Density of States and Isotope Effect in BiO Superconductors: Evidence for Nonphonon Mechanism
B. Batlogg, R. J. Cava, L. W. Rupp, Jr., A. M. Mujsce, J. J. Krajewski, J. P. Remeika, W. F. Peck, Jr., A. S. Cooper, G. P. Espinosa
DOI 10.1103/PhysRevLett.61.1670 · Physical Review Letters
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Abstract
We report measurements of the physical properties of the 30-K superconductor Ba0.6K0.4BiO3, including upper and lower critical fields and normal-state susceptibility. From the results and from comparison with BaPb0.75Bi0.25O3 and band-structure calculations it is concluded that the BiO superconductors are in the weak-coupling limit, implying that the anomalously high Tc's are not due to conventional, strong electron-phonon coupling. A sizable oxygen isotope effect of very similar magnitude is found for both compounds (α=0.2−0.25). We speculate that "phononic" effects in these materials are actually only indicative of dressed electronic excitations mediating superconducting pairing.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Ba0.6K0.4BiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 30 | Pressure not reported | onset |
| BaPb0.75Bi0.25O3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 12 | Pressure not reported | unknown |
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