High Critical Current Density in the High-T c Superconductor: Generation of Efficient Pinning Centers (SOLID STATE CHEMISTRY-Multicomponent Materials)

Abstract

We have found novel flux pinning centers in high-Tc oxide superconductor Bi2Sr2CaCu2O8 with Tc = 80 K that dramatically increase the critical current density (Jc). Single crystals with a large amount of Pb substituting for Bi were grown by the floating zone method, and their magnetic properties and microstructures have been studied by means of SQUID magnetometory and electron microscopy. Jc increases remarkably beyond a critical Pb content of ~0.4 per formula unit, where characteristic two-phase microstructures are revealed by high-resolution electron microscopy: The “single” crystals consist of alternating thin (several tens of nanometers) lamellar plates of two phases with the (010) interface; one with lower Pb content (~0.4) and a modulated structure and the other with higher Pb content (~0.6) and a modulation-free structure.