In situ comparison of the critical current density in $Y Ba_2 Cu_3 O_{7-\delta}$ thin films measured by the screening technique under two criteria

TL;DR

This study compares two inductive screening techniques for measuring the critical current density in YBa2Cu3O7−δ thin films, validating their reliability and proposing a method to estimate coil factors in situ.

Contribution

It introduces a comparative analysis of the $ ext{Im}\, ext{χ}_1$ and $V_3$ criteria for $J_c$ measurement, and proposes an in situ coil factor estimation method.

Findings

Both techniques agree near $T_c$

The $V_3$ criterion aligns better at lower temperatures

A methodology for in situ coil factor estimation is proposed.

Abstract

In this investigation we report the determination of the critical current density $J_c$ flowing in a $\mathrm{Y}\mathrm{Ba}_2\mathrm{Cu}_3\mathrm{O}_{7-\delta}$ superconducting thin film. Estimation of $J_c$ was carried out by an inductive technique, the so-called screening technique, in which both the imaginary part of the fundamental harmonic of susceptibility $\chi''_1$ and third harmonic voltage $V_3$ criteria were considered for the determination of the full penetration field. In order to verify the reliability of this technique under two criteria, we investigated the homogeneity of $J_c$ via transport measurements conducted on four microbridges patterned in the same film. Based on the transport method we found that both techniques yield similar results in the determination of $J_c$ for temperatures close to critical temperature $T_c$. However, at temperatures relatively far from $T_c$, the $V_3$ criterion showed a better agreement with the transport data. Furthermore, using both criteria, we propose a methodology to estimate in situ the coil factor associated with the $V_3$ criterion, avoiding in this way the need of implementing an additional technique.