Magnetism and charge and spin transport in graphene nanostructures

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Graphene is not only a very interesting material for science but also probably one of the most promising candidates for future spintronic and nano-electronic devices. Due to its electronic structure it exhibits the highest charge carrier mobilities ever measured and the low hyperfine interaction as well as the low spin-orbit coupling result in large spin diffusion lengths and spin lifetimes. Based on our recent observation of huge mobilities (100.000 cm²/(Vs)) in turbostratic graphene, we will study the thickness dependence of the properties to reveal the influence of the environment, the dominating scattering and charge transport mechanisms and ascertain the ultimate limit for mobilities in this multilayer-system. The optimized efficient spin injection without tunneling barriers will allow us to obtain large diffusive spin currents and we will ascertain the spin relaxation mechanisms to maximize the spin diffusion lengths and spin accumulation with a view of using spin currents to manipulate magnetisation.The ultimate graphene-based nanostructure are graphene nanoribbons where so-called armchair- and zigzag-edges can be tailored with atomistic structural precision using bottom-up synthesis and single atom transmission electron microscopy-based sculpting as post-patterning. We will study key characteristic charge and spin transport properties, such as the charge carrier mobility, Hall coefficient and spin diffusion length in these atomically perfect structures. In addition to classical transport, we will probe the exciting unconventional properties that have been predicted for these nano-structures: Quantum confinement leading to bandgaps and magnetic defect- or edge-induced states will be studied using electromigrated nano-gap geometries for nanoribbons with different widths and tailored edge geometries to test a variety of partly contradicting theoretical predictions. Furthermore by using specially functionalized nanoribbons that can be lithographically contacted on insulating substrates, the quantum transport over long distances in these effectively 1D structures will be analyzed for the first time.