Nonequilibrium Transport through a Kondo Dot: Decoherence Effects

TL;DR

This paper studies how voltage-induced spin relaxation affects electron transport in a quantum dot within the Kondo regime, revealing that decoherence suppresses divergences and maintains weak coupling at high voltages.

Contribution

It introduces a nonequilibrium perturbation approach to analyze decoherence effects on the Kondo effect in quantum dots under high bias voltage.

Findings

Spin-relaxation rates cut off logarithmic divergences near chemical potentials.

The Kondo problem remains at weak coupling when voltage exceeds Kondo temperature.

Decoherence effects stabilize the nonequilibrium Kondo state at high bias.

Abstract

We investigate the effects of voltage induced spin-relaxation in a quantum dot in the Kondo regime. Using nonequilibrium perturbation theory, we determine the joint effect of self-energy and vertex corrections to the conduction electron T-matrix in the limit of transport voltage much larger than temperature. The logarithmic divergences, developing near the different chemical potentials of the leads, are found to be cut off by spin-relaxation rates, implying that the nonequilibrium Kondo-problem remains at weak coupling as long as voltage is much larger than the Kondo temperature.