Doping Evolution of Oxygen K-edge X-ray Absorption Spectra in Cuprate Superconductors

TL;DR

This study uses advanced theoretical modeling to analyze oxygen K-edge X-ray absorption spectra in cuprate superconductors, confirming the persistent relevance of the Zhang-Rice singlet state even in overdoped regimes.

Contribution

It provides a detailed theoretical investigation of spectral weight transfer and validates the ZRS picture in overdoped cuprates through large-scale exact diagonalization.

Findings

Spectral weight transfer from upper Hubbard band to ZRS band observed.

Theoretical results agree quantitatively with experimental data.

ZRS remains relevant in the overdoped region.

Abstract

We study oxygen K-edge x-ray absorption spectroscopy (XAS) and investigate the validity of the Zhang-Rice singlet (ZRS) picture in overdoped cuprate superconductors. Using large-scale exact diagonalization of the three-orbital Hubbard model, we observe the effect of strong correlations manifesting in a dynamical spectral weight transfer from the upper Hubbard band to the ZRS band. The quantitative agreement between theory and experiment highlights an additional spectral weight reshuffling due to core-hole interaction. Our results confirm the important correlated nature of the cuprates and elucidate the changing orbital character of the low-energy quasi-particles, but also demonstrate the continued relevance of the ZRS even in the overdoped region.