Microstructure and substrate dependent enhanced critical current density in Pb-substituted Bi-based high temperature superconducting thin films

Abstract

Abstract A comparative study was carried out using magnetization measurements to understand the diamagnetic response of the superconducting thin films of Bi1.75Pb0.25Sr2Ca2Cu3O10±δ grown on two different substrates. The film grown on SrTiO3 substrate was found to exhibit enhanced superconducting properties than the film grown on LaAlO3 substrate. The strengthening of the intergrain coupling by the growth of the larger grains with better grain connectivity and enhanced pinning mechanism yielded a critical current density as high as ∼4.8 × 105 Acm−2 in the film grown on SrTiO3 substrate. An enhancement in the value of the critical current density with the decrease in the dimensionality of the sample on account of a change in the microstructure was observed. As revealed from the AC susceptibility measurements, the metallic nature of the weak links conveys that the weak links are essentially the coexisting secondary phases in these films. Furthermore, the paramagnetic Meissner effect was observed in these films, which can be explained within the realm of the flux compression models.