Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 46: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 46.4: Vortrag
Freitag, 27. März 2009, 11:00–11:15, HSZ 301
Kondo physics in regular and chaotic mesoscopic systems — •Rainer Bedrich1, Sebastien Burdin2, and Martina Hentschel1 — 1Max-Planck-Institut für Physik komplexer Systeme, Dresden — 2Institute of Theoretical Physics, Cologne University
We study the Kondo effect induced by a magnetic impurity interacting with a small metallic grain. Here, in contrast with the Kondo effect occurring in a bulk material, the metallic host is characterised by a finite mean level spacing. This low energy scale can generate deviations from the universal behavior which would be expected for a bulk system. The physical properties of the system are computed within a mean-field approximation for the Kondo interaction. In particular, we study the local magnetic susceptibility, the conductance, and the local density of electronic states as a function of the temperature, the mean level spacing, the Kondo coupling, and the number of electrons on the dot. As a first step, we consider a constant distribution of the non-interacting energy levels. Our results are in agreement with the results obtained from different approaches, suggesting that the mean-field approximation is valid. A more realistic situation is then considered, for which the energy levels are distributed randomly. This is realised within the random matrix theory. Finally we compare between chaotic and regular (e.g. parabolic quantum dot) systems.