Atomic-sized metallic contacts: Mechanical properties and electronic transport.

Measuring simultaneously the force and the conductance during the formation and rupture of an atomic-sized gold contact at room temperature, we observe that deformation occurs as a sequence of structural transformations involving elastic and yielding stages and that force and conductance before rupture have definite values which are likely to correspond to a single atom contact. We measure the mechanical properties of contacts consisting of only a few atoms and show that the stepwise variation of the conductance is always due to the atomic rearrangements in the contact.