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Josephson Memory Cell With Magnetic Film

IP.com Disclosure Number: IPCOM000089806D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Broom, RF: AUTHOR [+4]

Abstract

Thin magnetic films are combined with Josephson devices. In a logic gate or in a memory cell a Josephson junction is provided with a thin magnetic film. The easy axis extends in the film plane parallel to the junction width dimension. The film, e.g., permalloy, shows a substantially rectangular hysteresis loop.

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Josephson Memory Cell With Magnetic Film

Thin magnetic films are combined with Josephson devices. In a logic gate or in a memory cell a Josephson junction is provided with a thin magnetic film. The easy axis extends in the film plane parallel to the junction width dimension. The film, e.g., permalloy, shows a substantially rectangular hysteresis loop.

By proper switching of the film's magnetization it can be utilized to bias the Josephson junction magnetically or to write-in the cell, respectively. In addition, the control lines for switching the Josephson junction can be used to switch the film magnetically. The coercive field of the magnetic film can be controlled to ensure that it switches at fields of greater magnitude than those normally required to switch the Josephson junction. An example shows a read-mostly memory. Readout with switching the Josephson junction is very fast, and the relatively slow magnetization change for writing has to occur only occasionally.

Depicted is a cross-section of a memory cell. On a gate string G the overlapping ends of alternating M2-M3 metallic strips comprise therebetween the thin oxide layer defining a Josephson junction. The superconducting ground- plane (M1) with its covering insulation layer is not shown for clarity. Two narrow control lines cross the junction area in parallel transverse to the gate line G and insulated therefrom. These X, Y lines are the coordinate access lines of the memory array. To permit parallelism in the junction area, the Y line has to be meandered in the memory matrix. A thin magnetic film...