Through-thickness superconducting and normal-state transport properties revealed by thinning of thick film ex situ YBa2Cu3O7-x coated conductors

TL;DR

This study investigates the through-thickness electrical transport properties of thick ex situ YBCO coated conductors by systematically thinning films and measuring their critical current density and resistivity, revealing potential for higher current capacities.

Contribution

It provides empirical evidence that thick YBCO films can maintain or increase critical current density through thickness, challenging previous assumptions about dead layers and processing limitations.

Findings

2.9 μm film had constant Jc through thickness (~1 MA/cm²).

2.0 μm film's Jc increased as it was thinned.

No significant dead layers observed in either film.

Abstract

A rapid decrease in the critical current density (Jc) of YBa2Cu3O7-x (YBCO) films with increasing film thickness has been observed for multiple YBCO growth processes. While such behavior is predicted from 2D collective pinning models under certain assumptions, empirical observations of the thickness dependence of Jc are believed to be largely processing dependent at present. To investigate this behavior in ex situ YBCO films, 2.0 and 2.9 um thick YBCO films on ion beam assisted deposition (IBAD) - yttria stabilized zirconia (YSZ) substrates were thinned and repeatedly measured for rho(T) and Jc(H). The 2.9 um film exhibited a constant Jc(77K,SF) through thickness of ~1 MA/cm2 while the 2.0 um film exhibited an increase in Jc(77K,SF) as it was thinned. Neither film offered evidence of significant dead layers, suggesting that further increases in critical current can be obtained by growing thicker YBCO layers.