Shiba-Rusinov theory of magnetic impurities in superconductors beyond s-wave scattering: Eliashberg formalism

Abstract

Shiba-Rusinov theory of magnetic impurities in isotropic superconductors beyond the s-wave scattering is generalized by using the Eliashberg formalism. The analytical expressions for the transition temperature Tc and the specific-heat jump C are given using the square-well model for the electron-phonon interaction. Taken as a function of the impurity concentration, the quantities TcTc0 and CC0 depend on the microscopic parameters , μ*, and D of the host material. However, this dependence is absent if one plots the above properties versus the normalized impurity concentration cr or if CC0 vs TcTc0 is studied. (Tc0 and C0 are values of Tc and C, respectively, in the absence of impurities; is the electron-phonon interaction parameter, μ* the Coulomb pseudopotential, and D the Debye cutoff frequency; is the spin-flip scattering rate; cr is the value of for which T becomes zero.) © 1984 The American Physical Society.