Two-color Fermi-liquid theory for transport through a multilevel Kondo impurity

Abstract

A multiorbital quantum impurity with effective spin S>1/2 connected to several reservoirs of conduction electrons can lead to a Kondo effect, exhibiting multistage screening. The ground state of a prototypical nanoscale device consisting of an S=1 quantum impurity connected to two conducting reservoirs is a spin singlet, formed via a two-stage Kondo screening mechanism. Understanding the equilibrium and nonequilibrium properties of the strong-coupling regime resulting from this two-stage screening has been an open problem for many years. Here, the authors offer a detailed description in terms of an effective local two-color Fermi liquid theory.