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-δ/YBa2Cu3O7-δ, namely with the structures of p×［NdBa2Cu3O7-δ(m)/YBa2Cu3O7-δ(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×(75/5)］ (island-like YBa2Cu3O7-δ distributed in NdBa2Cu3O7-δ films) exhibit not only the highest Tc, but also the best magnetic properties. The critical current density of such a quasi-multilayers can be as high as 4×106 A/cm2 under self fields, showing the promising potential application for coated conductors.