Improvement of Jc Properties for Hf and La Co-Doped Gd123 Films Fabricated by Fluorine-Free MOD Method

In this study we have successfully fabricated La and Hf co-doped Gd123 thin films on LaAlO
₃
single crystal substrates by the fluorine-free metal organic deposition method with tetrakishafnium as a new organic metal salt. Hf doping is the effective means to introduce the perovskite nano-structure BaHfO
₃
as artificial pinning centers (APCs) into REBa
₂
Cu
₃
O
_y
coated conductors. On the other hand, La doping is valid method in promoting high quality epitaxial crystallization of the superconducting phase. By possessing both advantages La 1 mol% and Hf 2 mol% co-doped film achieved high critical current densities of 3.1 MA cm
^-2
at 0 T, and 0.25 MA cm
^-2
at 1 T, 77.3 K. The detailed study of the flux pinning revealed that APCs introduced by Hf doping brought about the increase of J
_c
in high fields, and La doping brought about the quality crystallization resulting in the increase of J
_c
in low fields.