JPH09212829A - Magnetoresistance element and magnetic recording and reproducing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the magnetoresistance element consisting of a multilayer film having an enough output and linearity and particularly an improved bias characteristic by providing a single magnetic domain forming film and a lateral bias film on the upper and lower surfaces of a magnetoresistance multilayer film, and to provide a magnetic recording device using the element. SOLUTION: The magnetoresistance multilayer film 10 is constituted by laminating plural ferromagnetic films 11-16 via nonmagnetic electroconductive films between them, and antiferromagnetic force is worked between the individual ferromagnetic films. The single magnetic domain forming film 21 is disposed by layering directly with the ferromagnetic film 11 to impress an exchanging combining bias upon the ferromagnetic film 11. The impressing direction 66 of the exchanging bias is almost parallel with the track widthwise direction 67, and the direction of a magnetic field to be sensed is almost parallel to the element height direction 65, whereas a bias magnetic field of the lateral bias film 22 is obtained by orienting the direction 61 of residual magnetization of this film toward the element height direction. The lateral bias film 22 is disposed laminatedly through the magnetoresistance multilayer film 10 via a pertinent nonmagnetic layer to impress the lateral bias magnetic field upon the magnetoresistance multilayer film 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus and a magneto-resistance effect element, and more particularly to a high recording density magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 2-61572 discloses a laminated film in which the electric resistance of a ferromagnetic thin film separated by an intermediate layer changes depending on the angle formed by the magnetizations thereof, a magnetic field sensor using the same, and a magnetic recording device. There is a description.

Japanese Unexamined Patent Publication (Kokai) No. 6-60336 describes a means for making the magnetization direction of a magnetic layer perpendicular, particularly a magnetoresistive sensing system having a hard magnetic film.

US Pat. No. 5,206,590 describes a structure in which an antiferromagnetic film is in close contact with a stack of ferromagnetic films separated by a non-magnetic film, and a hard magnetic material is in contact with the end of the stack. .

Japanese Unexamined Patent Publication No. 50-1712 describes a magnetoresistive element using a permanent magnet thin film as a bias film.

[0006]

In the prior art, a magnetic recording device having a sufficiently high recording density, in particular, a magnetoresistive effect element which acts on the reproducing portion with sufficient sensitivity and output to an external magnetic field, is realized. Furthermore, it was not possible to obtain good characteristics with good symmetry, and it was difficult to realize the function as a recording device.

In order to improve the recording density, it is necessary to narrow one unit of the recording area on the recording medium and to miniaturize the reproducing portion of the magnetic recording device. As a solution to such a problem, a method is known in which a magnetoresistive effect element is arranged in the reproducing portion of a thin film magnetic head and a change in electric resistance due to the magnetoresistive effect is used as an output. In this case, the problem is that in a small magnetoresistive effect element, a slight deterioration in the symmetry of the reproduction signal distorts the output, leading to performance degradation. That is,
It is important that the output characteristics of the device with respect to the external magnetic field are symmetrical about the zero magnetic field. As a conventional technique, there is known a means for correcting a lateral bias of an element by providing a magnetic film called a SAL film by laminating it on a magnetoresistive film. A film provided to correct the lateral bias characteristics of such an element is called a lateral bias film.

In recent years, due to the magnetoresistive effect of a multi-layered film in which ferromagnetic metal films are laminated via a nonmagnetic metal film, so-called giant magnetoresistive effect, the change in resistance is larger than that of a conventional single-layered ferromagnetic thin film. It has been known. In this case, in the magnetoresistive effect, the electric resistance changes depending on the angle formed by the magnetizations of the ferromagnetic films separated by the nonmagnetic film. Between the ferromagnetic films separated by the non-magnetic film, an antiferromagnetic coupling force that tries to make their magnetizations antiparallel is working. When used as a magnetoresistive element, there are two required characteristics.
It has a linear output with respect to an external magnetic field, and has no noise generated due to domain wall movement. In order to obtain a linear output due to the giant magnetoresistive effect of the multilayer film, the magnetization directions of the respective ferromagnetic films must be perpendicular to each other in the state of zero magnetic field, as pointed out in the known example. For example, it is possible to obtain the output of the magnetoresistive effect with good linearity by making the respective magnetizations alternate ± 45 degrees with respect to the direction of the magnetic field to be sensed. In the magnetic disk device, the direction of the magnetic field to be sensed is the element height direction. A film for applying a bias to the magnetoresistive film in the element height direction for the purpose of improving linearity or adjusting the magnetic field response point of the device is called a lateral bias film.

