Due to its exceptional conduction properties, graphene has been proposed as a candidate to replace silicon in future electronics. However, several problems need to be overcome prior to its implantation in the production chain. Among these difficulties, one of the most fundamental unknown aspects is how to contact graphene with the macroscopic leads made of metal – typically copper- in a clean and reliable methodology. Understanding the properties of nanoscale electric contacts of graphene with metals is therefore a necessary step towards these atomically precise future devices. Graphene-metal contacts are, by definition, 1-dimensional as graphene itself is a 2D material, and thus new quantum phenomena arising from this low dimensionality can be expected altering the conductance far from the usual ohmic laws.
In the paper appearing in ACS Nano, our group, in collaboration with the group of Prof. Perez of UAM, has performed a combined experimental-theoretical characterization of an atomically precise graphene-metal edge-boundary. In our work we have used the surface of Pt(111) as a model for metal contacts and grown epitaxial graphene onto it. We found that the edge between graphene and Pt(111) follows an ordered reconstruction and that the electronic structure of the interface exhibits unusual phenomena. Unexpected 1-dimensional states appearing in one of the two hexagonal sublattices of carbon atoms within graphene appear when contacting graphene to Pt(111) and maybe will appear on other metals as well. This electronic structure can, in principle, be used in future electronic devices to run two independent currents on the same graphene wire opening new paradigms in the design of future graphene-based electronic circuits.
It has been published in the journal ACS Nano, 2014, 8 (4), pp 3590–3596