2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

Ferromagnet/Insulator/Ferromagnet Electrodes for Molecule-Based Spin Coupling

P. Tyagi and B.J. Hinds
Univ. KY, US

molecular electronics spin-electronics molecular electrodes

Producing reliable electrical contacts with gaps having the dimensions of molecular lengths is a difficult challenge for molecular electronics. As a promising alternative to break-junctions, we use conventional film deposition and photolithography to form an exposed edge of a thin film multilayer structure (metal/insulator/metal). Molecules can self-assemble on the exposed edge offering an alternative conduction path through the molecules with angstrom-scale dimensional control. Critical to this approach is to have minimal background tunnel current between metal planes. We find the role of stresses to be the primary factor in reducing background current Electrodes were successfully fabricated with this strategy with current measured through a metal coordination compound cluster composed of a cube with cyano linked Ni or Fe at the corners. Thiolacetate ligand tethers come off of the cluster core and bind the complex to the metal leads, allowing the molecule to span the insulator gap on the surface of the etched pattern. Molecules that do not bridge the gap are not electrically active. Along the 10um pattern edge approximately 6000 molecules are involved in conduction. 10nA per molecule is seen at 10mV bias. Tunnel current through the molecules is analyzed with Simmons model and barrier height is found to be 1.1 eV and tunnel length of 1.2nm. Photo-enhancement of current is also seen. Control experiments show the controlled removal and attachment of the surface bound molecules. Antiferromagnetic coupling between metal layers is observed only with bridging molecules across the electrode. The electrode allows a simple and scalable technique to electrically contact molecules from end to end.

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Nanotech 2007 Conference Program Abstract


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