As a method of suppressing the noise caused by the domain wall motion of the magnetoresistive element, the ferromagnetic film is generally made into a single magnetic domain. For example, it is effective to apply a bias magnetic field to the magnetoresistive effect film in a direction perpendicular to the direction of the magnetic field to be sensed to form a single magnetic domain. That is, the domain wall can be eliminated and the direction of magnetization can be set so that the magnetization process is caused by magnetization rotation. The means for applying this bias is to arrange a ferromagnetic film to which exchange coupling is applied by a hard magnetic film or an antiferromagnetic film in contact with the end portion of the magnetoresistive film in the track width direction, and A method using a leaking static magnetic field is known. In this case, the direction of remanent magnetization or exchange coupling is perpendicular to the magnetic field to be sensed, that is, the track width direction of the magnetic disk device. A film for applying this bias is called a vertical bias film. Also,
A film intended to make a ferromagnetic film into a single domain is called a single domain film.

As described above, it is desirable that the magnetic head compatible with a high recording density applies the giant magnetoresistive effect, and the longitudinal bias film is applied to the magnetoresistive effect multi-layer film. It is magnetic domain.

Generally, in order to make the ferromagnetic film into a single magnetic domain, a longitudinal bias film can be used as the single magnetic domain forming film. That is, a bias magnetic field can be applied to the ferromagnetic film to form a single magnetic domain, but this is difficult when the magnetoresistive film is a multilayer film. That is, as described above, in order to obtain a linear output, the ferromagnetic films of the multilayer film should be arranged alternately in the positive and negative directions with respect to the element height direction. Indicates what should be done in the direction. If a longitudinal bias film is applied to the multilayer film to achieve a single magnetic domain by the conventional method, all the magnetizations of the ferromagnetic film are oriented in one direction, and the magnetoresistive effect of the multilayer film does not linearly occur. It ends up.

It is an object of the present invention to provide a magnetic recording device compatible with high density recording and a magnetoresistive effect element composed of a multilayer film with improved sufficient output and linearity, particularly improved bias characteristics.

[0013]

In order to solve the above-mentioned problems, the present invention adheres to the surface of a ferromagnetic film located on the surface (or bottom surface) of a magnetoresistive effect multilayer film constituting a magnetoresistive effect element. A single domain domainization film for applying directional anisotropy, especially an antiferromagnetic film was arranged. Further, a lateral bias means for optimizing the linearity, in particular, a lateral bias film was laminated adjacent to the multilayer film. That is, a lateral bias film that directs the magnetizations of all the ferromagnetic films constituting the magnetoresistive effect multilayer film in one direction in the element height direction, and one or two ferromagnetic films located on the surface of the magnetoresistive effect multilayer film. The magnetization is fixed and a single magnetic domain is formed. As a result, the direction of magnetization of the ferromagnetic film is closer to the single domain film due to the interaction of lateral bias, single domain, and antiferromagnetic coupling force acting between the ferromagnetic films of the multilayer film. Is close to ± 180 degrees, and it is ±
An array approaching 45 degrees becomes stable.

