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 language | English (US) |
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Pages (from-to) | 40-51 |
Number of pages | 12 |
Journal | Beilstein Journal of Nanotechnology |
Volume | 3 |
Issue number | 1 |
DOIs | |
State | Published - 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
- General Materials Science
- General Physics and Astronomy
- Electrical and Electronic Engineering