Columnar tilt and vortex stress in superconducting thin films of NdBa2Cu3O7-δ: Magnetization critical current-density measurements.

C-axis-oriented NdBa2Cu3O7-δ thin films (thickness ∼2000 Å) on LaAlO3 substrates have been prepared and irradiated with Ag+14 (200 MeV) ions at different inclinations (θd=0°, 15°, 30°, and 45°) to the c axis. Magnetization-field hysteresis loops have been obtained on pristine and irradiated thin films at two different temperatures in applied magnetic fields up to 5 T. Estimates of the critical current density Jc(H,θ) and the volume pinning force Fp(H,θ) from the magnetization data reveal a strong dependence on track inclination. An increase and a subsequent saturation in Fp(H,θ), instead of the usual Gaussian peak around the equivalent matching field, B[lowercase_phi_synonym], is observed. It is suggested that this dependence of Jc (or Fp) on θd is a consequence of the effective modification of vortex pinning by tilted columnar defects. [ABSTRACT FROM AUTHOR]