hamiltonian analysis.

Findings

Spin interactions induce ferromagnetic correlations among Cu spins.

Holes carry a spin polarization cloud that reduces effective hopping.

Results align with angle-resolved photoemission data.

Abstract

Holes doped within the square CuO2 network specific to the cuprate superconducting materials have oxygen 2p character. We investigate the basic properties of such oxygen holes by wavefunction-based quantum chemical calculations on large embedded clusters. We find that a 2p hole induces ferromagnetic correlations among the nearest-neighbor Cu 3d spins. When moving through the antiferromagnetic background the hole must bring along this spin polarization cloud at nearby Cu sites, which gives rise to a substantial reduction of the effective hopping parameters. Such interactions can explain the relatively low values inferred for the effective hoppings by fitting the angle-resolved photoemission data. The effect of the background antiferromagnetic couplings of renormalizing the effective nearest-neighbor hopping is also confirmed by density-matrix renormalization-group model Hamiltonian calculations for chains and ladders of CuO4 plaquettes.