Pinning Enhancement by Heterovalent Substitution in Y$_{1-x}$RE$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-\delta}$

TL;DR

This study investigates how heterovalent substitution of rare-earth elements in YBCO superconductors enhances vortex pinning, with optimal effects at specific impurity concentrations that match vortex dimensions.

Contribution

It demonstrates that pinning is maximized at a specific impurity concentration where the average impurity spacing aligns with vortex size, revealing a new way to optimize superconductor performance.

Findings

Pinning peaks at a specific RE concentration.

Optimal impurity spacing matches vortex diameter.

Heterovalent substitution improves vortex pinning.

Abstract

The intragrain pinning in high-$T_c$ superconductor compounds Y$_{1-x}$RE$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-\delta}$ with low concentration of RE (La, Ce, Pr) was investigated. Magnetic and transport measurements reveal that the pinning is maximal for the concentration of heterovalent RE such that the average distance between the impurity ions in the plane of rare-earth elements close to the diameter of Abrikosov vortices in YBCO.