Study of higher-order harmonics of complex ac susceptibility in $YB_2C_3O_{7-\delta}$ thin films by the mutual inductive method

TL;DR

This study investigates higher-order harmonics of complex ac susceptibility in YBCO thin films using the mutual inductive method, comparing experimental results with theoretical models to understand their behavior and extract key superconducting parameters.

Contribution

It applies the mutual inductive method to analyze higher-order harmonics in YBCO thin films and compares experimental data with analytical and numerical models, highlighting model limitations.

Findings

Models reproduce main experimental features

Numerical model shows discrepancies at higher harmonics

Extracted activation energy and critical current density

Abstract

We have applied the mutual inductive method to study higher-order harmonics of complex ac susceptibility $\chi_n=\chi'_n-i\chi"_n$ for $$YB_2C_3O_{7-\delta}$ thin films as function of the temperature and the applied field. The experimental results were compared with analytical and numerical results obtained from the Ishida-Mazaki model and the solution of the integral equation for the current density, respectively. Both models allow us to reproduced the main experimental features, however, as $n$ increases the numerical model shows notable discrepancies. This failure can be attributed to the current-voltage characteristics. Also this investigation yields the activation energy $U_c$ and the critical current density $J_c$ for two samples both at T=0.