| AVS 60th International Symposium and Exhibition | |
| Actinides and Rare Earths Focus Topic | Monday Sessions |
| Session AC+MI+SA+TF-MoA |
| Session: | Actinides and Rare Earths: Theory and Electron Correlation |
| Presenter: | G. Zwicknagl, Technische Universität Braunschweig, Germany |
| Correspondent: | Click to Email |
The f-electron systems lie at the intersection of a large number of long-standing problems in the physics of metals. In metals containing ions with partially filled inner shells, we immediately face the fundamental question which picture provides the better starting point for theoretical models, a delocalized description in terms of energy bands or a localized representation which accounts for the atomic properties. The answer to the question which of the above-mentioned pictures is the appropriate starting point seems to depend on the physical quantities under consideration. This fact is a consequence of electronic correlations which prevent to describe the influence of the f-states over the entire temperature and energy range in terms of a unique simple model. While the high-temperature (high-energy) properties of lanthanide compounds can be understood in terms of localized f-moments it is generally accepted by now that the f-electrons should also be described in within a band picture as delocalized states as far as the low-energy excitations are concerned.
Concerning the underlying microscopic picture, it is generally accepted that the formation of strongly renormalized 4f-bands in lanthanides is a consequence of the Kondo effect where the degrees of freedom of the 4f-shell form a collective singlet ground state with the conduction electrons. The Kondo model, however, does not apply to actinide compounds where the situation is more complex. In some compounds, experiments suggest the co-existence of both localized atomic-like 5f-degrees of freedom with itinerant 5f-band states at low temperatures/ low energies. Microscopic model calculations suggest that partial localization of 5f-electrons may result from the intra-atomic Hund’s rule-type correlations.
In the present talk, I shall give an overview over our present understanding of the “Dual Nature” of f-electrons. I present recent results on the suppression of the Kondo state in YbRh2Si2 [1]. I discuss microscopic calculations for electron spectroscopies in actinide compounds emphasizing the consequences of strong intra-atomic correlations of the 5f -shell [2,3].
[1] H. Pfau et. al., arXiv:1302.6867
[2] Gertrud Zwicknagl, MRS Online Proceedings Library, Volume 1444, (2012)
[3] Gertrud Zwicknagl, Phys. Stat. Sol. B 250, 634 (2013)