Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 46: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 46.5: Vortrag
Freitag, 27. März 2009, 11:30–11:45, HSZ 301
Kondo decoherence: finding the right spin model for iron impurities in gold and silver — •Theodoulos Costi1, Lars Bergqvist1, Andreas Weichselbaum2, Jan von Delft2, Phivos Mavropoulos1, Peter Dederichs1, Tobias Micklitz3,5, Achim Rosch3, Francois Mallet4, Laurent Saminadayar4, and Christopher Bäuerle4 — 1Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany — 2Physics Department, Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience,Ludwig-Maximilians-Universität München, 80333 München, Germany — 3Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany — 4Institut Néel - CNRS and Université Joseph Fourier, 38042 Grenoble Cedex 09, France — 5Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
We exploit the decoherence of electrons due to magnetic impurities, studied via weak localization, to resolve a longstanding question concerning the classic Kondo systems of Fe impurities in the noble metals gold and silver: which Kondo-type model yields a realistic description of the relevant multiple bands, spin and orbital degrees of freedom? Previous studies suggest a fully screened spin S Kondo model, but the value of S remained ambiguous. We perform density functional theory calculations that suggest S = 3/2. We also compare previous and new measurements of both the resistivity and decoherence rate in quasi 1-dimensional wires to numerical renormalization group predictions for S=1/2,1 and 3/2, finding excellent agreement for S=3/2.