Angular dependence of critical current properties in YBCO coated tape under high magnetic field up to 18 T

Critical current properties in a YBCO coated tape have been studied as a function of temperature, magnetic field and field angle under high magnetic field up to 18 T. 1 <f>μ</f>m thick YBCO film was deposited on a bi-axially aligned Y2O3/YSZ/Hastelloy substrate fabricated by the IBAD technique. The value of critical current, <f>Ic</f>, of the 1 cm wide tape reached as high as 85 A at 77 K in self-field condition. After etching the tape into 100 <f>μ</f>m wide and 1 mm long bridge, we measured extended E–J characteristics. The value of critical current density, <f>Jc</f>, is maintained higher than 105 A/cm2 at 70 K in 5 T perpendicular to the tape surface. Moreover, the power index n and the so called glass–liquid transition field, <f>BGL</f>, of the tape in perpendicular field are superior to those of epitaxial film deposited on a SrTiO3 single crystalline substrate. <f>Jc</f> vs. angle relationship shows broad peak around 90<f>°</f> where field is perpendicular to the tape surface, in addition to a sharp peak at 0<f>°</f>. These results suggest that the tape is highly uniform and correlated defects along c-axis direction contribute to flux pinning. [Copyright &y& Elsevier]