Interface control in all metalorganic deposited coated conductors: Influence on critical currents

In this work, we report recent progress in the control of the interface quality between buffer layers and YBa2Cu3O7 (YBCO) thin films grown by the trifluoroacetates route (TFA) and how it influences the critical current Jc of the coated conductors (CCs). We have mainly focused on the two most used cap layers, i.e., CeO2 and SrTiO3. We show that for CeO2 buffer layers, the key for high-quality YBCO epitaxy is to obtain atomically flat (001) terraced CeO2 surfaces. CC YBCOTFA/CeO2sputt/YSZ/CeO2/Ni with Jc (77 K) ∼ 1 MA/cm2 and chemical CC YBCOTFA/CeO2MOD/y-stabilized zirconia and ion beam assisted deposition (YSZIBAD)/stainless steel (SS) with Jc (60 K)=2.3MA/cm2 were obtained. For metalorganic deposited (MOD) SrTiO3 the main issue is to reduce the overall surface roughness that tends to increase film porosity due to an enhanced {100} YBCO nucleation. Improved roughness can be achieved by growing the buffer layers at lower temperatures. An all-chemical CC, YBCOTFA/SrTiO3MOD/BaZrO3MOD/NiO–SOE/Ni, with promising in-plane texture, ΔϕYBCO = 6.6° was grown