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

## TL;DR

This study demonstrates a reversible, polarity-dependent change in excess current in $Y(Ho)-Ba-Cu-O$ point contacts under high voltages, attributed to electric field-induced oxygen migration affecting local superconducting properties.

## Contribution

It reveals a reversible control of excess current in high-temperature superconductor point contacts via electric field, without altering the energy gap or critical temperature.

## Key findings

- Reversible excess current change observed under high voltages.
- Effect is polarity-dependent and not accompanied by energy gap variation.
- Intermediate states of excess current are stable up to 110 K.

## 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 $Ag-ReB{{a}_{2}}C{{u}_{3}}{{O}_{7-x}}$ $\left( Re\text{ }=\text{ }Y,\text{ }Ho \right)$ 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 $110 \ K$. 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.