Coupling behavior of Bi2Sr2-xInxCaCu2O8+d

The interplay between intrinsic grain and inter-grain effects at the superconducting state defines the behavior of bulk high-temperature superconductors. In this work, we use DC resistivity and AC magnetic susceptibility measurements to show how the intrinsic and inter-grain properties influence the intergrain phase coherence and flux dynamics of Bi2Sr2-xInxCaCu2O8+d. High In-doped samples, x >= 0.4, have broad resistive and diamagnetic superconducting transitions due to weak intergrain coupling caused by segregated impurities. Low doping levels, x <= 0.3, have sharp superconducting resistive and diamagnetic transitions, with higher transition temperature T-C attributed to an increase superconducting pair density. This results to enhanced intergrain coupling and strong diamagnetic screening of intergrain void networks. An applied AC field of 0.77 mT amplitude deteriorates the intergrain diamagnetic screening at x = 0.2 through AC flux slip between grains.