Genomics of carbon atomic chains

Abstract

To realise the technological potential of subnanometer graphene junctions, there is a need to understand how their electronic and spintronic properties are controlled by the carbon chains bridging their gaps. Motivated by the recent experimental efforts to form in-situ all-carbon junctions using graphene electrodes connected to carbon chains, here we systematically study a wide variety of such structures. We find that although a wide range of transport properties are possible, the junctions can be divided into a small number of categories, according to their qualitative transport properties. For example, we find that junctions bridged by even-numbered chains of carbon atoms tend to have a lower conductance than those bridged by odd-numbered atomic chains. We also find that junctions with ferromagnetically aligned electrode surface edges have a higher transmission than anti-ferromagnetically aligned ones, because ferromagnetic alignment tends to increase the transmission of one of the spin carriers. We also examine the effect of terminal rings, electrode terminal edges and the effect of saturation of edges with hydrogen on transport properties of all-carbon junctions. Just like genomics, our findings provide a complete set of information to construct junctions formed by carbon chains with desired properties for spintronic applications.