US3576552A
Expired / Lapsed
US
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Cylindrical magnetic memory element having plural concentric magnetic layers separated by a nonmagnetic barrier layer
Assignee: International Business Machines Corp
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Filing: 1967-12-26
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Granted: 1971-04-27
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Expires: 1987-12-26
Abstract
Abstract A cylindrical magnetic film memory element. Plural concentric film layers are deposited on a cylindrical substrate. The substrate is either a solid conductive cylinder such as a wire or rod, or is a composite cylinder comprising a conductive film deposited on a solid or hollow nonconductive tube support. The magnetic films are either all anisotropic or mixed anisotropic and isotropic. In one embodiment, the anisotropic films have a closed hard axis and the easy or preferred axis of magnetization is parallel with the longitudinal axis of the substrate and the quiescent saturation magnetization within the film layers are disposed in an antiparallel longitudinal manner. In a second embodiment, dual anisotropic films have a preferred easy axis orientation circumferentially directed, thereby giving a closed easy axis.
Inventors
- 👤 Albert W Vinal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:06
CPC Classifications
G; G11; G11C; G11C19/00; G11C19/02; G11C19/10
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
188 words
A bistable magnetic data storage device comprisiNg: a cylindrical conductive substrate of nonmagnetic material; a data storage medium on said substrate comprising at least a first, second, and third closed, concentric, and longitudinally coextensive layers; said first and third layers comprising an alloy including NiFe which is magnetic; said first and third layers having a coercivity to anisotropy field ratio within the range of 0.5 and 1.3 and a skew angle not to exceed 3*; said first and third layers being anisotropic with an easy axis orientation parallel with said axis of said substrate; said first and third layers having magnetization vectors directed in antiparallel mode; and said second layer which is between said first and third layers comprising nonmagnetic conductive materials, said second layer having a thickness thin enough to permit mutual coupling of the easy axis demagnetizing components of said magnetic layers and thick enough to eliminate magnetic exchange coupling between said magnetic layers and capable of sustaining circumferential eddy currents whereby a solenoidal whereby is generated parallel with the axis of said substrate upon rotation of the magnetization vectors of said first and third layers.
Claim 2
Dependent Claim
188 words
A bistable magnetic data storage device comprisiNg: a cylindrical conductive substrate of nonmagnetic material; a data storage medium on said substrate comprising at least a first, second, and third closed, concentric, and longitudinally coextensive layers; said first and third layers comprising an alloy including NiFe which is magnetic; said first and third layers having a coercivity to anisotropy field ratio within the range of 0.5 and 1.3 and a skew angle not to exceed 3*; said first and third layers being anisotropic with an easy axis orientation parallel with said axis of said substrate; said first and third layers having magnetization vectors directed in antiparallel mode; and said second layer which is between said first and third layers comprising nonmagnetic conductive materials, said second layer having a thickness thin enough to permit mutual coupling of the easy axis demagnetizing components of said magnetic layers and thick enough to eliminate magnetic exchange coupling between said magnetic layers and capable of sustaining circumferential eddy currents whereby a solenoidal whereby is generated parallel with the axis of said substrate upon rotation of the magnetization vectors of said first and third layers.
Claim 3
Dependent Claim
128 words
A bistable magnetic data storage device comprising: a cylindrical substrate of conductive nonmagnetic material; a data storage medium superimposed on said substrate comprising at least a first, second, and third circumferentially continuous, concentric and longitudinally coextensive layers; said first and third layers comprising an alloy including NiFe; said first and third layers each having an easy axis orientation substantially parallel with said longitudinal substrate; and said second layer which is between said first and third layers comprising a material which is nonmagnetic and which forms a barrier layer between said first and third layers; said second layer being thin enough to permit mutual coupling of the easy axis demagnetizing components of said magnetic layer and thick enough to substantially eliminate transverse magnetic exchange coupling between said magnetic layers.
Claim 4
Dependent Claim
128 words
A bistable magnetic data storage device comprising: a cylindrical substrate of conductive nonmagnetic material; a data storage medium superimposed on said substrate comprising at least a first, second, and third circumferentially continuous, concentric and longitudinally coextensive layers; said first and third layers comprising an alloy including NiFe; said first and third layers each having an easy axis orientation substantially parallel with said longitudinal substrate; and said second layer which is between said first and third layers comprising a material which is nonmagnetic and which forms a barrier layer between said first and third layers; said second layer being thin enough to permit mutual coupling of the easy axis demagnetizing components of said magnetic layer and thick enough to substantially eliminate transverse magnetic exchange coupling between said magnetic layers.
Claim 5
Dependent Claim
21 words
A magnetic storage device in accordance with claim 2 in which said second layer has a thickness greater than 200 A.
Claim 6
Dependent Claim
69 words
A bistable magnetic data storage device in accordance with claim 2 in which said first and third magnetic layers have substantially equal anisotropy field strength; and said second layer is a conductive material having a thickness further sufficient to sustain circumferential eddy currents whereby a solenoidal field is generated parallel with the axis of said substrate upon rotation of the magnetization vectors of said first and third magnetic layers.
Claim 7
Dependent Claim
24 words
A bistable magnetic data storage device in accordance with claim 2 in which said first and third magnetic layers have unequal anisotropy field strength.
Claim 8
Dependent Claim
20 words
A bistable magnetic data storage device in accordance with claim 5 in which said second layer is a conductive material.
Claim 9
Dependent Claim
19 words
A bistable magnetic storage device in accordance with claim 5 in which said second layer is a dielectric material.
Claim 10
Dependent Claim
116 words
A bistable magnetic data storage device comprising in combination: a cylindrical substrate of conductive nonmagnetic material; a data storage medium on said substrate comprising first, second, and third closed concentric magnetic layers; said magnetic layers comprising an alloy including NiFe; each of said magnetic layers having a preferred direction of magnetic orientation parallel with the axis of said substrate; and said storage medium further comprising conductive barrier layers separating said magnetic layers; said conductive barrier layers being thin enough to permit mutual coupling of the easy axis demagnetizing components of said magnetic layers and thick enough to substantially eliminate transverse magnetic exchange coupling between said magnetic layers; said magnetic and said barrier layers beIng longitudinally coextensive.
Claim 11
Dependent Claim
116 words
A bistable magnetic data storage device comprising in combination: a cylindrical substrate of conductive nonmagnetic material; a data storage medium on said substrate comprising first, second, and third closed concentric magnetic layers; said magnetic layers comprising an alloy including NiFe; each of said magnetic layers having a preferred direction of magnetic orientation parallel with the axis of said substrate; and said storage medium further comprising conductive barrier layers separating said magnetic layers; said conductive barrier layers being thin enough to permit mutual coupling of the easy axis demagnetizing components of said magnetic layers and thick enough to substantially eliminate transverse magnetic exchange coupling between said magnetic layers; said magnetic and said barrier layers beIng longitudinally coextensive.
Claim 12
Dependent Claim
38 words
A bistable magnetic data storage device in accordance with claim 8 in which said third layer is the outer layer and has a magnetic thickness substantially equal to the combined magnetic thickness of said first and second layers.
Claim 13
Dependent Claim
48 words
A bistable magnetic data storage element in accordance with claim 9 in which said first and second inner magnetic layers have magnetization vectors oriented parallel with each other and said third magnetic layer has a magnetization vector antiparallel with said magnetization vectors of said first and second layers.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-26 | 1974-10-26 | 1975-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-26 | 1978-10-26 | 1979-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-26 | 1982-10-26 | 1983-04-27 | $7700.00 | Window Closed / Lapsed |