Using our recently developed pulsed critical current density (J c) measuring system, the Jc of the high Jc melt-textured YBa2Cu3O7-δ (Y123) bulk samples has been determined. I-V curves with a voltage resolution of 0.5 μV were obtained, and transport Jc's along the a-b plane (J c∥ a-b) as high as 7.2×1 04 A/cm2 were extracted. These results are comparable to the values obtained magnetically. On the other hand, transport Jc along the c axis (Jc∥c) were found to be two orders of magnitude smaller, even though the magnetic Jc∥c is only about five times smaller than Jc∥a-b. We suggest that for the high-temperature superconducting materials which are highly anisotropic, caution should be taken when using the nontransport magnetic methods to determine Jc.
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