Anomalous impurity effects in nonadiabatic superconductors

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.

10 pages, euromacr.tex, europhys.sty, 6 figures. Replaced with accepted version (Europhysics Letters)

References in corpus (2)

• Combined effect of nonmagnetic and magnetic scatterers on critical temperatures of superconductors with different gap anisotropy
• Vertex-corrected perturbation theory for the electron-phonon problem with non-constant density of states

Cited by in corpus (6)

• High $T_c$ superconductivity in MgB${}_2$ by nonadiabatic pairing
• Nonadiabatic Pauli susceptibility in fullerene compounds
• Nonadiabatic Superconductivity and Vertex Corrections in Uncorrelated Systems
• Poor screening and nonadiabatic superconductivity in correlated systems
• Isotope Effect in the Presence of Magnetic and Nonmagnetic Impurities
• Failure of the Migdal-Eliashberg Theory of Superconductivity in Rb_3C_60