Transport properties of individual C60-molecules

TL;DR

This study uses density functional theory to analyze the electrical and thermal transport properties of individual C60 molecules, revealing complex quantum interference effects that influence conductance.

Contribution

It provides new insights into the contact geometry and quantum interference effects in C60 molecular junctions, advancing understanding of their transport properties.

Findings

Optimal contact involves binding to one or two carbon atoms.

Transport occurs mainly through an unoccupied orbital hybridized with Au.

Quantum interference suppresses conductance near the Fermi energy.

Abstract

Electrical and thermal transport properties of C60 molecules are investigated with density-functional-theory based calculations. These calculations suggest that the optimum contact geometry for an electrode terminated with a single-Au atom is through binding to one or two C-atoms of C60 with a tendency to promote the sp2-hybridization into an sp3-type one. Transport in these junctions is primarily through an unoccupied molecular orbital that is partly hybridized with the Au, which results in splitting the degeneracy of the lowest unoccupied molecular orbital triplet. The transmission through these junctions, however, cannot be modeled by a single Lorentzian resonance, as our results show evidence of quantum interference between an occupied and an unoccupied orbital. The interference results in a suppression of conductance around the Fermi energy. Our numerical findings are readily analyzed analytically within a simple two-level model.