The graphene edge state has long been predicted to be a zero energy, one-dimensional electronic waveguide mode that dominates transport in neutral graphene nanostructures, with potential application to graphene devices. However, its exceptional properties have been observed in only a few cases, each employing novel fabrication methods without a clear path to large-scale integration. We show here that interconnected edge-state networks can be produced using non-conventional facets of electronics grade silicon carbide wafers and scalable lithography, which cuts the epitaxial graphene and apparently fuses its edge atoms to the silicon carbide substrate. Measured epigraphene edge state (EGES) conduction is ballistic with mean free paths exceeding tens of microns, thousands of times greater than for the diffusive 2D bulk. It is essentially independent of temperature, decoupled from the bulk and substantially immune to disorder. Remarkably, EGES transport involves a non-degenerate conductance channel that is pinned at zero energy, yet it does not generate a Hall voltage, implying balanced electron and hole components. These properties, observed at all tested temperatures, magnetic fields, and charge densities, are not predicted by present theories, and point to a zero-energy spin one-half quasiparticle, composed of half an electron and a half a hole moving in opposite directions.
Download