Nonequilibrium electron-vibration coupling and conductance fluctuations in a C-60 junction

Soren Ulstrup, Thomas Frederiksen, Mads Brandbyge

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    We investigate chemical bond formation and conductance in a molecular C-60 junction under finite bias voltage using first-principles calculations based on density functional theory and nonequilibrium Green's functions (DFT-NEGF). At the point of contact formation we identify a remarkably strong coupling between the C-60 motion and the molecular electronic structure. This is only seen for positive sample bias, although the conductance itself is not strongly polarity dependent. The nonequilibrium effect is traced back to a sudden shift in the position of the voltage drop with a small C-60 displacement. Combined with a vibrational heating mechanism we construct a model from our results that explain the polarity-dependent two-level conductance fluctuations observed in recent scanning tunneling microscopy (STM) experiments [N. Neel et al., Nano Lett. 11, 3593 (2011)]. These findings highlight the significance of nonequilibrium effects in chemical bond formation/breaking and in electron-vibration coupling in molecular electronics.
    Original languageEnglish
    JournalPhysical Review B Condensed Matter
    Volume86
    Issue number24
    Number of pages8
    ISSN0163-1829
    DOIs
    Publication statusPublished - 2012

    Keywords

    • PHYSICS
    • SCANNING TUNNELING MICROSCOPE
    • SINGLE-ATOM
    • MOLECULE
    • CONTACTS
    • SCALE

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