From spin and orbital SU(4) to spin SU(2) Kondo effect in double quantum dot

TL;DR

This paper investigates the crossover between SU(4) and SU(2) Kondo effects in a double quantum dot system, analyzing how electron exchange and magnetic fields influence the Kondo temperature and conductance.

Contribution

It introduces a detailed analysis of the smooth transition from SU(4) to SU(2) Kondo regimes in coupled quantum dots, highlighting experimental signatures and parameter dependencies.

Findings

Kondo temperature slightly drops in the intermediate regime.

Differential conductance varies with exchange strength and Zeeman field.

Two types of Kondo effects can be distinguished experimentally.

Abstract

We consider spin and orbital Kondo effect in a parallel arrangement of two strongly electrostatically coupled quantum dots. Increasing the exchange of electrons between the dots through the attached leads induces a smooth crossover between SU(4) spin- and orbital Kondo effect and SU(2) spin Kondo effect. Being the same for the SU(4) and SU(2) symmetry points, the Kondo temperature drops slightly in the intermediate regime. Experimentally, two kinds of Kondo effect can be discriminated by the sensitivity to the suppression of the spin Kondo effect by Zeeman field. The dependence of the Kondo temperature and of the differential conductance on the strength of electronic exchange through the leads and Zeeman field is analyzed in detail.