JP3420154B2 - Magnetic head and magnetic recording / reproducing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head having a magnetic transducer utilizing unidirectional anisotropy and a magnetic recording / reproducing apparatus for reproducing information using the magnetic head.

[0002]

2. Description of the Related Art The change in resistance of a magnetic transducer
It is known that spin-dependent electrical conduction of conduction electrons between magnetic layers via a non-magnetic layer, and the magnetoresistive effect attributable to the accompanying spin-dependent scattering at the layer interface. This magnetoresistive effect is called a giant magnetoresistive effect or spin valve.

European Patent EP-490608A2 describes a magnetic transducer utilizing the spin valve effect (hereinafter referred to as a spin valve sensor).
This spin valve sensor includes a laminated structure formed on a suitable material including a ferromagnetic film A and a ferromagnetic film B separated by a non-magnetic film. A typical spin valve sensor has a laminated structure in which a ferromagnetic film B, a nonmagnetic film, a ferromagnetic film A, and an antiferromagnetic film are laminated in this order. Here, the lowermost layer is the ferromagnetic film B and the uppermost layer is the antiferromagnetic film. Hereinafter, in the present specification, a laminated film having such a laminated structure is expressed as “ferromagnetic film B / nonmagnetic film / ferromagnetic film A / antiferromagnetic film”.

The magnetization direction of one of the ferromagnetic films, eg, the ferromagnetic film A, is fixed to the direction perpendicular to the magnetization direction of the ferromagnetic film B with no externally applied magnetic field. The magnetization direction of the ferromagnetic film A is fixed by imparting unidirectional anisotropy to the ferromagnetic film A by the exchange coupling generated at the interface between the antiferromagnetic film and the ferromagnetic film A by adjoining the antiferromagnetic films. It is done by doing. for that reason,
The ferromagnetic film A is called a fixed layer, and the expression fixed layer is also used in this specification. A typical magnetization fixed direction of the fixed layer is a direction perpendicular to the air bearing surface.

On the other hand, the magnetization direction of the ferromagnetic film B is called a free layer because it can be freely rotated by an external magnetic field. In the spin valve sensor, the magnetic field generated from the magnetic medium is used as the applied magnetic field, and the magnetization direction of the free layer freely rotates in response to this magnetic field, and as a result, the angle between the magnetization direction of the fixed layer and that of the free layer changes. Occurs. The spin valve sensor is a magnetoresistive sensor that converts a magnetic signal from a magnetic medium into an electric signal by utilizing the fact that the electric resistance changes according to the change in the angle formed by the magnetization directions of the fixed layer and the free layer. is there.

Next, the antiferromagnetic film for the fixed layer will be described. For example, in Japanese Laid-Open Patent Publication No. 54-10997, exchange coupling between a ferromagnetic NiFe alloy film and an antiferromagnetic FeMn alloy film causes unidirectional anisotropy in the NiFe alloy film, resulting in NiF
It is disclosed that the magnetization curve of the e-alloy film is shifted from the origin in the direction of the magnetic field axis. Further, the shift amount from the origin of this magnetization curve is defined as a coupling magnetic field, and the expression of this coupling magnetic field will be appropriately used in this specification.

[0007]

Problems to be Solved by the Invention US Pat. No. 57268
No. 38 describes NiO as an antiferromagnetic film.
It In addition, the inventors have used NiO / F as an antiferromagnetic film.
e₂O₃Laminated film (however, Fe ₂O₃Is very thin (a few nm), Ni
O / Fe₂O₃/ CoO laminated film (however, Fe₂O₃, CoO
Is very thin (several nm), and a patent is currently pending.

The exchange coupling film between the ferromagnetic film for the fixed layer of the spin valve sensor and the antiferromagnetic film has (1) the antiferromagnetic film exhibits high contact resistance, and (2) a large unidirectional anisotropic property. Having a strong energy constant (high coupling magnetic field), (3) exhibiting a high blocking temperature, (4) the antiferromagnetic film having a high specific resistance, (5) the antiferromagnetic film having a high exchange coupling characteristic. It is required that the film can be thinned while maintaining it, and (6) the heat treatment temperature for obtaining the coupling magnetic field is low. Here, the blocking temperature is defined as the temperature at which the coupling magnetic field disappears.

