Reversible recovery of excess current in $Y(Ho)-Ba-Cu-O$-normal metal point contacts under high voltages

Abstract

A polarity-dependent reversible change in the current-voltage characteristics between states corresponding to different values of the excess current $I_{exc}$ is observed for bias voltages of several hundred millivolts in $Ag-ReB{a}_{2}C{u}_3{O}_{7-x}$ $\left(Re=Y,Ho\right)$ point contacts in the current-carrying state. The observed effect has a high intensity (right up to a complete suppression or recovery of $I_{exc}$) and is not accompanied by a noticeable variation of the energy gap or the critical temperature in the point contact region. It is also established that the states with intermediate values of $I_{exc}$ are stable for zero bias voltages across the point contacts, at least up to $110K$. It is assumed that the variation of $I_{exc}$ and the corresponding modification of IVC are due to the oxygen migration processes induced by the electric field and current, resulting in a local variation of the superconducting parameters in the point-contact region.

6 pages, 4 figures