Kondo Impurity Physics

The Kondo effect in Real Metals – Iron Impurities in Gold and Silver

Despite being discovered in the 1930's, the Kondo effect of real magnetic impurities (such as Fe) in real metals (such as Au, Ag or Cu) has proven difficult to describe quantitatively, although qualitatively the Kondo effect for simple model systems is well understood (e.g. the S=1/2 Kondo model). By using a combination of density functional theory and numerical renormalization group techniques, a 3 channel fully screened S=3/2 Kondo model has been proposed to describe the above classic Kondo systems.

Comparison of the dephasing rate for this model supports the S=3/2 fully screened Kondo model as giving the best description for the Kondo effect of Fe impurities in Au and Ag.  Similar strategies apply to modeling Kondo impurities on surfaces or the Kondo effect in molecular junctions. Complex Kondo impurities arise also as effective impurity models within dynamical mean field theory of correlated lattice models (e.g. heavy fermions, metal-insulator transitions in oxides) and in diverse quantum dot nanostructures.   

T. A. Costi, L. Bergqvist, A. Weichselbaum et al., Phys Rev. Lett., 102, 056802 (2009)
(T. Costi, P. Mavropoulos, P. H. Dederichs)