The circulation radius and critical current density in type-II superconductors

TL;DR

This paper introduces a new method to estimate the circulation radius and critical current density in type-II superconductors using magnetic measurements, applicable to various sample types, and verifies it with experimental data.

Contribution

A novel approach for estimating circulation radius and critical current density in type-II superconductors from magnetic measurements, applicable to samples with small demagnetizing factors and polycrystalline materials.

Findings

Method accurately estimates critical current density from magnetization data.

Validated with experimental magnetization loops for YBa2Cu3O7-d and Bi-based superconductors.

Applicable to samples with small demagnetizing factors and polycrystalline superconductors.

Abstract

A method is proposed for estimating the length scale of currents circulating in superconductors. The estimated circulation radius is used to determine the critical current density on the basis of magnetic measurements. The obtained formulas are applicable to samples with negligibly small demagnetizing factors and to polycrystalline superconductors. The proposed method has been verified using experimental magnetization loops measured for polycrystalline YBa$_2$Cu$_3$O$_{7-d}$ and Bi$_{1.8}$Pb$_{0.3}$Sr$_{1.9}$Ca$_2$Cu$_3$O$_x$ superconductors.