Superconductivity in two-band non-adiabatic systems
Abstract
Theory of superconductivity in two-band non-adiabatic systems with strong electron correlations in the linear approximation over non-adiabaticity is built in the article. Having assumed weak electron-phonon interaction analytical expressions for the vertex functions and "intersecting " functions for each energy band are obtained. Mass operators of Green functions with account of diagrams with intersection of two lines of electron- phonon interaction (exceeding the frameworks of Migdal theorem) are derived as well as main equations of theory of superconductivity in two-band systems. Analytical formulas for the temperature of superconducting transition Tc are obtained as well as renormalization of the quantities which enter these formulas because of effects of non-adiabaticity and strong electron correlations. Dependence of Tc and coefficient of isotope effect on Migdal parameter m is studied. Overlapping of energy bands on Fermi surface with effects of non-adiabaticity at low values of transferred momentum is shown to obtain high values of Tc even assuming weak electron-phonon interaction.
Cite
@article{arxiv.cond-mat/0602551,
title = {Superconductivity in two-band non-adiabatic systems},
author = {M. E. Palistrant and V. A. Ursu},
journal= {arXiv preprint arXiv:cond-mat/0602551},
year = {2007}
}
Comments
17 pages, 3 figures