Browsing by Author "Barraza-Lopez, Salvador"

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    The interaction between a monolayer of single-molecule magnets and a metal surface
    Barraza-Lopez, Salvador; Avery, Michael C.; Park, Kyungwha (American Institute of Physics, 2008-04-01)
    We calculate within density functional theory (DFT) and the LSDA+U formalism the electronic properties of a nanostructure in which single-molecule magnets Mn(12) are adsorbed via thiol groups onto the Au(111) surface. Our DFT calculation shows 1.23 electrons being transferred from the surface to the Mn(12) molecule, dominated by the tail on the electronic charge distribution from the gold slab. LSDA+U calculations reveal that the on-site Coulomb repulsion U does not alter the direction of the electronic charge transfer obtained from DFT, because the gold Fermi level still lies above the lowest unoccupied molecular orbital (LUMO). The U term opens up the energy gap between the highest occupied molecular orbital (HOMO) and the LUMO for an isolated standard Mn(12) but it minimally affects the gap for a sulfur-terminated Mn(12). (c) 2008 American Institute of Physics.
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    Spin-filtering effect in the transport through a single-molecule magnet Mn-12 bridged between metallic electrodes
    Barraza-Lopez, Salvador; Park, Kyungwha; Garcia-Suarez, Victor; Ferrer, Jaime (American Institute of Physics, 2009-04-01)
    Electronic transport through a single-molecule magnet Mn-12 in a two-terminal setup is calculated using the nonequilibrium Green's function method in conjunction with density-functional theory. A single-molecule magnet Mn-12 is bridged between Au(111) electrodes via thiol group and alkane chains such that its magnetic easy axis is normal to the transport direction. A computed spin-polarized transmission coefficient in zero bias reveals that resonant tunneling near the Fermi level occurs through some molecular orbitals of majority spin only. Thus, for low bias voltages, a spin-filtering effect such as only one spin component contributing to the conductance is expected. This effect would persist even with inclusion of additional electron correlations. c 2009 American Institute of Physics. [DOI: 10.1063/1.3072789]