Mechanisms of jump to contact and conductance plateau formation in copper atomic junctions in vacuum and aqueous environments

Abstract

The interplay between groups of water molecules and single-atom contacts, as reflected in the electrical conductances and mechanical forces of copper atomic junctions, is explored by means of first-principles theory and semi-empirical calculations. We study the influence of the atomic geometries of copper electrodes with pyramidal and non-crystalline structures in the presence and absence of water on the conductance profiles as the electrodes approach each other. It is shown that the atomic arrangements of nano-contacts have crucial effects on the formation of plateaus and the conductance values. Groups of hydrogen bonded water molecules bridge the junction electrodes before a direct Cu-Cu contact between the electrodes is made. However, the bridging of the two copper electrodes by a single H${}_2$O molecule only occurs in the junctions with pyramidal electrodes. Our findings reveal that the presence of H${}_2$O molecules modifies strongly the conductance profile of these junctions. In the absence of water molecules, the pyramidal junctions exhibit continuous transitions between integer conductance plateaus, while in the presence of H${}_2$O molecules, these junctions show abrupt jump to contact behavior and no well-defined conductance plateaus. By contrast, in the absence of H${}_2$O molecules, the non-crystalline junctions display jump to contact behavior and no well-defined plateaus, while in the presence of H${}_2$O molecules they exhibit a jump to contact and abrupt transitions between fractional and integer plateaus.

arXiv comment8 pages, 4 figures

References in corpus (24)

• Quantum properties of atomic-sized conductors
• Measurement of the conductance of a hydrogen molecule
• A stellar relic from the early Milky Way
• Observation of a parity oscillation in the conductance of atomic wires
• Atom Transfer and Single-Adatom Contacts
• Electron-vibration interaction in single-molecule junctions: from contact to tunneling regime
• Stretching dependence of the vibration modes of a single-molecule Pt-H2-Pt bridge
• Oxygen enhanced atomic chain formation
• Heat transport through atomic contacts
• Conductance of Pd-H nanojunctions
• Formation of a Metallic Contact: Jump to Contact Revisited
• Evidence for a single hydrogen molecule connected by an atomic chain
• Linear Chains of Styrene and Methyl-Styrene Molecules and their Heterojunctions on Silicon: Theory and Experiment
• Conduction Mechanism in a Molecular Hydrogen Contact
• Oxygen clamps in gold nanowires
• Formation and properties of metal-oxygen atomic chains
• Different wavelength oscillations in the conductance of 5d metal atomic chains
• Transition from tunneling to direct contact in tungsten nanojunctions
• Probing the Orbital Origin of Conductance Oscillations in Atomic Chains
• Non-Local Conductance Modulation by Molecules: STM of Substituted Styrene Heterostructures on H-Terminated Si(100)
• Mechanism of the enhanced conductance of a molecular junction under tensile stress
• Influence of relativistic effects on the contact formation of transition metals
• Controlling the thermoelectric effect by mechanical manipulation of the electron's quantum phase in atomic junctions
• Thermoelectric voltage switching in gold atomic wire junctions