In the present invention, with such a simple structure, the multilayer magnetoresistive effect film effectively functions as a magnetoresistive effect element, and a magnetic recording / reproducing apparatus using this as a reproducing portion has a high recording density, that is, The recording wavelength recorded on the recording medium is short, and the recording track width is narrow.
It is possible to obtain a sufficient reproduction output and maintain good recording.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The film constituting the magnetoresistive effect element of the present invention was produced by a high frequency magnetron sputtering apparatus as follows. The following materials were sequentially laminated on a ceramic substrate having a thickness of 1 mm and a diameter of 3 inches in an atmosphere of 3 mTorr of argon. As a sputtering target, nickel oxide, tantalum, chromium, nickel-20 at% iron alloy, cobalt-20% platinum, and copper targets were used. In the laminated film, high frequency power was applied to the cathodes on which the targets were arranged to generate plasma in the apparatus, and the shutters arranged on the respective cathodes were opened and closed one by one to sequentially form the layers. At the time of film formation, a magnetic field of about 50 Oersted is applied in parallel to the substrate by using two pairs of electromagnets orthogonal to each other in the plane of the substrate to give uniaxial anisotropy, and the direction of the exchange coupling bias of the nickel oxide film is set, respectively. Was guided in the direction of.

In order to induce the anisotropy, the antiferromagnetic film was cooled in a magnetic field from near the Neel temperature of the antiferromagnetic film after the formation of the laminated film to induce the antiferromagnetic bias direction in the magnetic field direction. Furthermore, the magnetization direction of the hard magnetic film was induced by performing a magnetization treatment of 3 kilo Oersted at room temperature.

The elements on the substrate were patterned by a photoresist process. Thereafter, the substrate was processed by a slider and mounted on a magnetic recording device.

A specific embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing the structure of the first example of the magnetoresistive effect element of the present invention.

The magnetoresistive effect multi-layered film 10 is composed of a plurality of ferromagnetic films 11, 12, 13, 14, 15, 16 laminated with a non-magnetic conductive film interposed between the ferromagnetic films. A ferromagnetic coupling force is working. Magnetoresistive multilayer film 1
A single domain domainization film 21 is directly laminated on the ferromagnetic film 11 on one side of 0, and an exchange coupling bias is applied to the ferromagnetic film 11. The exchange coupling bias application direction 66 is substantially parallel to the track width direction 67. The direction of the magnetic field to be sensed is almost parallel to the element height direction 65, and the bias magnetic field of the lateral bias film 22 is the direction 61 of the residual magnetization of this film.
Is obtained in the element height direction. The lateral bias film 22 is laminated with the magnetoresistive effect multilayer film 10 via an appropriate non-magnetic layer, or is arranged at an adjacent position, and applies a lateral bias magnetic field to the magnetoresistive effect multilayer film 10.

Here, a Ni—Fe film was used as the ferromagnetic film and a Cu film was used as the non-magnetic conductive film. A nickel oxide film was used for the single domain film 21, and a Co—Pt film was used for the lateral bias film 22.

In the figure, the arrow marked on the ferromagnetic film indicates the direction of magnetization of the ferromagnetic film in the absence of an external magnetic field. In the ferromagnetic film 15, the magnetization direction of the ferromagnetic film is substantially parallel to the anisotropy direction of the single domain domainization film 21, that is, the track width direction 67. Approaches the element height direction 65, and the ferromagnetic film 1
With 4, 15 and 16, the angle can be set to about 45 degrees.

As described above, the magnetoresistive effect film 20 is composed of the magnetoresistive effect multi-layer film 10, the single magnetic domain dividing film 21 and the lateral bias film 22. The lateral bias film 22 may be laminated in the thickness direction with the magnetoresistive film, or may be arranged so that its end portion is in contact with the element height direction. In that case, the direction of the residual magnetization of the lateral bias film 22 is opposite to that in FIG.

