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US3609719A
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First order transition recording utilizing incomplete transition iron-rhodium films
Assignee: General Electric Co
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Filing: 1969-12-17
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Granted: 1971-09-28
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Expires: 1989-12-17
Abstract
Abstract Information is thermally recorded along an iron-rhodium film exhibiting a thermal transition between the ferromagnetic and antiferromagnetic states of substantially less than 50 percent by applying strain to the film in excess of 0.3 percent to increase the percentage of film undergoing transition to the antiferromagnetic state by an amount greater than approximately 40 percent of the original transition. Selective sites of the highly antiferromagnetic film then are heated, e.g. utilizing an addressable electron beam gun, to produce a first order transition of the heated sites to the ferromagnetic state for storage of information at the site and after applying a uniform magnetic field to the film, the magnetization of each bit site is read out utilizing conventional electron mirror microscopy or secondary electron emission techniques.
Inventors
- 👤 James M Lommel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 11:12
CPC Classifications
G; G11; G11B; G11B5/00; G11B11/00; G11B11/10; H; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J31/00; H01J31/08; H01J31/58; H01J31/60
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
40 words
A method of recording information in digital form according to claim 1 wherein the percentage of film undergoing transition from the ferromagnetic state to the antiferromagnetic state is increased by at least 40 percent relative to the original thermal transition.
Claim 2
Dependent Claim
24 words
A method of recording information in digital form according to claim 1 wherein said strain is produced by frictional agitation of the film surface.
Claim 3
Dependent Claim
29 words
A method of recording information in digital form according to claim 1 wherein said strain is produced by mechanical deflection of the substrate to which the film is secured.
Claim 4
Dependent Claim
38 words
A method of recording information in digital form according to claim 1 wherein said film is formed by sequentially depositing iron and rhodium films atop a refractory substrate and subsequently annealing the laminar structure to diffuse the layers.
Claim 5
Dependent Claim
85 words
A recording medium comprising a resilient nonmetallic substrate capable of withstanding a strain in excess of 0.3 percent, an iron-rhodium film situated atop said substrate, said iron-rhodium film having a composition range between 50 and 65 percent rhodium and exhibiting a magnetic transition of less than 50 percent of the film when cycled through the thermal hysteresis loop of the film and means contiguous with said film for applying strain to said film for increasing the percentage of film undergoing transition to the antiferromagnetic state.
Claim 6
Dependent Claim
38 words
A recording medium according to claim 6 wherein the percentage of film undergoing transition to the antiferromagnetic state is increased by at least 40 percent relative to the percent of film undergoing thermal transition to the antiferromagnetic state.
Claim 7
Dependent Claim
32 words
A recording medium according to claim 7 wherein said substrate is selected from the group consisting of mica, alumina, beryllia, silicon and fused silica having a thickness between 100 and 10,000 microns.
Claim 8
Dependent Claim
26 words
A recording medium according to claim 7 wherein said means for applying strain to said film comprise of a bimetal strip mechanically secured to said substrate.
Claim 9
Dependent Claim
26 words
A recording medium according to claim 7 wherein said substrate is fixedly secured to an electromechanical transducer to permit application of strain to said iron-rhodium film.
Claim 10
Dependent Claim
25 words
A recording medium according to claim 7 wherein said means for applying strain to said film comprise an electrostrictive base fixedly secured to said substrate.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |