Thermopower and thermal conductance through parallel coupled quantum dots

Abstract

We study the thermoelectric transport properties through two parallel coupled, gate-defined quantum dots (QDs), in the framework of the X-boson treatment for the impurity Anderson model. We compute the thermopower S, the thermal conductance κ, the electrical conductance G, and the product of the thermoelectric figure of merit and the temperature ZT, as function of the dot energy. We concentrate the calculations on ZT, that is, a measure of the usefulness of materials or devices as thermopower generators or cooling systems. If the coupling between the QDs is weak, ZT is greater than 1 when T≃Δ (Δ is the mixing width between the QD and the leads) but when the system is coupled, the second dot can tune the temperature region where ZT>1. This result increases the possibilities of practical application of the system in mesoscopic cooling process.