ATOMIC-STRUCTURE AND QUANTIZED CONDUCTANCE IN METAL POINT CONTACTS

New techniques are being employed to produce adjustable point contacts of atomic size. The conductance of the contacts is found to evolve in a stepwise fashion. The steps can, in principle, result from the atom ic structure of the contact and from quantization of the conductance. It is possible to separate the two effects and to show that the steps are due to the atomic structure of the contact. For free-electron meta ls, the distribution of conductance values at the plateaus demonstrate s that the conductance preferentially assumes quantized values.