Thermopower simulation of a two level spinless quantum dot

Abstract: Quantum dots are interesting candidates for a broad variety of electronic components, with single electron transistors and LEDs being two examples already well on their way. In nanostructures, such as quantum dots, quantum effects greatly influence the transport. In a spin polarized quantum dot system with two energy levels, interference effects have been found to cause a strong suppression of conductance [Phys. Rev. Lett. 104, 186804 (2010)]. In the present work, this system is further investigated with thermopower acting as probing tool. Thermopower is a measure of the voltage induced by a temperature difference, attributed to the Seebeck effect, at vanishing current. While conductance probes transport at and around the Fermi level, thermopower does so for a wider range of energies. For the system addressed in this work, thermopower is evaluated as a probing tool complementary to conduction. To simulate transport, a generalized master equation approach is used; the second order von Neumann approach. This method takes into account second order tunneling as well as interference effects; coherence and correlations. The simulations show that the conductance suppression manifest itself also in the thermopower and furthermore, with a more prominent signal.