Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 27: Spintronics (incl. Quantum Dynamics)

MA 27.6: Vortrag

Dienstag, 21. März 2017, 15:15–15:30, HSZ 301

Adsorption and element-specific detection of transition metal porphyrins by spin-dependent conductance of a graphene nanoribbon — •Peter Kratzer1, Sherif A. Tawfik2, Xiang Yuan Cui2, and Catherine Stampfl21Fakultät für Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany — 2The University of Sydney, Sydney, New South Wales 2006, Australia

Transition metal porphyrins, their adsorption on graphene nanoribbons (GNRs), and its consequences for electronic transport through the GNRs are investigated by means of density functional theory calculations. Interaction with a single-atom vacancy in the GNR is found to be a prerequisite for chemical bonding of the transition metal centre. In both the physisorbed and the chemisorbed geometry, the inclusion of van der Waals interaction results in a significant enlargement of the binding energy. Electronic transport calculations using non-equilibrium Greens functions show that the conductivity of the edge states in the GNR is altered by the chemisorbed porphyrin molecules. Since the metal centers of porphyrins carry an element-specific magnetic moment, the spin-dependence of the conductance of the GNR is altered, too. In particular, the adsorption of Ru-porphyrin or Fe-porphyrin on the single-atom vacancy results in a large spin polarization of the current of 88% and -62%, respectively, at small applied source-drain voltages. Based on our results, we suggest that a spin valve constructed from a GNR with ferromagnetic contacts could be used as a sensitive detector that could discriminate between various metal porphyrins.

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