Epitaxial growth of La 2Zr 2O 7 buffer layers for YBa 2Cu 3O 7−δ coated conductors on metallic substrates using pulsed laser deposition

Abstract

In the present work, La 2Zr 2O 7 (LZO) buffer layers were deposited using pulsed laser deposition (PLD) on various metallic substrates including epitaxial pure Ni on a LaAlO 3 (LAO) substrate as well as highly textured Ni–5 at.%W tapes. It is shown that the LZO deposited on pure Ni-buffered LAO exhibits a mixed orientation while LZO on Ni–5 at.%W grows epitaxially. This difference may be explained by the existence of a sulphur superstructure on the surface of Ni–5 at.%W tapes, promoting the epitaxial (0 0 l) nucleation of seed layers. Highly textured YBa 2Cu 3O 7− δ layers were prepared either by using a single buffer layer of LZO or bilayer buffers of CeO 2/LZO on Ni–5 at.%W. The superconducting transition temperature ( T c ) increases with the LZO thickness, reaching a value of 90 K with a very narrow transition width (1.5 K) for 240 nm thick LZO layers. Inductive J c measurements at 77 K in self-field show a value of about 0.96 MA/cm 2 for the thickest LZO layers, which is comparable to the value observed on standard buffer architectures such as CeO 2/YSZ/Y 2O 3.