Bicrystalline Grain Boundary Junctions of Co-doped and P-doped Ba-122 Thin Films

We prepared GB junctions of Ba(Fe 0.9 Co 0.1 ) 2 As 2 thin films on bicrystalline [00 l]-tilt SrTiO 3 substrates. The junctions show clear Josephson effects. Electrical characterization shows asymmetric I-V characteristics which can be described within the resistively shunted junction (RSJ) model. A large excess current is observed. Their formal I C R N product is 20.2 μV at 4.2 K, which is decreased to 6.5 μV when taking Iex into account. Fabrication methods to increase this value are discussed. Additionally, measurements on GB junctions of BaFe 2 (As 0.66 P 0.34 ) 2 thin films on LSAT bicrystalline substrates are shown. Their symmetric RSJ/flux flow-behavior exhibits a formal I C R N product of 45 μV, whereas the excess corrected value is ll μV.