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

摘要

A rapid decrease in the critical current density (Jc) of YBa2Cu3O7-x (YBCO)films with increasing film thickness has been observed for multiple YBCO growthprocesses. While such behavior is predicted from 2D collective pinning modelsunder certain assumptions, empirical observations of the thickness dependenceof Jc are believed to be largely processing dependent at present. Toinvestigate this behavior in ex situ YBCO films, 2.0 and 2.9 um thick YBCOfilms on ion beam assisted deposition (IBAD) - yttria stabilized zirconia (YSZ)substrates were thinned and repeatedly measured for rho(T) and Jc(H). The 2.9um film exhibited a constant Jc(77K,SF) through thickness of ~1 MA/cm2 whilethe 2.0 um film exhibited an increase in Jc(77K,SF) as it was thinned. Neitherfilm offered evidence of significant dead layers, suggesting that furtherincreases in critical current can be obtained by growing thicker YBCO layers.