Dynamic susceptibility of intermediate-valence compounds: a random-phase-approximation study of the anderson lattice

Abstract

We present a calculation of the dynamical transverse susceptibility, in the random-phase approximation, of a model of mixed-valence systems, the Anderson lattice. Our calculation shows behavior similar to the paramagnetic behavior found in Ce, Sm, and Yb compounds, as well as the antiferromagnetic behavior observed in Tm mixed-valence compounds. We also find that a ferromagnetic phase can also be stable at low temperatures. Ferromagnetism becomes favored over antiferromagnetism in our theory as the hybridization between the $4f$ levels and the itinerant electrons is increased. We have calculated the imaginary part of the frequency-dependent susceptibility, to find results which compare favorably with neutron scattering data.