Resistance Anomalies in Some Rare-Earth Metals

It is shown that the anomalies observed in the resistance of the lighter rare-earth metals can be explained in form and order of magnitude by a simple model of the interaction between the conduction electrons and the $f$ electrons which are tightly bound to each atom. The $f$ electrons interact with the crystal field set up by the surrounding atoms, so that there is a Stark splitting of their energy levels. The extra resistance arises because ion cores with $f$ electrons in different states present different cross sections to the conduction electrons, and also because the conduction electrons can knock ions from one state to another. All exchange effects are neglected.