NON-KONDO PREDICTION OF WILSON RATIO FOR HEAVY-FERMION SYSTEMS

We propose a new two-electron band theory approach to treat correlated f-electron systems. This involves: first, an exact two-body treatment of the local correlations for a 'solid-state atom', i.e. non-spherical local environment of a cerium (or other pertinent) nucleus; then, turning on the interactions giving extended two-electron states (bands). This approach treats the hybridization and exchange Coulomb interaction effects within this two-body treatment on an equal footing. Without invoking the concept of Kondo resonance, it provides a non-magnetic singlet state competing, side by side with other, magnetic states. It explains the wide diversity in f magnetism and the heavy fermion phenomenology, including the specific heat and susceptibility, and most significant, provides an absolute prediction of the Wilson ratio, reproducing the experimental scale and trend in change of the Wilson (low-temperature susceptibility to specific heat) ratio on going from non-magnetic to magnetic heavy fermion materials.