Much simplified ion-beam assisted deposition-TiN template for high-performance coated conductors

A much simplified template, i.e., two nonsuperconducting layers between the superconducting YBa₂ Cu₃ O7-δ (YBCO) and the polycrystalline metal substrate, has been developed for high-performance coated conductors by using biaxially aligned TiN as a seed layer. A combination of a thin TiN (∼10 nm by ion-beam assisted deposition) layer and an epitaxial buffer LaMnO₃ layer (∼120 nm) allows us to grow epitaxial YBCO films with values of full width at half-maximum around 3.5° and 1.7° for the φ -scan of (103) and rocking curve of (005) YBCO, respectively. The YBCO films grown on electropolished polycrystalline Hastelloy using this two-layer template exhibited a superconducting transition temperature of 89.5 K, a critical current density of 1.2 MA/ cm² at 75.5 K, and an α value (proportional factor of critical current density J_c ∼ H-α) of around 0.33, indicating a high density of pinning centers and an absence of weak links.