High-resistance YBa2Cu3O7-x grain-boundary Josephson junctions fabricated by electromigration

TL;DR

This paper introduces a novel oxygen electromigration method to modify the barrier properties of high-Tc YBCO grain-boundary Josephson junctions, increasing their resistance while maintaining their quantum characteristics, enabling better quantum phenomena studies.

Contribution

It presents a new approach using oxygen electromigration to control the resistance of YBCO junctions without degrading their performance.

Findings

Resistance increased from tens to hundreds of Ohms.

Barrier height and thickness were quantitatively determined.

Characteristic voltage IcRn remained unchanged.

Abstract

[100]-tilt grain-boundary YBa2Cu3O7-x (YBCO) junctions are promising for investigation of macroscopic quantum phenomena in high-Tc Josephson junctions. However, fabrication of the [100]-tilt grain-boundary YBCO junctions with a high resistance, which are required to study quantum effects, is difficult because of a high transparency of a tunnel barrier in this type of junctions. Here, we demonstrate a modification of grain-boundary barrier properties with a new approach to an oxygen electromigration in the YBCO grain-boundary junctions when the oxygen diffuses under an applied electric field from the grain-boundary to a BaTbO3 layer deposited atop of an YBCO film. Using this approach, we changed the normal-state resistance of the junctions from tens to several hundred Ohms without a degradation of their characteristic voltage IcRn and determined a barrier height and thickness by measuring the quasiparticle tunnelling current.