Fabrication and Characteristic of$rm Ho$-123 Coated Conductors

We have developed
$ Ho Ba_2 Cu_3 O_7- x$
(
$ Ho$
-123) coated conductors on flexible metal tape substrates. Oxide buffer layers such as YSZ and
$ CeO_2$
have been deposited on textured Ni-alloy tapes. A basic technique of the formation of buffer layer was investigated, and hetero-epitaxial buffer layer of
$ CeO_2/ YSZ/ CeO_2$
showed excellent in-plane alignment with the delta phi value in the range of 5 to 7 degrees. Surface roughness (Ra) of 3rd buffer layer was several nm and the surface was almost flat with few particles. Ho-123 deposition was conducted on the buffer layers by PLD method. Sample less than 0.2
$mu m$
in thickness of superconducting layer showed Jc (77.3 K, self field) over 4
$ MA/ cm^2$
. Sample with 1.3
$mu m$
in thickness of superconducting layer showed Jc (77.3 K, self field) was 1.8
$ MA/ cm^2$
near 2
$ MA/ cm^2$
and Ic (77.3 K, self field) was 231 A/cm-width. SEM photograph of Ho-123 layer revealed relatively smooth film morphology with some particles. This demonstrated fine epitaxial Ho-123 growth on
$ Ce O_2/ YSZ/ Ce O_2$
textured Ni-alloy tape. Furthermore, Jc-B characteristics at 4.2 K under the high magnetic field up to 30 T were evaluated. Ic (4.2 K, 30 T) was over 2,000 A/cm-width when the external magnetic field was applied parallel to the tape surface.