Thermoelectricity of interacting particles: a numerical approach

Power, efficiency, and fluctuations in steady-state heat engines

We consider the quality factor Q, which quantifies the trade-off between power, efficiency, and fluctuations in steady-state heat engines modeled by dynamical systems. We show that the nonlinear scattering theory, in both classical and quantum mechanics, sets the bound Q=3/8 when approaching the Carnot efficiency. On the other hand, interacting, nonintegrable, and momentum-conserving systems can achieve the value Q=1/2, which is the universal upper bound in linear response. This result shows that interactions are necessary to achieve the optimal performance of a steady-state heat engine.

Inverse Currents in Hamiltonian Coupled Transport

The occurrence of an inverse current, where the sign of the induced current is opposite to the applied force, is a highly counterintuitive phenomenon. We show that inverse currents in coupled transport (ICC) of energy and particle can occur in a one-dimensional interacting Hamiltonian system when its equilibrium state is perturbed by coupled thermodynamic forces. This seemingly paradoxical result is possible due to the self-organization occurring in the system in response to the applied forces.

Thermodynamic Bound on Heat-to-Power Conversion

In systems described by the scattering theory, there is an upper bound, lower than Carnot, on the efficiency of steady-state heat-to-work conversion at a given output power. We show that interacting systems can overcome such bound and saturate, in the thermodynamic limit, the much more favorable linear-response bound. This result is rooted in the possibility for interacting systems to achieve the Carnot efficiency at the thermodynamic limit without delta-energy filtering, so that large efficiencies can be obtained without greatly reducing power.

Transport properties and enhanced figure of merit of quantum dot-based spintronic thermoelectric device

Transport properties of quantum dot-based thermoelectric device with magnetic leads placed in external magnetic field are considered. The exact expressions for the thermoelectric coefficients are obtained by the equation of motion method, assuming noninteracting electrons. It is shown that at the maximum power mode the figure of merit of the proposed spintronic device is several times higher than that of a device with unpolarized electrons. The influence of electron-electron interaction on the figure of merit is analyzed and it is shown that in the limit of strong Coulomb repulsion the optimal thermoelectric performance predicted for noninteracting electrons is restored.