Highly textured oxypnictide superconducting thin films on metal substrates

TL;DR

This paper reports the growth of highly textured NdFeAs(O,F) superconducting thin films on metal substrates, achieving notable critical current densities and revealing the importance of grain boundary control for high performance.

Contribution

It demonstrates the successful fabrication of textured oxypnictide superconducting films on metal substrates using molecular beam epitaxy, highlighting the role of biaxial texture in optimizing critical current density.

Findings

Tc of 43 K achieved in films

Critical current density of 7.0 x 10^4 A/cm^2 at 5 K

Grain boundaries significantly affect Jc performance

Abstract

Highly textured NdFeAs(O,F) thin films have been grown on ion beam assisted deposition (IBAD)-MgO/Y2O3/Hastelloy substrates by molecular beam epitaxy. The oxypnictide coated conductors showed a superconducting transition temperature (Tc) of 43 K with a self-field critical current density (Jc) of 7.0 x 104 A/cm2 at 5 K, more than 20 times higher than powder-in-tube processed SmFeAs(O,F) wires. Albeit higher Tc as well as better crystalline quality than Co-doped BaFe2As2 coated conductors, in-field Jc of NdFeAs(O,F) was lower than that of Co-doped BaFe2As2. These results suggest that grain boundaries in oxypnictides reduce Jc significantly compared to that in Co-doped BaFe2As2 and, hence biaxial texture is necessary for high Jc.