FIG. 2 is an explanatory view showing an example of the film structure of the magnetoresistive effect film 20 of the present invention. Magnetoresistive multilayer film 10
Is formed by alternately stacking ferromagnetic films 11, 12, 13, 14, 15, 16 and non-magnetic conductive films 31, 32, 33, 34, 35. The single domain domainization film 21 is formed by directly adhering to the ferromagnetic film 11 on the surface of the magnetoresistive multilayer film 10 to generate unidirectional anisotropy due to exchange coupling. The lateral bias film 22 is laminated with the magnetoresistive effect multilayer film 10 with the intermediate film 23 interposed therebetween. By disposing the base film 25 on the base side of the lateral bias film 22, the characteristics of the lateral bias film 22 can be stabilized. Here, tantalum is used for the intermediate film 23 and chromium is used for the base film 25. Here, the single domain domainization film 21 is used for the base 5 with respect to the lateral bias film 22.
Although the configuration on the side of 0 is shown, the characteristics are not impaired even if this positional relationship is reversed. In that case, the lamination position of the base film 25 is arranged on the base side of the lateral bias film 22.

FIG. 3 is an explanatory view showing a second example of the film structure of the magnetoresistive effect film 20 of the present invention. Magnetoresistive multilayer film 1
0 is formed by alternately stacking ferromagnetic films 11, 12, 13, 14, 15, 16 and nonmagnetic conductive films 31, 32, 33, 34, 35. The single domain domainization film 21 is formed by directly adhering to the ferromagnetic film 11 on the surface of the magnetoresistive multilayer film 10 to generate unidirectional anisotropy due to exchange coupling. The lateral bias film 22 is laminated with the magnetoresistive effect multilayer film 10 via the single domain domainization film 21 and the intermediate film 24. By disposing the base film 25 on the base side of the lateral bias film 22, the characteristics of the lateral bias film 22 can be stabilized. Here, tantalum is used for the intermediate film 24 and chromium is used for the base film 25. Here, with respect to the magnetoresistive effect multilayer film 10, the single domain domainization film 21 and the lateral bias film 22 are formed on the substrate 50.
Although the configuration on the side of is shown, even if this positional relationship is reversed, the characteristics are not impaired. In that case, the lamination position of the base film 25 is arranged on the base side of the lateral bias film 22. By forming the lateral bias film 22 from a hard magnetic film or a soft magnetic film exchange-coupled with an antiferromagnetic film, the residual magnetization can be directed in a predetermined direction by a predetermined magnetizing process. Similarly, the single-domain film 21 is formed of an antiferromagnetic film or a hard magnetic film, and anisotropy in a predetermined direction can be induced in a directly laminated ferromagnetic film by a predetermined magnetizing process.

FIG. 4 is a magnetoresistive effect curve measured only with the magnetoresistive effect multilayer film 10. The magnetoresistive effect curve is symmetrical to the positive and negative of the magnetic field, and linearity is not obtained. Further, the reciprocating magnetic field causes hysteresis, which causes noise. FIG. 5 is a magnetoresistive effect curve when the lateral bias film 22 and the single domain domainization film 21 are used for the magnetoresistive effect multilayer film 10.
The signal has linearity and a good response without hysteresis was obtained.

FIG. 6 is an explanatory diagram of a magnetic head device using the magnetoresistive effect element of the present invention. Information is recorded in a track shape with a predetermined track width 44 on a disk 91 having a recording medium on its surface. The magnetically recorded signal appears as a leakage magnetic field 64, and the magnetic head slider 90 brings the opposing surface 63 close to the surface of the disk 91 and introduces the leakage magnetic field 64 into the mounted magnetoresistive element to convert it into a signal. . The magnetoresistive effect element includes a magnetoresistive effect film 20 and an electrode 40.
And converts changes in the magnetic field into electrical signals. Although the recording head is not shown in the figure, the recording head can be formed on the same slider to perform recording and reproduction, respectively.

