Angular effects of transport critical currents in high-temperature superconductor tapes

Measurements of the critical current dependence on the angular orientation of the applied magnetic field for (Bi, Pb)(2)Sr2Ca2Cu3O10 (BSCCO-2223)/AgMg -sheathed, mono-core BSCCO-2223/Ag-sheathed and Bi2Sr2CaCu2O8 (BSCCO-2212) dip coat tapes are presented. We have demonstrated that the procedure of me asurement is an important factor for the angular effect to show. For a magn etic field only applied during the measurement of I-c(theta) (during the ro tation the magnetic field is set to zero) we have found a symmetric curve, while when the magnetic field is applied during the rotation the curve is a symmetric. Moreover, we found a large difference in the critical current va lue between the different procedures. From our measurements, we imply two c onditions are necessary to have an angular effect: (1) the magnetic field m ust be applied during the rotation and (2) we have to start the rotation fo r a magnetic field parallel to the c-axis. The results are discussed in the context of the accommodation of vortices to planar defects and surface pin ning.