The NiO film, the NiO / Fe ₂ O ₃ laminated film, or the exchange coupling film of the NiO / Fe ₂ O ₃ / CoO laminated film and the ferromagnetic film satisfies the above conditions (1) to (6). .
However, in a high-density magnetic disk device-compatible magnetic transducer having an areal recording density of more than 40 Gb / in ² , the gap between the upper shield film and the lower shield film forming the magnetic transducer must be narrowed to about 100 nm or less. For that purpose, in the NiO film, the NiO / Fe ₂ O ₃ laminated film, or the NiO / Fe ₂ O ₃ / CoO laminated film which is an oxide antiferromagnetic film, while maintaining the high exchange coupling characteristics, for the following reasons. NiO should be thinned to about 40 nm or less.

In general, a magnetic transducer comprises a lower shield film, a lower gap film, for example, a spin valve sensor portion composed of an antiferromagnetic film / ferromagnetic film A / nonmagnetic film / ferromagnetic film B from the substrate side, The upper gap film and the upper shield film are sequentially stacked. The spin valve sensor except the antiferromagnetic film is about 30n in total.
m, the upper gap film needs to be about 30 nm. Ni
O film, NiO / Fe ₂ O ₃ laminated film, or NiO / Fe
_{Since the 2} O ₃ / CoO laminated film has excellent insulating properties, it can also serve as the lower gap film. Fe ₂ on NiO
2 nm and 0.5 nm for O ₃ and CoO, respectively
It is necessary to some extent. Therefore, in a magnetic transducer compatible with a high-density magnetic disk device exceeding 40 Gb / in ² , the oxide antiferromagnetic film NiO must be thinned to about 40 nm or less while maintaining high exchange coupling characteristics.

Therefore, an object of the present invention is to provide a technique capable of thinning an oxide antiferromagnetic film while maintaining high exchange coupling characteristics in an exchange coupling film composed of a ferromagnetic film and an oxide antiferromagnetic film. Especially. Further, it is to provide a magnetic transducer, a magnetic head and a magnetic recording / reproducing apparatus using this exchange coupling film.

[0012]

When considering a magnetic laminated film (exchange coupling film) of a ferromagnetic film and an oxide antiferromagnetic film which adheres to the ferromagnetic film, the above-mentioned object is to achieve a NiO film, a NiO / F film.
This is achieved by arranging ZnO as a base film of an oxide antiferromagnetic film such as an e ₂ O ₃ laminated film or a NiO / Fe ₂ O ₃ / CoO laminated film.

That is, the magnetic head according to the present invention is a magnetic head including a magnetic laminated film in which an antiferromagnetic film and a ferromagnetic film are sequentially laminated, and the antiferromagnetic film is a NiO film or a Ni film.
A laminated film in which a film made of Fe ₂ O ₃ is formed on a film made of O (NiO / Fe ₂ O ₃ laminated film), or a film made of Fe ₂ O ₃ is formed on a film made of NiO A laminated film (NiO / Fe ₂ O ₃ / CoO) on which a film made of CoO is formed.
It is a laminated film), and a ZnO film is arranged as a base film of the antiferromagnetic film.

In the magnetic head according to the present invention, the antiferromagnetic film, the first ferromagnetic film whose magnetization direction is fixed by the antiferromagnetic film, and the magnetization direction which freely changes in response to an external magnetic field. A magnetic head including a second ferromagnetic film, a non-magnetic film that magnetically separates the first ferromagnetic film and the second ferromagnetic film, and a pair of electrodes provided on the second ferromagnetic film. The antiferromagnetic film is a NiO film, a laminated film in which a film made of Fe ₂ O ₃ is formed on a film made of NiO (NiO / Fe ₂ O ₃ laminated film), and an Fe ₂ O ₃ film made of NiO. A laminated film (N is formed on which a film made of CoO is formed and a film made of CoO is formed thereon.
iO / Fe ₂ O ₃ / CoO laminated film), and a ZnO film is arranged as a base film of the antiferromagnetic film.

Fe ₂ O _{3 is formed} on the NiO film and the film made of NiO.
Laminated film (NiO / Fe ₂ O ₃ laminated film) in which a film made of Co is formed, or a laminated film in which a film made of Fe ₂ O ₃ is formed on a film made of NiO and a film made of CoO is formed thereon In an exchange coupling film of an oxide antiferromagnetic film and a ferromagnetic film made of (NiO / Fe ₂ O ₃ / CoO laminated film), a NiO film is obtained by using a ZnO film as a base film of the oxide antiferromagnetic film. Even if the film thickness of is reduced to 20-40 nm,
It is possible to obtain a sufficient coupling magnetic field.

