Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 11: Quantum Impurities, Kondo Physics
TT 11.3: Talk
Tuesday, March 27, 2007, 10:00–10:15, H19
Dephasing rate due to diluted Kondo impurities — Tobias Micklitz2, Alexander Altland2, •Theodoulos Costi1, and Achim Rosch2 — 1Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich — 2Institut für Theoretische Physik, Universität zu Köln, 50937 Köln
We calculate the dephasing rate, 1/τϕ, of electrons due to magnetic impurities in a weakly disordered metal as measured in a weak-localization experiment. For sufficiently low impurity concentrations, nS, the dephasing rate is a universal function, 1/τϕ=(nS/ν)f(T/TK), of T/TK, where TK is the Kondo scale and ν is the density of states [1,2]. Recent measurements of the dephasing rate due Fe impurities in Ag wires with TK=4.3K [3] are shown to be well described by the above universal function for the fully screened Kondo model calculated with the numerical renormalization group method. Purely underscreened or overscreened Kondo impurities are ruled out for explaining the experiments, although a small fraction of underscreened Kondo impurities (sitting at lower symmetry sites, for example) might account for the observed slower than predicted decay of the dephasing rate at the lowest temperatures measured, T<0.1TK.
[1] T. Micklitz et al., Phys. Rev. Lett. 96, 226601 (2006).
[2] T. Micklitz et al., cond-mat/0610304 (2006).
[3] F. Mallet et al., Phys. Rev. Lett. 97, 226804 (2006).