Evidence for Irradiation Triggered Nonuniform Defect Distribution In Multiharmonic Magnetic Susceptibility of Neutron Irradiated YBa2Cu3O7-x

TL;DR

This study investigates how neutron irradiation causes nonuniform defect distributions in YBa2Cu3O7-x, affecting its magnetic susceptibility and superconducting properties, with evidence of defect-rich and defectless regions forming at high fluences.

Contribution

It provides experimental evidence of irradiation-induced nonuniform defect distributions in YBa2Cu3O7-x, linking defect patterns to changes in magnetic susceptibility and superconductivity.

Findings

Nonmonotonic harmonic dependence on neutron fluence.

Increased intergranular Josephson junction thickness at moderate fluence.

Enhanced intragranular superconducting properties at high fluence.

Abstract

Multiharmonic ac-magnetic susceptibility \ch11,\chi2,chi3, of neutron irradiated Li-doped YBa2Cu3O7-x has revealed a nonmonotonic dependence of all harmonics on the neutron fluence. The irradiation has a strongly depressive influence on the intergrain connection suggesting an increase of the effective thickness of the intergranular Josephson junction at aneutron fluence of 0.98x10$^{17}$ cm$_{-2}$. Less damaged are the intragrain properties. A spectacular enhancement of the superconducting intragranular properties reflected in the characteristics of all harmonics was observed at highest fluence \Phi = 9.98x10$^{17}$ cm$_{-2}$. We assume that this effect results from the development of a space inhomogeneous distribution with alternating defectless and defect rich regions.