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Spin-dependent transport through interacting graphene armchair nanoribbons

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

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New journal of physics. Online journal 12 (2010), No.3, Art.033038, 36 pp.
ISSN: 1367-2630
Journal Article, Electronic Publication
Fraunhofer IWM ()
PACS 72.25.-b; spin polarized transport; PACS 75.47.Pq; PACS 73.63.Rt; nanoscale contacts; PACS 73.23.Hk; coulomb blockade; single-electron tunneling; PACS 61.46.-w; structure of nanoscale materials

We investigate spin effects in transport across fully interacting, finite size graphene armchair nanoribbons (ACNs) contacted to collinearly spin-polarized leads. In such systems, the presence of short ranged Coulomb interaction between bulk states and states localized at the ribbon ends leads to novel spin-dependent phenomena. Specifically, the total spin of the low energy many-body states is conserved during tunneling but that of the bulk and end states is not. As a consequence, in the single-electron regime, dominated by Coulomb blockade phenomena, we find pronounced negative differential conductance features for ACNs contacted to parallel polarized leads. These features are however absent for an anti-parallel contact configuration, which in turn leads within a certain gate and bias voltage region to a negative tunneling magneto-resistance. Moreover, we analyze the changes in the transport characteristics under the influence of an external magnetic field.