Effect of c-axis-correlated disorders on the vortex diagram of the pinning state

The introduction of the c-axis-correlated disorder is a promising technique for the improvement of the critical current density J_c for B // c of REBa₂Cu₃O_y, (RE123) films and tapes. In order to understand the vortex pinning mechanism with the different variety of the c-axis-correlated disorder, the angular dependence of J_c was measured in detail for an Y123 film with BaZrO₃ nano-rods, a Sm123 film with fine nano-particles and edge dislocations and an Y123 film with columnar defects introduced by the heavy-ion irradiation parallel to the c-axis. We found that the vortex pinning state for the variety of the c-axis-correlated pinning is similar in low fields below the matching field, but it shows different behaviors in high fields above the matching field. It is considered that the interstitial vortices interacted with the c-axis-correlated disorders through the vortex interaction may play an important role for the appearance of the c-axis-correlated pinning behavior in a high-field region above the matching field.