JPH09274712A - Magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recorder which subjects a shielding magnetic film for magnetic shielding a magneto-resistance effect element to magnetic domain control and generates less noise in order to avoid the fluctuation of reproducing output when the recording/reproduction is repeated in a magnetic reluctance type magnetic head. SOLUTION: Magnetic domain control is performed so that a static magnetic field generated on the end face of the shielding magnetic film does not change the bias characteristic of the magneto-resistance effect element and also the magnetic characteristic of a ferromagnetic film in contact with non magnetic gaps 31, 32 is not deteriorated by constituting the shielding magnetic film 34 for magnetic shielding the magneto-resistance effect element 30 of a laminating structure consisting of the ferromagnetic film 35/antiferromagnetic film 36/ferromagnetic film 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used in a magnetic recording device such as a hard disk device or a VTR, and more particularly to the structure of a magnetic pole or a shield magnetic film forming a magnetic circuit of the magnetic head.

[0002]

2. Description of the Related Art The miniaturization and large capacity of magnetic recording devices such as hard disk drives and VTRs are rapidly progressing. In response to such trends, the performance of magnetic heads has been improved, and from thin film magnetic heads of the electromagnetic induction type to magnetoresistive effect type magnetic heads (hereinafter referred to as MR heads) utilizing the magnetoresistive effect phenomenon of thin films. It has evolved. Conventional MR
The head is, for example, a known document IEEE Trans. Ma
gn. It has the structure shown in FIG. 9 as described in MAG26 (1990) pp1689. A magnetoresistive effect element (hereinafter referred to as an MR element) 91 for reproducing a magnetic signal on a magnetic recording medium has a shield magnetic film 93 which magnetically shields the MR element via a reproducing gap 92 made of a non-magnetic material.
Is facing. On the other hand, an inductive magnetic head is used as a magnetic pole for recording a magnetic signal on the magnetic recording medium, and has a structure laminated on the shield magnetic film 93. A magnetic recording device that requires a large capacity requires high accuracy in detecting the width or position of a recording signal track. In particular, since the rotary actuator used in most hard disk devices controls the position of the magnetic head on an arc, the positional relationship of the recording head and the reproducing head with respect to the track changes at the inner and outer peripheral positions of the magnetic disk. . This difference in position is a function of the difference in radius between the recording head and the reproducing head viewed from the center of the rotary actuator, and the larger the difference in radius, the greater the positional deviation between the inner and outer circumferences. Therefore, it is necessary that the gap between the MR element forming the detecting section shown in FIG. 9 and the induction type magnetic head forming the recording section be sufficiently small.

[0003]

An MR having such a configuration.
In the head, the recording magnetic field generated by the inductive magnetic head during recording of the information signal magnetizes a part of the shield magnetic film for magnetically shielding the MR element, which adversely affects the reproduction signal. In particular, the high density MR head is a serious problem because the induction type magnetic head and the MR element are close to each other.
On the other hand, in a magnetic head which reproduces a signal using an MR element, a method of magnetically biasing the MR element is adopted in order to improve the linearity of a reproduced signal. Although various configurations of the bias magnetic field generating means have been devised, in any case, a magnetic field is applied from the outside to the soft magnetic film having the magnetoresistive effect. When a magnetic field other than the set bias generating means is added, the linearity of the transfer curve of the MR element or the bias characteristics such as the bias amount changes, and as a result, the reproduced signal is distorted or noise is generated. Will have an impact. As mentioned above, M
The phenomenon that the shield magnetic film facing the R element is magnetized by the recording magnetic field is one of the major causes for changing the bias characteristics. In order to control this phenomenon, Japanese Patent Laid-Open No.
A technique as described in Japanese Patent No. 2720 is devised. This prior art is a method of fixing the magnetization of the shield magnetic film and controlling the magnetic domain by attaching an antiferromagnetic film to the surface of the shield magnetic film facing the MR element with a non-magnetic gap interposed therebetween. . The outline of this configuration is shown in FIG. In the structure according to this conventional technique, the magnetic domain control of the shield magnetic film in the vicinity of the medium facing surface that generates the largest static magnetic field is not performed. Therefore, the magnetization of the tip of the shield magnetic film can move freely without being restricted, and the magnitude of the static magnetic field that affects the bias characteristics also changes. As a result, the expected stabilization of the bias characteristics becomes insufficient. In addition, since the magnetic permeability of the shield magnetic film whose magnetic domains are controlled in the deep part of the reproduction gap decreases,
The reproduction waveform of the MR element is affected, and the symmetry of the reproduction waveform deteriorates depending on the controlled magnetization direction in the shield magnetic film.

