# US 8,570,689 B2 · Differential magnetoresistive effect head and magnetic recording/reading device

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- Number: US 8,570,689 B2
- Document ID: US8570689B2
- Status: Granted
- Kind: B2
- Application number: 12/628,577
- Filed: 2009-12-01
- Published: 2010-06-10
- Granted: 2013-10-29
- Earliest claimed: 2008-12-09
- Assignees: HGST Netherlands B.V.
- Applicants: Yo Sato; Katsumi Hoshino; Masato Shiimoto; Takeshi Nakagawa; Hiroyuki Hoshiya
- Inventors: Yo Sato; Katsumi Hoshino; Masato Shiimoto; Takeshi Nakagawa; Hiroyuki Hoshiya
- Web page: https://patentgrep.com/patent/US8570689B2

## CPC

- G11B 5/3948: {the sensitive elements being active read-out elements}
- B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
- G01R 33/093: {using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00)}
- G11B 5/3906: {Details related to the use of magnetic thin film layers or to their effects}
- H01F 10/3268: {the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn}
- H10N 50/10: Magnetoresistive devices
- H01F 10/3254: {the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]}
- 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)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

According to one embodiment, a differential magnetoresistive effect element comprises a first magnetoresistive effect element having a first pinning layer, a first intermediate layer, and a first free layer. The differential magnetoresistive effect element also comprises a second magnetoresistive effect element stacked via a spacer layer above the first magnetoresistive effect element, the second magnetoresistive effect element having a second pinning layer, a second intermediate layer, and a second free layer. The first magnetoresistive effect element and the second magnetoresistive effect element show in-opposite-phase resistance change in response to a magnetic field in the same direction, and tp2>tp1 is satisfied when a thickness of the first pinning layer is tp1, and a thickness of the second pinning layer is tp2. In another embodiment, the first and second magnetoresistive effect elements may be CPP-GMR elements. Other elements, heads, and magnetic recording/reading devices are described according to other embodiments.

## Claims

### Claim 1

A differential magnetoresistive effect element comprising:
a first magnetoresistive effect element having:
a first pinning layer;
a first intermediate layer; and
a first free layer; and
a second magnetoresistive effect element stacked above a spacer layer that is positioned above the first magnetoresistive effect element, the second magnetoresistive effect element having:
a second pinning layer;
a second intermediate layer; and
a second free layer;
wherein the first magnetoresistive effect element and the second magnetoresistive effect element show in-opposite-phase resistance change in response to a magnetic field in the same direction, and
wherein tp2>tp1 is satisfied when a thickness of the first pinning layer is tp1, and a thickness of the second pinning layer is tp2,
wherein the first pinning layer has more ferromagnetic layers than the second pinning layer.

### Claim 2 (depends on 1)

The differential magnetoresistive effect element according to claim 1, wherein the first magnetoresistive effect element is physically characterized as having layers positioned in the following order: the first pinning layer, the first intermediate layer, and the first free layer from a substrate side, and wherein the second magnetoresistive effect element is physically characterized as having layers in the following order: the second free layer, the second intermediate layer, and the second pinning layer from a side closer to the spacer layer.

### Claim 3 (depends on 1)

The differential magnetoresistive effect element according to claim 1, wherein the first magnetoresistive effect element is physically characterized as having layers in the following order: the first pinning layer, the first intermediate layer, and the first free layer in order from a substrate side, and the second magnetoresistive effect element is physically characterized as having layers in the following order the second pinning layer, the second intermediate layer, and the second free layer from a spacer layer side.

### Claim 4 (depends on 1)

The differential magnetoresistive effect element according to claim 1, wherein the first magnetoresistive effect element and the second magnetoresistive effect element are CPP-GMR elements.

### Claim 5 (depends on 1)

The differential magnetoresistive effect element according to claim 1, wherein tp2-tpl is less than about 2.0 nm and greater than about 0.2 nm.

### Claim 6 (depends on 1)

A magnetic head having a recording head and a read head, wherein the read head comprises the differential magnetoresistive effect element as recited in claim 1, wherein the second pinning layer is positioned between the first and second free layers.

### Claim 7 (depends on 1)

A magnetic recording reading device, comprising:
a magnetic recording medium;
a medium drive section that drives the magnetic recording medium;
a magnetic head having:
a recording head;
a read head having the differential magnetoresistive effect element as recited in claim 1; and
a head drive section that positions the magnetic head onto a desired track of the magnetic recording medium.

