Distribution of 1G0 plateau length of Au contacts at room temperature

We have measured the 1G(0) (G(0) is the conductance quantum unit) plateau length tau of Au breaking contacts at room temperature and examined the plateau-length distribution P(tau) for biases 0.1-2.0 V. We observed that P(tau) exhibits a long tail and obeys the power-law distribution P(tau) alpha tau(-gamma) with gamma similar to 1, indicating a strong diversity in the atomic configuration of the An single-atom contacts. The exponent gamma little varies with the bias voltage and ranges between 0. 8 and 1.1. We changed the contact breaking conditions, by slowing down the breaking speed and lowering the contact current, and again observed the same power-law distribution for P(tau) with gamma similar to 1, whereas the average plateau length increases at slower breaks. We also found that the An 1G(0) contacts in air show longer than those in ultrahigh vacuum, suggesting contact stabilization by ambient air molecules.