un 2 00 8 Theory of non - equilibrium thermoelectric effects in nanoscale junctions

Despite its intrinsic non-equilibrium origin, thermoelectricity in nanoscale systems is usually described within a static scattering approach which disregards the dynamical interaction with the thermal baths that maintain energy flow. Using the theory of open quantum systems we show instead that unexpected properties, such as a resonant structure and large sign sensitivity, emerge if the non-equilibrium nature of this problem is considered. Our approach also allows us to define and study a local temperature, which shows hot spots and oscillations along the system according to the coupling of the latter to the electrodes. This demonstrates that Fourier’s law – a paradigm of statistical mechanics – is violated at the nanoscale.