Dimensionality of flux pinning in various superconducting YBCO/PYBCO superlattices

Angular dependent of critical current densities J_c(θ) for a 960 Å-thick pure YBa₂Cu₃O_7-y thin film (denoted by sample A) and the YBa₂Cu₃O_7-y/Pr_0.5Y _0.5Ba₂Cu₃O_7-y superlattices with 960 Å total thickness of YBa₂Cu₃O_7-y layers (denoted by samples B, C and D) under the magnetic field H = 0.1 T at the reduced temperature t = 0.92 was measured to investigate the dimensionality of the flux pinning. Samples B, C and D in our study are (120Å/24Å)×8, (60Å/24Å)×16 and (48Å/24Å)×20 respectively. In this report, it is found that the dimensionality of the flux pinning deviates from 2D for the sample A whereas it shows a 2D behavior for the sample B. Moreover, the dimensionality of the flux pinning deviates from 2D gradually for samples C and D. The cause will be discussed.