A known technique for controlling the magnetic domain of the shield magnetic film is disclosed in Japanese Patent Laid-Open No. 4-98608. In this technique, an antiferromagnetic film is laminated on the magnetic core or the shield magnetic film of the recording magnetic pole laminated on the MR element for reproduction. The configuration of this known example is shown in FIG. As shown, an antiferromagnetic film is provided on the upper side of the shield magnetic film or the magnetic film forming the magnetic pole. In this known technique, in the portion where the antiferromagnetic film is arranged in the recording gap, the magnetic permeability of the magnetic film facing the recording gap deteriorates, so that the deterioration of the recording characteristics becomes a problem. In particular, since the decrease in magnetic permeability slows the rise of the recording magnetic field, problems such as recording bit noise or bit transitions occur. Similarly, in the portion where the antiferromagnetic film is arranged in the reproduction gap, the same effect as that of the reproduction gap widened due to the deterioration of the magnetic permeability of the shield magnetic film is brought about, which causes the distortion of the reproduction waveform to increase. For example, the full width at half maximum (PW50) of the reproduced signal waveform is an important problem, and the characteristic deterioration of the shield magnetic film is caused by PW5.
The result is that 0 is increased. In high-density magnetic recording, the reproduction waveform is sharper, that is, the smaller the PW50, the higher the density that can be achieved. Therefore, increasing the PW50 makes it difficult to improve the performance of the hard disk drive.

Further, as a known technique for controlling the magnetic domain of the shield magnetic film, as disclosed in Japanese Patent Application Laid-Open No. 62-270016, an AC magnetic field is demagnetized by an AC magnetic field by causing an AC current to flow through a bias magnetic field generating conductor. Is the technology of doing. However, AC degaussing requires a secondary current generating means, and degaussing takes a long time, so that it cannot be used in a compact and high recording density device having a high data transfer rate.

In another conventional technique, Japanese Patent Laid-Open No. 4-35361 is used.
There is one described in Japanese Patent Publication No. This technique is to dispose a permanent magnet film inside the reproducing gap adjacent to the MR element in order to suppress noise due to discontinuity of magnetization change inside the MR element. The magnetic field generated by the permanent magnet film applies a bias magnetic field to the soft magnetic film forming the MR element to control the magnetic domain of the MR element. The permanent magnet film that generates the bias magnetic field also exerts a magnetic field on the opposing shield magnetic film via the gap, so that a part of the shield magnetic film can be magnetic domain controlled. However, the structure in which the magnetic field enters the shield magnetic film facing the MR element to stabilize the magnetization has the drawback of lowering the magnetic permeability of the shield magnetic film forming the read gap portion, and therefore has the effect of increasing the read gap length. Results in a wide half-value width of the reproduced waveform. Further, since the magnetic field generated from the permanent magnet film acts more strongly on the MR element than the shield magnetic film, if the magnitude of the magnetic field is increased to sufficiently control the magnetic domain of the shield magnetic film, M
The bias magnetic field applied to the R element becomes excessively higher than an appropriate value, which also causes a reduction in reproduction sensitivity of the MR element.

