High critical current density YBa2Cu3O7 coating on conductive Nb-doped SrTiO3 and Ni double-buffered {100}〈001〉 textured pure Cu tape for low-cost coated conductors without generation of any insulative oxides at interfaces

For development of a low-cost superconducting wire operating at high-temperature, we propose a new approach using conductive rather than insulating buffer layers, combined with {100}〈001〉 textured pure Cu tape to form YBa2Cu3O7 (YBCO)/Nb-doped SrTiO3/Ni/Cu/stainless steel. The critical current density of the YBCO layer was 2.5 MA cm−2 at 77 K in a magnetic self-field. We also confirmed that some current flowed into the Cu tape through the conductive buffer layers when the current exceeded the critical current of the YBCO layer, suggesting that the textured Cu tape worked not only as a biaxial template but also as a stabilizer layer.