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, and G. P. Espinosa
Phys. Rev. Lett. 61, 1670 – Published 3 October 1988
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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=0.20.25). 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

Authors & Affiliations

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, and G. P. Espinosa

  • AT & T Bell Laboratories, Murray Hill, New Jersey 07974

  • *Deceased.

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Vol. 61, Iss. 14 — 3 October 1988

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