HEAVY FERMIONS IN THE KONDO-LATTICE AS NEUTRAL QUASI-PARTICLES AND DHVA EFFECT

The origin of heavy fermions in f-electron compounds with nearly integ er valence is discussed. General arguments in favor of uncharged Fermi excitations of spin origin as the quasiparticles giving the main cont ribution to the low-T thermodynamics are present. We find a strong ren ormalization of the conduction band energy spectrum due to inelastic s cattering by the spin-liquid which, however, is non-universal, and in the general case the effective mass of the charged carriers is less th an the low-T thermodynamic mass. We show that the interaction with the spin liquid, in contrast with phonons, leads to the explicit Dingle f actor in the amplitude of the dHvA effect