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Anomalous impurity effects in nonadiabatic superconductors

M. Scattoni·C. Grimaldi·L. Pietronero
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Abstract

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 non-magnetic impurities. Our results suggest that the recently observed Tc-suppression driven by disorder in K3C60 [Phys. Rev. B vol.55, 3866 (1997)] and in Nd(2-x)CexCuO(4-delta) [Phys. Rev. B vol.58, 8800 (1998)] 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.

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M. Scattoni, C. Grimaldi, L. Pietronero. 1999-07-12. Anomalous impurity effects in nonadiabatic superconductors. https://doi.org/10.1209/epl%2Fi1999-00429-5

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