Magnetic-field anisotropy of high-critical current YBCO coated conductors

High-critical current (>100 A) YBCO thick films, or coated conductors, are being developed for superconductor applications. The critical current I, of these materials exhibits a magnetic-field dependence that depends on the a ngle of the applied field. Measurement of this anisotropy is critical to th e development of high temperature superconductor applications. We have deve loped the capability to characterize the magnetic-field anisotropy of large , high critical current YBCO superconductors as a function of angle. We hav e measured the magnetic-field anisotropy of the critical current in the H p erpendicular to I orientation of three samples in fields from 0 to 7 T and at temperatures from 75 K to 64 K. The results of these measurements charac terize the field dependence of these materials and reveal performance issue s of importance to applications. In contrast to previous measurements on thin films, which show that I-c for the H parallel to c orientation has the strongest field dependence, we dem onstrate that the intermediate angle of similar to 45 degrees to the normal to the tape plane shows the greatest field dependence for these coated con ductors on technical substrates. The field performance, anisotropy, and tem perature dependence are discussed in relation to sample quality.