Modified charge bag model of superconductivity

The modified charge bag model essentially provides a microscopical derivation of the nested Fermi liquid (NFL) theory. The model has wide range of applicability to non-cuprate high temperature superconductors, including some of the organic superconductors like (BEDT-TTF)2I3. The model invokes a completely new mechanism of superconductivity based on the strong electron-phonon interaction which explains the expected behaviour of superconducting (SC) transition temperature Tc with the dopant concentration (δ). Tc increases with δ in low-doping regime where as it decreases with δ in higher doping regime. The SC order parameter possesses d-wave like symmetry. However, explicit evaluation of the SC-gap function derived from the SC-gap equation supports anisotropic but s-wave like pairing. The s-wave nature of superconductivity is confirmed, as the SC-gap function carries exactly similar in-built symmetry of the original 2-d square lattice. (author). 13 refs., 1 fig