Van Hove singularities and nonadiabatic effects in superconductivity
Dipartimento di Fisica, Università di Roma I
P.le A. Moro 2, and INFM, Sezione
di Roma I, I-00185 Roma, Italy
Accepted: 25 October 1996
The breakdown of Migdal's theorem implies the generalization of the electron-phonon theory of superconductivity to include various nonadiabatic effects. The reduced electronic screening due to the small carrier density and the presence of a van Hove singularity for the optimized cuprates complete a new scenario for both the superconductive and the normal state. In particular the van Hove singularity can be related to highest values of Tc, to the reduction of the isotope effect and to the linear resistivity.
PACS: 74.20.Mn – Microscopic theory of high-Tc superconductivity; insulator-superconductor transitions / 63.20.Kr – Phonon-electron interactions / 71.38.+i – Polarons and electron-phonon interactions
© EDP Sciences, 1996