Theoretical Investigation of Spin-Dependent Transport from Adsorbates to Magnetic Substrates

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Self-assembled monolayers (SAMs) of organic molecules on metal surfaces offer intriguing properties for future molecular electronics. In recent experiments by the group of P. Feulner at the TU München this idea has been extended to molecular spintronics on magnetic iron, cobalt, and nickel. We propose in this project to investigate these kinds of processes using first principles electronic structure and quantum dynamical methods. To do so, we propose to proceed in two directions: On the one hand, the formation, stability, and structure of SAMs need to to be investigated. Spin-polarized DFT calculations with semi-local exchange-correlation functionals provide a powerful framework to describe the magnetism of itinerant electrons in elemental metals. For the treatment of surfaces we will combine them with periodic boundary condition supercell geometry approaches. On the other hand, we will study the spin-dependent charge transport through the adsorbates to a magnetic substrate with a variety of real-time time-dependent DFT and time-dependent CI calculations, using a cluster approach. The most approximate quantum dynamical approach can treat of the order of 10,000 electrons, which makes us confident that the clusters can be made large enough for convergence on the relevant time-scale. Special attention will be given to various mechanisms that influence the difference of the time-scales of the charge transfer, such as spin-dependent barrier heights or density of states.