As described above, in the MR head in which the MR element having the magnetoresistive effect for detecting or reproducing the signal and the inductive magnetic head for recording the information signal are combined, the MR element is operated by the action of the recording magnetic field. There is a problem that the bias characteristic to be controlled fluctuates. The change in the bias characteristic changes the resistance value of the MR element which is the reproducing element, distorts the transfer curve of the element with respect to the applied magnetic field, and causes the reproducing characteristic of the head to be reduced. Particularly, when the recording / reproducing process is repeated, the magnetization state of the shield magnetic film after recording changes depending on the pattern of the signal to be recorded, and the reproduction output fluctuates or the reproduction waveform is distorted each time. This phenomenon has the same effect as noise at the time of signal reproduction and significantly deteriorates the performance of the device. Therefore, in order to stabilize the bias characteristics of the MR element, it is necessary to control so that the magnetization state of the shield magnetic film is not changed by the recording magnetic field. However, it is necessary to prevent the magnetic domain control of the shield magnetic film from affecting the reproducing characteristic due to deterioration of magnetic permeability as in the above-mentioned conventional technique.

According to the present invention, since the fluctuation of the reproducing output of the MR head is suppressed, the influence of the recording magnetic field on the shield magnetic film of the MR element is reduced, and the reproducing characteristics are not deteriorated by the magnetic domain control of the shield magnetic film. It is an object of the present invention to provide an MR head having such a structure.

[0009]

According to the present invention, a detection element or MR element mainly having a magnetoresistive effect, a pair of shield magnetic films for magnetically shielding the MR element, and a laminated layer on the shield magnetic film are provided. In a magnetic head having a signal recording magnetic pole, at least one of the pair of shield magnetic films has a laminated structure of a ferromagnetic film / antiferromagnetic film / ferromagnetic film. It is provided. The configuration and principle of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the laminated film of ferromagnetic film / antiferromagnetic film / ferromagnetic film has a structure in which an antiferromagnetic film is sandwiched by ferromagnetic films. As an antiferromagnetic film, FeM
n, NiMn, FeNiMn, NiO, CoO, Ni
It is possible to use CoO, TbCo, or the like. Since the laminated film of the present invention has a three-layer structure instead of the layer structure shown in the above-mentioned known example, the antiferromagnetic film is not exposed on the surface but appears only in the cross section of the laminated film. Is. FIG. 2 is a perspective view of the recording / reproducing separated magnetic head as viewed from the side facing the magnetic recording medium, and shows a cross section obtained by dividing the central portion into two. A read-only head is mounted on the substrate (not shown) side, and an inductive magnetic head 29 is mounted as a write-only head. The MR element 21 as a detection element of the read-only head is arranged to face the shield magnetic films 24 and 25 via the nonmagnetic gaps 22 and 23. At least one of the shield magnetic films 24 and 25 has a laminated structure of ferromagnetic film / antiferromagnetic film / ferromagnetic film. Further, since the shield magnetic film 25 is not shared with the magnetic pole of the recording induction type magnetic head 29, the magnetic circuit has an independent structure.

As a result of adopting the configuration shown in FIGS. 1 and 2, at the interface of the ferromagnetic film in contact with the antiferromagnetic film in the shield magnetic film, the exchange that acts between the magnetic atoms in the antiferromagnetic film and in the ferromagnetic film. The directions of magnetization in the ferromagnetic film are uniformly arranged by the interaction. In this state, the magnetic domain structure is fixed, and the magnetic domain structure in the ferromagnetic film is fixed. In this case, the magnetization in the ferromagnetic film at the portion apart from the thickness direction of the antiferromagnetic film is magnetized by the ferromagnetic coupling in the film. Therefore,
When the external magnetic field is sufficiently small, the magnetization is rearranged in a uniform direction, and the magnetic domain control of the entire shield magnetic film is performed. On the other hand, at the surface of the shield magnetic film that is in contact with the gap farthest from the antiferromagnetic film, the effect of the exchange coupling generated by the antiferromagnetic film is weakened, so the direction of magnetization can be changed by the external magnetic field, and the magnetic permeability Is less deteriorated. Therefore, it is possible to obtain a magnetoresistive effect magnetic head which is less affected by the recording magnetic field by using the shield magnetic film having the structure according to the present invention and less deteriorated in characteristics of the shield magnetic film near the reproducing gap.

