Disorder effects on the intrinsic nonlinear current density in YBa$_2$Cu$_3$O$_{7-\delta}$

TL;DR

This study investigates how disorder affects the intrinsic nonlinear current density in YBa2Cu3O7−δ superconducting films near the critical temperature, combining experimental harmonic generation measurements with theoretical modeling of impurity effects.

Contribution

It provides the first combined experimental and theoretical analysis of disorder effects on the nonlinear current response in YBCO superconductors.

Findings

Nonmagnetic impurities significantly influence the nonlinear current density.

The experimental data correlates with the theoretical model considering impurity scattering.

The results enhance understanding of disorder effects in high-temperature superconductors.

Abstract

We present harmonic generation measurements of the intrinsic nonlinear current density $j_2$ of YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films at temperatures close the $T_c$. Experiments on a range of different quality samples allow us to extract the dependence of $j_2$ on the penetration depth of the superconductor. In order to model these results, we calculate the intrinsic nonlinear current response of $d_{x^2-y^2}$-wave superconductors in the Meissner regime in the presence of nonmagnetic impurities within the self-consistent T-matrix approximation.