Nonequilibrium thermoelectrics of a Kondo-correlated molecular junction

Thermoelectric properties of nanostructures, such as quantum dots or molecular junctions, have been shown to contain the signatures of the Kondo correlations. Such systems have been extensively investigated theoretically in the equilibrium regime, whereas the nonequilibrium thermoelectric behavior has been much less explored due to difficulties arising when treating electron correlations accurately at out-of-equilibrium conditions. Here, we study the nonequilibrium thermoelectrics of a molecular junction with asymmetric coupling to the leads. This asymmetric coupling, present in various experimental setups, allows for treating the weakly coupled subsystem perturbatively whereas the strongly coupled part is accurately solved by using the numerical renormalization group method. We demonstrate that the electron transport across such a junction with finite potential and temperature gradient can be calculated using perturbation theory and it contains the signatures of the Kondo correlations. Furthermore, we study the behavior of the Seebeck coefficient, extended to the non-equilibrium regime, for different system parameters, and observe new regions of sign change in the non-equilibrium Seebeck coefficient due to the presence of Kondo correlations.