Static characteristics of superconducting interferometers with Nb-NbO x -PbIn Josephson junctions

Planar interferometers with two Nb-NbO x -PbIn junctions have been fabricated. Because of the peculiar configuration adopted, both a symmetric and an asymmetric current bias are possible on the same sample. The loop area is on a plane perpendicular to the cross section of the junctions, and, therefore, the flux coupled to them is negligible. Threshold curves have been measured for different values of the characteristic parameter β=LI 1/Φ0, whereI 1 andL are the maximum Josephson current and the inductance of the interferometer andΦ 0 is the flux quantum. The dependence of the current modulation depth upon β has been also investigated. A comparison of the experimental data with the theory shows quantitative agreement.