US5768183A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-layer magnetic memory cells with improved switching characteristics
Assignee: Everspin Technologies Inc
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Filing: 1996-09-25
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Granted: 1998-06-16
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Expires: 2016-09-25
Abstract
Abstract A plurality of layers of magnetic material are stacked in parallel, overlying relationship and separated by layers of non-magnetic material so as to form a multi-layer magnetic memory cell. The width of the cell is less than a width of magnetic domain walls within the magnetic layers so that magnetic vectors in the magnetic layers point along a length of the magnetic layers, and the ratio of the length to the width of the magnetic memory cell is in a range of 1.5 to 10. The magnetic layers are antiferromagnetically coupled when the ratio is less than 4 and ferromagnetically coupled when the ratio is greater than 4.
Inventors
- 👤 Xiaodong T. Zhu
- 👤 Saied N. Tehrani
- 👤 Mark Durlam
- 👤 Eugene Chen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:46
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/56; G11C11/5607; G11C11/02; G11C11/14; G11C11/15; G11C2211/00; G11C2211/56; G11C2211/561; G11C2211/5615
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
113 words
A multi-state, multi-layer magnetic memory cell comprising: a plurality of layers of magnetic material stacked in parallel, overlying relationship and separated by layers of non-magnetic material so as to form a multi-layer magnetic memory cell having a length and a width; the width of the multi-layer magnetic memory cell being less than a width of magnetic domain walls within the layers of magnetic material wherein magnetic vectors in the layers of magnetic material point substantially along a length of the layers of magnetic material; and a ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell being in a range of 1.5 to 10.
Claim 2
Dependent Claim
113 words
A multi-state, multi-layer magnetic memory cell comprising: a plurality of layers of magnetic material stacked in parallel, overlying relationship and separated by layers of non-magnetic material so as to form a multi-layer magnetic memory cell having a length and a width; the width of the multi-layer magnetic memory cell being less than a width of magnetic domain walls within the layers of magnetic material wherein magnetic vectors in the layers of magnetic material point substantially along a length of the layers of magnetic material; and a ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell being in a range of 1.5 to 10.
Claim 3
Dependent Claim
69 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 1 wherein the plurality of layers of magnetic material stacked in parallel, overlying relationship and separated by layers of non-magnetic material define a central plane parallel with the stacked layers, the plurality of layers of magnetic material being formed and positioned on either side of the central plane so as to form a symmetrical stack about the central plane.
Claim 4
Dependent Claim
95 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 2 wherein the plurality of layers of magnetic material includes two substantially similar first layers positioned on opposite sides of the central plane and each having a first thickness, the two substantially similar first layers being separated by a layer of non-magnetic material, and two substantially similar second layers positioned on opposite sides of the first layers and separated from the first layers by layers of non-magnetic material, each of the two substantially similar second layers having a second thickness greater than the first thickness.
Claim 5
Dependent Claim
24 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 2 wherein the layers of non-magnetic material are formed with non-magnetic, electrically insulative material.
Claim 6
Dependent Claim
24 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 1 wherein the layers of non-magnetic material are formed with non-magnetic, electrically conductive material.
Claim 7
Dependent Claim
47 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 1 wherein the ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell is approximately 5 and the first and second layers of magnetic material are ferromagnetically coupled.
Claim 8
Dependent Claim
49 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 1 wherein the ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell is less than approximately 4 and the first and second layers of magnetic material are antiferromagnetically coupled.
Claim 9
Dependent Claim
170 words
A multi-state, multi-layer magnetic memory cell comprising: a first layer of magnetic material having a first thickness; a layer of non-magnetic material positioned adjacent the first layer of magnetic material; a second layer of magnetic material positioned adjacent the layer of non-magnetic material and having a second thickness greater than the first thickness, the first layer of magnetic material and the second layer of magnetic material being separated by the layer of non-magnetic material and stacked in parallel overlying relationship to form a multi-layer magnetic memory cell having a length and a width; the first and second layers of magnetic material each having a width that is less than a width of magnetic domain walls within the layer of magnetic material wherein magnetic vectors in the layers of magnetic material point substantially along a length of the layers of magnetic material; and a ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell being in a range of 1.5 to 10.
Claim 10
Dependent Claim
170 words
A multi-state, multi-layer magnetic memory cell comprising: a first layer of magnetic material having a first thickness; a layer of non-magnetic material positioned adjacent the first layer of magnetic material; a second layer of magnetic material positioned adjacent the layer of non-magnetic material and having a second thickness greater than the first thickness, the first layer of magnetic material and the second layer of magnetic material being separated by the layer of non-magnetic material and stacked in parallel overlying relationship to form a multi-layer magnetic memory cell having a length and a width; the first and second layers of magnetic material each having a width that is less than a width of magnetic domain walls within the layer of magnetic material wherein magnetic vectors in the layers of magnetic material point substantially along a length of the layers of magnetic material; and a ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell being in a range of 1.5 to 10.
Claim 11
Dependent Claim
25 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 8 wherein the width of the multi-layer magnetic memory cell is less than 1 micrometer.
Claim 12
Dependent Claim
24 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 9 wherein the width of the multi-layer magnetic memory cell is approximately 0.1 micrometers.
Claim 13
Dependent Claim
47 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 8 wherein the ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell is approximately 5 and the first and second layers of magnetic material are ferromagnetically coupled.
Claim 14
Dependent Claim
49 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 8 wherein the ratio of the length of the multi-layer magnetic memory cell to the width of the multi-layer magnetic memory cell is less than approximately 4 and the first and second layers of magnetic material are antiferromagnetically coupled.
Claim 15
Dependent Claim
91 words
A multi-state, multi-layer magnetic memory cell as claimed in claim 8 wherein the first layer of magnetic material has a first magnetic state and a second magnetic state and is switchable between the first and second magnetic states by a magnetic field with a strength of less than approximately 20 Oersteds and the second layer of magnetic material has a first magnetic state and a second magnetic state and is switchable between the first and second magnetic states by a magnetic field with a strength of greater than approximately 60 Oersteds.
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) | 2001-06-15 | 2001-12-15 | 2002-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-06-15 | 2005-12-15 | 2006-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-06-15 | 2009-12-15 | 2010-06-16 | $7700.00 | Window Closed / Lapsed |