Enhanced flux pinning in YBa2Cu3O7-d films by nano-scaled substrate surface roughness

TL;DR

This study demonstrates that nano-scaled surface roughness on substrates significantly enhances flux pinning and critical current density in YBa2Cu3O7-d films, with a 30% increase confirmed by multiple measurement techniques.

Contribution

The paper introduces a method of increasing flux pinning in YBCO films through nano-scaled substrate surface roughness created during deposition.

Findings

30% increase in critical current density Jc

Enhanced flux pinning observed via magneto-optical imaging

Confirmation by direct transport measurement

Abstract

Nano-scaled substrate surface roughness is shown to strongly influence the critical current density Jc in YBCO films made by pulse-laser-deposition on the crystalline LaAlO3 substrates consisting of two separate twin-free and twin-rich regions. The nano-scaled corrugated surface was created in the twin-rich region during the deposition process. Using magneto-optical imaging techniques coupled with optical and atomic force microscopy, we observed an enhanced flux pinning in the YBCO films in the twin-rich region, resulted in \~30% increase in Jc, which was unambiguously confirmed by the direct transport measurement.