On epitaxial structure and flux pinning of NdBa2Cu3O7-δ/YBa2Cu3O7-δ superconducting multilayers

By using pulsed-laser deposition technique, a series of multilayers of NdBa2Cu3O7-delta/YBa2Cu3O7-delta, namely with the structures of p x [NdBa2Cu3O7-delta(m)/YBa2Cu3O7-delta(n)], are prepared on single-crystal SrTiO3, where m and n denotes the number of laser pulses and p is the number of repetetions. XRD patterns indicate that all samples are highly c-axis oriented, and the superconducting transition temperatures of these samples are in the range of 87-91 K, depending on different modulating structures. The larger the modulation period p and consequently the more the interfacial surfaces, the lower the superconducting transition temperature. Magneto-transport measurements reveal that the quasi-multilayers such as NY3[40 x (75/5)] (island-like YBa2 Cu-3 O7-delta distributed in NdBa2 Cu-3 O7-delta films) exhibit not only the highest T-c but also the best magnetic properties. The critical current density of such a quasi-multilayers can be as high as 4 x 10(6) A/cm(2) under self fields, showing the promising potential application for coated conductors.