Thermoelectric transport properties of a T-coupled quantum dot: Atomic approach for the finite U case

We study thermoelectric transport properties through a gate defined T-coupled quantum dot, describing the system at base with the single impurity Anderson model (SIAM), whose corresponding Green׳s functions are calculated employing the finite correlation U atomic approach. We compute, with the linear approximation for the thermoelectric transport coefficients, the electrical and thermal conductance (G and K), the thermopower S, the product of the thermoelectric figure of merit and the temperature ZT, for all the regimes of the SIAM: empty quantum dot, intermediate valence, Kondo, and double occupation, at different temperatures; the treatment employed extends the results obtained for the limit of infinite U-Coulomb repulsion in the quantum dot, and has a many-body character, which is absent in Green׳s function descriptions that employ mean field approximations. Our main result connects the ZT behavior with the interplay between the thermopower and the violation of the Wiedemann–Franz relation; the results are in good agreement with other recent theoretical papers that employ the numerical renormalization group (NRG), different Green׳s function approximations, and some experimental reports.