A Bipodal Dicyano Anchor Unit for Single-Molecule Spintronic Devices

Authors

  • Dr. Yuta Tsuji,

    1. Institute for Materials Chemistry and Engineering and International Research Center for Molecular Systems, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan), Fax: (+81) 92-802-2528
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  • Takayuki Semoto,

    1. Institute for Materials Chemistry and Engineering and International Research Center for Molecular Systems, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan), Fax: (+81) 92-802-2528
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  • Prof. Kazunari Yoshizawa

    Corresponding author
    1. Institute for Materials Chemistry and Engineering and International Research Center for Molecular Systems, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan), Fax: (+81) 92-802-2528
    • Institute for Materials Chemistry and Engineering and International Research Center for Molecular Systems, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan), Fax: (+81) 92-802-2528
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Abstract

The conductance through single 7,7,8,8-tetracyanoquinodimethane (TCNQ) connected to gold electrodes is studied with the nonequilibrium Green’s function method combined with density functional theory. The aim of the study is to derive the effect of a dicyano anchor group, [DOUBLE BOND]C(CN)2, on energy level alignment between the electrode Fermi level and a molecular energy level. The strong electron-withdrawing nature of the dicyano anchor group lowers the LUMO level of TCNQ, resulting in an extremely small energy barrier for electron injection. At zero bias, electron transfer from electrodes easily occurs and, as a consequence, the anion radical state of TCNQ with a magnetic moment is formed. The unpaired electron in the TCNQ anion radical causes an exchange splitting between the spin-α and spin-β transmission spectra, allowing the single TCNQ junction to act as a spin-filtering device.

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