Columnar defect formation in nanorod/Tl2Ba2Ca2Cu3Oz superconducting composites

Nanorod/superconductor composites were formed by depositing Tl2Ba2Ca2Cu3Oz ~Tl-2223! thick films on high density MgO nanorod arrays that were grown on MgO single crystal substrates. Electron microscopy studies show that this approach creates a high density of columnar defects normal to the CuO2 planes within crystal grains of the composites. The nanorod/superconductor composites exhibited enhanced critical current densities and an upward shift in the irreversibility line compared with reference samples. These results demonstrate that a nanorod-composite approach represents an effective strategy for introducing correlated defects into high-Tc superconductors, and thus may be useful for applications. © 1997 American Institute of Physics. @S0003-6951~97!02723-X#