The decrease of the critical current of coated conductors when a perpendicular magnetic field is applied : a Josephson effect point of view

TL;DR

This paper investigates the significant decrease in critical current of YBCO coated conductors under perpendicular magnetic fields, attributing it to Josephson effects at twin boundaries across a wide temperature range.

Contribution

It introduces a magnetic measurement technique to assess critical current over various temperatures and links the current reduction to Josephson behavior at twin boundaries.

Findings

Critical current decreases significantly under perpendicular magnetic fields.

The reduction is observed across a wide temperature range.

Josephson behavior at twin boundaries explains the critical current decrease.

Abstract

A large decrease is observed in the critical current density of YBCO coated conductors (CC) and related compounds when a strong perpendicular magnetic field is applied. While measurements are generally carried out at 77K only, here we present a magnetic technique permitting to determine the critical current per unit width of conductor (Icr/w) in a large temperature range. We report measurements carried out on various CCs that show that, in addition to the reduction in the critical temperature that can be attributed to the low value of the irreversibility field near Tc, the field application results in a large decrease of Icr/w at all temperatures. We ascribe this reduction to the Josephson behaviour of the twin boundaries included in the YBCO layer.