DESIGN AND FABRICATION OF THIN-FILM RESISTIVE SQUIDS

A partly resistive superconducting quantum interference device, or, RSQUID, is a device utilizing the nonstationary Josephson effect. The resistive part of the device makes it possible to apply a voltage to the Josephson junctions and in this way, to convert it into frequency. The transconductance ratio of this conversion is defined by the physical constants. 1/phi(0) = 2e/h (phi(0) is the flux quantum). Five different types of thin-film RSQUIDs are described in this paper. They are: an rf RSQUID with an rf pump and one Josephson - junction, a dc RSQUID with de bias and two Josephson junctions, and three topologically different double RSQUIDs with an rf pump, two Josephson junctions and two quantization loops. All five types were successfully fabricated. The resistive part of all devices was an S-N-S sandwich with Nb as the superconductor (S) and Cu as the nor mal metal (N). Such a design of the resistive part sets its resistance on the order of a few tens of mu Omega.