Edge-type Josephson junctions with Co-doped Ba-122 thin films

Abstract

In this work we present preparation details and measurement results for an edge-type hybrid Josephson junction based on Co-doped BaFe2As2. The base electrode was formed by ion beam etching of a Ba-122 thin film, while the counter-electrode was patterned by evaporating lead. Finally, an indium protection layer was evaporated. The junction shows asymmetric I–V-characteristics with a total IC RN -product of about 12 μV . The characteristics can be fitted within a resistively shunted junction model assuming different fitting parameters for the positive and negative branches. There is a high excess current of unknown origin. The magnetic field dependence of the critical current indicates a non-homogeneous junction network and effects by flux trapping. It shows a variation of IC in the positive as well as in the negative bias branch, but does not suppress it completely. Also the influence of microwave irradiation on the junctions is shown. Thereby IC as well as the excess current can be suppressed, while first and higher order Shapiro steps can be observed.