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

Abstract

Abstract – 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.