The direction 61 of remanent magnetization of the lateral bias film and the direction 66 of anisotropy of the single domain domainization film 21 are defined as the directions perpendicular and parallel to the facing surface 63 of the head slider 90, respectively, and the element height. It is almost the same as the direction 65 and the track width direction 67. The electrode 40 passes a current through the magnetoresistive laminated film 10 and takes out the electric resistance of the magnetoresistive laminated film 10 which is changed by an external magnetic field as an electric signal, particularly a voltage.

FIG. 7 is an explanatory diagram of the magnetic recording / reproducing apparatus of the present invention. A disk 91 having a recording medium for magnetically recording information formed on its surface is rotated by a spindle motor 93, and an actuator 92 guides a head slider 90 onto a track of the recording medium 91. That is, in the magnetic disk device, the reproducing head and the recording head formed on the head slider 90 relatively move close to a predetermined recording position on the recording medium 91 by this mechanism, and sequentially write and read signals. The recording signal is recorded on the medium by the recording head through the signal processing system 94, and the output of the reproducing head is obtained as a signal through the signal processing system 94. Further, when the reproducing head is moved to a desired recording track, the position on the track can be detected by using a highly sensitive output from the reproducing head, and the actuator can be controlled to position the head slider. Although one head slider 90 and one disk 91 are shown in this figure, they may be plural. The recording medium may record information on both sides of the disc 91. When information is recorded on both sides of the disc, the head sliders 90 are arranged on both sides of the disc 91.

FIG. 8 is an explanatory view showing the structure of the second example of the magnetoresistive effect element of the present invention. The magnetoresistive effect multilayer film 10 is composed of a plurality of ferromagnetic films 11, 12, 13, 14, 15, 16 laminated via non-magnetic conductive films, and antiferromagnetic films are provided between the respective ferromagnetic films. A strong bond is working. The single magnetic domain dividing films 21 and 25 are directly laminated to the ferromagnetic films 11 and 16 on both sides of the magnetoresistive effect multilayer film 10,
An exchange coupling bias is applied to the ferromagnetic films 11 and 16. The exchange coupling bias application directions 66 and 68 are substantially parallel to the track width direction 67 and opposite to each other. The direction of the magnetic field to be sensed is almost parallel to the element height direction 65,
The bias magnetic field of the lateral bias film 22 is obtained by setting the direction 61 of the residual magnetization of this film to the element height direction. The lateral bias film 22 is laminated with the single domain domainization film 25 via an appropriate non-magnetic layer, or is arranged with its ends in contact with each other at adjacent positions in the element height direction. Apply a magnetic field.

FIG. 9 is an explanatory view showing the structure of the third example of the magnetoresistive effect element of the present invention. The magnetoresistive effect multilayer film 10 includes a plurality of ferromagnetic films 11, 12, 13, 14, 15, 16,
It is composed of films in which 17 are laminated via a non-magnetic conductive film, and an antiferromagnetic coupling force works between the ferromagnetic films.
Ferromagnetic films 11 and 1 on both sides of the magnetoresistive effect multilayer film 10.
In FIG. 7, the single domain domainization films 21 and 25 are directly laminated and arranged, and the exchange coupling bias is applied to the ferromagnetic films 11 and 17. The exchange coupling bias application directions 66 and 68 are substantially parallel to the track width direction 67 and opposite to each other. The direction of the magnetic field to be sensed is almost parallel to the element height direction 65, and the bias magnetic field of the lateral bias film 22 is obtained by setting the direction 61 of the residual magnetization of this film to the element height direction. The lateral bias film 22 is laminated with the single domain domainization film 25 via an appropriate non-magnetic layer, or is arranged in contact with its end at an adjacent position in the element height direction.
A lateral bias magnetic field is applied to. As described above, the number of multilayer films of the magnetoresistive effect element of the present invention may be odd or even if the number of ferromagnetic films is three or more, and it is particularly preferable to use a multilayer film including 4 to 10 ferromagnetic films. .

[0032]

According to the present invention, a magnetoresistive effect element in which magnetic domains are controlled and an output with good linearity can be obtained, and a highly reliable high density magnetic recording / reproducing apparatus can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first example of a magnetoresistive effect element according to the present invention.

