Anisotropy and field dependence of critical current density in YBa₂Cu₃O_7-δ epitaxial thin film

The critical current density J_c of the epitaxial YBa₂Cu₃O_7-δ thin film was measured as a function of applied magnetic field H up to 6 T for three special configurations: (1) H||c axis and H⊥J; (2) H⊥c axis and H⊥J; (3) H⊥c axis and H||J. We observed a large anisotropy of J_c(H) between H||c axis and H⊥c axis with H⊥J, and a very small anisotropy of J_c(H) between H||J and H⊥J with H⊥c axis. The field dependence of the critical current density can be well described by the modified Kim–Anderson model taking into account the Kramer scaling law. The weak dependence of the transport critical current density on its orientation relative to the applied magnetic field is discussed. © 1997 American Institute of Physics.