Breakdown of Migdal`s theorem and intensity of electron-phonon coupling in high-T{sub c} superconductors
- INFM-Dipartimento di Fisica, Politecnico di Torino, 10129 Torino (Italy)
In this article we quantify the possible effects of the breakdown of Migdal`s theorem on the electron-phonon coupling constant {lambda}, on the critical temperature T{sub c}, and on the superconducting gap {Delta} by examining different kinds of superconducting materials either with low or high critical temperature. We use the theoretical approach developed by Pietronero and co-workers [Phys. Rev. B {bold 52}, 10516 (1995); {bold 52}, 10530 (1995)] on experimental data taken both from literature and from our recent break-junction tunneling experiments in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}. The results show that a large violation of Migdal`s theorem (as in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}) yields a large increase of {lambda} and, to a first approximation, a large but different increase of T{sub c} and {Delta}. The same theory gives no modifications when applied to low-T{sub c} conventional superconductors. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 565119
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 22 Vol. 56; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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