Issue |
Europhys. Lett.
Volume 47, Number 5, September I 1999
|
|
---|---|---|
Page(s) | 588 - 594 | |
Section | Condensed matter: electronic structure, electrical, magnetic and optical properties | |
DOI | https://doi.org/10.1209/epl/i1999-00429-5 | |
Published online | 01 September 2002 |
Anomalous impurity effects in nonadiabatic superconductors
1
Dipartimento di Fisica, Università di Roma I "La Sapienza" and Piazzale A. Moro, 2, 00185 Roma, Italy
2
Istituto Nazionale Fisica della Materia, Unità di Roma 1 - Roma, Italy
Received:
26
March
1999
Accepted:
5
July
1999
We show that, in contrast with the usual electron-phonon
Migdal-Eliashberg theory, the critical temperature Tc
of an isotropic s-wave nonadiabatic superconductor is
strongly reduced by the presence of diluted nonmagnetic impurities.
Our results suggest that the recently observed Tc-suppression
driven by disorder in K3C60
(Phys. Rev. B, 55 (1997) 3866)
and in NdCexCuO
(Phys. Rev. B, 58
(1998) 8800)
could be explained in terms of a
nonadiabatic electron-phonon coupling. Moreover, we predict
that the isotope effect on Tc has an impurity dependence qualitatively
different from the one expected for anisotropic superconductors.
PACS: 71.38.+i – Polarons and electron-phonon interactions / 74.20.Mn – Nonconventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.) / 74.62.Dh – Effects of crystal defects, doping and substitution
© EDP Sciences, 1999
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