High-temperature superconductivity in the presence of O 2p−Cu 3d holes: A spectroscopic study
S. Horn, J. Cai, S. A. Shaheen, Y. Jeon, M. Croft, C. L. Chang, M. L. denBoer
DOI 10.1103/PhysRevB.36.3895 · Physical Review B
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Abstract
We report core-level spectroscopic measurements of several cuprate perovskites comparing those which exhibit superconductivity above 90 K to others which do not. Both x-ray photoemission and x-ray absorption results show that in the former Cu is more oxidized, as in CuO (nominally Cu2+), than in the latter. Trivalent Cu is clearly excluded. The O 1s core level is at higher binding energy in the superconductors, implying the presence of O 2p holes. The rare-earth valence in Ce- and Pr-based perovskites is more than 3+, apparently related to their failure to superconduct.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| YBa2Cu3O6+x Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 93 | Pressure not reported | unknown |
| YbBa2Cu3O6+x Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 88 | Pressure not reported | unknown |
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