Restoring the SU(4) Kondo regime in a double quantum dot system

Abstract

We calculate the spectral density and occupations of a system of two capacitively coupled quantum dots, each one connected to its own pair of conducting leads, in a regime of parameters in which the total coupling to the leads for each dot ${\Gamma }_i$ are different. The system has been used recently to perform pseudospin spectroscopy by controlling independently the voltages of the four leads. For an odd number of electrons in the system, ${\Gamma }_1={\Gamma }_2$, equal dot levels $E_1=E_2$ and sufficiently large interdot repulsion $U_{12}$ the system lies in the SU(4) symmetric point of spin and pseudospin degeneracy in the Kondo regime. In the more realistic case ${\Gamma }_1\ne {\Gamma }_2$, pseudospin degeneracy is broken and the symmetry is reduced to SU(2). Nevertheless we find that the essential features of the SU(4) symmetric case are recovered by appropriately tuning the level difference $\delta =E_2-E_1$. The system behaves as an SU(4) Kondo one at low energies. Our results are relevant for experiments which look for signatures of SU(4) symmetry in the Kondo regime of similar systems.

9 pages, 10 figures

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• Quantifying the leading role of the surface state in the Kondo effect of Co/Ag(111)
• Conditions for observing emergent SU(4) symmetry in a double quantum dot
• Relation between width of the zero-bias anomaly and Kondo temperaure in transport measurements through correlated quantum dots: Effect of asymmetric coupling to the leads
• Replicas of the Kondo peak due to electron-vibration interaction in molecular transport properties
• Abrupt disappearance and reemergence of the SU(2) and SU(4) Kondo effects due to population inversion
• Manipulability of the Kondo effect in a T-shaped triple-quantum-dot structure
• Width of the charge-transfer peak in the SU(N) impurity Anderson model and its relevance to non-equilibrium transport
• Kondo behavior and conductance through $3d$ impurities in gold chains doped with oxygen
• Destructive quantum interference in transport through molecules with electron-electron and electron-vibration interactions
• Thermoelectric properties of a double quantum dot out of equilibrium in Kondo and intermediate valence regimes
• SU(4) Kondo entanglement in double quantum dot devices
• Kondo temperature when the Fermi level is near a step in the conduction density of states
• Role of asymmetry in thermoelectric properties of a double quantum dot out of equilibrium
• Impact of electron-phonon coupling on electron transport through T-shaped arrangements of quantum dots in the Kondo regime