JPH09115114A - Magnetoresistance element, and magnetic head and magnetic recording and reproducing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high reproduction output even when a longitudinal bias magnetic field is applied by setting the angle between the easy magnetization axis of a magnetoresistance film and the magnetization direction at the time of bias magnetic field application within a specific range, and setting the strength of an anisotropic magnetic field above a specific value. SOLUTION: On a substrate 5, a lower shield film 10, an insulating film 20 for magnetic gap formation, a soft magnetic film 30, a nonmagnetic conductive film 40, and a magnetoresistance film 50 are laminated. Then, an organic resist film is laminated and then patterned in a desired shape. Further, a permanent magnet film 60 is laminated and processed into an electrode 70, and an insulating film 80 for magnetic gap formation and an upper shield film 90 are laminated and processed to obtain a magnetic head. When the magnetoresistance film 50 is formed, the film is slanted at 60-120 deg. to its length direction and the strength of the anisotropic magnetic field of the magnetoresistance film 50 is set above 70e.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive effect element, a magnetic head using the same, and a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, a magnetic read transducer called a magnetoresistive effect (MR) sensor or head is known. The MR sensor utilizes the resistance change of a read element made of a magnetoresistive material to detect a magnetic signal as a function of the amount and direction of magnetic flux sensed by the element.
Compared with the case of using the conventional inductive head,
A larger reproduction output can be obtained.

In order to optimize the operation of the MR element, M
It is necessary to apply two types of bias magnetic fields to the R element. The first bias magnetic field is called the lateral bias magnetic field,
It is applied to make the response to the magnetic flux from the magnetic recording medium linear. The lateral bias magnetic field is perpendicular to the surface of the magnetic recording medium and parallel to the flat surface of the MR element. Current bias method, shunt bias method,
Soft bias method, Soft Ajacent Layer (SA
L) There are various methods such as the bias method. These lateral bias fields are generated at a level sufficient to bias the MR element into the most linear range of the RH characteristic curve.

The second bias magnetic field for optimizing the operation of the MR element is called a longitudinal bias magnetic field and is applied parallel to the surface of the magnetic recording medium and parallel to the longitudinal direction of the MR element. The function of the longitudinal bias is to suppress Barkhausen noise caused by the multi-domain structure in the MR element.

A method for applying a longitudinal bias magnetic field is disclosed in Japanese Patent Laid-Open No.
No. 2-40610, Japanese Patent Application Laid-Open No. 63-117309, or Japanese Patent Application No. 5-33036, a method using an antiferromagnetic film, Japanese Patent Application Laid-Open No. 2-220213, and Japanese Patent Application Laid-Open No. 4-78826. There is a method using a permanent magnet film shown in. As shown in Journal of Applied Magnetics of Japan, Volume 16, Supplement S1, page 85 (1992), a method using an antiferromagnetic film can obtain a larger reproduction output than a method using a permanent magnet film. Can be done,
There is a problem that Barkhausen noise cannot be suppressed sufficiently. As one method for suppressing Barkhausen noise, a soft Ajacent layer bias method is used as a lateral bias magnetic field application method and an antiferromagnetic film is used as a longitudinal bias magnetic field application method.
As disclosed in Japanese Patent No. 18, the easy axis of magnetization of the MR film is tilted at a predetermined angle from the longitudinal direction, and the easy axis of the soft magnetic film (SAL) for transverse bias magnetic field application is set in the easy axis direction of the MR film. There is a way to tilt to the opposite side. Although this method has a certain degree of effectiveness in suppressing Barkhausen noise, in the manufacturing process, the easy axis direction of magnetization of the MR film and the easy axis direction of SAL are opposite to the longitudinal direction. Leave problems of difficulty and poor yield.

Further, the easy axis of SAL is tilted at a predetermined angle from the longitudinal direction, and the easy axis of MR film is also SAL.
Japanese Patent Laid-Open No. 6-166854 describes a method of tilting in the same rotation direction as the direction of the easy magnetization axis. This method has also been shown to be effective in suppressing Barkhausen noise.

