Magnetoresistance Anisotropy and Scaling in Textured High-Temperature Superconductor Bi1.8Pb0.3Sr1.9Ca2Cu3Ox

Abstract

The magnetoresistance of the textured high-temperature superconductor (HTSC) Bi1.8Pb0.3Sr1.9Ca2Cu3Ox + 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 sin2φ, 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 ≈ 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.