Growth and characterization of SrRuO₃ buffer layer on MgO template for coated conductors

Recently, it has been shown that biaxially oriented MgO deposited by ion-beam-assisted-deposition (IBAD) is a significantly more cost-effective template for coated conductors. Nevertheless, the lack of good buffer layer materials for MgO has limited the accomplishment of high quality YBCO films. We, for the first time, have used SrRuO₃ as a single buffer layer directly on an MgO template (homo-epitaxial MgO/IBAD-MgO) for growth of thick YBCO films on polycrystalline metal substrates. By using SrRuO₃ as a buffer layer, we have routinely obtained YBCO films with an in-plane mosaic spread in the range of 3 - 6° full width at half maximum. A critical current density of 1.8 × 10₆ A/cm₂ in self-field at 75 K for a film thickness of over 1.0 μm has been achieved. We have further achieved a current per unit width of over 245 A/cm, which is the highest reported so far for a YBCO film on a polycrystalline metal substrate using MgO as a template.