The present invention is also directed to a signal recording magnetic pole having a detection element having a magnetoresistive effect, a pair of shield magnetic films for magnetically shielding the detection element, and one of the shield magnetic films shared as a part of a magnetic circuit. In the magnetic head having the above, the shield magnetic film shared with the recording magnetic pole is a laminated film of a ferromagnetic film / an antiferromagnetic film / a ferromagnetic film. The configuration of the present invention will be described below with reference to the drawings. In FIG. 3, the MR element 30
Faces the shield magnetic films 33 and 34 via the non-magnetic gaps 31 and 32. One of the shield magnetic films 34
Share the magnetic pole of the recording induction type magnetic head, and another recording magnetic pole 39 through the non-magnetic recording gap 38.
Is facing. At this time, the shield magnetic film 34 has a laminated structure of a ferromagnetic film 35, an antiferromagnetic film 36, and a ferromagnetic film 37.

In the recording / reproducing separated type magnetic head, it is desirable to make the distance between the recording magnetic pole and the reproducing element as small as possible in order to improve the reliability of track control. The reason for this is
In a small-sized magnetic recording device, the magnetic head moves in an arc shape on the magnetic recording medium. is there. The smaller the difference in radius of the circular arc between the recording gap position and the reproducing gap position, that is, the closer the recording head is to the reproducing element, the higher the reliability. From this, a composite magnetoresistive head of the type in which a part of the shield magnetic film of the magnetoresistive magnetic head is used also as a magnetic pole of the recording induction magnetic head has been devised. However, if the shield magnetic film is shared as a part of the recording magnetic pole, the recording magnetic field directly affects the magnetization in the shield magnetic film, and the bias characteristic of the MR element becomes unstable. Therefore, the magnetic domain control of the shield magnetic film is inevitable. By using the shield magnetic film according to the configuration of the present invention, at the interface of the ferromagnetic film in contact with the antiferromagnetic film in the shield magnetic film, the exchange mutual action that acts between the magnetic atoms in the antiferromagnetic film and the ferromagnetic film. Since the action occurs, the magnetization directions in the ferromagnetic film are uniformly arranged. In this state, magnetic domain control is performed, and the magnetic domain structure in the ferromagnetic film is fixed. At this time, the magnetization in the portion of the ferromagnetic film remote from the antiferromagnetic film is magnetized by the ferromagnetic coupling in the film. Therefore, when the external magnetic field is sufficiently small, the magnetization is rearranged in a uniform direction, and the magnetic domain control of the entire shield magnetic film is performed. On the other hand, at the surface of the shield magnetic film that is in contact with the gap farthest from the antiferromagnetic film, the effect of the exchange coupling generated by the antiferromagnetic film is weakened, so the direction of magnetization can be changed by the external magnetic field, and the magnetic permeability Is less deteriorated.
Moreover, since the magnetic permeability of the antiferromagnetic film is generally sufficiently small, it is possible to prevent the influence of the recording magnetic field from directly propagating to the reproducing gap portion in the shield magnetic film divided by the antiferromagnetic film. In addition, even if the characteristics of the inserted film deteriorate, it is possible to reduce the influence of the recording magnetic field with the same effect as when the conventional non-magnetic film is inserted into the magnetic film. Therefore, by using the shield magnetic film having the structure according to the present invention, it is possible to obtain a magnetoresistive effect magnetic head that is less affected by the recording magnetic field and less deteriorated in characteristics of the shield magnetic film near the reproducing gap.

According to the present invention, a detection element having a magnetoresistive effect, a pair of shield magnetic films for magnetically shielding the detection element, and a signal sharing at least one of the shield magnetic films as a part of a magnetic circuit. A magnetic head having a recording magnetic pole, wherein the shield magnetic film shared with the recording magnetic pole has a laminated structure of a ferromagnetic film / antiferromagnetic film / ferromagnetic film. The magnetoresistive head is characterized in that the material of the antiferromagnetic film forming the shield magnetic film is an insulating material or the conductivity thereof is smaller than that of the ferromagnetic film.

