EP0613148A2
Expired / Lapsed
EP
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Nonvolatile magnetoresistive storage device
Assignee: International Business Machines Corp
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Filing: 1994-01-25
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Granted: —
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Expires: 2014-01-25
Abstract
Abstract A nonvolatile magnetoresistive (MR) storage device comprising a plurality of MR storage elements, each comprising a substrate and a multilayered structure including two thin film layers of ferromagnetic material separated by a thin layer of nonmagnetic metallic material. The magnetization easy axis of both ferromagnetic layers in each storage element is oriented substantially lengthwise of the storage elements and substantially parallel to the direction of an applied sense current. The magnetization direction of one of the ferromagnetic layers is fixed in a direction substantially lengthwise of the storage elements, and the magnetization direction of the other layer is free to switch between two digital states in which the magnetization is substantially parallel or substantially antiparallel to the magnetization direction in the one layer.
Inventors
- 👤 Kenneth Ting-Yuan Kung
- 👤 Denny Duan-Lee Tang
- 👤 Po-Kang Wang
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 20:21
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/02; G11C11/16; G11C11/161; G11C11/165; G11C11/1673; G11C11/1675
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
103 words
A nonvolatile magnetoresistive storage device including at least one nonvolatile magnetoresistive storage element comprising: a substrate having a rectangular multilayered structure deposited thereon, including two layers of ferromagnetic material separated by a layer of nonmagnetic metallic material, the magnetisation easy axis of both ferromagnetic layers being oriented substantially lengthwise of the storage element, the magnetisation of one of the ferromagnetic layers being fixed in one direction substantially lengthwise of the storage element, and the magnetisation of the other ferromagnetic layer being free to change direction between substantially parallel and substantially antiparallel to the fixed one direction in response to an applied magnetic field.
Claim 2
Dependent Claim
33 words
A nonvolatile magnetoresistive storage device as claimed in claim 1 wherein the width of the storage element is less than the width of magnetic domain walls of the layers of the multilayered structure.
Claim 3
Dependent Claim
52 words
A nonvolatile magnetoresistive storage device as claimed in any of claims 1 or 2 further comprising means for applying magnetic fields to a storage element for switching it between two states representing a "1" or a "0" according to whether the magnetisation directions of the ferromagnetic layers are parallel or antiparallel respectively.
Claim 4
Dependent Claim
46 words
A nonvolatile magnetoresistive storage device as claimed in any of the preceding claims wherein the width of each storage element is less than the length of the storage element by an amount sufficient to ensure that said other layer will remain in a selected domain state.
Claim 5
Dependent Claim
47 words
A nonvolatile magnetoresistive storage device as claimed in any of the preceding claims wherein the electrical resistance is at a minimum or a maximum according to whether the magnetization of said other layer is substantially parallel or substantially antiparallel, respectively, to the magnetization of said one layer.
Claim 6
Dependent Claim
31 words
A nonvolatile magnetoresistive storage device as claimed in any of the preceding claims, further comprising an antiferromagnetic layer for magnetizing said one layer in said fixed one direction by exchange coupling.
Claim 7
Dependent Claim
33 words
A nonvolatile magnetoresistive storage device as claimed in any of the preceding claims wherein said one layer is of a hard magnetic material having greater coercivity than the coercivity of said other layer.
Claim 8
Dependent Claim
29 words
A nonvolatile magnetoresistive storage device as claimed in any of the preceding claims wherein said one layer has sufficiently high anisotropy to retain its magnetization during state switching operations.
Claim 9
Dependent Claim
90 words
A nonvolatile magnetoresistive storage device as claimed in any of the preceding claims comprising: a plurality of spin valve cells, each cell comprising two of the nonvolatile magnetoresistive storage elements, one being an active storage element and the other a reference storage element; at least one differential amplifier; and means for supplying sense current via the active and reference elements of a selectable one of the cells to an associated amplifier to provide a differential output voltage of a magnitude denoting the then current magnetic state of the selected cell.
Claim 10
Dependent Claim
59 words
A nonvolatile magnetoresistive storage device as claimed in claim 9, including means for applying to a desired one of the cells a write current that flows in a direction orthogonal to the direction of the sense current while concurrently supplying the sense current solely to the active element of the desired cell, for storing data in the desired cell.
Claim 11
Dependent Claim
66 words
A nonvolatile magnetoresistive storage device as claimed in any of claims 9 or 10 wherein the sense current induces a transverse magnetic field and the write current induces a longitudinal magnetic field, for thereby writing a "1" or a "0" in the selected cell according to whether the magnetization directions of the ferromagnetic layers of said active storage element are substantially parallel or substantially antiparallel, respectively.
References Cited (Backward Citations)
No citation records indexed.
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