Critical current properties in YBCO coated IBAD tapes

Abstract Current transport properties in YBCO coated ion beam assisted deposition tapes have been studied as a function of temperature, magnetic field and field angle under high magnetic fields up to 18 T. The value of critical current, I c , for 1 cm wide tape was 85 A at 77.3 K in self-field. Detailed properties of critical current density, J c , were studied using 100 μm wide and 1 mm long bridge patterned in the tape. The results were compared with the properties of epitaxial YBCO thin films deposited on SrTiO 3 single crystalline substrate. The value of critical current density, J c , was maintained higher than 10 5 A/cm 2 at 70 K in 5 T perpendicular to the tape surface. The value is ≈1/4 of J c value in epitaxial thin film. In higher magnetic field, the difference becomes smaller. Power E–J relationship was observed over wide range of temperature and magnetic field. The power index n were superior to those of epitaxial thin films. And, the so-called glass–liquid transition field, B GL , of the coated tape was also superior to that of epitaxial thin films. Angle dependences of J c showed a broad peak around 90° (∥ c ), in addition to a sharp peak at 0° (⊥ c ). These results suggest that correlated defects along c -axis direction contribute as pinning sites.