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

Publication: Research - peer-reviewJournal article – Annual report year: 2012

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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
StatePublished - 2012
CitationsWeb of Science® Times Cited: 7

    Keywords

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