Enhanced critical current density of YBa2Cu3Ox films grown on Nd1/3Eu1/3Gd1/3Ba2Cu3Ox with nano-undulated surface morphology

TL;DR

This study demonstrates that nano-undulated surface morphology of NEG films significantly enhances the critical current density of YBCO superconducting films, due to increased flux pinning sites, with uniform magnetic properties across the film.

Contribution

It introduces a simple method to improve YBCO film performance by using nano-undulated NEG layers, leading to higher critical current densities and better flux pinning.

Findings

Critical current density increased across various fields and temperatures.

High density of localized atomic plane distortions observed.

Uniform magnetic flux distribution confirmed by magneto-optical imaging.

Abstract

We report a simple and easily controllable method where a nano-undulated surface morphology of Nd1/3Eu1/3Gd1/3Ba2Cu3Ox (NEG) films leads to a substantial increase in the critical current density in superconducting YBa2Cu3Ox (YBCO) films deposited by pulsed laser deposition on such NEG layers. The enhancement is observed over a wide range of fields and temperatures. Transmission electron microscopy shows that such YBCO films possess a high density of localized areas, typically 20 x 20 nm2 in size, where distortion of atomic planes give rotational (2 to 5 degrees) moire patterns. Their distribution is random and uniform, and expected to be the origin of the enhanced flux pinning. Magneto-optical imaging shows that these films have excellent macroscopic magnetic uniformity.