Objectives of the project
This project is inspired by our recent discovery of ballistic and fully spin-polarized transport at room temperature for graphene nanoribbons (GNRs) grown on pre-structured SiC(0001) surfaces (see Fig.1) . We have obtained clear evidence that the origin of the observed unique properties is governed by the presence of the robust edge states.
The unique role of the electronic and magnetic properties of these edge states is the central research topic in this proposal, which in combination with electronic charge and spin transport studies in dedicated devices will reveal crucial information about the underlying mechanism for the ballistic and magnetic behaviour. The major objective is to explore the unique possibilities of this system to realize "all-graphene" spintronic devices where the entire spin valve architecture is made in a single GNR. This creates an entirely new platform for both fundamental as well as application driven research of quasi one-dimensional carbon based magnetism and spintronics.. The close entanglement of both charge and electron spin within the transport channel demands the study of both signatures.In order to reach our major objective, combining expertise and close collaboration between partners from the fields of growth, spin-resolved and other electron spectroscopies, local probe techniques and transport is of crucial importance. In detail, the following aspects shall be addressed:
A) Precise engineering of tailored, robust graphene edge states is needed to reveal ballistic charge transport at room temperature. Optimization of the growth process for a large scale needs to be promoted for future applications.
B) Microscopic understanding of the ballistic and spin-polarized behaviour by the anomalous electronic structure of the edge states by combining different electron spectroscopic and spin transport studies to discover the exotic state in which the "electrons" are in as well as their relevant interactions on various lengths scales.
C) Functionalization of GNRs via selective atomistic manipulation under consideration of defects. For instance, selective hydrogenation and/or the intercalation of heavy group V elements (e.g. CoBi) leads to an enhancement of the SOC over extended regions around the adsorption/intercalation sites and thus triggers the total magnetic moment of the charge carriers in the edge states of the GNR. A precise tuning of the carrier concentration - even on the nanoscale - will be possible by intercalation e.g. of Lanthanides.
D) Engineering of prototype spin-valve devices and exploringe the transport properties as a function of the size of the applied magnetic field, temperature, and functionalization of the GNR.