US5757056A
Expired / Lapsed
US
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Multiple magnetic tunnel structures
Assignee: University of Delaware
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Filing: 1996-11-12
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Granted: 1998-05-26
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Expires: 2016-11-12
Abstract
Abstract A double tunnel junction is disclosed that can be used as a magnetic sensor or as random access memories. The preferred embodiment comprises three magnetic metal materials separated by two insulating layers. A current is passed through the first tunnel junction thereby developing a voltage in the second junction. The resistance of this device can be changed over a 100% when an external magnetic field of just a few gauss is applied.
Inventors
- 👤 Siu-Tat Chui
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:38
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; G11B5/3906; G11B5/3909; B; B82; B82Y; B82Y10/00; B82Y25/00; G11C; G11C11/00; G11C11/56; G11C11/5607; H; H10; H10D; H10D48/00; H10D48/40; H10N; H10N50/00; H10N50/10
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
98 words
A double tunnel junction comprising: a first ferromagnetic layer; a first insulating layer disposed on the first ferromagnetic layer; a second layer consisting of a ferromagnetic or paramagnetic material disposed on the first insulating layer and aligned with the first ferromagnetic layer; a second insulating layer disposed on the second layer; a third ferromagnetic layer disposed on the second insulating layer and aligned with the second layer; and means for passing a biasing current from the first ferromagnetic layer to the second layer, wherein a resultant voltage across the second layer and the third ferromagnetic layer is measured.
Claim 2
Dependent Claim
98 words
A double tunnel junction comprising: a first ferromagnetic layer; a first insulating layer disposed on the first ferromagnetic layer; a second layer consisting of a ferromagnetic or paramagnetic material disposed on the first insulating layer and aligned with the first ferromagnetic layer; a second insulating layer disposed on the second layer; a third ferromagnetic layer disposed on the second insulating layer and aligned with the second layer; and means for passing a biasing current from the first ferromagnetic layer to the second layer, wherein a resultant voltage across the second layer and the third ferromagnetic layer is measured.
Claim 3
Dependent Claim
23 words
The double tunnel junction of claim 1, wherein an external magnetic field is imposed on the second layer and the third ferromagnetic layer.
Claim 4
Dependent Claim
26 words
The double tunnel junction of claim 2, wherein a change in the external magnetic field causes a change in the resistance across the double tunnel junction.
Claim 5
Dependent Claim
30 words
The double tunnel junction of claim 3, wherein a change of 100 oersted (Oe) in the magnetic field results in a 100% change in resistance across the double tunnel junction.
Claim 6
Dependent Claim
19 words
The double tunnel junction of claim 1, wherein the ferromagnetic material is iron, Permadur, Permalloy, cobalt, nickel or manganese.
Claim 7
Dependent Claim
20 words
The double tunnel junction of claim 1, wherein the first and second insulating layers comprise aluminum oxide and magnesium oxide.
Claim 8
Dependent Claim
33 words
The double tunnel junction of claim 1, wherein the first and second insulating layers, the first and third ferromagnetic layers, and the second layer each have a thickness of 1 to 10 nanometers.
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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) | 2001-05-25 | 2001-11-24 | 2002-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-25 | 2005-11-24 | 2006-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-25 | 2009-11-24 | 2010-05-26 | $7700.00 | Window Closed / Lapsed |