Flux Pinning of Y-Ba-Cu-O Films Doped With BaZrO3 Nanoparticles by Multilayer and Single Target Methods

The superconducting properties of YBa
₂
Cu
₃
O
_7-x
(YBCO or 123) thin films doped with BaZrO
₃
(BZO) nanoparticles by multilayer and single-target methods were studied and compared. Thin films of 123 + BZO were processed by pulsed laser deposition on LaAlO
₃
and SrTiO
₃
and single crystal substrates. Multilayer (BZO
<sub>0.6nm-1.4

nm</sub>
/123
<sub>15

nm</sub>
) structures were grown by alternating deposition from 123 and BZO targets, and BZO additions of 0-2 vol% were deposited using (123
_1-x
BZO
_x
) single-targets. The multilayer and single-target methods of BZO addition caused significant differences of superconducting transition temperatures (T
_c
) measured by AC susceptibility, and critical current densities (J
_c
) measured by both magnetic and transport methods as a function of temperature (T), applied magnetic field (H) and angle of H field incidence (θ). Single-target films had almost linear decrease T
_c
of and self-field J
_c
with BZO vol% addition, and compared to multilayer films had lower J
_c
(77K,H < 4T) however had improved high-field properties for J
_c
(77K,H >; 4T). Multilayer films had almost no decrease of T
_c
and self-field J
_c
for high BZO additions up to 10 vol% and very strong peak of J
_c
(H//ab in–plane) and constant and high J
_c
(H,0 < θ < 80°) . Single-target BZO-2 vol% films had slightly enhanced J
_c
(H//c–axis), consistent with results by other authors.