Observation of a parity oscillation in the conductance of atomic wires

Using a scanning tunnel microscope or mechanically controllable break junctions atomic contacts for Au, Pt, and Ir are pulled to form chains of atoms. We have recorded traces of conductance during the pulling process and averaged these for a large number of contacts. An oscillatory evolution of conductance is observed during the formation of the monoatomic chain suggesting a dependence on the numbers of atoms forming the chain being even or odd. This behavior is not only observed for the monovalent metal Au, as was predicted, but is also found for the other chain-forming metals, suggesting it to be a universal feature of atomic wires.

This work is part of the research program of the “Stichting FOM.” G. R. acknowledges support of the Spanish DGI by the Project No. MAT 2001-1281. C.U. has been supported by the European Union under Contract No. HPMF-CT-2000-00724.