ALTERNATING-CURRENT LOSSES IN BIAXIALLY TEXTURED YBA2CU3O7-DELTA FILMS DEPOSITED ON NI TAPES

YBa2Cu3O7-delta films grown on rolling-assisted biaxially textured sub strates carry critical current densities 10(5)-10(6) A/cm(2) at 77 K a nd low applied magnetic fields. In the low-field and low-current regim e, ac transport current studies show hysteresis energy loss (per cycle and per unit length) roughly the value expected for a superconductor of elliptic cross section. The critical current I-c was deduced from o bserved de and dynamic current-voltage relations. The power loss rises sharply as I-0 (the maximum current in each cycle) is raised above I- c. In the present configuration, ferromagnetic hysteresis of the Ni su bstrate contributes little or no loss. (C) 1997 American Institute of Physics.