Growth andc-axis flux pinning of nanostructured YBCO/BZO multilayers

Abstract

A systematic investigation of superconducting multilayered films composed of alternating nanostructured YBa2Cu3O6+x (YBCO) and secondary phase BaZrO3 (BZO) layers is carried out. Detailed growth mechanism studies of these structures as well as superconducting properties in a wide temperature and magnetic field range are investigated by varying the thicknesses of layers grown by pulsed laser deposition. Structural analysis shows that multilayering changes clearly the growth mechanism of YBCO. Alternating thin BZO layers smoothen the film surface, create in-plane mosaic spread structure of the YBCO crystals, produce stress in the BZO interface region and moreover improve the out-of-plane alignment of YBCO. Magnetic measurements of superconducting properties demonstrate that the critical temperature decreases slightly when the thickness of the BZO layers increases relative to the YBCO layers. This indicates a growing strain effect at the layer interfaces. At the same time, critical current densities of multilayers in the whole used temperature and magnetic field range are increased to the same level as in conventionally BZO-doped YBCO films when very thin alternating YBCO/BZO layer structures are deposited. This thickness dependent result is explained by the dense flux pinning centre network in layered superconductors, giving the opportunity to increase the overall thickness of a film and further enhance the current-carrying capability.

Self-assembled Nanocomposite Oxide Films: Design, Fabrication, and Properties

“…It should be pointed out that multilayers have been found to increase the density of misfit dislocations at the layer interfaces which compensate the mismatch between YBCO and BZO lattices in the current study (Jia et al, 2002;Pan et al, 2006). This is the main reason that the c lattice constant of YBCO phase is close to the bulk value which also contributes to the high Tc value (Huhtinen et al, 2009) the relation of J c~H -α was calculated to be 0.06, which is much lower than the typical value of pure YBCO film (~0.51) and indicates a weaker field dependence of J c . Secondly, for H//c J c (H) drops much faster than standard pure YBCO with a α value of 1.48.…”

“…Considering the multilayer structure in the YBCO:BZO films, a T c of 88 K is not completely unexpected. Huhtinen et al represented a systematic investigation of superconductivity of YBCO/BZO multilayers fabricated from two different targets by PLD (Huhtinen et al, 2009). T c s from 88 K to 89.3 K have been observed which dependent on the thickness of BZO layer relative to the YBCO layer and agree well with our results.…”

Optimization of Pr0.9Ca0.1MnO3thin films with varying in-situ oxygen annealing treatments

“…Also the B sample has higher r c value than that of A and C samples. The obtained r c values are typical for pulsed laser deposition films [17], indicating that the growth process of the films is normal.…”

Influence of nano-particle diameter on superconducting properties in BaMO3(M = Sn, Hf)/YBa2Cu3O quasi-multilayered films

“…Flux pinning by 1D-PCs, however, is less effective when the magnetic field direction deviates from the direction of 1D-PCs. This is the crucial problem because coated conductors might be exposed to variously oriented magnetic fields [4].…”