The magnetic recording / reproducing apparatus according to the present invention moves a magnetic recording medium for recording information, a magnetic head for reading information recorded on the magnetic recording medium, and the magnetic head to a predetermined position on the magnetic recording medium. In the magnetic recording / reproducing apparatus including the actuator means for controlling and the control means for controlling the actuator means, the above-mentioned magnetic head is used as the magnetic head.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. First, a method for producing a magnetic laminated film (exchange coupling film) according to the present invention will be described. The magnetic laminated film was produced by the sputtering method. Figure 1 shows the simplest membrane structure.
Is shown in the schematic cross-sectional view of FIG. The base film 1, the oxide antiferromagnetic film 102, and the ferromagnetic film 101 were sequentially grown on the substrate 100 by sputtering. Glass was used for the substrate 100. A NiFe alloy film was used as the ferromagnetic film 101. ZnO was used for the base film 1. The oxide antiferromagnetic film 102 is
It is composed of antiferromagnetic films 2 and 3, and is composed of NiO and Fe ₂ respectively.
An O ₃ film was used. The most typical film structure is glass / Zn.
O (5 nm) / NiO (20 nm) / Fe ₂ O ₃ (2n
m) / NiFe (6 nm).

FIG. 2 shows the glass of the present invention / ZnO (5n
m) / NiO (10 to 50 nm) / Fe ₂ O ₃ (2 nm)
/ NiFe (6 nm) of the coupling field of the exchange coupling film, NiO
The thickness dependency is shown by a white circle. For comparison, the prior art glass / NiO (10 to 50 nm) / Fe ₂ O ₃ (2
nm) / NiFe (6 nm) exchange coupling film,
The NiO film thickness dependency is shown by an open square. In the prior art, the minimum required NiO film thickness for obtaining a stable coupling magnetic field was about 50 nm, but as in the present invention, a ZnO / NiO / Fe ₂ O ₃ antiferromagnetic film stack in which ZnO is arranged as a base film is used. It was found that the structure can reduce the minimum required NiO film thickness for obtaining a stable coupling magnetic field to about 20 nm.

As described above, by arranging ZnO as the base film of the NiO / Fe ₂ O ₃ laminated film, it has succeeded in reducing NiO to about 20 nm while maintaining high exchange coupling characteristics (substantially ZnO ( 5 nm) has been arranged, so it has succeeded in thinning down to about 25 nm).

By the same method, glass / ZnO (5
nm) / NiO (10 to 50 nm) / Fe ₂ O ₃ (2n
m) / CoO (0.5 nm) / NiFe (6 nm) exchange coupling film and glass / ZnO (5 nm) / NiO (10
A 50 nm) / NiFe (6 nm) exchange coupling film was prepared.

FIG. 3 shows the glass of the present invention / ZnO (5n
m) / NiO (10 to 50 nm) / Fe ₂ O ₃ (2 nm)
/ CoO (0.5 nm) / NiFe (6 nm) exchange coupling film's coupling magnetic field dependence on NiO film thickness is shown by white circles. For comparison, glass / NiO (10 to 50 nm) / Fe ₂ O ₃
(2 nm) / CoO (0.5 nm) / NiFe (6n
m) The dependence of the coupling magnetic field of the exchange coupling film on the NiO film thickness is shown by an open square.

Further, FIG. 4 shows the glass / ZnO of the present invention.
(5 nm) / NiO (10-50 nm) / NiFe (6
nm) The dependence of the coupling magnetic field of the exchange coupling film on the NiO film thickness is shown by white circles. For comparison, glass / NiO (10-50n
m) / NiFe (6 nm) exchange coupling film of the coupling magnetic field, N
The dependence of iO film thickness is shown by an open square.

From FIGS. 3 and 4, by arranging ZnO as a base film, NiO /
It can be seen that even in the exchange coupling film using the Fe ₂ O ₃ / CoO laminated film or the NiO single layer film, NiO can be reduced to about 20 nm while maintaining high exchange coupling characteristics.

FIG. 5 is a schematic sectional view showing a structural example of the magnetic transducer according to the present invention. The main part of this magnetic transducer is a magnetic laminated film (exchange coupling film) of an oxide antiferromagnetic film / ferromagnetic film in which ZnO is used as a base film, and a ferromagnetic film laminated via a nonmagnetic film. Consists of. This is generally called a spin valve sensor, and in the figure, 100 is a substrate, 1 is a ZnO base film, and 121 is a ferromagnetic film (free layer) whose magnetization freely rotates by an external magnetic field. 101 is a ferromagnetic film (fixed layer) whose magnetization direction is fixed by the oxide antiferromagnetic film. In this example, CoF is used as the free layer 121 and the fixed layer 101.
e film was used. 122 is a non-magnetic film for separating the fixed layer and the free layer, and is made of Cu. Reference numeral 102 denotes an oxide antiferromagnetic film for directing the magnetization of the fixed layer in one direction, which is a layer in which an antiferromagnetic film (NiO film) 2 and an antiferromagnetic film (Fe ₂ O ₃ film) 3 are sequentially stacked. Composed. The oxide antiferromagnetic film 1
No. 02 is NiO / Fe ₂ O ₃ / C even if it is a NiO single layer film.
It may be an oO laminated film. Reference numeral 125 is an electrode for supplying a detection current to this transducer.

