US3810131A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Devices employing the interaction of laser light with magnetic domains
Assignee: AT&T Inc
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Filing: 1972-07-18
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Granted: 1974-05-07
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Expires: 1992-07-18
Abstract
Abstract Focused laser light, when partially absorbed to cause localized heating in low coercivity magnetic layers of the type used in conventional bubble devices, is employed to manipulate bubble and strip magnetic domains. Bubbles and strips are thermally nucleated or annihilated as well as captured and moved about freely, by an incident laser beam of variable power without the use of outside connections, conductor loops or magnetic elements. Bubbles are arranged in fixed arrays and propagated at high velocities through well-defined patterns. Simplified memory devices are disclosed using laser techniques. There is also disclosed a novel form of reversible strip domain writing in low coercivity layers with the laser beam. Each of the disclosed arrangements has potential application to bubble devices and to various magneto-optical information storage, processing and display devices.
Inventors
- 👤 A Ashkin
- 👤 J Dziedzic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:08
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/06
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
223 words
A magnetic device of the type comprising a layer of low coercivity magnetic material in which magnetic domains can be stored and propagated, said layer being a magnetically anisotropic single crystalline material selected from the group of materials consisting of orthoferrites and synthetic ferrimagnetic garnets, said material having a preferred direction of magnetization normal to the plane of said layer, a characteristic thermal time constant, and a characteristic Curie point temperature above which the magnetization of said layer becomes negligible, and including means for applying a magnetic bias field to said layer essentially along said preferred direction, said device being characterized by means external to said layer for nucleating magnetic domains therein without altering the applied magnetic bias field, said nucleating means comprising a source of at least one beam of radiant energy, means for directing the incidence of the beam to a localized region of said layer having a cross-sectional area less than that of the desired magnetic domain, means for controlling the power of the beam, and means for controlling the time period of the incidence of the beam, the beam being at least partially absorbable in said localized region to cause localized heating thereof to a temperature above the Curie point temperature of the material within a time period of the order of the thermal time constant of the material.
Claim 2
Dependent Claim
223 words
A magnetic device of the type comprising a layer of low coercivity magnetic material in which magnetic domains can be stored and propagated, said layer being a magnetically anisotropic single crystalline material selected from the group of materials consisting of orthoferrites and synthetic ferrimagnetic garnets, said material having a preferred direction of magnetization normal to the plane of said layer, a characteristic thermal time constant, and a characteristic Curie point temperature above which the magnetization of said layer becomes negligible, and including means for applying a magnetic bias field to said layer essentially along said preferred direction, said device being characterized by means external to said layer for nucleating magnetic domains therein without altering the applied magnetic bias field, said nucleating means comprising a source of at least one beam of radiant energy, means for directing the incidence of the beam to a localized region of said layer having a cross-sectional area less than that of the desired magnetic domain, means for controlling the power of the beam, and means for controlling the time period of the incidence of the beam, the beam being at least partially absorbable in said localized region to cause localized heating thereof to a temperature above the Curie point temperature of the material within a time period of the order of the thermal time constant of the material.
Claim 3
Dependent Claim
211 words
A magnetic device of the type comprising a layer of low coercivity magnetic material in which magnetic domains can be stored and propagated, said layer being a magnetically anisotropic single crystalline material selected from the group of materials consisting of orthoferrites and synthetic ferrimagnetic garnets, said material having a preferred direction of magnetization normal to the plane of said layer and including means for applying a magnetic bias field to said layer essentially along said preferred direction, said device being characterized by means external to said layer for propagating magnetic domains therein without altering the applied magnetic bias field, said propagating means comprising a source of at least one beam of radiant energy, means for directing the incidence of the beam to a localized region of said layer, the beam being at least partially absorbable in said region to cause localized heating thereof, means for continuously moving the beam relative to said layer, and means for controlling the power of the beam to provide the beam with a beam power sufficient to yield attractive forces on magnetic domains in said layer such that a magnetic domain positioned near the center of the beam is trapped there and continuously propagated in said layer as the beam is moved relative to said layer.
Claim 4
Dependent Claim
211 words
A magnetic device of the type comprising a layer of low coercivity magnetic material in which magnetic domains can be stored and propagated, said layer being a magnetically anisotropic single crystalline material selected from the group of materials consisting of orthoferrites and synthetic ferrimagnetic garnets, said material having a preferred direction of magnetization normal to the plane of said layer and including means for applying a magnetic bias field to said layer essentially along said preferred direction, said device being characterized by means external to said layer for propagating magnetic domains therein without altering the applied magnetic bias field, said propagating means comprising a source of at least one beam of radiant energy, means for directing the incidence of the beam to a localized region of said layer, the beam being at least partially absorbable in said region to cause localized heating thereof, means for continuously moving the beam relative to said layer, and means for controlling the power of the beam to provide the beam with a beam power sufficient to yield attractive forces on magnetic domains in said layer such that a magnetic domain positioned near the center of the beam is trapped there and continuously propagated in said layer as the beam is moved relative to said layer.
Claim 5
Dependent Claim
72 words
The device of claim 2 in which said power controlling means provides the beam with a power sufficient to burn the material of said layer, and including means for focusing the beam to a cross-sectional area substantially smaller than that of the magnetic Domains, the beam yielding a discrete burn spot in said layer upon which a magnetic domain can be fixed for a selected time and subsequently removed with the beam.
Claim 6
Dependent Claim
159 words
A magnetic device of the type comprising a layer of low coercivity magnetic material in which strip magnetic domains can be stored and means for extending the area of the strip domains into selected domain patterns in said layer, said device being characterized in that said extending means comprises a source of at least one beam of radiant energy, means for directing the incidence of the beam to localized regions of said layer, the beam being at least partially absorbable in said regions to cause localized heating thereof, means for controllably moving the beam relative to said layer, and means for varying the power of the beam to provide successively attractive and repulsive forces on strip domains in said layer at a first beam power and a second relatively higher beam power, respectively, said forces being of sufficient magnitude to extend the area of the strip domains controllably in said layer in response to the motion of the beam.
Claim 7
Dependent Claim
159 words
A magnetic device of the type comprising a layer of low coercivity magnetic material in which strip magnetic domains can be stored and means for extending the area of the strip domains into selected domain patterns in said layer, said device being characterized in that said extending means comprises a source of at least one beam of radiant energy, means for directing the incidence of the beam to localized regions of said layer, the beam being at least partially absorbable in said regions to cause localized heating thereof, means for controllably moving the beam relative to said layer, and means for varying the power of the beam to provide successively attractive and repulsive forces on strip domains in said layer at a first beam power and a second relatively higher beam power, respectively, said forces being of sufficient magnitude to extend the area of the strip domains controllably in said layer in response to the motion of the beam.
Claim 8
Dependent Claim
42 words
The device of claim 4 in which said directing means directs the beam to an end of a strip domain in said layer, and said moving means moves the beam in a manner to extend the domain longitudinally into the selected pattern.
Claim 9
Dependent Claim
55 words
The device of claim 4 in which said directing means directs the beam to approximately the center area of a strip domain in said layer, and said moving means moves the beam transverse to the domain in a manner to extend the center area into a hairpin-shaped pattern in a form of magnetic script writing.
Claim 10
Dependent Claim
21 words
The device of claim 6 in which the pattern written by the beam is reversible by moving the beam in reverse.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-06 | 1977-11-05 | 1978-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-06 | 1981-11-05 | 1982-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-06 | 1985-11-05 | 1986-05-07 | $7700.00 | Window Closed / Lapsed |