Transition from heavy-fermion to mixed-valence behavior in Ce(1-x)Y(x)Al3: a quantitative comparison with the anderson impurity model.

We present a neutron scattering investigation of Ce1-xYxAl3 as a function of chemical pressure, which induces a transition from heavy-fermion behavior in CeAl3 (T{K}=5 K) to a mixed-valence state at x=0.5 (T{K}=150 K). The crossover can be modeled accurately on an absolute intensity scale by an increase in the k-f hybridization, V{kf}, within the Anderson impurity model. Surprisingly, the principal effect of the increasing V{kf} is not to broaden the low-energy components of the dynamic magnetic susceptibility but to transfer spectral weight to high energy.