Soft nanostructuring of YBCO Josephson Junctions by phase separation

TL;DR

This paper introduces a novel nanoscale fabrication method for YBCO Josephson junctions that minimizes damage and enables exploration of intrinsic grain boundary properties.

Contribution

A new fabrication technique utilizing phase separation during film growth to create nanoscale YBCO Josephson junctions without conventional damage.

Findings

Junctions as small as 100 nm achieved

High-resolution TEM confirms nanometer-sized grain boundaries

Electrical measurements indicate proximity to intrinsic boundary properties

Abstract

We have developed a new method to fabricate biepitaxial YBa2Cu3O(7-x) (YBCO) Josephson junctions at the nanoscale, allowing junctions widths down to 100 nm and simultaneously avoiding the typical damage in grain boundary interfaces due to conventional patterning procedures. By using the competition between the superconducting YBCO and the insulating Y2BaCuO5 phases during film growth, we formed nanometer sized grain boundary junctions in the insulating Y2BaCuO5 matrix as confirmed by high resolution transmission electron microscopy. Electrical transport measurements give clear indications that we are close to probing the intrinsic properties of the grain boundaries.