Charge fluctuations, spin fluctuations, and superconductivity in the Anderson lattice model of heavy-fermion systems

We determine the quasiparticle-quasiparticle interaction within the U→∞ Anderson lattice model via an auxiliary boson (1N) expansion to order (1N)2. At leading order the interaction which is mediated by the exchange of a single zero-frequency fluctuation of the Bose field is repulsive in the p channel and attractive in the d channel. The dominant contribution to the interaction at order (1N)2, which is due to spin fluctuations involving high-frequency, ω>T/sub K/, fluctuations of the Bose field, is attractive in both p and d channels. The strength of this term relative to the charge fluctuation contribution is of order (m/sup */m)ln-2(Nm/sup */m), where m/sup */ is the heavy-fermion mass. Thus, for parameters corresponding to the majority of systems of interest, pairing in this model is allowed in both p and d channels;the origin of the attractive interaction, as in 3He, is in the exchange of spin fluctuations