Tuesday, May 01, 2012

Observation of quantum interference in molecular charge transport

Observation of quantum interference in molecular charge transport
By: Omar Gómez Rojas ID:139236

As the dimensions of a conductor approach the nanoscale, quantum effects begin to dominate, and it becomes possible to control the conductance through direct manipulation of the electron wavefunction. Such control has been demonstrated in various mesoscopic devices at cryogenic temperatures but it has proved to be difficult to exert control over the wavefunction at higher temperatures. Molecules have typical energy level spacings (~eV) that are much larger than the thermal energy at 300 K (~25 meV), and are therefore natural candidates for such experiments. Previously, phenomena such as giant magnetoresistance5, Kondo effects and conductance switching have been observed in single molecules, and theorists have predicted that it should also be possible to observe quantum interference in molecular conductors, but until now all the evidence for such behaviour has been indirect. Here, we report the observation of destructive quantum interference in charge transport through two-terminal molecular junctions at room temperature. We studied five different rigid π-conjugated molecular wires, all of which form self-assembled monolayers on a gold surface, and find that the degree of interference can be controlled by simple chemical modifications of the molecular wire.

Find more information on this work in: http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2012.37.html
Nature Nanotechnology (2012)

Observation of quantum interference in molecular charge transport
Constant M. Guédon, Hennie Valkenier, Troels Markussen, Kristian S. Thygesen,          Jan C. Hummelen & Sense Jan van der Molen
Published online 25 March 2012
DOI: 10.1038/nnano.2012.37

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