Magnetoresistive element in which pinned magnetization layers have antiparallel pinned directions, magnetic head and magnetic recording/reproducing apparatus

• US 7,116,529 B2
• Filed: 09/05/2003
• Issued: 10/03/2006
• Est. Priority Date: 09/06/2002
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yoshikawa, Masatoshi, Sahashi, Masashi, Takagishi, Masayuki
• Primary Examiner(s): HEINZ, ALLEN J
• Application Number:
  US10/654,988
• Publication Number:
  US 20040114280A1
• Time in Patent Office: 1,124 Days
• Field of Search: 3603241-3242
• US Class Current: 360/324.1
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/3906 Details related to the use of magnetic thin film layers or to their effects
• CPC Class Codes: G11B 5/3954 the active elements transducing on a single track

Abstract

A magnetoresistive element has a magnetoresistive film and a pair of electrodes adapted to flow a sense current in a direction substantially perpendicular to a plane of the magnetoresistive film. The magnetoresistive film includes first and second magnetization free layers and first to fourth magnetization pinned layers with nonmagnetic intermediate layers interposed therebetween. The second magnetization pinned layer and the third magnetization pinned layer are formed between the second nonmagnetic intermediate layer and the third nonmagnetic intermediate layer. The directions of magnetization of the first and second magnetization pinned layers are substantially parallel to each other. The directions of magnetization of the third and fourth magnetization pinned layers are substantially parallel to each other. Further, the direction of magnetization of the second magnetization pinned layer is substantially antiparallel to the direction of magnetization of the third magnetization pinned layer.

Claims

1. A magnetoresistive element, comprising:

a magnetoresistive film; and

a pair of electrodes electrically connected to upper and lower surfaces of the magnetoresistive film, respectively, so as to flow a sense current in a direction substantially perpendicular to a plane of the magnetoresistive film,

in which the magnetoresistive film comprises;

a first magnetization free layer of a ferromagnetic film whose magnetization direction is changed in response to the external magnetic field,

a second magnetization free layer of a ferromagnetic film whose magnetization direction is changed in response to the external magnetic field,

a first magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,

a second magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,

a first nonmagnetic intermediate layer formed between the first magnetization free layer and the first magnetization pinned layer, and

a second nonmagnetic intermediate layer formed between the second magnetization free layer and the second magnetization pinned layer,

the first magnetization pinned layer and the second magnetization pinned layer being formed between the first nonmagnetic intermediate layer and the second nonmagnetic intermediate layer;

the pinned direction of magnetization of a ferromagnetic layer included in the first magnetization pinned layer which is in contact with the first nonmagnetic intermediate layer being substantially antiparallel to the pinned direction of magnetization of a ferromagnetic layer included in the second magnetization pinned layer which is in contact with the second nonmagnetic intermediate layer, and the magnetization of each of the first magnetization pinned layer and the second magnetization pinned layer being pinned by exchange coupling with one antiferromagnetic layer.

2. The magnetoresistive element according to claim 1, wherein one of the first magnetization pinned layer and the second magnetization pinned layer is formed of a single ferromagnetic layer or is formed of a stack of an odd number of ferromagnetic layers and nonmagnetic layers, and the other magnetization pinned layer is formed of a stack of an even number of ferromagnetic layers and nonmagnetic layers.

3. The magnetoresistive element according to claim 1, wherein the pair of electrodes electrically connected to upper and lower surfaces of the magnetoresistive film, respectively, provides a differential output.

4. The magnetoresistive element according to claim 1, wherein a gap between the first and second magnetization free layers ranges from 1 nm to 50 nm.

5. The magnetoresistive element according to claim 1, wherein at least one layer of the first and second nonmagnetic intermediate layers contains an oxide.

6. The magnetoresistive element according to claim 5, wherein the nonmagnetic intermediate layer containing the oxide has a thickness ranging from 0.5 nm to 5 nm.

7. A magnetic head comprising the magnetoresistive element according to claim 1.

8. A magnetic recording/reproducing apparatus, comprising:

the magnetic head according to claim 7; and

a perpendicular magnetic recording medium.

9. A magnetoresistive element, comprising:

a magnetoresistive film; and

a pair of electrodes electrically connected to upper and lower surfaces of the magnetoresistive film, respectively, so as to flow a sense current in a direction substantially perpendicular to a plane of the magnetoresistive film,

in which the magnetoresistive film comprises;

a first magnetization free layer of a ferromagnetic film whose magnetization direction is changed in response to the external magnetic field,

a second magnetization free layer of a ferromagnetic film whose magnetization direction is changed in response to the external magnetic field,

a first magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,

a second magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,

a third magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,

a fourth magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,

a first nonmagnetic intermediate layer formed between the first magnetization free layer and the first magnetization pinned layer,

a second nonmagnetic intermediate layer formed between the first magnetization free layer and the second magnetization pinned layer,

a third nonmagnetic intermediate layer formed between the second magnetization free layer and the third magnetization pinned layer, and

a fourth nonmagnetic intermediate layer formed between the second magnetization free layer and the fourth magnetization pinned layer,

the second magnetization pinned layer and the third magnetization pinned layer being formed between the second nonmagnetic intermediate layer and the third nonmagnetic intermediate layer;

the pinned direction of magnetization of the first magnetization pinned layer is substantially parallel to the pinned direction of magnetization of the second magnetization pinned layer, the pinned direction of magnetization of the third magnetization pinned layer is substantially parallel to the pinned direction of magnetization of the fourth magnetization pinned layer, and the pinned direction of magnetization of the second magnetization pinned layer is substantially antiparallel to the pinned direction of magnetization of the third magnetization pinned layer.

10. The magnetoresistive element according to claim 9, wherein, when the magnetization pinned layers are classified into two sets consisting of a first set of the first magnetization pinned layer and the second magnetization pinned layer and a second set of the third magnetization pinned layer and the fourth magnetization pinned layer, each of the magnetization pinned layers for one set is formed of a single ferromagnetic layer or is formed of a stack of an odd number of ferromagnetic layers and nonmagnetic layers, and each of the magnetization pinned layers for the other set is formed of a stack of an even number of ferromagnetic layers and nonmagnetic layers.

11. The magnetoresistive element according to claim 9, wherein,

the magnetization of the first magnetization pinned layer is pinned by exchange coupling with a first ferromagnetic layer;

the magnetization of each of the second magnetization pinned layer and the third magnetization pinned layer is pinned by exchange coupling with a second antiferromagnetic layer; and

the magnetization of the fourth magnetization pinned layer is pinned by exchange coupling with a third antiferromagnetic layer.

12. The magnetoresistive element according to claim 9, wherein the pair of electrodes electrically connected to upper and lower surfaces of the magnetoresistive film, respectively, provides a differential output.

13. The magnetoresistive element according to claim 9, wherein a gap between the first and second magnetization free layers ranges from 1 nm to 50 nm.

14. The magnetoresistive element according to claim 9, wherein at least one layer of the first to fourth nonmagnetic intermediate layers contains an oxide.

15. The magnetoresistive element according to claim 14, wherein the nonmagnetic intermediate layer containing the oxide has a thickness ranging from 0.5 nm to 5 nm.

16. A magnetic head comprising the magnetoresistive element according to claim 9.

17. A magnetic recording/reproducing apparatus, comprising:

the magnetic head according to claim 16, and

a perpendicular magnetic recording medium.