We describe a surface probe instrument capable of sustaining single-atomic-bond junctions in the electronic quantum-conduction regime for tens of minutes, and present results for Au junctions that can be locked stably in n = 1 and n = 2 quantum conduction states with electrical conductivity nG0 (G0 = 2e2/h) and switched in a controlled way. The instrument measures and controls the gap formed between a probe and a flat surface with better than 5 pm long-term stability in a high-vacuum chamber at 4 K using a high-sensitivity fiber-optic interferometer that forms a Fabry-Perot cavity immediately adjacent and parallel to the probe. We also report the experimental observation of stable non-integer conduction states, along with preliminary density-functional-theory-based calculations of one-dimensional and two-dimensional Au bridges that also produce non-integer conduction states. Finally, we report the observation of novel stochastic processes related to non-ballistic electron transport through strained single-atomic-bond junctions. The instrument permits detailed study of electron transport in one-dimensional systems, and the long-term picometer stability of the junction holds great promise for application to single-molecule spectroscopy.
Citation: Journal of Applied Physics
Pub Type: Journals
nanomechanics, quantized conductance, nanowire, single atom chain, interferometry