Inter-grain Josephson currents in two-gap superconductors

Ota, Yukihiro; Machida, Masahiko  ; Koyama, Tomio*

We microscopically study inter-grain Josephson current in iron-pnictide superconductors. The theoretical examination predicts that the inter-grain Josephson current is significantly reduced by -wave symmetry as the incoherent tunneling process becomes dominant and the density of states and the gap amplitude between two bands are identical. In addition, we suggest important points to improve the inter-grain critical current density.