Nonequilibrium Transport through a Kondo Dot in a Magnetic Field: Perturbation Theory

TL;DR

This paper uses nonequilibrium perturbation theory to analyze how magnetic fields and bias voltages affect the Kondo effect in quantum dots, revealing new logarithmic corrections and conductance features.

Contribution

It introduces a method to calculate nonequilibrium magnetization and conductance corrections in the Kondo regime under magnetic fields and bias voltages.

Findings

Logarithmic corrections are modified out of equilibrium.

Finite bias and magnetic field induce new conductance features.

Perturbative renormalization group needs modification for nonequilibrium.

Abstract

Using nonequilibrium perturbation theory, we investigate the nonlinear transport through a quantum dot in the Kondo regime in the presence of a magnetic field. We calculate the leading logarithmic corrections to the local magnetization and the differential conductance, which are characteristic of the Kondo effect out of equilibrium. By solving a quantum Boltzmann equation, we determine the nonequilibrium magnetization on the dot and show that the application of both a finite bias voltage and a magnetic field induces a novel structure of logarithmic corrections not present in equilibrium. These corrections lead to more pronounced features in the conductance, and their form calls for a modification of the perturbative renormalization group.