Spin phenomena and higher order effects in transport across interacting quantum-dots [Elektronische Ressource] / Sonja Koller

Which mechanisms rule the current flow across a nanostructure? We address in this thesis two aspects concerning this question. At first, we deal with a theory of electron transfer through a quantum system weakly coupled to metallic leads. The charge carriers can only be exchanged by tunnelling processes. Although the tunnelling probability decreases with the number of simul-taneously tunnelling electrons, still such higher order processes are responsible for various re-markable effects. We reveal a new structuring within the transport theory, which eases nume-rical as well as analytical studies of these higher order events. In the second part of this work, weapply the theory to four different quantum-dot systems. A single-level quantum-dot and a double-quantum-dot system serve as simple mo-dels for the investigation of transport up to fourth order (simultaneous tunnelling of two electrons). Narrow graphene nanoribbons and thin carbon Sonja Kollernanotubes require first a sophisticated theoreti-cal description to determine their complex elec-Spin phenomena and higher tronic spectra and eigenstates. In particular, the peculiar spin configurations of the eigenstates order effects in transport across manifest themselves for both systems in specific phenomena in unpolarised as well as in spin-po-interacting quantum-dotslarised transport with or without magnetic field.