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

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 HartreeFock 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.

Enhancing thermoelectric properties of graphene quantum rings

“…On the other hand, quantum interference effects can also play a role in the observed thermoelectric properties of single-molecule heterojunctions [14] and zerodimensional systems [15]. In particular, quantum effects giving rise to Fano resonances in the transmission probability were predicted to have an impact on the thermopower magnitude and the thermoelectric efficiency of quantum dot systems [16][17][18], single-molecule devices [19], and nanoscale junctions [20].…”

Functional renormalization group study of parallel double quantum dots: Effects of asymmetric dot-lead couplings

“…The essential feature of these effects is appearance of resonance peak structures in the conductance, making electronic transport properties very sensitive to small changes of parameters, which may be important for practical applications. In this context, the interplay and cooperation between the correlation effects and quantum interference, associated with a system geometry, can be significantly important and provide unexpected electron transport features [24][25][26][27][28].…”

Thermoelectric transport properties in graphene connected molecular junctions

“…Quantum dot molecular junctions are another class of low dimensional systems with enhanced thermoelectric properties. For example, in a double quantum dot system ZT ≃ 300 in the vicinity of a Fano resonance when we neglect the onsite Coulomb interaction within the system component quantum dots [7]. Such a high figure of merit corresponds to an ideal configuration of the molecular junction, however, even for more realistic situations ZT > 1 [7,8].…”

“…In the linear response theory, the system thermoelectric coefficients can be evaluated using the general function L nσ [7,9]:…”