On the other hand, Japanese Patent Laid-Open No. 7-44827 discloses a method of inclining the magnetization direction of a permanent magnet film for applying a longitudinal bias magnetic field from the longitudinal direction for the purpose of improving the reproduction output. However, in this method, no consideration is given to the direction of the easy axis of magnetization of the MR film or SAL.

In the prior art in which the easy axis of magnetization is oriented in the longitudinal direction, the reproduction output is lowered if the anisotropic magnetic field Hk is made too large, so that it is desirable that Hk be around 5 Oe.

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The prior art in which the direction of the easy axis of magnetization of the R film and SAL is tilted from the longitudinal direction of the film was mainly aimed at suppressing Barkhausen noise. In these conventional techniques, when a longitudinal bias magnetic field is applied to suppress Barkhausen noise, there is a problem that the reproduction output is reduced.

An object of the present invention is to provide an MR head which can obtain a high reproduction output even when a longitudinal bias magnetic field is applied.

[0011]

The above-mentioned object is to make the angle between the direction of the easy axis of magnetization of the MR film and the direction of magnetization in the MR film when a bias magnetic field is applied to be 60 ° to 120 °. When the direction of the easy axis of magnetization of the MR film is tilted, the magnitude of the anisotropic magnetic field of the MR film is 7 Oe or more, preferably 10 Oe
It is achieved by setting it to 30 Oe. Here, the easy axis of magnetization means that generated by magnetocrystalline anisotropy or the like,
It does not include those due to shape anisotropy. That is, MR
The direction of the easy axis of magnetization in the film means the direction in which a magnetic field is applied when the MR film is manufactured.

The magnetoresistive effect element according to the present invention comprises a magnetoresistive effect film, a pair of electrodes for passing a current through the magnetoresistive effect film, a means for applying a transverse bias magnetic field to the magnetoresistive effect film, and a magnetic element. And a means for applying a longitudinal bias magnetic field to the resistance effect film, wherein an angle formed by the direction of the easy axis of magnetization of the magnetoresistive effect film and the magnetization direction when the bias magnetic field is applied is 60.
It is characterized in that the anisotropic magnetic field of the magnetoresistive effect film has a magnitude of 7 Oe or more, preferably 10 Oe to 30 Oe at a temperature of 120 ° to 120 °.

The lateral bias magnetic field is SAL using a soft magnetic film.
The bias method is preferably applied, and the longitudinal bias magnetic field can be applied by a permanent magnet or an antiferromagnetic film.

As a concrete structure of the magnetoresistive effect element, (1) a soft magnetic film for applying a lateral bias magnetic field, a non-magnetic conductive film and a magnetoresistive effect film, which are laminated on the substrate,
A structure including a pair of permanent magnet films for applying a longitudinal bias magnetic field provided at both ends of the magnetoresistive film in the longitudinal direction, and a pair of electrodes provided on the pair of permanent magnet films, (2) substrate A soft magnetic film for applying a lateral bias magnetic field, a non-magnetic conductive film, a magnetoresistive effect film, and a pair of antiferromagnetic films provided on the magnetoresistive effect film so as to be spaced apart in the longitudinal direction. A structure including a multi-layer film including, and a pair of electrodes provided on the multi-layer film, wherein the pair of antiferromagnetic films is provided in a region below the electrodes, or
(3) An antiferromagnetic film laminated on the substrate, a magnetoresistive film laminated so that both ends in the longitudinal direction contact the antiferromagnetic film, and a nonmagnetic conductive film laminated thereon. A multilayer film including a film and a soft magnetic film for applying a lateral bias magnetic field;
A structure including a pair of electrodes provided on the multilayer film can be adopted.

The magnetoresistive effect element of the present invention can be incorporated in a magnetic head. The magnetoresistive effect reproducing head of the present invention can be combined with an inductive thin film head for magnetic recording to form a recording / reproducing separated type magnetic head.

The reproduction output of the MR head is proportional to cos ² θ with respect to the magnetization rotation angle θ in the MR film. Therefore, the MR that changes when the magnetic field from the medium is applied to the MR head.
The larger the rotation angle of the magnetization in the film, the larger the reproduction output.

