SUPERCONDUCTING INTERFEROMETERS WITH TWO NB - NBO-X - PB - IN "WINDOW" JUNCTIONS
One of the most attractive applications of the Josephson effect is obtained by connecting two Josephson junctions in a superconducting loop. This simple interferometer configuration, a SQUID (Superconducting Quantum Interference Device), is the basic element of both the highest speed logic circuits and the most sensitive magnetic field detectors available at present. A good characterization of the behaviour of these devices is achieved by the knowledge of the I-c vs phi-e threshold curve, where I-c is the maximum zero voltage current of the interferometer and phi-e is the magnetic flux threading the loop. In this communication we describe the fabrication procedure and performance of planar interferometers with two Nb - NbO-x.Pb/In Josephson junctions. The junction dimensions are defined by opening two "windows" in an SiO insulating layer between the two superconducting electrodes. The applied magnetic field is in the plane of the device and is coupled both to the loop and the junctions. Experimental threshold curves at different values of the characteristic parameter beta are reported. In the case of beta < 1, a comparison of the experimental data with a simple theoretical model is also presented.
Bibliographic Reference: CRYOGENICS, 1983, PP. 639-642
Record Number: 1989122023200 / Last updated on: 1987-01-01
Available languages: en