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Graphene armchair nanoribbon single-electron transistors: The peculiar influence of end states

: Koller, S.; Mayrhofer, L.; Grifoni, M.


epl. A letters journal exploring the frontiers of physics 88 (2009), No.5, Art. 57001, 6 pp.
ISSN: 0302-072X
ISSN: 0295-5075
ISSN: 1286-4854
Journal Article
Fraunhofer IWM ()
PACS 73.23.Hk; PACS 73.63.-b; PACS 71.10.Pm; coulomb blockade; single-electron tunneling; fermions in reduced dimensions; electronic transport in nanoscale materials and structures

We present a microscopic theory for interacting graphene armchair nanoribbon quantum dots. Long range interaction processes are responsible for Coulomb blockade and spin-charge separation. Short range ones, arising from the underlying honeycomb lattice of graphene, smear the spin-charge separation and induce exchange correlations between bulk electrons - delocalized on the ribbon - and single electrons localized at the two ends. As a consequence, entangled end-bulk states where the bulk spin is no longer a conserved quantity occur. Entanglement's signature is the occurrence of negative differential conductance effects in a fully symmetric set-up due to symmetry-forbidden transitions.