title: Graphene nanoribbons with smooth edges behave as quantum wires.
abstract: Graphene nanoribbons with perfect edges are predicted to exhibit interesting electronic and spintronic properties, notably quantum-confined bandgaps and magnetic edge states. However, so far, graphene nanoribbons produced by lithography have had rough edges, as well as low-temperature transport characteristics dominated by defects (mainly variable range hopping between localized states in a transport gap near the Dirac point). Here, we report that one- and two-layer nanoribbon quantum dots made by unzipping carbon nanotubes exhibit well-defined quantum transport phenomena, including Coulomb blockade, the Kondo effect, clear excited states up to ∼20 meV, and inelastic co-tunnelling. Together with the signatures of intrinsic quantum-confined bandgaps and high conductivities, our data indicate that the nanoribbons behave as clean quantum wires at low temperatures, and are not dominated by defects.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305, USA.
authors.forename: Xinran
authors.initials: X
authors.lastname: Wang
authors.forename: Yijian
authors.initials: Y
authors.lastname: Ouyang
authors.forename: Liying
authors.initials: L
authors.lastname: Jiao
authors.forename: Hailiang
authors.initials: H
authors.lastname: Wang
authors.forename: Liming
authors.initials: L
authors.lastname: Xie
authors.forename: Justin
authors.initials: J
authors.lastname: Wu
authors.forename: Jing
authors.initials: J
authors.lastname: Guo
authors.forename: Hongjie
authors.initials: H
authors.lastname: Dai