Finite U thermoelectrical transport in graphene based quantum dots

TL;DR

This paper investigates thermoelectric transport in graphene-based quantum dots, revealing unique conductance behaviors due to the pseudogap density of states and highlighting deviations from classical laws like Wiedemann-Franz.

Contribution

It derives the Onsager matrix for thermoelectric transport in interacting graphene quantum dots, emphasizing the effects of pseudogap density of states on transport properties.

Findings

Double peak structures in conductances due to Coulomb blockade

Thermal conductance is much smaller than electrical conductance

Significant deviation from Wiedemann-Franz law caused by pseudogap DOS

Abstract

We study the thermoelectrical transports for an interacting dot attached to two graphene electrodes. Graphene band structure shows a pseudogap density of states that affects strongly the transport properties. In this work, we focus on the Coulomb blockade regime and derive the expression for Onsager matrix O_{ij} that relates the electrical and heat currents with electrical and thermal biases in the linear response regime. Our findings show double peak structures for the electrical and thermal conductances versus the dot level in accordance with the Coulom blockade phenomenon. Remarkably, however, the thermal conductance is much smaller than the electrical conductance, resulting in high figure of merit value for some gate voltage. Finally, we report a large departure from the Wiedemann-Franz law caused mainly by the pseudogap density of states in the contacts and weakly affected by interactions.