# US 5,702,831 A · Ferromagnetic GMR material

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- Number: US 5,702,831 A
- Document ID: US5702831A
- Status: Granted
- Kind: A
- Application number: 08/553,933
- Filed: 1995-11-06
- Granted: 1997-12-30
- Earliest claimed: 1995-11-06
- Assignees: Motorola, Inc.
- Inventors: Eugene Chen; Saied N. Tehrani
- Web page: https://patentgrep.com/patent/US5702831A

## CPC

- H10N 50/10: Magnetoresistive devices
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
- G11C 11/15: using multiple magnetic layers (G11C11/155 takes precedence)
- H01F 10/324: {Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer}
- H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- Y10S 428/90: Magnetic feature
- Y10S 428/928: Magnetic property
- Y10T 428/1129: Super lattice [e.g., giant magneto resistance [GMR] or colossal magneto resistance [CMR], etc.]
- Y10T 428/12465: having magnetic properties, or preformed fiber orientation coordinate with shape
- Y10T 428/12632: Four or more distinct components with alternate recurrence of each type component
- Y10T 428/1275: Next to Group VIII or IB metal-base component
- Y10T 428/12854: Next to Co-, Fe-, or Ni-base component
- Y10T 428/12861: Group VIII or IB metal-base component
- Y10T 428/1291: Next to Co-, Cu-, or Ni-base component
- Y10T 428/12917: Next to Fe-base component
- Y10T 428/12931: Co-, Fe-, or Ni-base components, alternative to each other
- Y10T 428/12944: Ni-base component
- Y10T 428/12951: Fe-base component
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H10B: ELECTRONIC MEMORY DEVICES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A multi-layer magnetic material (10) has magnetic vectors (21,22) that point along a length (27) of the material (10). Opposing magnetic fields cause the vectors to snap past the perpendicular position with a rapid change in the resistance of the material. The material is used as a memory cell (37,38,39,41) of a memory (36).

## Claims

### Claim 1

A ferromagnetically coupled GMR material comprising:
a plurality of magnetic layers having a width and a length wherein the width is no greater than a transition width and wherein each magnetic layer is ferromagnetically coupled to an adjacent magnetic layer and substantially all magnetic vectors in each layer of the plurality of magnetic layers substantially align along the length; and
a plurality of conductive spacers separating the plurality of magnetic layers.

### Claim 2 (depends on 1)

The material of claim 1 wherein a first magnetic layer of the plurality of magnetic layers has a first thickness and a second magnetic layer of the plurality of magnetic layers has a second thickness that is greater than the first thickness.

### Claim 3 (depends on 2)

The material of claim 2 wherein magnetic vectors in a first layer of the plurality of layers substantially point in the same direction as magnetic vectors in all other layers of the plurality of magnetic layers.

### Claim 4 (depends on 1)

The material of claim 1 wherein magnetic vectors within each layer of the plurality of layers all point toward a first end of the material to represent a first logic state and toward a second end of the material to represent a second logic state.

### Claim 5

A multilayer ferromagnetically coupled GMR material comprising:
a first composite magnetic layer having a first width, a first thickness, and a first length;
a first conductive spacer layer; and
a second composite magnetic layer having a second width, a second thickness that is greater than the first thickness, and a second length wherein the first conductive spacer layer is between the first and second magnetic layers wherein the first and second widths are no greater than a first transition width and wherein the first and second magnetic layers are ferromagnetically coupled and magnetic vectors in the first and second composite magnetic layers point substantially parallel to the first and second lengths.

### Claim 6 (depends on 5)

The material of claim 5 further including a third composite magnetic layer having a third width, a third thickness, and a third length, and a second conductive spacer layer between the second and third composite magnetic layers wherein the third composite magnetic layer is ferromagnetically coupled to the second composite magnetic layer and wherein the third width is no greater than a second transition width that causes magnetic vectors in the third composite magnetic layer to point substantially along the third length.

### Claim 7 (depends on 6)

The material of claim 6 wherein the third thickness is approximately equal to the first thickness.

### Claim 8 (depends on 6)

The material of claim 6 further including a fourth composite magnetic layer having a fourth width, a fourth thickness, and a fourth length, and a third conductive spacer layer between the third and fourth composite magnetic layers wherein the fourth composite magnetic layer is ferromagnetically coupled to the third composite magnetic layer and wherein the fourth width is no greater than a third transition width that causes neighboring magnetization's in the fourth composite magnetic layer to point substantially along the fourth length.

### Claim 9 (depends on 5)

The material of claim 5 wherein the first and second lengths are substantially equal.

### Claim 10 (depends on 8)

The material of claim 8 wherein the first, second, third, and fourth lengths are equal.

### Claim 11 (depends on 5)

The material of claim 5 wherein the first and second widths are substantially equal and less than one micron.

### Claim 12 (depends on 8)

The material of claim 8 wherein both the first and third composite magnetic layers composite structures that include a layer of nickel-iron-cobalt and a layer of cobalt-iron.

### Claim 13 (depends on 5)

The material of claim 5 wherein one of the first or second magnetic layers include a layer of one of nickel, iron, cobalt, or alloys thereof including alloys having one of palladium or platinum.

### Claim 14 (depends on 8)

The material of claim 8 wherein one of the first or second magnetic layers include a layer of one of nickel, iron, cobalt, or alloys thereof including alloys having one of palladium or platinum.

### Claim 15 (depends on 5)

The material of claim 5 wherein the first conductive spacer includes a layer of one of copper, a copper alloy, chromium, or a chromium alloy.