Non-equilibrium Transport and Relaxation in Diffusive Nanowires with Kondo Impurities

Abstract

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,V) as a function of the quasiparticle energy E approximately obeys the scaling property, f(E,V) = f(E/V), if the transport voltage V exceeds a certain crossover scale V^*. 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 a perturbative renormalization group method to describe the Kondo effect in an arbitrary stationary non-equilibrium situation 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 V^* ≈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. KeywordsRenormalization GroupQuantum WireRenormalization Group EquationDecoherence TimeSpin Relaxation RateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.