Electronic transmission through a metallic cluster attached to an adsorbed nanowire: creation of a nanoscale electronic on/off switch

The electron transport in a nanowire formed by an infinite atomic chain containing an extended cluster of the same atomic species is studied. From the single-electron Schrodinger equation, a decimation procedure is introduced to reduce the influence of the cluster to a point defect with renormalized self-energy and coupling parameters. The behavior of the transmittance of the electron in the nanowire through the attached cluster is discussed for various sizes and shapes of the cluster. Special emphasis is devoted to a small, single row cluster which displays specific resonances and anti-resonances. We show that such a nanostructure can be used to accomplish one of the fundamental operations of electronic devices at the nanoscale, namely to switch the electronic current.