Temperature and Magnetic Field Dependence of Critical Current Density of YBCO With Varying Flux Pinning Additions

The critical current density (J
_c
) of YBa
₂
Cu
₃
O
_7-z
films doped with varying flux pinning nanoparticle additions was systematically studied, for applied magnetic fields of H = 0-9 T and operation temperatures T = 20-77 K. Films were prepared with pulsed laser deposition by (M/YBCO)
_N
multilayer or (YBCO)
_1-x
M
_x
single-target methods, for different M phases including Y
₂
O
₃
, Y
₂
BaCuO
₅
(Y211) green-phase, and BaZrO
₃
. Very significant differences of J
_c
(H//c,20-77 K) were measured for optimized M phase additions, that are difficult to model or predict at present. Multilayer films with Y211 and Y
₂
O
₃
nanoparticle additions had the highest J
_c
(20-77 K) for H < 4 T, and YBCO+BZO-nanorod samples had the strongest J
_c
(H) for H > 4 T and 65-77 K, however not for T < 50 K. Seemingly unusual J
_c
(H,T) properties were measured for (BZO/YBCO)
_N
multilayer films when compared to YBCO and other doped films; J
_c
(H) was almost the same as YBCO at 77 K, however at 30 K J
_c
(H > 2 T) had the strongest properties increasing 70% compared to YBCO+nanoaddition films and increasing 400% compared to YBCO.