Screening of Magnetic Moments in PuAm Alloy: Local Density Approximation and Dynamical Mean Field Theory Study

The puzzling absence of Pu magnetic moments in a PuAm environment is explored using the self-consistent dynamical mean field theory calculations in combination with the local density approximation. We argue that δ-Pu-Am alloys provide an ideal testbed for investigating the screening of moments from the single impurity limit to the dense limit. Several important effects can be studied: volume expansion, shift of the bare Pu on-site f energy level, and the reduction of the hybridization cloud resulting from the collective character of the Kondo effect in the Anderson lattice. These effects compensate each other and result in a coherence scale, which is independent of alloy composition, and is around 800 K.