Transmission eigenvalue distributions in highly conductive molecular junctions

Justin P. Bergfield, Joshua D. Barr, Charles A. Stafford

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Background: The transport through a quantum-scale device may be uniquely characterized by its transmission eigenvalues τ n. Recently, highly conductive single-molecule junctions (SMJ) with multiple transport channels (i.e., several τ n > 0) have been formed from benzene molecules between Pt electrodes. Transport through these multichannel SMJs is a probe of both the bonding properties at the lead-molecule interface and of the molecular symmetry. Results: We use a many-body theory that properly describes the complementary wave-particle nature of the electron to investigate transport in an ensemble of Pt-benzene-Pt junctions. We utilize an effective-field theory of interacting π-electrons to accurately model the electrostatic influence of the leads, and we develop an ab initio tunneling model to describe the details of the lead-molecule bonding over an ensemble of junction geometries. We also develop a simple decomposition of transmission eigenchannels into molecular resonances based on the isolated resonance approximation, which helps to illustrate the workings of our many-body theory, and facilitates unambiguous interpretation of transmission spectra. Conclusion: We confirm that Pt-benzene-Pt junctions have two dominant transmission channels, with only a small contribution from a third channel with τ n << 1. In addition, we demonstrate that the isolated resonance approximation is extremely accurate and determine that transport occurs predominantly via the HOMO orbital in Pt-benzene-Pt junctions. Finally, we show that the transport occurs in a lead-molecule coupling regime where the charge carriers are both particle-like and wave-like simultaneously, requiring a many-body description.

Original languageEnglish (US)
Pages (from-to)40-51
Number of pages12
JournalBeilstein Journal of Nanotechnology
Volume3
Issue number1
DOIs
StatePublished - Feb 14 2012

Keywords

  • Benzene-platinum junction
  • Effective-field theory
  • Isolated-resonance approximation
  • Lead-molecule interface
  • Many-body theory
  • Multichannel
  • Quantum transport
  • Single-molecule junction
  • Transmission eigenchannels

ASJC Scopus subject areas

  • Materials Science(all)
  • Physics and Astronomy(all)
  • Electrical and Electronic Engineering

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