Superconductivity in heavy-Fermion systems

Abstract

DeHaas-van Alphen experiments have established the character of the heavy mass: an enhancement factor of 15 to 40 from f-electron many-body effects occurs in the quasi-particle mass, and the band mass is comparable to 10 m e or less. From this, we show that “Migdal's theorem” holds in superconductivity theory for heavy-Fermion systems. The mass-renormalization alone, in combination with the usual coulomb and phonon-mediated interactions (in compounds that are the same except for absence of f-electrons), cannot cause the heavy-Fermion superconductivity to occur. Some kind of “Kondo boson” interaction peculiar to the heavy-Fermion metal must therefore definitely occur.