Kondo physics and orbital degeneracy interact to boost thermoelectrics on the nanoscale

Abstract

We investigate the transport through a nanoscale device consisting of a degenerate double-orbital Anderson dot coupled to two uncorrelated leads. We determine the thermoelectric transport properties close to the one-electron regime and compare them to a corresponding single-orbital dot. The linear and nonlinear regimes are addressed, the latter via a non-equilibrium generalization of the non-crossing approximation based on the Keldysh formalism. Power output and efficiency in the Kondo regime are shown to be strongly enhanced through the presence of a second orbital. We predict an experimentally relevant optimal operating point which benefits from the concomitant increase of the Kondo temperature in the two-orbital setup. An approximation based on the transport coefficients and fulfilling the thermodynamic balance is proven to remain appropriate even far beyond the expected range of validity of such approaches. Finally, the double-orbital Kondo regime reveals itself as a promising candidate to avoid, at least partially, the generic dilemma between optimal thermoelectric efficiency on one hand, and fair power output on the other.

5 pages, 2 figures

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• Optimal energy quanta to current conversion
• Thermopower of a Kondo-correlated quantum dot
• Thermoelectric transport through strongly correlated quantum dots
• Optimal thermoelectric figure of merit of a molecular junction
• Tuning the Kondo effect with a mechanically controllable break junction
• Quantum-fluctuation effects on the thermopower of a single-electron transistor
• Thermoelectric phenomena in a quantum dot asymmetrically coupled to external leads
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Cited by in corpus (9)

• Conditions for requiring nonlinear thermoelectric transport theory in nanodevices
• Spin-dependent thermoelectric effects in a strongly correlated double quantum dot
• Thermopower of an SU(4) Kondo resonance under an SU(2) symmetry-breaking field
• Mixed, charge and heat noises in thermoelectric nanosystems
• Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime
• Statistics of heat transport across capacitively coupled double quantum dot circuit
• Thermoelectric effects in quantum Hall systems beyond linear response
• Thermoelectric properties of a double quantum dot out of equilibrium in Kondo and intermediate valence regimes
• Role of asymmetry in thermoelectric properties of a double quantum dot out of equilibrium