When the angle between the magnetization direction of the MR film when a bias magnetic field is applied and the direction of the easy axis of magnetization is set to about 90 °, the magnetization of the MR film is oriented in the direction of the hard axis, which is unstable. It will be in a state. When a magnetic field from the medium is applied in this state, the magnetization tends to move in the easy magnetization direction, so that the rotation angle of the magnetization increases. As the anisotropic magnetic field of the MR film is increased, the force of the magnetization toward the easy magnetization direction is increased, so that the rotation angle is further increased and the reproduction output is increased.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

(Embodiment 1) FIG. 1 is a sectional view of an embodiment of a magnetic head having a magnetoresistive (MR) element according to the present invention. In manufacturing this magnetic head, a lower shield film (NiFe film) 1 having a thickness of 2 μm was formed on a substrate 5.
0, 0.2 μm thick insulating film for magnetic gap formation (Al
₂ O ₃ film) 20, 20 nm thick soft magnetic film (CoZrTa)
Film) 30 and a non-magnetic conductive film (Ta film) 4 having a thickness of 15 nm 4
0, 20 nm thick magnetoresistive film (NiFeCo film)
50 were laminated. Next, after laminating the organic resist film,
The pattern was formed into a desired shape. In addition, thickness 30
After a permanent magnet film (CoCrPt film) 60 nm having a thickness of 10 nm was laminated and processed into a desired shape, Nb / Au / Nb was laminated and processed to form an electrode 70. Further, an insulating film (Al ₂ O ₃ film) 80 having a thickness of 0.155 μm and an upper shield film (NiFe film) 90 having a thickness of 2 μm are laminated and processed into a desired shape to form a magnetic head. did.

When manufacturing the MR film, the MR shown in FIG.
A magnetic field of 30 Oe was applied in the direction shown by arrow e, which was tilted at -45 ° from the longitudinal direction x of the film plane, and the easy axis of magnetization was attached. Further, also when the SAL was manufactured, a magnetic field of 30 Oe was applied in the same direction as the easy axis of magnetization of the MR film to attach the easy axis of magnetization.
Further, after the permanent magnet film was produced, a magnetic field for magnetization of 1000 Oe was applied in the direction of arrow x.

The anisotropic magnetic field of the magnetoresistive film is Co
It was adjusted by the addition amount of. In the magnetoresistive film of this example, 18% of Co was added and the anisotropic magnetic field was set to 20 Oe.

A sense current was passed through this MR head so that the current flowing through the MR film was 1.5 × 10 ⁷ A / cm ² .
The direction of the magnetization M when the bias magnetic field was applied was inclined about + 45 ° from the longitudinal direction x (Fig. 2). That is, the angle θd formed by the direction e of the easy magnetization axis and M is set to about 90 °. Here, the tilt angle from the longitudinal direction x when the bias magnetic field was applied was taken as the bias angle θb, and the bias angle was measured as shown below. FIG. 3 shows the results of measuring the voltage change ΔV when a uniform magnetic field H is applied to the MR head from the outside when a lateral bias magnetic field is applied. The bias angle θb is the voltage change ΔV when the external magnetic field is zero.
_{Based on 0} and the maximum value ΔVmax of voltage change, it was calculated from the following relational expression.

ΔV ₀ / ΔVmax = cos ² θb The reproducing output of this head was measured and the anisotropic magnetic field H of the MR film was measured.
As a result of comparison with the reproduction output of the conventional head having k of 5 Oe, it was confirmed that the output was improved to about twice.

Further, the anisotropic magnetic field Hk of the MR film is set to 5 Oe.
To 50 Oe, a head having the structure shown in FIG. 1 was manufactured, and the reproduction output was measured. At this time, the current flowing through the MR head is constant, and the current density of the MR film is 1.5 × 10 ^7.
A sense current was passed so that the current became A / cm ² . As shown in FIG. 4, the reproduction output increases as Hk increases,
The reproduction output of the head whose k is 50 Oe is about four times that of the conventional one. However, in a head having an Hk of more than 30 Oe, the reproduced waveform may fluctuate, and there is a problem in the stability of the head. A head having an Hk of 10 Oe to 30 Oe has a reproduction output 1.5 to 2.5 times that of the conventional head and operates stably.

