Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 58: Metal Substrates: Adsorption IV

O 58.3: Talk

Thursday, March 29, 2007, 16:15–16:30, H39

Controlled Contact to a C60 Molecule — •Neel Nicolas, Kröger Jörg, Limot Laurent, and Berndt Richard — Institut für Experimentelle und Angewandte Physik CAU Kiel

The tip of a low-temperature scanning tunneling microscope is approached towards a C60 molecule adsorbed on Cu(100) to form a tip-molecule contact. Beyond the tunnelling regime the conductance rapidly increases in a transition region to contact regime. At contact formation, a conductance well below a quantum of conductance is observed. The conductance increases slowly upon further approach of the tip until a jump to one quantum of conductance occurs. The contact properties depend on the adsorption geometry of the molecule on the surface. Ab-initio calculations within density functional theory and non-equilibrium Green's function techniques explain the experimental data in terms of the conductance of an essentially undeformed C60. The conductance at the transition from tunneling to contact is strongly affected by structural fluctuations which modulate the tip-molecule distance.