Model for the low-temperature transport of Bi-based high-temperature superconducting tapes

A grain-structure model is used to obtain the low-temperature transport properties of polycrystalline Bi-based high-temperature superconducting tapes, including the magnetic-field-dependent critical current. The grain structure is regarded as resembling a brick wall, such that the net horizontal supercurrent passes from brick to brick chiefly through the horizontal junctions between bricks. A high-field critical-current plateau is predicted, assuming inhomogeneous Josephson junctions between highly anisotropic superconducting grains.