Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 11: Nanoelektronik I: Quantenpunkte, -dr
ähte, -punktkontakte

TT 11.13: Talk

Tuesday, March 9, 2004, 12:30–12:45, H19

Non-equilibrium quasiparticle distribution in diffusive quantum wires in a magnetic field — •J. Kroha¹, J. Paaske², A. Rosch², O. Uhsaghy³, P. Wölfle² und A. Zawadowski³ — ¹PI, Univ. Bonn — ²TKM, Univ. Karlsruhe — ³Dept. of Physics, TU Budapest

The non-equilibrium distribution function f(E,V) of quasiparticles with energy E in a diffusive quantum wire at bias V has a doublestep shape due to the different chemical potentials in the leads [1]. The Fermi steps display an anomalous rounding whose origin has been identified with a tiny concentration of Kondo impurities (Kondo temperature T_K) present in the wire [2]. The magnetic field B dependence of f(E,V), in particular its non-monotonic behavior as B crosses from B<V to B>V, suggests qualitatively the Kondo impurities to be of magnetic origin. However, there is a strong quantitative discrepancy between experiments and theory [3] both concerning the B dependence and the expected Kondo impurity concentration. We generalize the perturbative RG method [4], which was recently developed for a Kondo impurity at finite V and B, to the case of a variable f(E,V) along the wire. We use this method to solve the quantum Boltzmann equation for f(E/eV) in the presence of Kondo impurities in a diffusive quantum wire at large bias V≫ T_K and arbitrary B and compare with experiments.

[1] A. Anthore et al. PRL 90, 076806 (2003).

[2] A. Kaminski, L.I. Glazman, PRL 86, 2400 (2001);

J. Kroha, A. Zawadowski, PRL 88, 176803 (2002).

[3] G. Göppert et al., PRB 66, 195328 (2002).