Tunable flux pinning landscapes achieved by functional ferromagnetic Fe2O3:CeO2 vertically aligned nanocomposites in YBa2Cu3O7-delta thin films

摘要

Functional ferromagnetic (Fe2O3)x:(CeO2)(1-x) vertically aligned nanocomposite (VAN) layers were deposited as either buffer or cap layers for YBa2Cu3O7-delta (YBCO) thin films. The composition of Fe2O3 dopants in the VAN nanolayers is controlled at 10%, 30% and 50% in order to create different arrangements of Fe2O3 and CeO2 nanopillars and therefore to tune the flux pining landscapes. The composition variation provides tunable and ordered arrangements of magnetic nanodopants and interfacial defects as pinning centers in the YBCO thin films. The superconducting property measurements show that most doped samples obtain a T-c above 90 K and the J(c)(sf) measured at 75 K and 65 K maximized at 3.07 MA/cm(2) and 9.2 MA/cm(2) for 30% Fe2O3 VAN doped sample. As the temperature decreased to 5 K, the sample with 50% Fe2O3 VAN doped sample show the best pinning effect due to pronounced magnetic pinning effects. This work demonstrates the tunable density of magnetic pinning centers can be achieved by VAN to meet the specific pinning requirement. (C) 2014 Elsevier B.V. All rights reserved.