Critical Current Densities of MOCVD Tapes for Different Current Directions

The critical current density J_c of an MOCVD/IBAD coated conductor was measured on tracks patterned longitudinally (L) and transversely (T) to the tape direction. Despite the samples´ vicinality no dependence of J_c on track direction was found for magnetic fields applied perpendicular to the film plane. In angular out-of-plane measurements the previously reported asymmetry due to tilted precipitate planes was observed in an L track, whereas curves from a T track were almost perfectly symmetric with similarly high absolute values of J_c. At low fields the effects of surface pinning were seen. Our results show that in most scenarios the current carrying capability is equally as good parallel and perpendicular to the tape direction, which is highly relevant for ROEBEL cables. In measurements where the magnetic field was swept in the film plane the anisotropy was found to be significantly higher than for MOD/RABiTS samples, which we explain by the different morphology of grain boundaries in the tapes. At low temperatures J_c of a T track exhibited a clear signature of vortex channeling.