One-by-One Introduction of Single Lattice Planes in a Bottlenecked Gold Contact during Stretching

We observed the structural and conductance evolution of bottleneck-shaped gold contacts with [111] and [100] axes ([111] and [100] contacts) simultaneously during stretching. The [111] and [100] contacts were elastically stretched until a single (111) or (100) lattice plane was introduced by plastic deformation. The conductance decreased gradually by about 0.5-0.8G(0) in the elastic regime, and subsequently stepped down at the plastic deformation. Since the conductance values changed depending on the strain, they were not quantized. The conductance histograms displayed rather broad peaks due to the elastic regime. These peaks reflected the particular sequence of the mechanical deformation of the contacts, in strong contrast to the peaks of the [110] contacts, which reflected the quantization as reported previously. Below 10G(0), we found that the gold [111] and [100] contacts had five and three specific structures, respectively, in addition to a single-atom contact at 1G(0). We conclude that, for a bottlenecked gold contact, the strain extends over many lattice fringes along the stretching axis and the yield do not occur until sufficient space is available to introduce an additional atomic layer.