Angular dependence of critical current density in Y-Ba-Cu-O thin films

c-axis oriented YBa2Cu3O7-delta (YBCO) thin films for coated conductor applications have anisotropic behaviors of critical current density (J(c)) in magnetic fields. The anisotropic vortex pinning in YBCO films fabricated on SrTiO3(100) single crystal substrates by pulsed laser deposition was investigated based on the field angular dependencies of J(c), which were measured using the constant Lorentz force configuration (CLFC) and a variable Lorentz force configuration (VLFC). J(c)(theta) as a function of angle theta between the ab-plane direction and the magnetic field direction had a sharp peak at theta = 0 degrees, which was attributed to the intrinsic pinning. Besides, J(c)(theta) did not depend on the intensity of the Lorentz force when the magnetic field was applied near theta = 90 degrees. This indicates that J(c)(theta) in this region is determined by the depinning of the vortex segment trapped by the pinning centers parallel to c-axis of the film. A transition from the intrinsic pinning to the extrinsic pinning is also discussed.