Critical current properties in YBCO coated IBAD tapes

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, Ic, for 1 cm wide tape was 85 A at 77.3 K in self-field. Detailed properties of critical current density, Jc, were studied using 100 <f>μ</f>m wide and 1 mm long bridge patterned in the tape. The results were compared with the properties of epitaxial YBCO thin films deposited on SrTiO3 single crystalline substrate. The value of critical current density, Jc, was maintained higher than 10<f>5</f> A/cm<f>2</f> at 70 K in 5 T perpendicular to the tape surface. The value is <f>&ap;1/4</f> of Jc 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, BGL, of the coated tape was also superior to that of epitaxial thin films. Angle dependences of Jc showed a broad peak around 90° (<f>&par;</f>c), in addition to a sharp peak at 0° (<f>⊥</f>c). These results suggest that correlated defects along c-axis direction contribute as pinning sites. [Copyright &y& Elsevier]