Direct observation of the on-site oxygen 2p two-hole Coulomb energy in La<sub>2</sub>CuO<sub>4</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41193474.
- Also identified by DOI 10.1038/s41467-025-65314-w and PMC identifier 12589636.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Electron correlation in functional materials has remained a challenge with strong deviations of electronic structure from mean field approaches. In high temperature superconductors the electron-electron and hole-hole interaction energies are essential in the underlying pairing mechanisms. For cuprates, oxygen holes have been considered of central importance for superconductivity. In La<sub>2</sub>CuO<sub>4</sub> the site specific oxygen 2p hole-hole Coulomb energy has been determined by Auger photoelectron coincidence spectroscopy. This experimental approach allows to separate the different oxygen sites, i.e. the lattice oxygen, and distinguish from otherwise overlapping signal from surface oxygen. Values of 6.3 ± 0.2 eV for oxygen in the Cu-O planes and an upper limit of 9.2 ± 0.2 eV for apical oxygen are found to be on the high energy side of reported computational values and narrows the range of experimentally reported values. Additionally, a much reduced hybridization in La<sub>2</sub>CuO<sub>4</sub> as compared to CuO is found in O 2p hybridization strengths.