Detection of adsorbed transition-metal porphyrins by spin-dependent conductance of graphene nanoribbon

Abstract

Electronic transport in a zig-zag-edge graphene nanoribbon (GNR) and its modification by adsorbed transition metal porphyrins is studied by means of density functional theory calculations. The detachment reaction of the metal centre of the porphyrin is investigated both in the gas phase and for molecules adsorbed on the GNR. As most metal porphyrins are very stable against this reaction, it is found that these molecules bind only weakly to a perfect nanoribbon. However, interaction with a single-atom vacancy in the GNR results in chemical bonding by the transition metal centre being shared between nitrogen atoms in the porphyrin ring and the carbon atoms next to the vacancy in the GNR. For both the physisorbed and the chemisorbed geometry, the inclusion of van der Waals interaction results in a significant enlargement of the binding energy and reduction of the adsorption height. Electronic transport calculations using non-equilibrium Greens functions show that the conductivity of the GNR is altered by the chemisorbed porphyrin molecules. Since the metal centers of porphyrins carry an element-specific magnetic moment, not only the net conductance, but also the spin-dependent conductance of the GNR is affected. In particular, the adsorption of Ru-porphyrin on the single-atom vacancy results in a very large spin polarization of the current of 88% 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.

arXiv comment12 pages, 8 figures, updated author affiliation, clarifications in captions of Fig. 2 and 4 added

References in corpus (10)

• Density functional method for nonequilibrium electron transport
• Energy Gaps in Graphene Nanoribbons
• Electronic spin transport and spin precession in single graphene layers at room temperature
• Resolution-of-identity approach to Hartree-Fock, hybrid density functionals, RPA, MP2, and \textit{GW} with numeric atom-centered orbital basis functions
• Role of Symmetry in the Transport Properties of Graphene Nanoribbons under Bias
• Magnetoresistance through a single molecule
• Carrier Density and Magnetism in Graphene Zigzag Nanoribbons
• Electronic spin drift in graphene field effect transistors
• Ab initio spin-flip conductance of hydrogenated graphene nanoribbons: Spin-orbit interaction and scattering with local impurity spins
• The role of the van der Waals interactions in the adsorption of anthracene and pentacene on the Ag(111) surface

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