Nonlinear cyclical transport phenomena in copper point contacts

The method of recording the current-voltage characteristic was used to study the processes occurring at the surface of a point contact conductance channel. The transport characteristics of the point contact in a liquid medium are studied for the first time. The current states of the conductance channel corresponding to the reversible, transient, and irreversible regimes of charge transport in a point contact are studied and identified. In the irreversible range of bias voltage, the famous cyclical effect of electromechanical switching is observed on the contact, which governs the growth and dissolution of dendritic point contacts of the test sample. The electric resistance of the point-contact structure changes over time, going through stages of increase, decrease, and stabilization. Subsequently, the stages of this process are repeated multiple times, reflecting the cyclical nature of the changes in the physiochemical properties of the test object. The current-voltage characteristic of the point contact has a step structure, due to shell effects. Copper point contact conductance histograms, formed spontaneously in the electric field under the influence of the shell effect, are built using the obtained curves. There is a demonstrated presence of preferred current states for the conductance channel, serving as evidence of the quantum nature of conductance changes in the process of dendritic point contact formation. (C) 2014 AIP Publishing LLC.