Large enhancement of thermoelectric effects in a double quantum dot system due to interference and Coulomb correlation phenomena

TL;DR

This paper theoretically investigates thermoelectric effects in a double quantum dot system, revealing significant enhancements in efficiency due to Coulomb interactions and quantum interference, with implications for spin-dependent transport.

Contribution

It demonstrates how Coulomb blockade and quantum interference can substantially enhance thermoelectric efficiency in quantum dot systems, including spin-dependent effects.

Findings

Coulomb blockade enhances the figure of merit ZT.

Quantum interference further increases ZT.

Strong violation of Wiedemann-Franz law observed.

Abstract

Thermoelectric effects in a double quantum dot system coupled to external magnetic/nonmagnetic leads are investigated theoretically. The basic thermoelectric transport characteristics, like thermopower, electronic contribution to heat conductance, and the corresponding figure of merit, have been calculated in terms of the linear response theory and Green function formalism in the Hartree-Fock approximation for Coulomb interactions. An enhancement of the thermal efficiency (figure of merit ZT) due to Coulomb blockade has been found. The magnitude of ZT is further considerably enhanced by quantum interference effects. Both the Coulomb correlations and interference effects lead to strong violation of the Wiedemann-Franz law. The influence of spin-dependent transport and spin bias on the thermoelectric effects (especially on Seebeck and spin Seebeck effects) is also analyzed.