Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Oberflächenphysik

O 34: Rastersondentechniken II

O 34.5: Vortrag

Montag, 7. März 2005, 11:45–12:00, TU EB407

Atomic transfer and single-adatom contacts — •Laurent Limot¹, Jörg Kröger¹, Richard Berndt¹, Aran Garcia-Lekue², and Werner A. Hofer² — ¹Institut für Experimentelle und Angewandte Physik,Christian-Albrechts-UniversitÄat zu Kiel, D-24098 Kiel, Germany — ²Surface Science Research Centre, University of Liverpool, Liverpool L69 3BX, United Kingdom

How do mechanical and transport properties change as matter is sized down to the atomic scale? Proximity probes like the Scanning Tunneling Microscope (STM), metal break junctions and related techniques, together with computational methods for simulating tip-sample interactions with atomic detail, have enabled to address this question by investigating atomic-size contacts to the surface. We employed a low temperature STM to investigate the point contact of the tunnel tip when approached towards Ag(111) and Cu(111) surfaces. On these metallic surfaces, a sharp jump-to-contact, random in nature, is observed in the conductance. Images acquired after point contact show that the tip-apex atom is transferred to the surface, suggesting that a one-atom contact is formed during the approach. In sharp contrast, the conductance over single silver and copper adatoms exhibits a smooth and reproducible transition from tunneling to contact regime. Numerical simulations indicate that this is a consequence of the increased stiffness of the adatom-contact.