Nonequilibrium Kondo transport through a quantum dot in a magnetic field

TL;DR

This paper investigates the universal transport properties of a strongly interacting quantum dot in the Kondo regime under an external magnetic field, providing analytical results for conductance behavior across energy ranges and conditions.

Contribution

It introduces an analytical expression for the tunneling density of states in the Kondo regime with magnetic field, revealing universal conductance features and nonequilibrium effects.

Findings

Universal differential conductance exhibits Fermi-liquid and logarithmic behavior.

Zero temperature conductance varies with bias voltage and magnetic field.

Critical magnetic field causes splitting of the zero bias conductance maximum.

Abstract

We analyze universal transport properties of a strongly interacting quantum dot in the Kondo regime when the quantum dot is placed in an external magnetic field. The quantum dot is described by the asymmetric Anderson model with the spin degeneracy removed by the magnetic field resulting in the Zeeman splitting. Using an analytical expression for the tunneling density of states found from a Keldysh effective field theory, we obtain in the whole energy range the universal differential conductance and analytically demonstrate its Fermi-liquid and logarithmic behavior at low- and high-energies, respectively, as a function of the magnetic field. We also show results on the zero temperature differential conductance as a function of the bias voltage at different magnetic fields as well as results on finite temperature effects out of equilibrium and at a finite magnetic field. The modern nonequilibrium experimental issues of the critical magnetic field, at which the zero bias maximum of the differential conductance starts to split into two maxima, as well as the distance between these maxima as a function of the magnetic field are also addressed.