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Spin Glass Superconductors for Programmable Read-Only Memory

IP.com Disclosure Number: IPCOM000046332D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Malozemoff, AP: AUTHOR

Abstract

Recently spin glass superconductors have been discovered 1, 2 which have interesting properties discussed below. Consider the case of GdxLa1-xOs2 as an example. The phase diagram is shown in Fig. 1. The second property (not discussed in the publications) is that when a composition, such as x = 15% in Fig. 1, is cooled in a magnetic field of, for example, about 100 Oe or so, through the spin glass transition temperature (Tsg), a magnetization is frozen in. Then, even if the external field is turned off, superconductivity is destroyed, i.e., Tsupercond drops to zero. Already several degrees below Tsg, the decay of remanent M is so slow as to be negligible for storage times of interest; so this effect forms a novel kind of memory.

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Spin Glass Superconductors for Programmable Read-Only Memory

Recently spin glass superconductors have been discovered 1, 2 which have interesting properties discussed below. Consider the case of GdxLa1-xOs2 as an example. The phase diagram is shown in Fig. 1. The second property (not discussed in the publications) is that when a composition, such as x = 15% in Fig. 1, is cooled in a magnetic field of, for example, about 100 Oe or so, through the spin glass transition temperature (Tsg), a magnetization is frozen in. Then, even if the external field is turned off, superconductivity is destroyed, i.e., Tsupercond drops to zero. Already several degrees below Tsg, the decay of remanent M is so slow as to be negligible for storage times of interest; so this effect forms a novel kind of memory.

This article describes a means for using these remarkable properties for a programmable read-only-memory. The idea is to have a small strip of "SGS" (Spin Glass Superconductor) in any of a variety of possible circuits (Fig. 2). At the operating temperature and when cooled in zero field, SGS is superconducting in the "zero" state, as shown in Fig. 3. When programming the memory, the temperature is raised to Tset or a sufficiently high field is applied to lower Tsup to Tset=Top so SGS is normal, then a current is run through those circuits which are to be reset to "one" until the temperature (T) exceeds Tsg. Alternatively, an independent heater can be employed. Although this proces...