FIG. 2 is an explanatory diagram of a first example of a magnetoresistive effect multilayer film according to the present invention.

FIG. 3 is an explanatory diagram of a second example of a magnetoresistive effect multilayer film according to the present invention.

FIG. 4 is a characteristic diagram of a magnetic field response when only a magnetoresistive multilayer film is used.

FIG. 5 is a characteristic diagram of a magnetic field response of the magnetoresistive effect element according to the present invention.

FIG. 6 is an explanatory diagram of a magnetic head according to the present invention.

FIG. 7 is an explanatory diagram of a magnetic recording / reproducing apparatus of the present invention.

FIG. 8 is an explanatory diagram of a second example of the magnetoresistive effect element of the present invention.

FIG. 9 is an explanatory diagram of a third example of the magnetoresistive effect element of the present invention.

[Explanation of symbols]

10 ... Magnetoresistive film, 11, 12, 13, 14, 1
5, 16 ... Ferromagnetic film, 20 ... Magnetoresistive multilayer film, 21
... single-domain film, 22 ... lateral bias film, 61 ... direction of residual magnetization of lateral bias film, 65 ... element height direction, 66 ... direction of single-domain film anisotropy, 67 ... track width direction.

Claims (9)

[Claims] 1. A multilayer film in which three or more ferromagnetic films are sequentially and directly laminated with a non-magnetic conductive film interposed between the ferromagnetic films adjacent to each other with the non-magnetic conductive film interposed therebetween. The electric resistance changes depending on the angle formed by the mutual magnetizations, and the antiferromagnetic coupling between the adjacent ferromagnetic films via the nonmagnetic conductive film tends to direct the mutual magnetizations in antiparallel directions. In a magnetoresistive effect element using a magnetoresistive effect multilayer film in which force exists, static magnetic field bias applying means having a component substantially parallel to the direction of a magnetic field to be detected and the magnetoresistive effect multilayer film are configured. A direction which is in direct contact with the uppermost or lowermost ferromagnetic film of the ferromagnetic films, and is substantially perpendicular to the direction of the magnetic field to be detected, on the uppermost or lowermost ferromagnetic film. Unidirectional anisotropy that induces unidirectional anisotropy in Magnetoresistive element characterized by having a scan film. 2. The order in which the ferromagnetic films are stacked is
The magnetoresistive effect element according to claim 1, wherein the products of the film thickness and the magnetic flux density are different from each other. 3. The magnetoresistive effect element according to claim 1, wherein the static magnetic field biasing means comprises a hard magnetic film laminated with the magnetoresistive effect multilayer film via a nonmagnetic layer. 4. A static magnetic field bias means is laminated directly on the soft magnetic film and the soft magnetic film, which are laminated with the magnetoresistive effect multilayer film via a non-magnetic layer, to induce unidirectional anisotropy. 3. The magnetoresistive effect element according to claim 1, which is made of an antiferromagnetic film. 5. The magnetoresistive effect element according to claim 1, wherein the unidirectional bias film is an antiferromagnetic film. 6. The magnetoresistive element according to claim 1, wherein the unidirectional bias film is a hard magnetic film. 7. The magnetoresistive element according to claim 4, wherein the antiferromagnetic film is a nickel oxide film. 8. The hard magnetic film is a mixed dispersion film of a cobalt-based alloy and an insulator or semiconductor such as a covalent compound such as an oxide, a nitride, a carbide and a boride. Magnetoresistive effect element. 9. A disk having a ferromagnetic recording medium on which a signal is magnetically recorded, and a magnetic head having a facing surface close to the disk and detecting a magnetic field leaking from the recording medium by a magnetoresistive element. A magnetic recording / reproducing apparatus having the above-mentioned magnetoresistive effect element, wherein the magnetoresistive effect element is the magnetoresistive effect element according to claim 1.