Conductance of Pd nanocontacts measured in air

Conductance histograms of palladium nanocontacts in air are experimentally studied at room temperature. The peak at 0.9G0 is consistent with the presence of hydrogen in the contacts. The increase of the bias voltage or the increase of the number of consecutive conductance traces considered in order to build the histograms produces a raise in the temperature of the nanocontacts. Then more adsorption and diffusion of the hydrogen in the nanocontacts take place allowing production of different structures of the nanowires with fractional values of the conductance, which are the responsible for the growing background in the histograms. At low bias voltage and avoiding the heating of the nanocontacts, peaks associated to nanocontacts of pure Pd and with hydrogen adsorbed are simultaneously observed in the histograms for first time in air.