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TT: Tiefe Temperaturen

TT 8: Posters Transport

TT 8.9: Poster

Freitag, 4. März 2005, 14:00–18:00, Poster TU C

Theoretical analysis of the conductance histograms of Au atomic contacts — •Markus Dreher¹, Jan Heurich², Carlos Cuevas², Elke Scheer¹, and Peter Nielaba¹ — ¹Physics Department, University of Konstanz, 78457 Konstanz, Germany — ²Institut für Theoretische Festkörperphysik, University of Karlsruhe, 76128 Karlsruhe, Germany

Many experiments have shown that the conductance histograms of metallic atomic-sized contacts exhibit a peak structure, which is characteristic for the corresponding material. The origin of these peaks still remains as an open problem. In order to shed some light on this issue, we present a theoretical analysis of the conductance histograms of Au atomic contacts. We have combined classical molecular dynamics simulations of the breaking of nanocontacts with conductance calculations based on a tight-binding model. This combination gives us access to crucial information such as contact geometries, forces, minimum cross section, total conductance and transmission coefficients of the individual conduction channels.

The ensemble of our results suggests that the low temperature Au conductance histograms are a consequence of a subtle interplay between mechanical and electrical properties of these nanocontacts. At variance with other suggestions in the literature, our results indicate that the Au conductance histograms are not a simple consequence of conductance quantization or of existence of exceptionally stable radii.