Evidence for weakly correlated oxygen holes in the highest-T$_{c}$ cuprate superconductor HgBa$_2$Ca$_2$Cu$_3$O$_{8+\delta}$

TL;DR

This study investigates the electronic structure of the high-Tc cuprate superconductor HgBa2Ca2Cu3O8+δ, revealing weakly correlated oxygen holes and providing detailed insights into the Coulomb interactions and electronic states.

Contribution

The paper presents experimental evidence for weakly correlated oxygen holes in Hg1223, contrasting with other cuprates, and quantifies the on-site Coulomb energies for Cu and O sites.

Findings

Identification of correlation satellites from O 2p and Cu 3d states.

Quantitative difference in Coulomb energies: U_dd=6.5 eV, U_pp=1.0 eV.

Evidence for the Zhang-Rice singlet state in Hg1223.

Abstract

We study the electronic structure of HgBa$_2$Ca$_2$Cu$_3$O$_{8+\delta}$ (Hg1223 ; T$_{c}$ = 134 K) using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). Resonant valence band PES across the O K-edge and Cu L-edge identify correlation satellites originating in O 2p and Cu 3d two-hole final states, respectively. Analyses using the experimental O 2p and Cu 3d partial density of states show quantitatively different on-site Coulomb energy for the Cu-site (U$_{dd}$ = 6.5$\pm$0.5 eV) and O-site (U$_{pp}$ = 1.0$\pm$0.5 eV). Cu$_{2}$O$_{7}$-cluster calculations with non-local screening explain the Cu 2p core level PES and Cu L-edge XAS spectra, confirm the U$_{dd}$ and U$_{pp}$ values, and provide evidence for the Zhang-Rice singlet state in Hg1223. In contrast to other hole-doped cuprates and 3d-transition metal oxides, the present results indicate weakly correlated oxygen holes in Hg1223.