Magnetic resonance in the cuprates -- exciton, plasmon, or \pi-mode

TL;DR

This paper re-analyzes the nature of the resonance peak in cuprates, concluding it is mainly an exciton and that the resonance peak alone cannot distinguish between different pairing mechanisms.

Contribution

It demonstrates through a toy model that the resonance peak is predominantly an exciton and challenges the ability to differentiate pairing interactions based solely on this feature.

Findings

Resonance peak is mainly an exciton in the model.

Magnetic interaction is not necessary for the resonance.

Resonance peak cannot distinguish pairing mechanisms.

Abstract

We re-analyzed the issue whether the resonance peak observed in neutron scattering experiments on the cuprates is an exciton, a \pi-resonance, or a magnetic plasmon. We considered a toy model with on-cite Hubbard U and nearest-neighbor interactions in both charge and spin channels. We found that the resonance is predominantly an exciton, even if magnetic interaction is absent and d-wave pairing originates from attractive density-density interaction. Our results indicate that one cannot distinguish between spin and charge-mediated pairing interactions by just looking at the resonance peak in the dynamic spin susceptibility.