Kondo effect and mesoscopic fluctuations |
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Authors: | DENIS ULLMO SÉBASTIEN BURDIN DONG E LIU HAROLD U BARANGER |
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Institution: | 1.LPTMS,Univ. Paris Sud, CNRS,Orsay Cedex,France;2.Condensed Matter Theory Group, LOMA, UMR 5798,Université de Bordeaux I,Talence,France;3.Department of Physics,Duke University,Durham,USA |
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Abstract: | Two important themes in nanoscale physics in the last two decades are correlations between electrons and mesoscopic fluctuations.
Here we review our recent work on the intersection of these two themes. The setting is the Kondo effect, a paradigmatic example
of correlated electron physics, in a nanoscale system with mesoscopic fluctuations; in particular, we consider a small quantum
dot coupled to a finite reservoir (which itself may be a large quantum dot). We discuss three aspects of this problem. First,
in the high-temperature regime, we argue that a Kondo temperature T
k which takes into account the mesoscopic fluctuations is a relevant concept: for instance, physical properties are universal
functions of T/T
k. Secondly, when the temperature is much less than the mean level spacing due to confinement, we characterize a natural cross-over
from weak to strong coupling. This strong coupling regime is itself characterized by well-defined single-particle levels,
as one can see from a Nozières Fermi-liquid theory argument. Finally, using a mean-field technique, we connect the mesoscopic
fluctuations of the quasiparticles in the weak coupling regime to those at strong coupling. |
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