Limiting-path model of the critical current in a textured YBa2Cu3O/sub 7-δ/ film

A limiting-path model for the determination of the critical current in a polycrystalline superconductor is presented which allows for the exact calculation of the critical current given the individual intergrain couplings. The model is used to determine the a-axis texturing dependence of the critical-current density in a c-axis--oriented polycrystalline YBa2Cu3O/sub 7-δ/ film. The critical-current density in untextured material is suppressed by a factor of congruent (1/30 as compared to the single-crystal value and can be raised considerably only by strong a-axis texturing to within 5 degree). A nontrivial length dependence of the critical-current density is found for long polycrystalline wires