Abstract
Superconductivity found in doped is puzzling as two local symmetries of doped layers compete, with presumably far-reaching implications for the involved mechanism: A cupratelike regime with Zhang-Rice singlets is replaced by local triplet states at realistic values of charge-transfer energy, which would suggest a rather different superconductivity scenario from high- cuprates. We address this competition by investigating clusters with periodic boundary conditions in the parameter range relevant for the superconducting nickelates. With increasing value of charge-transfer energy we observe upon hole doping the expected crossover from the cuprate regime dominated by Zhang-Rice singlets to the local triplet states. We find that smaller charge-transfer energy is able to drive this change in the ground-state character when realistic values for nickel-oxygen repulsion are taken into account. For large values of the charge-transfer energy, oxygen orbitals are less important than in superconducting cuprates as their spectral weight is found only at rather high excitation energies. However, a second ) orbital can easily become relevant, with either the or the orbitals contributing in addition to the orbital to the formation of triplet states. In addition, our result that (acting between Ni and O) favors on-site triplets implies that correlation effects beyond purely on-site interactions should be taken into account when obtaining effective two-band models.
4 More- Received 18 December 2020
- Accepted 8 March 2021
DOI:https://doi.org/10.1103/PhysRevB.103.104513
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society.
Published by the American Physical Society