Improving HTc Josephson Junctions (HTc JJ) by annealing: the role of vacancy-interstitial annihilation

TL;DR

This study demonstrates that low-temperature annealing improves the transport properties of high-temperature Josephson junctions by reducing variability and increasing performance, explained by vacancy-interstitial annihilation rather than oxygen diffusion.

Contribution

It reveals that vacancy-interstitial annihilation governs annealing effects in HTc Josephson junctions, offering a new understanding of defect dynamics during annealing.

Findings

Annealing increases TJ and Ic.Rn in HTc JJs.

Longer annealing reduces characteristic spread in JJ properties.

Vacancy-interstitial annihilation explains the annealing process.

Abstract

We have studied the annealing effect in transport properties of High temperature Josephson Junctions (HTc JJ) made by ion irradiation. Low temperature annealing (80 degrees Celsius) increases the JJ transition temperature (TJ) and the Ic.Rn product, where Ic is the critical current and Rn the normal resistance. We found that the spread in JJ characteristics can be lowered by sufficient long annealing times. Using random walk numerical simulations, we showed that the characteristic annealing time and the evolution of the spread in JJ characteristics can be explained by a vacancy-interstitial annihilation process rather than by an oxygen diffusion one.