Development of Electrically Conductive Buffer for REBCO Conductors

An electrically conductive buffer architecture can enable defect-tolerant RE-Ba-Cu-O (REBCO) superconductor tapes by providing a current shunt path to the substrate. We are developing suitable electrically conductive buffers based on Titanium Nitride (TiN) grown on an ion beam-assisted deposition (IBAD) template on Hastelloy C276 substrate. The aim is to prevent the oxidation of TiN during metal-organic chemical vapor deposition (MOCVD) of REBCO. The buffer architecture was modified to render TiN more oxidation-resistant while maintaining good electrical conductivity. A strong biaxial texture was achieved and a low electrical resistivity of 43 µΩcm was measured with this modified buffer architecture. An oxide layer based on the SrTiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (STO) cap layer was epitaxially grown using RF magnetron sputtering followed by REBCO film growth by MOCVD. By avoiding oxidation of the modified buffer architecture based on TiN, we achieved a strong epitaxy of REBCO with a sharp texture, without non-00L orientations. Scanning Hall Probe Microscopy (SHPM) data showed uniformly high critical current density throughout the entire REBCO tape.