(Embodiment 2) FIG. 5 shows a sectional view of another embodiment of a magnetoresistive head having an MR element according to the present invention. In manufacturing this head, on the substrate 5,
Lower shield film (NiFe film) 10 having a thickness of 2 μm, insulating film for magnetic gap formation (Al ₂ O ₃ film) having a thickness of 0.2 μm
20, soft magnetic film (CoTaZr film) 3 having a thickness of 20 nm 3
0, a 15-nm-thick non-magnetic conductive film (Ta film) 40, a 20-nm-thick magnetoresistive film (NiFeCo film) 50, and a 20-nm-thick FeMn film 100 for controlling magnetic domains are laminated and then processed into a desired shape. To do. Next, Nb / Au / for electrodes
After laminating Nb70 and processing it into a desired shape, a thickness of 0.
155 μm magnetic gap forming film (Al ₂ O ₃ film) 80,
A magnetic shield film (NiFe film) 90 having a thickness of 2 μm was laminated and processed into a desired shape to obtain a magnetic head. The direction e of the easy axis of the MR film of this head and the average magnetization direction M inclined by the lateral bias magnetic field are θe as shown in FIG.
≅-45 ° and θd≅90 ° were set. The Hk of the MR film was 20 Oe. The playback output obtained with this head is also
The anisotropic magnetic field Hk of the MR film was improved about twice as compared with the conventional head having 5 Oe.

(Embodiment 3) FIG. 6 shows a sectional view of another embodiment of a magnetoresistive head having an MR element according to the present invention. In manufacturing this head, on the substrate 5,
Lower shield film (NiFe film) 10 having a thickness of 2 μm, insulating film for magnetic gap formation (Al ₂ O ₃ film) having a thickness of 0.2 μm
20, a magnetic domain control NiO film 100 having a thickness of 20 nm, and an insulating Al ₂ O ₃ film 110 having a thickness of 10 nm are laminated, and then a magnetoresistive effect film (NiFeCo film) 50 having a thickness of 20 nm and a nonmagnetic property having a thickness of 15 nm Conductive film (Ta film) 40, thickness 20n
m soft magnetic film (CoTaZr film) 30 was laminated and processed into a desired shape. Next, Nb / Au / Nb70 for electrodes is laminated and processed into a desired shape, and then the thickness is 0.155 μm.
Magnetic gap forming film (Al ₂ O ₃ film) 80 of 2 μm thick
Magnetic shield film (NiFe film) 90 was laminated and processed into a desired shape to obtain a magnetic head.

The direction e of the easy axis of magnetization of the MR film and the direction of magnetization M inclined by the transverse bias magnetic field are θe as shown in FIG.
≅-45 ° and θd≅90 ° were set. The Hk of the MR film was 20 Oe. The playback output obtained with this head is also
The anisotropic magnetic field Hk of the MR film was improved about twice as compared with the conventional head having 5 Oe.

(Example 4) The magnetoresistive effect element of the present invention was used as a reproducing head, and a recording / reproducing separated type magnetic head using a conventionally known inductive type thin film head as a recording head was manufactured. FIG. 7 shows a perspective view in which a part of the recording / reproducing separated type head according to the present embodiment is cut.

A sintered body containing Al ₂ O ₃ .TiC as a main component was used as the substrate 5 for the slider. The lower shield film 10 is formed by the method shown in the first embodiment, and an insulating film (Al ₂ O ₃ film) for forming a magnetic gap, a soft magnetic film (NiFeNb film) 30 having a thickness of 20 nm, and a non-magnetic layer are formed on the lower shield film 10. Conductive film (Ta film) 4
0, a magnetoresistive film (NiFeCo film) 50, and an organic resist film are laminated, and then patterned into a desired shape. Furthermore, a permanent magnet film (CoCrPt) having a thickness of 30 nm is used.
Film) is laminated and processed into a desired shape, then Nb / Au / N
b70 was laminated and processed into an electrode. Further on that,
A magnetic gap forming film (Al ₂ O ₃ film) and a magnetic shield film (NiFe film) 90 were formed. The above part functions as a reproducing head. The direction e of the easy axis of magnetization of the MR film and SAL was set to approximately −45 °, and the magnetization direction of the permanent magnet film was set to the longitudinal direction x, as shown in FIG. Also, MR
The Hk of the film was 20 Oe.