In a composite magnetoresistive effect magnetic head of the type in which the shield magnetic film of the reproducing magnetoresistive effect element and the magnetic pole of the recording inductive magnetic head are shared, the magnetic characteristic of the shield magnetic film becomes the recording characteristic of the head. It has a big impact. In the case of high recording density, a high frequency recording magnetic field is required, but there is a problem of eddy current loss in the magnetic pole as the frequency increases. By using the shield magnetic film of the configuration according to the present invention, since the shield magnetic film is divided by the insulating material, the penetration depth capable of entering the high frequency magnetic field is sufficient,
The skin effect of magnetic flux can be reduced. Therefore, it is possible to obtain the magnetoresistive effect magnetic head in which the eddy current loss is reduced and the magnetic domain is well controlled. In this case, NiO, CoO, NiCoO or the like can be used as the antiferromagnetic film.

Further, the present invention is a signal recording device which has a detection element having a magnetoresistive effect, a pair of shield magnetic films for magnetically shielding the detection element, and one of the shield magnetic films which is also used as a part of a magnetic circuit. In a magnetic head having a magnetic pole, the shield magnetic film which is also used as a recording magnetic pole has a laminated structure of a ferromagnetic film / antiferromagnetic film / ferromagnetic film. The ferromagnetic film / antiferromagnetic film / laminated as a magnetic film /
Among the ferromagnetic films, the film thickness of the ferromagnetic film arranged on the recording magnetic pole side is 30% or more of the magnetic film thickness which constitutes the recording magnetic pole facing the ferromagnetic film. The present invention provides a magnetoresistive effect magnetic head.
The configuration of the present invention will be described below with reference to the drawings. FIG. 4 shows the end surface of the magnetoresistive effect magnetic head as seen from the medium facing surface. The MR element 40 has a non-magnetic reproducing gap 41, 4
It is formed so as to be sandwiched between the shield magnetic films 43 and 44 with the film 2 interposed therebetween. The shield magnetic film 44 has a non-magnetic gap 48,
It forms a part of a magnetic circuit of the recording induction type magnetic head by forming a pair with the recording magnetic pole 49. At this time, of the ferromagnetic film 45, the antiferromagnetic film 46, and the ferromagnetic film 47 forming the shield magnetic film 43, the ferromagnetic film 47 arranged on the recording magnetic pole 49 side has the same film thickness as the recording magnetic pole 49. It is 30% or more of the film thickness.

The magnetic field generated by the recording magnetic pole 49 propagates and flows into the shield magnetic film 44 of the MR element. At this time, if the ferromagnetic film 47 forming the shield magnetic film 44 is too thin, the ferromagnetic film 47 is saturated. When the ferromagnetic film 47 is saturated, the gradient of the recording magnetic field becomes small and the recording characteristics deteriorate. Further, if the ferromagnetic film 47 on the recording magnetic pole 49 side in the laminated shield magnetic film 44 is saturated, the magnetic field from the recording magnetic pole 49 will flow into the ferromagnetic film 45 on the opposite side. The effect of magnetic domain control deteriorates. By using the shield magnetic film having the configuration of the present patent, it is possible to prevent the ferromagnetic film stacked in the shield magnetic film from being saturated when a recording magnetic field is generated, and at the same time, a good magnetoresistive effect can be obtained for recording and reproducing characteristics. Type magnetic head.

