Friday, 2E-01, -

Direct Growth of LaMnO₃ Cap Layers on IBAD-MgO (without homo-epi MgO) Template for YBCO Coated Conductors

Tolga Aytug

Oak Ridge National Laboratory, Oak Ridge, TN 37831
Phone: (865) 574-6271, Fax: (865) 574-6263, aytugt@ornl.gov

Simplification of the IBAD buffer architecture is one of the key issues for reduced manufacturing and labor costs of second generation superconducting wire production. Structural and chemical compatibility of LaMnO₃ (LMO) buffer layers on homo-epi MgO in IBAD (MgO)-based architectures and the growth of high current density YBCO films on these LMO templates are well established. In this work, we studied various rf-magnetron sputter growth parameters/conditions for epitaxial growth of LMO layers directly on IBAD(MgO) without the need of the homo-epi MgO layers. LMO thicknesses ranged from 30 - 240 nm. The performance of the LMO/IBAD (MgO) samples was qualified by depositing 1 μm-thick YBCO coatings by pulsed laser deposition. Detailed XRD, SEM, AFM, and transport measurements were done. Results showed that while the growth temperature has a substantial effect on the texture of LMO and hence on the J_c values of YBCO, neither LMO thickness nor different sputter gas ambients had a significant effect on the performance of YBCO films. In addition, surface roughness of LMO layers on IBAD (MgO) is found to be similar to that of LMO deposited on homo-epi MgO layers. The results underscore the strong potential of LMO as a single cap layer directly on IBAD (MgO) for the development of a simplified IBAD architecture.

Research sponsored by the U.S. Department of Energy, Office of Electricity Delivery and Energy Reliability, Superconductivity Program for Electric Power Systems.

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