BZO Films Research Articles

The incorporation of nanoscale columnar defects comprised of self-assembledBaZrO3 nanodots to improve the flux pinning and critical current density ofNdBa2Cu3O7−δ films grown on RABiTS

We report significant enhancement in the flux-pinning of epitaxialNdBa2Cu3O7−δ (NdBCO) films on rolling-assisted biaxially textured substrates (RABiTS) via theincorporation of a two-dimensional array of columnar defects comprised of self-assembledBaZrO3 (BZO)nanodots. Pure NdBCO films and NdBCO films incorporating BZO nanodots, both with the same thicknessof 0.6 µm, were epitaxially grown on RABiTS by pulsed laser deposition. A verydense and homogeneous distribution of BZO nanodot columns withtypical intercolumn spacing of around 15–20 nm oriented along thec-axis of the filmwas observed in the NdBCO+BZO film. Compared to the pure NBCO film on RABiTS, theNdBCO+BZO film on RABiTS has an in-field critical current density(Jc) of a factor of more than 2 in 0.1–1.5 T and a smaller power-law exponentα∼0.21 in the fieldregime where Jc∼H−α.

Preparation of LSAT and BZO insulating layer on superconducting ground plane for high- Tc device

As an insulating layer between a superconducting ground plane and a base electrode of Josephson junctions for high- T c devices, (LaAlO 3) 0.3–(SrAl 0.5Ta 0.5O 3) 0.7 (LSAT) thin films and BaZrO 3 (BZO) thin films were studied. LSAT films deposited on LPE–YBCO and La–YBCO films exhibited columnar grain growth. Insertion of thin SrTiO 3 (STO) buffer layer between LSAT and YBCO was found effective to suppress this columnar grain growth. Although BZO films on LSAT and STO substrates had smooth surfaces with the average roughness R a∼0.2 nm, the film deposited on La–YBCO showed a rough surface and poor adhesion. By employing a thin STO or LSAT buffer layer between BZO and La–YBCO, the film adhesion and surface quality were much improved. The relative permittivity values of STO/LSAT/STO and STO/BZO/STO were 30 and 20, respectively, indicating a high potential of STO-buffered BZO for use as insulating layers in high- T c devices.