Next, as a magnetic recording head, the thickness is 3 μm.
After forming an insulating film of Al ₂ O _{3 of} m, the lower magnetic pole 1
An inductive thin film head composed of 20, the upper magnetic pole 130 and the coil 140 was formed. Lower magnetic pole 120, upper magnetic pole 1
30 has a film thickness of 3.0 μm formed by a sputtering method.
Ni-20 at% Fe alloy was used. Lower magnetic pole 120
For the gap layer between the upper magnetic pole 130 and the upper magnetic pole 130, Al ₂ O ₃ having a film thickness of 0.2 μm formed by the sputtering method was used. For the coil 140, Cu having a film thickness of 3.0 μm was used. The lower magnetic pole 120 and the upper magnetic pole 130 are magnetically coupled to form a magnetic circuit, and the coil 140 is linked to the magnetic circuit.

Using the magnetic head having the structure described above, the sense current (MR film) is set so that the average magnetization direction of the magnetoresistive effect film is almost the same direction (θd≈90 °) as the arrow M in FIG. Recording / reproducing experiment was conducted by applying a current density of 1.5 × 10 ⁷ A / cm ² ). As a result, an output value about twice as large as that in the case of using the conventional magnetic head in which the direction of the easy axis of magnetization of the MR film is parallel to the longitudinal direction of the film was obtained.

(Embodiment 5) Using the magnetic head described in Embodiment 4, a magnetic disk device was manufactured. FIG. 8 (a)
FIG. 8 is a schematic plan view of the magnetic disk device, and FIG. 8B is a sectional view taken along the line AA ′.

For the magnetic recording medium 150, a material made of a Co--Ni--Pt--Ta alloy having a residual magnetic flux density of 0.75T was used. The magnetic recording medium 150 is rotationally driven by the driving unit 160. The track width of the recording head of the magnetic head 170 is 2 μm, and the track width of the reproducing head is 1.5 μm.
m. The magnetic head 170 is rotationally driven by the drive unit 180 and can select a track on the magnetic recording medium 150. The recording / reproducing signal from the magnetic head 170 is processed by the recording / reproducing signal processing system 190.

The magnetoresistive effect element used in the magnetic head 170 produces 2.0 times the output of the magnetoresistive effect element of the conventional structure, so that a magnetic disk device having a narrower track width and a higher recording density is manufactured. You can also

[0035]

According to the present invention, it is possible to increase the reproduction output of the magnetoresistive reproducing head.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a magnetoresistive effect element of the present invention.

FIG. 2 is an explanatory diagram showing the relationship between the direction of the easy axis e of the magnetoresistive film of the present invention and the magnetization direction M when a bias magnetic field is applied.

FIG. 3 is a diagram showing a relationship between an external magnetic field H and a voltage change ΔV of a magnetic head.

FIG. 4 is a diagram showing a relationship between an anisotropic magnetic field Hk of a magnetoresistive film and a reproduction output.

FIG. 5 is a cross-sectional view showing another embodiment of the magnetoresistive effect element of the present invention.

FIG. 6 is a cross-sectional view showing another embodiment of the magnetoresistive effect element of the present invention.

FIG. 7 is a perspective view showing the structure of a recording / reproducing separated type magnetic head of the present invention.

FIG. 8 is a schematic diagram of a magnetic recording / reproducing apparatus of the present invention.

