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US3662359A
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Method and apparatus for creation of cylindrical, single wall domains
Assignee: International Business Machines Corp
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Filing: 1970-12-31
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Granted: 1972-05-09
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Expires: 1990-12-31
Abstract
Abstract A method and apparatus for creation of cylindrical, single wall domains in selected locations in a magnetic sheet, such as orthoferrite or garnet films. A bias (stabilizing) magnetic field is applied normal to the magnetic sheet to saturate the sheet in one direction so that no reversely magnetized domains are present in the storage area. A localized magnetic field normal to the magnetic sheet but oppositely directed with respect to the bias field is then created. This localized field is produced by the action of an in-plane field and a bar of magnetic material on the sheet, or by a small current loop. The bias field is then reduced until a domain in nucleated at the site of the localized field. The domain will nucleate when the net reversely directed local field is greater than the nucleation field Hn at that location. The bias field is then increased to regulate the diameter of the domain produced. Means are provided to create a variable bias field normal to the sheet and to create an oppositely directed variable localized field at selected locations in the shett.
Inventors
- 👤 Eugene R Genovese
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:18
CPC Classifications
G; G11; G11C; G11C19/00; G11C19/02; G11C19/08; G11C19/0858
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
103 words
A method for nucleating a cylindrical magnetic domain in a magnetic sheet, said domain having a magnetization normal to the plane of said sheet, comprising the steps of: magnetically saturating said sheet by a first magnetic field Hz normal to said sheet; producing a localized magnetic field Hp oppositely directed to said first magnetic field; reducing the magnitude of said first magnetic field to a value at which Hp-Hz is at least equal to Hn, where Hn is the nucleation field of said sheet at the location of said Hp field, thereby nucleating a cylindrical domain at the site of said localized field.
Claim 2
Independent Claim
103 words
A method for nucleating a cylindrical magnetic domain in a magnetic sheet, said domain having a magnetization normal to the plane of said sheet, comprising the steps of: magnetically saturating said sheet by a first magnetic field Hz normal to said sheet; producing a localized magnetic field Hp oppositely directed to said first magnetic field; reducing the magnitude of said first magnetic field to a value at which Hp-Hz is at least equal to Hn, where Hn is the nucleation field of said sheet at the location of said Hp field, thereby nucleating a cylindrical domain at the site of said localized field.
Claim 3
Dependent Claim
25 words
The method of claim 1, having the further step of increasing the magnitude of said first field to regulate the diameter of said nucleated domain.
Claim 4
Dependent Claim
27 words
The method of claim 1, where said localized field is created by the action of an in-plane magnetic field on a magnetic element located on said sheet.
Claim 5
Dependent Claim
19 words
The method of claim 3, where said in-plane field is used to propagate said nucleated domains in said sheet.
Claim 6
Dependent Claim
21 words
The method of claim 1, where said localized field is produced by a current loop in the plane of said sheet.
Claim 7
Dependent Claim
21 words
The method of claim 1, where said localized field is produced by magnetic elements located on both sides of said sheet.
Claim 8
Dependent Claim
30 words
The method of claim 1, where said localized field is produced by current loops in the plane of said sheet, said loops being located on opposite sides of said sheet.
Claim 9
Dependent Claim
27 words
The method of claim 1, further including the step of creating a magnetic non-uniformity at the site of said localized field before said localized field is produced.
Claim 10
Independent Claim
80 words
A method for nucleating a cylindrical magnetic domain in a magnetic sheet, said domain having a magnetization normal to the plane of said sheet, comprising the steps of: establishing a magnetic non-uniformity in said sheet at a desired location; magnetically saturating said sheet; producing a localized magnetic field at the location of said non-uniformity, said localized field being at least equal in magnitude to the nucleation field of said sheet at said location, thereby nucleating said domain at said location.
Claim 11
Independent Claim
80 words
A method for nucleating a cylindrical magnetic domain in a magnetic sheet, said domain having a magnetization normal to the plane of said sheet, comprising the steps of: establishing a magnetic non-uniformity in said sheet at a desired location; magnetically saturating said sheet; producing a localized magnetic field at the location of said non-uniformity, said localized field being at least equal in magnitude to the nucleation field of said sheet at said location, thereby nucleating said domain at said location.
Claim 12
Dependent Claim
22 words
The method of claim 9, where said localized field is created by the magnetization of a magnetic element located on said sheet.
Claim 13
Dependent Claim
32 words
The method of claim 9, where said localized field is produced by the action of a current through a conductor loop whose plane is substantially parallel to the plane of said sheet.
Claim 14
Dependent Claim
27 words
The method of claim 9, where said localized field is produced by a magnetic field existing between magnetic elements located on both sides of said magnetic sheet.
Claim 15
Independent Claim
84 words
An apparatus for producing cylindrical domains at desired locations in a magnetic sheet capable of supporting said domains, comprising: means for producing a uniform magnetic field normal to said sheet of variable magnitude sufficient to magnetically saturate said sheet; means for producing a localized magnetic field normal to said sheet and oppositely directed to said uniform field, said local field being sufficient to enable nucleation of a domain at the site of said localized magnetic field when said uniform field is reduced in magnitude.
Claim 16
Independent Claim
84 words
An apparatus for producing cylindrical domains at desired locations in a magnetic sheet capable of supporting said domains, comprising: means for producing a uniform magnetic field normal to said sheet of variable magnitude sufficient to magnetically saturate said sheet; means for producing a localized magnetic field normal to said sheet and oppositely directed to said uniform field, said local field being sufficient to enable nucleation of a domain at the site of said localized magnetic field when said uniform field is reduced in magnitude.
Claim 17
Dependent Claim
17 words
The apparatus of claim 13, further including means for creating a localized magnetic non-uniformity in said sheet.
Claim 18
Dependent Claim
33 words
The apparatus of claim 13, where said means for producing said localized field comprises a magnetic element located on said sheet, and a means for producing a magnetic field to magnetize said element.
Claim 19
Dependent Claim
28 words
The apparatus of claim 13, where Said means for producing said localized field comprises a current loop whose plane is parallel to the plane of said magnetic sheet.
Claim 20
Independent Claim
83 words
An apparatus for producing cylindrical magnetic domains at desired locations in a magnetic sheet capable of supporting said domains, comprising: means for producing a localized magnetic non-uniformity in said sheet; means for producing a uniform magnetic field normal to said sheet of magnitude sufficient to magnetically saturate said sheet; means for producing a magnetic field oppositely directed to said uniform field at the location of said magnetic non-uniformity, said localized field being of magnitude sufficient to nucleate a cylindrical domain at said non-uniformity.
Claim 21
Independent Claim
83 words
An apparatus for producing cylindrical magnetic domains at desired locations in a magnetic sheet capable of supporting said domains, comprising: means for producing a localized magnetic non-uniformity in said sheet; means for producing a uniform magnetic field normal to said sheet of magnitude sufficient to magnetically saturate said sheet; means for producing a magnetic field oppositely directed to said uniform field at the location of said magnetic non-uniformity, said localized field being of magnitude sufficient to nucleate a cylindrical domain at said non-uniformity.
Claim 22
Dependent Claim
25 words
The apparatus of claim 17, where said means for producing a localized field is comprised of at least one magnetic element located on said sheet.
Claim 23
Dependent Claim
31 words
The apparatus of claim 17, where said means for producing a localized field is comprised of at least one current carrying conductor loop whose plane is parallel to said magnetic sheet.
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) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |