Nonvolatile magneto-optical memory element and a method of writing thereon
Abstract
Abstract A magneto-optical memory element for use as a light beam addressable memory element is formed of permalloy and europium oxide films arranged in adjoining layers. Information is written into the permalloy layer while the device is at room temperature. The ambient temperature is then reduced below the Curie point of europium oxide causing the magnetization of the permalloy layer to be directly transferred by negative or anti-parallel exchange coupling to the europium oxide layer. The europium oxide then preserves the stored information in a form suitable for optical read-out which will take place at this low temperature. The device has the advantage that if the ambient temperature accidentally should rise above the Curie point of europium oxide going even as high as room temperature, the stored information will be preserved in the permalloy film until the temperature again is brought below the Curie point of europium oxide. Whereupon the europium oxide film is restored to its previous magnetic state by negative exchange coupling. Thus, the subject magneto-optical memory device is nonvolatile under fluctuating temperature conditions.
Inventors
- 👤 George S Almasi
- 👤 Eugene R Genovese
Bibliographic Details
Claims Analysis
Total Claims: 5References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |