Enhancement of Isotropic Pinning Force in YBCO Films With BaZrO3 Nanorods and Y2O 3 Nanoparticles

Self-assembled artificial pinning centers (APCs) with controlled morphology are key to optimal pinning in superconducting YBa
₂
Cu
₃
O
_7-x
(YBCO) thin films and coated conductors. Here, we investigate the transport critical current density
$J_{c}$
(
H
,
T
,
θ
) of YBCO films with BaZrO
₃
nanorods (BZO-NRs) and 3 vol.% Y
₂
O
₃
nanoparticles (Y
₂
O
₃
-NPs) as the BZO-NRs concentration is systematically varied in the range of 2–6 vol.%. We show that the growth kinetics of APCs in these BZO-Y
₂
O
₃
double-doped YBCO films differs significantly from YBCO films doped with BZO only. In particular, the presence of Y
₂
O
₃
-NPs reduced the formation of the aligned BZO-NRs in the c-axis or normal of the film, enabling a high-concentration isotropic BZO-based APCs to form at high BZO doping. This resulted in a significantly enhanced pinning force density
$F_{p}\,(H)$
as well as isotropic pinning landscape. By fitting the Dew–Hughes equation of the pinning force density
$F_{{{p}}}\,(H)$
at different temperatures
$T\,= \,{\text{50}}\hbox{--} {\text{80}}\,{\text{K}}$
and angles of
H
at
$\theta \,= \,0\,(H{\rm{/ / }}$
c-axis), 45°, and 90° (
H
//ab), we extract the scaling behaviors of the
$F_{{{p}}}\,(H)$
associated with the BZO-NRs and isotropic BZO and Y
₂
O
₃
NPs. This result sheds light on approaches towards interactive control of strong and isotropic APCs in YBCO films and coated conductors.