Effect of mesoscopic inhomogeneities on the critical current of bulk melt-textured YBCO

TL;DR

This study investigates how mesoscopic inhomogeneities, specifically the distribution of 211-inclusions, affect the local critical current in melt-textured YBCO, revealing a correlation but with notable quantitative discrepancies.

Contribution

It provides a detailed analysis of local critical current variations in YBCO ceramics considering inhomogeneous inclusions, combining magneto-optic, electron microscopy, and microanalysis techniques.

Findings

Correlation between inclusion density and local critical current

Quantitative disagreement between estimated pinning and measured current

Inhomogeneity impacts critical current distribution

Abstract

The downsizing 211-inclusions and an increase of their density leads to rise in mean critical current value in Y-based melt textured material. Very often 211-inclusion are spread in the material volume non-homogeneous, with typical scale 50 - 100 micrometer. Therefore it is difficult to find the real correlation between local critical current and the inclusions distribution. We performed a study of a local critical current using modified magneto-optic technique on a melt-textured YBaCuO ceramic, found the areas with constant current and studied the real structure of the material in the areas, inclusions distribution and their sizes, by scanning electron microscopy and X-ray microanalysis. The estimation of a pinning in these places, by taking into account the amount of inclusions and the length of their boundaries, and comparison with the value of local critical current reveals a strait correlation between the density of inclusions and the current but shows remarkable quantitative disagreement.