Abstract
We report measurements of the physical properties of the 30-K superconductor Bi, including upper and lower critical fields and normal-state susceptibility. From the results and from comparison with Ba and band-structure calculations it is concluded that the BiO superconductors are in the weak-coupling limit, implying that the anomalously high are not due to conventional, strong electron-phonon coupling. A sizable oxygen isotope effect of very similar magnitude is found for both compounds (). We speculate that "phononic" effects in these materials are actually only indicative of dressed electronic excitations mediating superconducting pairing.
- Received 8 August 1988
DOI:https://doi.org/10.1103/PhysRevLett.61.1670
©1988 American Physical Society