Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Metal Substrates: Adsorption of Organic/Bio Molecules I
O 8.7: Vortrag
Montag, 25. Februar 2008, 13:30–13:45, MA 041
Local control of the conductivity of single atoms and molecule probed by scanning tunneling microscopy and spectroscopy — •Lucia Vitali1, Robin Ohmann1, Sebastian Stepanow2, and Klaus Kern1 — 1MPI for Solid State Research, Stuttgart — 2ICREA, Barcelona
The implementation of molecule-based electronics is a pressing challenge of nanotechnology. The realization of such a circuit is still facing challenges such as the contact of the molecule to the electrodes. In order to clarify this, we studied the conductivity through single atoms and more complex molecular systems. Here, we present an experimental study of the electronic transport through single Co atoms and 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid (PVBA) molecules adsorbed on Cu(111) studied by local probe spectroscopy at low temperatures. Morphology and electronic structure of atoms and molecules, obtained by conventional scanning tunneling microscopy/spectroscopy, are combined with transport properties measurements extracted from point contact spectroscopy. For Co single atoms the transport properties are modulated by the Kondo screening. The Kondo temperatures observed in tunneling and in point contact regime are comparable. A general model to explain our experimental evidence is proposed. For the PVBA molecules, the transport properties are strongly affected by the molecule-metal adsorption orientation. This deepens our understanding of the role of the molecular arrangement in the nano-junction and in molecular electronic transport, and addresses the determining role of the molecule-metal contacts.