Effect of Introducing RE ₂CuO4-x (RE = Gd, Sm, Nd) Artificial Pinning Centers on J C-B Properties for FF-MOD Gd123 High-Temperature Superconductors

We fabricated GdBa 2 Cu 3 O 7-δ (Gd123) superconducting thin films on LaAlO 3 single-crystal substrates using the FF-MOD method. The superconducting properties of thin films doped with various volume fractions of Gd 2 CuO 4-x (Gd214) as new type of artificial pinning centers (APCs) were evaluated. As a result, we successfully introduced up to 5.95vol% of the c-axis oriented Gd214 into Gd123 films. The maximum J C at 4.2 K was observed in the film doped with 1.98vol% Gd214, reaching 3.05 MA/cm 2 at 3.0 T and 2.00 MA/cm 2 at 6.9 T, which are 2.21 times and 2.75 times higher than those of the non-doped film, respectively. Building on these results, we attempted to introduce various types of RE 2 CuO 4-x ( RE 214: RE = Gd, Sm, Nd) microcrystals as APCs and investigated their superconducting properties. The findings revealed that lattice matching between the c-axis lattice constants of the base material and the pinning material is critical to improve J C -B properties.