The Intra- and Interband Phonon-Electron Potentials in a Two-Band Model of Interacting Lattice Fermions

Abstract

A new two-band polaronic Hamiltonian is derived from a generalized periodic Anderson model. The generalization consists in the completion of the periodic Anderson model with intra-and inter-band local phononelectron interactions. The derivation is achieved by making use of two canonical transformations which enable us to remove these phonon-electron potentials from the initial Hamiltonian. This decoupling procedure leads to the appearance of new terms such as a pair-exchange potential, anisotropic Kondo-lattice terms, and a density-dependent hybridization. The final Hamiltonian describes a complicated interplay between different tendencies in the investigated system. Superconductivity can compete with the Kondo effect or magnetism as well. A simplified scenario in which the effect of the single-particle hybridization on superconductivity is investigated. It is shown that this factor is very efficient as a pair-breaker.

Anisotropic evolution of energy gap in Bi2212 superconductor

“…Various theories have been proposed for the mechanism of high-temperature superconductivity, but thus far, a consensus in this matter has been lacking [7][8][9][10][11][12][13][14][15][16][17]. Recent attempts to describe the thermodynamic properties of the superconducting state in cuprates within the framework of the microscopic theory based on the electronphonon (EPh) and electron-electron-phonon (EEPh) interactions has been presented and tested in various papers [18][19][20][21].…”