The fixed layer 101 and the free layer 121 each have a thickness of 1 to 5 nm, and the nonmagnetic film 122 has a thickness of 1 to 5 nm.
It is 3 nm. The ZnO base film 1 has a film thickness of 5 nm, the antiferromagnetic film (NiO film) 2 has a film thickness of 20 to 40 nm, and the antiferromagnetic film (Fe ₂ O ₃ film) 3 has a film thickness of 1 to 4 nm. In the magnetic transducer having this structure, the oxide antiferromagnetic film can be thinned to about 40 nm or less while maintaining the high exchange coupling characteristic, and thus a magnetic transducer compatible with a high-density magnetic disk device can be provided.

In the above embodiment, the magnetic laminated film (exchange coupling film) of the present invention is applied to the spin valve sensor, but it can also be used for the magnetic domain control film of the MR head using the so-called anisotropic magnetoresistive effect. It is possible. Further, the magnetic laminated film of the present invention can be applied to a fixed layer of a so-called tunnel type GMR sensor, an antiferromagnetic film for the fixed layer, and a magnetic domain control film. Further, the magnetic laminated film of the present invention can be applied to an antiferromagnetic film for a fixed layer of a so-called laminated ferri type spin valve sensor in which the fixed layer 101 is a ferromagnetic layer / Ru / ferromagnetic layer.

FIG. 6 is a schematic block diagram of a magnetic recording / reproducing apparatus according to the present invention. In this magnetic recording / reproducing apparatus, a magnetic disk is used as a magnetic recording medium, and a magnetic transducer whose schematic sectional view is shown in FIG. 5 is used for a reproducing head. Here, an example in which a magnetic disk is used as the magnetic recording medium will be described, but the magnetic transducer of the present invention can also be applied to a magnetic recording / reproducing apparatus using a magnetic tape or the like as the magnetic recording medium.

The illustrated magnetic recording / reproducing apparatus has a magnetic disk 10 as a magnetic recording medium formed in a disk shape for recording data in a recording area called a concentric circular track, and a reproducing head according to the present invention. A magnetic head 18 having a magnetic transducer for reading and writing the above data, and a magnetic head 18
An actuator means for supporting the magnetic disk 10 and moving it to a predetermined position on the magnetic disk 10, and a control means 26 for controlling the transmission / reception of data to be read / written by the magnetic head 18 and the movement of the actuator means.

Further, the structure and operation will be described below. At least one rotatable magnetic disk 10 is supported by a rotating shaft 12 and rotated by a drive motor 14. At least one slider 16
Is installed on the magnetic disk 10 and has a slider 16
Supports a magnetic head 18 for reading and writing.

At the same time when the magnetic disk 10 rotates, the slider 16 moves on the disk surface,
A predetermined location where the target data is recorded is accessed. The slider 16 is attached to the arm 22 by the gimbal 20. The gimbal 20 has a slight elasticity so that the slider 16 can be brought into close contact with the magnetic disk 10. The arm 22 is attached to the actuator 24.

A voice coil motor (hereinafter referred to as VCM) can be used as the actuator 24. The VCM is composed of a movable coil placed in a fixed magnetic field, and the moving direction and moving speed of the coil are controlled by an electric signal given from the control means 26 through a line 30. Therefore, the actuator means in the present embodiment is, for example, the slider 1
6, gimbal 20, arm 22, actuator 2
4 and the line 30.

During operation of the magnetic disk, the magnetic disk 10
Rotation of the slider creates an air bearing between the slider 16 and the disk surface due to the air flow, which is the slider 1.
6 is levitated from the surface of the magnetic disk 10. Therefore, during operation of the magnetic disk device, the air bearing balances with the slight elastic force of the gimbal 20, so that the slider 16 floats without contacting the magnetic disk surface and at a certain distance from the magnetic disk 10. Maintained.

Usually, the control means 26 is composed of a logic circuit, a memory, a microprocessor and the like. Then, the control means 26 transmits / receives a control signal via each line and controls various constituent means of the magnetic disk device. For example, motor 14 is controlled by a motor drive signal transmitted via line 28. The actuator 24 is controlled by a head position control signal and a seek control signal via the line 30 so as to optimally move and position the selected slider 16 to a target data track on the associated magnetic disk 10. .

