Tailoring of graphene's electronic and magnetic properties via edge functionalization

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This project endeavours to develop chemical edge functionalization into a reliable tool for tailoring the electronic and magnetic structure of graphene sheets and nanoribbons. The key strategy to achieve well-defined chemical edge terminations consists of in situ saturating the reactive dangling bonds that are created upon rupture of the graphene basal plane. On this basis, it is targeted to implement different functionalization protocols, including the Edge-functionalized graphene mechanical exfoliation of highly oriented pyrolytic graphite (HOPG) for the fabrication of edge-functionalized graphene sheets with sizes of several micrometers, as well as solutionbased exfoliation methods to yield larger quantities of functionalized graphene sheets and nanoribbons with a width down to a few nanometres. In case of the latter, a two-stage approach is envisioned, whereby first ribbons without defined crystallographic orientation, and then ribbons with controlled edge geometry shall be obtained. Achieving the latter task is projected by the use of two different functionalizing agents capable of selectively stabilizing either armchair or zigzag edges. A first purpose of the attached groups is to enhance the electrical performance of the (nanostructured) graphene, in particular by imparting unprecedented carrier mobility and breakdown current density, as well as the possibility of band gap tuning. In addition, the edge groups shall be exploited toward controlling the local spin alignment, in order to render the nanoribbons into useful components of spin valve devices. The major objective with regard to both, the electronic and magnetic properties, is to explore the influence of the chemical nature of the edge groups, as well as the ribbon width as the relevant confinement dimension. To this end, the experimental work will be complemented by theoretical studies performed in collaboration within the priority program.Finally, the controlled assembly of the edge-functionalized graphene onto patterned substrates shall be explored as a tool for the parallel fabrication of graphene-based devices.