The antiferromagnetic material has a strong exchange interaction acting between magnetic atoms in the material, and its magnetization direction is unlikely to change with respect to an external magnetic field and is stable. When the antiferromagnetic material and the ferromagnetic material are stacked, the magnetization in the ferromagnetic material and the magnetization in the antiferromagnetic material are arranged in parallel or antiparallel by exchange interaction at the stacking interface. Therefore, when an external magnetic field is applied to this laminated body, the magnetization in the antiferromagnetic material is kept stable even if the magnetization of the ferromagnetic material is reversed. When the external magnetic field disappears, the magnetization in the ferromagnetic material rearranges following the magnetization in the antiferromagnetic material due to the exchange interaction generated at the interface. This effect is the principle of the magnetic domain control technology in which the antiferromagnetic material and the ferromagnetic material are laminated. FIG. 5 shows the principle of this operation. The ferromagnetic material 50 is joined to the antiferromagnetic material 51. The magnetization 52 in the ferromagnetic material exchange-exchanges with the magnetization 53 in the antiferromagnetic material through the interface between the ferromagnetic material 50 and the antiferromagnetic material 51. As a result, the magnetization 52 in the ferromagnetic material follows and aligns with the magnetization 53 in the antiferromagnetic material.

The instability of the magnetic domain structure of the shield magnetic film is
The intensity or distribution of the static magnetic field generated from the shield magnetic film is changed. The MR element adjacent to the shield magnetic film via the non-magnetic gap is magnetically biased for the purpose of controlling the reproduction characteristics. Since the static magnetic field generated from the shield magnetic film also affects the bias state of the MR element, the disturbance of the magnetic domain structure of the shield magnetic film structure, especially the fluctuation of the static magnetic field after repeated recording / reproduction is caused by the stability of the reproduction characteristics. Deteriorate. For example, when the bias state changes, the resistance of the MR element is changed and the reproduction output is changed. The fluctuation of the reproduction output increases the error rate of the reproduction signal as well as the noise. From the above consideration, in order to stabilize the reproducing characteristic, it is necessary to make the magnetization state of the shield magnetic film constant by controlling the magnetic domain so that the static magnetic field generated from the shield magnetic film does not change. In the present invention, the above-mentioned magnetic domain control technique can be applied to the shield magnetic film of the magnetic effect type magnetic head to obtain a magnetoresistive effect type magnetic head with little reproduction output fluctuation.

In magnetic domain control of a ferromagnetic material, a force acts to keep the magnetization in a stable arrangement, but the stable magnetization direction means that the magnetic permeability of the material becomes low. Therefore, if the magnetic domain control technique is directly applied to the shield magnetic film surface forming the gap, the gap length is changed and the reproduction waveform is changed. In particular, when the reproduction gap length becomes large, the half width of the reproduction waveform becomes large, which is not suitable for high density recording. In the present invention, since the magnetic domain control is performed inside the shield magnetic film, the magnetic permeability near the surface of the shield magnetic film can be kept high as compared with the method of directly controlling the magnetic domain on the film surface. This means that the reproduction gap is defined by the normal magnetic shielding by the shield magnetic film having a high magnetic permeability, which enables a narrow gap suitable for high density recording.

[0020]

Embodiments of the present invention will be described with reference to the drawings. FIG. 6 shows the calculation of the magnetization distribution in the shield magnetic film when the surface of the shield magnetic film is magnetized. The curve shown in the figure shows the presence or absence of magnetic domain control by the antiferromagnetic film. The thickness of the shield magnetic film was 3 μm, and the position of the antiferromagnetic film for controlling magnetic domains was 2 μm from the film surface. The magnetic field exists only on the surface of the shield magnetic film, and the magnetization is freely changed on the opposite side of the shield magnetic film. The static magnetic field generated on the surface of the film due to the effect of the applied magnetic field is a condition that affects the entire film. After applying a magnetic field, the magnetization distribution in a state where the shield magnetic film is saturated on the film surface is observed. In the absence of the antiferromagnetic film, the magnetization decreases asymptotically from the surface. However, the opposite side (3 μm) of the shield magnetic film
Then, it can be seen that the value of the magnetization is not 0, and the influence appears on the reproducing gap side.

