Study of Bi2Sr2CaCu2O8/BiFeO3 nano-composite for electrical transport applications

The Bi2Sr2CaCu2O8/BiFeO3 (BSCCO/BFO) nano composite for various BFO weight percentage is prepared and studied for electrical transport. Double resistive superconducting transition is seen in all composite samples with increasing semiconducting nature as a function of BFO content. Initially, the added BFO goes mainly to the grain boundary and from 10% onwards, it enters grains as well, acting as pinning centers. The conduction mechanism in BSCCO shows weak localization for low BFO, tunneling in intermediate BFO, and power law behavior (similar to metal-insulator boundary) for higher BFO samples. The paraconductivity studies reveal the 2D-3D transition in parent BSCCO and the composites, with a signature of percolative behavior in the composites. The study of critical current density reveals two types of Josephson junction in the composites: (1) thin intrinsic superconductor-insulator-superconductor (SIS) type present in all samples including parent BSCCO and (2) extrinsic type due to BFO added, present only in composite samples. The extrinsic junction is SIS with tunneling for low BFO and goes to proximity SIS type for increasing BFO. The Jc(0) as a function of BFO content, first decreases with increasing BFO, attains minima at 5% BFO, and increases thereafter. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4751277]