Nanodot arrays of Y2O3 were dispersed in thin films of YBa2Cu3O7−δ (YBCO) by growing alternating layers of these two species using a pulsed laser deposition method. As a result, critical current density Jc both in applied magnetic field and self-field is enhanced by as much as an order of magnitude, along with a significant increase in the irreversibility field Hirr. High-resolution scanning transmission electron microscopy (STEM) and Z-contrast STEM show that the nanoparticles are crystalline and coherent with the YBCO matrix. Whereas in most other studies pinning has been attributed to the strain fields around the nanoparticles, in this case pinning may actually be due to the nanoparticles themselves, since the delineation between the two species is very sharp and STEM reveals no discernible strain fields in the superconducting material around the nanoparticles.

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The controlled synthesis of nanostructured particles with uniform size, shape, composition, and preferred orientation is a formidable task. Some conventional techniques have been demonstrated with limited success; however, reproducible processing schemes for heterogeneous multifunctional materials are still not satisfactory. To realize the advantageous technical applications of nanostructured materials, self-assembly or self-organizing methods are currently under investigation. Our results show that the matrix or template used for directed growth of nanoparticles (Fe, Ni) significantly affects the resultant mechanical properties of the multilayered structure. For example, a crystalline material like TiN, which grows epitaxially on silicon, results in embedded epitaxial nanoparticles. Conversely, an amorphous template like Al2O3 results in polycrystalline magnetic particles. In this work, we will discuss the effect of matrix type, specifically yttria stabilized zirconia (YSZ), on the orientation of nanoparticle assemblies. The resultant mechanical and magnetic properties of the multilayer structures will be discussed in the oral presentation.