The control signal 26 is sent to the magnetic head 18
Receives and decodes the electric signal obtained by reading and converting the data of the magnetic disk 10 via the line 32. Further, an electric signal for writing as data on the magnetic disk 10 is transmitted to the magnetic head 18 via the line 32. That is, the control unit 26 controls transmission / reception of information read or written by the magnetic head 18.

The above read and write signals are
Means transmitted directly from the magnetic head 18 are also possible.
Further, the control signal includes, for example, an access control signal and a clock signal. Further, the magnetic disk device has a plurality of magnetic disks, actuators, etc., and the actuator may have a plurality of magnetic heads.

[0036]

As described above in detail, according to the present invention,
By disposing ZnO as the base film, the NiO film, which is an oxide antiferromagnetic film, can be thinned. Therefore, ZnO
Of ZnO / NiO / Fe ₂ O ₃ ,
ZnO / NiO, or ZnO / NiO / Fe ₂ O ₃ /
When the exchange coupling film of the CoO oxide antiferromagnetic laminated film and the ferromagnetic film is adopted, a magnetic transducer (magnetic head) compatible with a high density magnetic disk device and a high recording density magnetic recording / reproducing device can be provided.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a magnetic laminated film (exchange coupling film) according to the present invention.

FIG. 2 Glass / ZnO (5 nm) / NiO (10-5)
_{0nm) / Fe 2 O 3 (} 2nm) / NiFe (6nm) of coupling magnetic field of the exchange coupling film, shows a NiO film thickness dependence.

FIG. 3 Glass / ZnO (5 nm) / NiO (10-5)
0 nm) / Fe ₂ O ₃ (2 nm) / CoO (0.5 nm)
/ NiFe (6 nm) of the coupling field of the exchange coupling film, NiO
The figure which shows film thickness dependence.

FIG. 4 Glass / ZnO (5 nm) / NiO (10-5)
The figure which shows the NiO film thickness dependence of the coupling magnetic field of a (0 nm) / NiFe (6 nm) exchange coupling film.

FIG. 5 is a schematic sectional view showing a structural example of a magnetic transducer according to the present invention.

FIG. 6 is a schematic configuration diagram of a magnetic recording / reproducing apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... ZnO base film, 10 ... Magnetic disk, 12 ... Rotating shaft, 14 ... Motor, 16 ... Slider, 18 ... Magnetic head, 20 ... Gimbal, 22 ... Arm, 24 ... Actuator, 26 ... Control means, 28, 30, 32 ... Line, 100 ... Substrate, 101 ... Ferromagnetic film (fixed layer), 10
2 ... Oxide antiferromagnetic film, 121 ... Ferromagnetic film (free layer),
122 ... Non-magnetic film, 125 ... Signal detection electrode

Claims (4)

(57) [Claims] 1. A magnetic head including a magnetic laminated film in which an antiferromagnetic film and a ferromagnetic film are sequentially laminated, wherein the antiferromagnetic film is a NiO film or a Fe film formed on a NiO film.
A laminated film having a film made of ₂ O ₃ formed thereon, or a film made of Fe ₂ O ₃ formed on a film made of NiO, and CoO formed thereon.
2. A magnetic head comprising a laminated film having a film made of, wherein a ZnO film is arranged as a base film of the antiferromagnetic film. 2. An antiferromagnetic film, a first ferromagnetic film whose magnetization direction is fixed by the antiferromagnetic film, and a second ferromagnetic film whose magnetization direction freely changes according to an external magnetic field. A magnetic head including a non-magnetic film that magnetically separates the first ferromagnetic film and the second ferromagnetic film, and a pair of electrodes provided on the second ferromagnetic film. The ferromagnetic film is a NiO film, and an Fe film is formed on the NiO film.
_{One of} a laminated film in which a film made of ₂ O ₃ is formed and a laminated film in which a film made of Fe ₂ O ₃ is formed on a film made of NiO and a film made of CoO is formed thereon. A magnetic head having a ZnO film disposed as a base film of a ferromagnetic film. 3. The magnetic head according to claim 1, wherein the NiO film has a thickness of 20 to 40 nm. 4. A magnetic recording medium for recording information, a magnetic head for reading information recorded on the magnetic recording medium, and an actuator for moving the magnetic head to a predetermined position on the magnetic recording medium. A magnetic recording / reproducing apparatus comprising: means and a control means for controlling the actuator means, wherein the magnetic head according to any one of claims 1 to 3 is used as the magnetic head. .