Conductance of individual C 60 molecules measured with controllable gold electrodes

We investigated the conductance of ${\mathrm{C}}_{60}$ molecules using mechanically controllable break-junction electrodes at $10\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in UHV. The molecules are evaporated in situ. With this method, we obtain clean and low-resistance contacts. From the analysis of conductance histograms and differential-conductance $(dI∕dV)$ traces, we deduce the preferred conductance value of a single ${\mathrm{C}}_{60}$ molecule between gold electrodes to be close to 0.1 ${G}_{0}$. The presence of ${\mathrm{C}}_{60}$ is evidenced by features in the derivative of the $dI∕dV$ at energies close to the molecular vibration energies. The characteristics of the molecules disappear upon cold working of the junctions.