### Claim 8

A differential magnetoresistive effect element comprising:
a first magnetoresistive effect element having:
a first pinning layer;
a first intermediate layer; and
a first free layer; and
a second magnetoresistive effect element stacked via a spacer layer above the first magnetoresistive effect element, the second magnetoresistive effect element having:
a second pinning layer;
a second intermediate layer; and
a second free layer;
wherein the first magnetoresistive effect element and the second magnetoresistive effect element show in-opposite-phase resistance change in response to a magnetic field in the same direction, and
wherein ti2<ti1 when a thickness of the first intermediate layer is ti1, and a thickness of the second intermediate layer is ti2,
wherein the second pinning layer and the spacer layer are positioned between the first and second free layers.

### Claim 9 (depends on 8)

The differential magnetoresistive effect element according to claim 8, wherein the first magnetoresistive effect element is physically characterized as having layers in the following order the first pinning layer, the first intermediate layer, and the first free layer from a substrate side, and wherein the second magnetoresistive effect element is physically characterized as having layers in the following order the second free layer, the second intermediate layer, and the second pinning layer from a spacer layer side wherein the first pinning layer has more ferromagnetic layers than the second pinning layer.

### Claim 10 (depends on 8)

The differential magnetoresistive effect element according to claim 8, wherein the first magnetoresistive effect element is physically characterized as having layers in the following order the first pinning layer, the first intermediate layer, and the first free layer in order from a substrate side, and the second magnetoresistive effect element is physically characterized as having layers in the following order the second pinning layer, the second intermediate layer, and the second free layer from a spacer layer side.

### Claim 11 (depends on 8)

The differential magnetoresistive effect element according to claim 8, wherein the first magnetoresistive effect element and the second magnetoresistive effect element are CPP-GMR elements.

### Claim 12 (depends on 11)

A magnetic head having a recording head and a read head, wherein the read head comprises the differential magnetoresistive effect element according to claim 11, wherein the first pinning layer has more ferromagnetic layers than the second pinning layer.

### Claim 13 (depends on 12)

A magnetic recording reading device, comprising:
a magnetic recording medium;
a medium drive section that drives the magnetic recording medium;
a magnetic head as recited in claim 12; and
a head drive section that positions the magnetic head onto a desired track of the magnetic recording medium.

### Claim 14 (depends on 8)

A magnetic head having a recording head and a read head, wherein the read head comprises the differential magnetoresistive effect element as recited in claim 8.

### Claim 15 (depends on 8)

A magnetic recording/reading device, comprising:
a magnetic recording medium;
a medium drive section that drives the magnetic recording medium;
a magnetic head having:
a recording head;
a read head having the differential magnetoresistive effect element as recited in claim 8; and
a head drive section that positions the magnetic head onto a desired track of the magnetic recording medium.

### Claim 16 (depends on 8)

The differential magnetoresistive effect element according to claim 8, wherein ti1-ti2 is less than about 3.0 nm and greater than about 0.2 nm.

### Claim 17

A magnetic recording/reading device, comprising:
a magnetic recording medium;
a medium drive section that drives the magnetic recording medium; and
a magnetic head, the magnetic head having:
a recording head;
a head drive section that positions the magnetic head onto a desired track of the magnetic recording medium; and
a read head, the read head including a differential magnetoresistive effect element, the differential magnetoresistive effect element comprising:
a first magnetoresistive effect element having:
a first pinning layer;
a first intermediate layer; and
a first free layer; and
a second magnetoresistive effect element stacked via a spacer layer above the first magnetoresistive effect element, the second magnetoresistive effect element having:
a second pinning layer;
a second intermediate layer; and
a second free layer;
wherein the first magnetoresistive effect element and the second magnetoresistive effect element show in-opposite-phase resistance change in response to a magnetic field in the same direction,
wherein the second pinning layer and the spacer layer are positioned between the first and second free layers,
wherein the first pinning layer has more ferromagnetic layers than the second pinning layer;
wherein tp2>tp1 is satisfied when a thickness of the first pinning layer is tp1, and a thickness of the second pinning layer is tp2.

### Claim 18 (depends on 17)

The device according to claim 17, wherein ti2<ti1 when a thickness of the first intermediate layer is ti1, and a thickness of the second intermediate layer is ti2.