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Overlay Josephson Microbridge

IP.com Disclosure Number: IPCOM000082743D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Laibowitz, RB: AUTHOR [+3]

Abstract

A thin film Josephson microbridge consists of a very small link of superconducting metal joining two larger superconducting layers. Although the actual dimensions depend on the type of material used, it has been shown that the link dimensions should be on the order of a few thousand angstroms for typical superconductors.

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Overlay Josephson Microbridge

A thin film Josephson microbridge consists of a very small link of superconducting metal joining two larger superconducting layers. Although the actual dimensions depend on the type of material used, it has been shown that the link dimensions should be on the order of a few thousand angstroms for typical superconductors.

The conventional Josephson microbridge inherently is a low-resistance device, because of its very short length. Therefore, any noise voltage on the lines leading to the device can generate sizeable currents in the bridge which may cause burn-out. There may be a problem due to hysteresis in the current- voltage curve of a Josephson microbridge. This is because the hysteresis characteristic is a rapidly changing capacitor-like circuit parameter, which interferes with the operation of a high-frequency circuit.

Under certain circumstances, Josephson microbridges have the two undesirable properties of burn-out and hysteresis in the current-voltage characteristic. By depositing thin films of a normal metal over the entire device, e.g., Au Approximately Less Than 200 Angstroms thick, these problems can either be eliminated or reduced to acceptable levels. For example, the entire device is overlaid with a very thin layer of Au having thicknesses less than about 200 Angstroms. Ag, Cu, Pt, Pd. Ir, Os, Re, Al, and W could also be used. The normal material overlay should not combine readily with the superconductor, should be nor...