Lattice defect induced nanorod growth in YBCO films deposited on an advanced IBAD-MgO template

We have studied the growth of self-assembled BaHfO3 (BHO), BaZrO3 (BZO) and BaSnO3 (BSO) dopants in YBa2Cu3O6 + x (YBCO) films grown on CeO2 cap layered IBAD-MgO based metallic template by pulsed layer deposition process. The substrate induced defect formation and its impact on the growth of columnar-type of nanorods within the YBCO matrix is structurally investigated and their effect on critical current anisotropy is studied via molecular dynamics simulation model. We observed that the developed template greatly directs the growth mechanisms of different nanorods and thus modifies the critical current anisotropy of differently doped YBCO thin films.</p

14th European Conference on Applied Superconductivity (EUCAS2019) 1-5 September 2019, Glasgow, UK

The role of variations in the buffer layer structure of IBAD-MgO based templates on the critical current anisotropy has been investigated in undoped and BaZrO3 (BZO) doped YBa2Cu3O6+x (YBCO) films. Not only do the natural defects grow distinct within the undoped YBCO lattice but also due to the different lengths of BZO induced nanorods within the YBCO matrix, the flux pinning properties are greatly affected by the underlying layers which in turn has a great impact on the angular dependent critical current density Jc(θ). This has been verified by transport measurements where the shape of the Jc(θ) varies in accordance with the substrates. Based on our results, the template having a cap layer with the minimum lattice mismatch and a good chemical compatibility with deposited YBCO is proven to be the best for growing both the undoped and BZO doped YBCO films. Furthermore, a model we can present based on the shapes of Jc(θ) curves depicts how the formation of nanosized defects affects the flux pinning anisotropy