Enhanced superconducting properties of Bi2Sr2CaCu2O8$+\delta $ thin films by incorporating Iridates nanoparticles

We incorporated CaIrO$_{3}$ (Ca-iridate) nanoparticles at the interface of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta }$ (Bi-2212) thin films and substrates by pulsed laser deposition and post-growth \textit{ex situ} annealing. The density of incorporated Ca-iridate strongly affected the superconducting properties and microstructure of the Bi-2212 thin films. For the incorporation of low density Ca-iridate (450 laser pulses) in the Bi-2212, its superconducting properties enhanced ($T_{c-onset} = $ 97 K, $T_{c-zero} = $ 84 K) over those of pure Bi-2212 ($T_{c-onset} = $ 94 K, $T_{c-zero} = $ 80 K). However, incorporating a higher density (1,800 pulses) significantly reduced $T_{c-zero}$ to $\approx $57 K. Incorporating a low density of Ca-iridate also decreased the $c$-axis lattice constant. Films with incorporated Ca-iridate exhibited greater critical current density, $J_{c}$(B), than the pure Bi-2212 film. These results indicate that incorporating low densities of Ca-iridate nanoparticles into Bi-2212 can improve its superconducting properties.