Pulsed laser deposition of epitaxial YBa2Cu3O7-y/oxide multilayers onto textured NiFe substrates for coated conductor applications

Pulsed laser depositions of double-buffer and triple-buffer YBa2Cu3O7-y (YBCO)/Y2O3(YSZ)/CeO2 heterostructures have been performed in situ onto commercially available biaxially textured NiFe 50%/50% tape. The deposition in the forming gas (4% H-2/Ar) from a CeO2 target and the deposition in vacuum from a CeO2:Pd composite target have been explored as two possible routes for cube-on-cube growth of the first buffer layer. The influence of the critical processing parameters on the texture is investigated and some of the issues involved in the reduction of NiO (111) and the formation of cube-on-cube NiO (200) growth are discussed. X-ray diffraction has been used for texture evaluation of the substrate and subsequent deposited layers. The substrate-buffer interface region has been studied by focused ion beam cross section electron microscopy. Both the buffers and YBCO layers show biaxial alignment with omega and phi scans having optimum YBCO full width at half maximum (FWHM) values of 4.3(z) and 8.8(z), respectively. The morphology has been characterized using atomic force microscopy and scanning electron microscopy. The value of T-c (onset) has been measured at 90 K (DeltaT(c) = 10 K). The critical current density, J(c), has been measured by transport measurements and magnetic measurements performed in a de SQUID magnetometer.