Linear Kondo conductance in a quantum dot

TL;DR

This paper explores the Kondo effect in quantum dots, detailing how conductance varies with coupling strength, magnetic field, and electron number, and discusses experimental and theoretical aspects of single and multi-channel Kondo physics.

Contribution

It provides a pedagogical review of single-channel Kondo physics and extends the analysis to two-channel overscreened Kondo effects in quantum dots.

Findings

Kondo resonant conductance emerges at low temperatures in Coulomb blockade valleys.

Orbital Kondo effect can occur in vertical quantum dots at level crossings.

Proposals for detecting non-Fermi liquid fixed points at strong coupling.

Abstract

In a tunneling experiment across a quantum dot it is possible to change the coupling between the dot and the contacts at will, by properly tuning the trasparency of the barriers and the temperature. Gate voltages allow for changes of the relative position of the dot addition energies and the Fermi level of the leads. Here we discuss the two limiting cases: weak and strong coupling in the tunneling Hamiltonian. In the latter case Kondo resonant conductance can emerge at low temperature in a Coulomb blockade valley. We give a pedagogical approach to the single-channel Kondo physics at equilibrium and review the Nozieres scattering picture of the correlated fixed point. We emphasize the effect of an applied magnetic field and show how an orbital Kondo effect can take place in vertical quantum dots tuned both to an even and to an odd number of electrons at a level crossing. We extend the approach to the two-channel overscreened Kondo case and discuss recent proposals for detecting the non-Fermi liquid fixed point which could be reached at strong coupling.