Graphene armchair nanoribbon single-electron transistors: The peculiar influence of end statesS. Koller1, L. Mayrhofer1, 2 and M. Grifoni1
1 Theoretische Physik, Universität Regensburg - 93040 Regensburg, Germany, EU
2 Fraunhofer IWM - Wöhlerstrae 11, 79108 Freiburg, Germany, EU
received 22 June 2009; accepted in final form 9 November 2009; published December 2009
published online 7 December 2009
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.
73.23.Hk - Coulomb blockade; single-electron tunneling.
71.10.Pm - Fermions in reduced dimensions (anyons, composite fermions, Luttinger liquid, etc.).
73.63.-b - Electronic transport in nanoscale materials and structures.
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