BaFe_1.8Co_0.2As₂ thin film hybrid Josephson junctions

Josephson junctions with iron pnictides open the way for fundamental experiments on superconductivity in these materials and their application in superconducting devices. Here, we present hybrid Josephson junctions with a BaFe_1.8Co_0.2As₂ thin film electrode, an Au barrier, and a PbIn counter electrode. The junction shows resistively shunted junction-like current-voltage characteristics up to the critical temperature of the counter electrode of about 7.2 K. The temperature dependence of the critical current shows nearly linear behavior near T_C. Well-pronounced Shapiro steps are observed at microwave frequencies of 10–18 GHz. Assuming an excess current of 200 μA at 4.2 K the effective I_CR_N product calculates to 7.9 μV.