[Explanation of symbols]

5 ... Substrate, 10 ... Lower shield film, 20 ... Lower magnetic gap forming insulating film, 30 ... Soft magnetic film, 40 ... Nonmagnetic conductive film, 50 ... Magnetoresistive film, 60 ... Permanent magnet film, 70 ...
Electrode, 80 ... Insulating film for forming upper magnetic gap, 90 ... Upper shield film, 100 ... Anti-ferromagnetic film for controlling magnetic domain, 110
... Al ₂ O ₃ film for insulation, 120 ... Lower magnetic pole for recording head,
130 ... upper magnetic pole for recording head, 140 ... coil, 15
0 ... Magnetic recording medium, 160 ... Magnetic recording medium driving unit, 17
0 ... Magnetic head, 180 ... Magnetic head drive unit, 190 ...
Recording / reproducing signal processing system, x ... Longitudinal direction of magnetoresistive film,
e ... easy axis of magnetization, M ... average direction of magnetization, .theta.e ...
The angle formed by x and e, the angle formed by θd ... e and M

Front Page Continuation (72) Inventor, Sugita 1-280, Higashi Koikekubo, Kokubunji, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (9)

[Claims] 1. A magnetoresistive effect film, a pair of electrodes for flowing a current through the magnetoresistive effect film, means for applying a lateral bias magnetic field to the magnetoresistive effect film, and the magnetoresistive effect film. Means for applying a longitudinal bias magnetic field, and the angle formed by the direction of the easy axis of magnetization of the magnetoresistive effect film and the magnetization direction when the bias magnetic field is applied is 60 ° to 120 °.
And the magnitude of the anisotropic magnetic field of the magnetoresistive film is 7 Oe.
The magnetoresistive effect element characterized by the above. 2. A magnetoresistive effect film, a pair of electrodes for flowing a current through the magnetoresistive effect film, means for applying a lateral bias magnetic field to the magnetoresistive effect film, and the magnetoresistive effect film. Means for applying a longitudinal bias magnetic field, and the angle formed by the direction of the easy axis of magnetization of the magnetoresistive effect film and the magnetization direction when the bias magnetic field is applied is 60 ° to 120 °.
And the magnitude of the anisotropic magnetic field of the magnetoresistive film is 10 O
A magnetoresistive effect element characterized by being e to 30 Oe. 3. A soft magnetic film for applying a lateral bias magnetic field, a non-magnetic conductive film and a magnetoresistive effect film, which are laminated on the substrate, and longitudinal biases provided at both longitudinal ends of the magnetoresistive effect film. The magnetoresistive effect element according to claim 1, further comprising a pair of permanent magnet films for applying a magnetic field, and a pair of electrodes provided on the pair of permanent magnet films. 4. A soft magnetic film for applying a lateral bias magnetic field, a non-magnetic conductive film and a magnetoresistive effect film, which are laminated on the substrate, and a pair of which are spaced apart from each other in the longitudinal direction of the magnetoresistive effect film. 7. A multilayer film including antiferromagnetism, and a pair of electrodes provided on the multilayer film, wherein the pair of antiferromagnetic films is provided in a region below the electrodes. The magnetoresistive effect element according to 1 or 2. 5. An antiferromagnetic film laminated on a substrate, a magnetoresistive effect film laminated such that both ends in the longitudinal direction of the antiferromagnetic film are in contact with the antiferromagnetic film, and a non-magnetic film laminated thereon. 3. The magnetoresistive effect element according to claim 1, further comprising a multilayer film including a magnetic conductive film and a soft magnetic film for applying a lateral bias magnetic field, and a pair of electrodes provided on the multilayer film. . 6. A magnetic head comprising the magnetoresistive effect element according to claim 1. Description: 7. A pair of magnetic shield films provided apart from each other in the stacking direction, the magnetoresistive effect element being arranged between the pair of magnetic shield films. The magnetic head described. 8. An inductive thin film head for magnetic recording, comprising: a pair of magnetic poles, magnetic circuit means for magnetically coupling the pair of magnetic poles, and a coil interlinking with the magnetic circuit; A recording / reproducing separated type magnetic head comprising: a magnetic head. 9. A magnetic recording medium, the magnetic head according to claim 6, 7 or 8, drive means for relatively driving the magnetic recording medium and the head, and the magnetic head. And a recording and reproducing signal processing system connected to the magnetic recording and reproducing apparatus.