Magnetoresistance anisotropy and scaling in textured high-temperature superconductor [Bi.sub.1.8][Pb.sub.0.3] [Sr.sub.1.9][Ca.sub.2][Cu.sub.3][O.sub.x]

The magnetoresistance of the textured high-temperature superconductor (HTSC) [Bi.sub.1.8][Pb.sub.0.3][Sr.sub.1.9][Ca.sub.2][Cu.sub.3][O.sub.x] + Ag has been studied at different directions of the transport current I and external magnetic field H with respect to crystallographic directions of HTSC crystallites. When I and H are oriented along the ab planes of crystallites and φ is the angle between H and I, the anisotropic part of the magnetoresistance follows the functional dependence [sin.sup.2]φ, which is characteristic of vortex flows under Lorentz forces. The magnetoresistance R at H parallel to the c axis of crystallites (H ∥ c) is higher than R at H ∥ ab for both cases of I ∥ c and I ∥ ab. The anisotropy coefficient γ [approximately equals] 2.3 has been estimated from the scaling of the dependences R(H) measured at H ∥ c and H ∥ ab. The inclusion of the magnetic field induced by the transport current allows scaling of the dependences R(H) at different values of I. A qualitative picture of the current flow along the c axis of crystallites in the textured HTSC has been proposed.