# US 7,609,489 B2 · Magnetic sensor using NiFe alloy for pinned layer

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- Number: US 7,609,489 B2
- Document ID: US7609489B2
- Status: Granted
- Kind: B2
- Application number: 11/366,002
- Filed: 2006-02-28
- Published: 2006-09-07
- Granted: 2009-10-27
- Earliest claimed: 2005-03-03
- Assignees: TDK Corporation
- Inventors: Yosuke Ide; Masamichi Saito; Masahiko Ishizone; Naoya Hasegawa
- Web page: https://patentgrep.com/patent/US7609489B2

## CPC

- G11B 5/3929: {Disposition of magnetic thin films not used for directly coupling magnetic flux from the track to the MR film or for shielding}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

A magnetic sensor comprising: a multilayer film which has a pinned magnetic layer, the magnetization thereof being pinned in one direction, and a free magnetic layer formed on the pinned magnetic layer with a nonmagnetic material layer provided therebetween, in which current is allowed to flow in a direction perpendicular to the surfaces of the layers forming the multilayer film, wherein the pinned magnetic layer has a NiaFeb alloy layer (where a and b each indicate atomic percent, and 0<a≦25 and a+b=100 are satisfied).

## Claims

### Claim 1

A magnetic sensor comprising: a multilayer film which has a pinned magnetic layer, the magnetization thereof being pinned in one direction, and a free magnetic layer formed on the pinned magnetic layer with a nonmagnetic material layer provided therebetween, in which current is allowed to flow in a direction perpendicular to the surfaces of the layers forming the multilayer film,
wherein the pinned magnetic layer has a NiaFeb alloy layer (where a and b each indicate atomic percent, and 0<a≦25 and a+b=100 are satisfied).

### Claim 2 (depends on 1)

The magnetic sensor according to claim 1, wherein the pinned magnetic layer has a NiaFeb alloy layer (where a and b each indicate atomic percent, and 4≦a≦23 and a+b=100 are satisfied).

### Claim 3 (depends on 2)

The magnetic sensor according to claim 2, wherein the pinned magnetic layer has a NiaFeb alloy layer (where a and b each indicate atomic percent, and 15≦a≦20 and a+b=100 are satisfied).

### Claim 4 (depends on 1)

The magnetic sensor according to claim 1, wherein the pinned magnetic layer has a three-layered structure composed of two CoFe layers provided on the top and the bottom of the NiaFeb alloy layer.

### Claim 5 (depends on 1)

The magnetic sensor according to claim 1, wherein a product ΔR·A is 5 mΩ·μm2 or more, ΔR being the change in resistance and A being an element area.

### Claim 6 (depends on 1)

The magnetic sensor according to claim 1, wherein the free magnetic layer has a Co2YZ alloy layer (where Y indicates at least one element selected from the group consisting of Mn, Fe, and Cr, and Z indicates at least one element selected from the group consisting of Al, Ga, Si, Ge, Sn, In, Sb, Pb, and Zn).

### Claim 7 (depends on 1)

The magnetic sensor according to claim 1, wherein the pinned magnetic layer is provided at an upper side of the free magnetic layer.

### Claim 8 (depends on 1)

The magnetic sensor according to claim 1, wherein the pinned magnetic layer is provided at a lower side of the free magnetic layer.

### Claim 9 (depends on 1)

The magnetic sensor according to claim 1, wherein the nonmagnetic material layer and the pinned magnetic layer are provided under the free magnetic layer, further comprising a nonmagnetic material layer and a pinned magnetic layer on the free magnetic layer.

### Claim 10 (depends on 7)

The magnetic sensor according to claim 7, wherein the magnetization of the pinned magnetic layer is pinned in one direction by uniaxial anisotropy thereof.

### Claim 11 (depends on 7)

The magnetic sensor according to claim 7, further comprising an antiferromagnetic layer which is provided on the pinned layer.

### Claim 12 (depends on 4)

The magnetic sensor according to claim 4, wherein the NiaFeb alloy layer has a thickness equal to or greater than a thickness of at least one of the two CoFe layers.

### Claim 13 (depends on 4)

The magnetic sensor according to claim 4, wherein the NiaFeb alloy layer has a thickness of 15 Å to 50 Å, and at least one of the two CoFe layers has a thickness of 5 Å to 15 Å.

### Claim 14 (depends on 1)

The magnetic sensor according to claim 1, wherein the pinned magnetic layer has an artificial ferrimagnetic coupling structure composed of a first magnetic layer, a second magnetic layer, and a nonmagnetic interlayer provided therebetween, wherein the second magnetic layer is provided at a side closer to the free magnetic layer.