Characteristics of NdBa2Cu3O7-δ/PrBa2Cu3O7-δ/NdBa2Cu3O7-δ planar Josephson junctions

We report on the well-characterized properties of a-axis oriented trilayer Josephson junctions made of NdBa2Cu3O7-δ and PrBa2(Cu, Co)3O7-δ films, and c-axis oriented trilayer Josephson junctions made of NdBa2Cu3O7-δ and PrBa2Cu3O7-δ films with smooth surface morphology and good crystallinity. a-Axis oriented NdBa2Cu3O7-δ/PrBa2(Cu, Co)3O7-δNdBa2Cu3O7-δ trilayers and c-axis oriented NdBa2Cu3O7-δ/PrBa2Cu3O7-δ/NdBa2Cu3O7-δ trilayers were prepared on (100) SrTiO3 substrates to obtain planar junctions. Their current-voltage characteristics are of the resistively-shunted-junction type at 4.2 K. They showed well-developed Shapiro steps corresponding to 5-20 GHz microwave irradiation. Moreover, the power dependences of the maximum amplitudes of the Shapiro steps were clearly obtained and consistent with the theoretical values expressed as Jn(2eV/hf). The magnetic field dependence of the Josephson current for a-axis oriented trilayer Josephson junctions showed a Fraunhofer-like pattern, suggesting the spatial uniformity of the critical current flowing over the PrBa2(Cu, Co)3O7-δ barrier layer. (author)