Study of the Flux Pinning Landscape of YBCO Thin Films With Single and Mixed Phase Additions BaMO3 + Z: M = Hf, Sn, Zr and Z = Y2O3, Y211

Addition of nanophase defects to YBa2Cu3O7 (YBCO) superconductor thin films enhances flux pinning, resulting in an increase in transport current densities (Jct). While previous studies focused on single-phase additions such as BaSnO
₃
, BaZrO
₃
, and Y
₂
BaCuO
₅
(Y211); the addition of several phases simultaneously has shown strong improvements by combining different flux pinning mechanisms. This paper further explores and compares the effect of mixed-phase nanoparticle pinning, with the addition of insulating, nonreactive phases of: 1) BaSnO
₃
+ Y
₂
O
₃
, 2) BaSnO
₃
+ Y211, 3) BaZrO
₃
+ Y
₂
O
₃
, and 4) BaHfO
₃
+ Y
₂
O
₃
. Processing parameters vary the doped YBCO single target volume percent of either BaHfO
₃
, BaSnO
₃
, or BaZrO
₃
, while maintaining either Y
₂
O
₃
or Y211 constant at 3 vol.%. Pulsed laser deposition produces films on LaAlO
₃
and SrTiO
₃
substrates at deposition temperatures of 750-840 °C. Current density is measured for fields ranging from H = 0-9 T with H // c, and temperatures from 5 to 77 K, providing a detailed picture of pinning effects. Optimized results of flux pinning, magnetic current densities J
_cm
(H, T), critical transition temperatures (T
_c
), lattice parameters, and microstructures are presented. The temperature dependence of the current density, J
_c
(T), is mathematically modeled to compare the isotropic weak and anisotropic strong pinning contributions, for each of the mixed phase systems studied.