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| The influence of chemical side groups is significant in physical orchemical understanding the transport through the single molecular junction.Motivated by the recent successful fabrication and measurement of asingle organic molecule sandwiched between graphene electrodes, herewe study the spin-dependent transport properties of a junction of afused oligothiophenes molecule embedded between two semi-infinitivelong ZGNR electrodes. The molecule with and without an attachedamino NH$_2$ side group is considered, respectively, and anexternal magnetic field or a FM stripe is applied onto the ZGNRs toinitially orient the magnetic alignment of the electrodes for thespin-dependent consideration. By the emph{ab initio} calculationsbased on the density functional theory combined with thenonequilibrium Green's function formalism, we have demonstrated theremarkable difference in the spin-charge transport property between thejunctions of the molecule with and without NH$_2$ side group. Inparticular, the junction with side group shows more obvious NDR. Inaddition, it exhibits an interesting dual spin-filtering effect whenthe magnetic alignment in electrodes is initiallyantiparallel-oriented. The mechanisms of the results are revealedand discussed in terms of the spin-resolved transmission spectrumassociated with the frontier molecular orbitals evolution, themolecular projected self-consistent Hamiltonian eigenvalues, and thelocal density of states. |
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| Keywords:graphene electrode, organic molecular junction, DFT, negative differential resistance, spin-filtering |
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