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SYMN: Metallic nanowires
SYMN 2: Metallic nanowires II
SYMN 2.2: Hauptvortrag
Freitag, 28. März 2003, 12:15–12:45, HSZ/01
Non-equilibrium transport and relaxation in diffusive quantum wires with Kondo impurities — •Johann Kroha — Physikalisches Institut, Universität Bonn, Nussallee 12, D-53115 Bonn, Germany
Combining non-equilibrium transport with spectroscopic measurements provides a unique tool for the investigation of the microscopic processes in mesoscopic conductors. Experiments on resistive quantum wires show that the non-equilibrium quasiparticle distribution function f(E,U) as a function of the quasiparticle energy E obeys the scaling property, f(E,U)=f(E/U), if the transport voltage U exceeds a certain crossover scale U*. This scaling indicates anomalous inelastic relaxation processes to be present. It is demonstrated that the latter can be induced by quantum impurities with a degenerate internal degree of freedom, i.e. by Kondo impurities. We review the theory of the Kondo effect in stationary non-equilibrium as well as in a magnetic field, and show that the experiments are explained in detail by a very low concentration of Kondo impurities, with U* ≃ TK, the Kondo temperature. It is discussed how this provides a possible explanation of the observed low-temperature plateau of the decoherence time in mesoscopic conductors.