On the other hand, when the magnetic domain control is performed using the antiferromagnetic film, the magnetization distribution in the film cross section sharply decreases toward the position of the antiferromagnetic film. Magnetic domain controlled position (2μ
In m), the magnetization once becomes 0, and slightly increases as the distance from the magnetic domain control film increases. The magnetization appearing on the surface of the shield magnetic film is reduced to about 10% as compared with the case where the magnetic domain control is not performed. The magnetization fixed at the interface of the magnetic domain control film controls the magnetization in the vicinity of the magnetic domain control film by ferromagnetic exchange coupling. The slight increase in the magnetization value on the side opposite to the magnetic domain control film is due to the static magnetic field appearing on the shield surface. This result shows that by controlling the magnetic domain composed of the antiferromagnetic film sandwiched in the shield magnetic film, the influence of the magnetization appearing on the surface of the shield magnetic film hardly reaches the reproducing gap side.

FIG. 7 shows the result of expressing the fluctuation of the reproduction output as a function of the detected current flowing through the element with and without the magnetic domain control. This is because the recording current is applied to the coil that excites the recording magnetic pole, the recording magnetic field is applied to the shield magnetic film, the signal magnetic field is applied to the magnetoresistive effect element after the recording current is cut off, and the fluctuation of the reproducing output of the element is investigated. It is a thing. The reproduction output fluctuation is obtained by reproducing the track recorded on the recording medium for one round and obtaining the average value of the outputs, and obtaining the standard deviation of the average outputs when this is repeated 100 times. Those with magnetic domain control are compared with those without magnetic domain control,
The output fluctuation is always small even if the detected current is changed. On the other hand, in the case where the magnetic domain control is not performed, the output fluctuation is about three times larger. Even if the detected current is changed, the value of the output fluctuation is large in the case where the magnetic domain control is not performed. The change in the output fluctuation value depending on the magnitude of the detected current is due to the change in the bias characteristic of the magnetoresistive variable element. With a small current, the bias of the element is insufficient and the magnetization arrangement in the element tends to become unstable. When the magnetic domain control is performed, the detection current dependency is also reduced, and the reproduction output fluctuation can be minimized.

FIG. 8 shows the magnetization state of the composite magnetoresistive magnetic head as seen from the medium facing surface. In this example, a recording current was passed through the recording magnetic pole excitation coil, and the magnetization distribution around the magnetic pole at that time was observed. A scanning Kerr effect microscope was used for the observation. In the figure, reference numeral 80 denotes an upper recording magnetic pole, and a shield magnetic film 82 which also serves as a lower magnetic pole is laminated via a recording gap 81. 83 is the other shield magnetic film. The exciting coil has 15 turns, and a recording frequency of 20 MHz and a recording current of 60 mA are applied. The contour lines in the figure show the output signal of the Kerr effect microscope, and the larger the output, the stronger the magnetization. The portion indicated by A indicates a strongly magnetized portion, and the portion indicated by B indicates a weakly magnetized portion. Area A strongly magnetized during application of recording current
Controls the recording of signals. Looking at the magnetization distribution of the recording magnetic pole shield magnetic film double-use portion 82 of the present embodiment, the width of the strongly magnetized A portion is about 1.5 μm. On the other hand, the film thickness of the upper recording magnetic pole 80 is about 5.5 μm, and the ratio is 3
0%. The magnetic flux propagating in the magnetic pole depends on the cross-sectional area of the magnetic path, but if the shield magnetic film 82 is too thin, the film saturates and sufficient recording cannot be performed. For example, when the film thickness becomes thin, the signal output of the portion A in the shield magnetic film 82 rapidly decreases. In the present embodiment, considering that the strongly magnetized portion A is a magnetic flux concentration region at the time of recording, the region of the shield magnetic film 82 affected by the recording time field has a film thickness of at least about 30%. I know there is. 60 mA from the saturated recording characteristics of this head
Considering that the recording current is already saturated, the magnetization distribution in the shield magnetic film that contributes during recording is
It can be said that the area is about 30% of the shield magnetic film thickness.
Therefore, it is desirable that the magnetic film thickness forming a part of the magnetic pole is 30% or more of that of the upper magnetic pole. Therefore, when the magnetic domain of the shield magnetic film 82 is controlled by the antiferromagnetic film, the thickness of the ferromagnetic film facing the upper magnetic pole is preferably 30% or more of the upper magnetic pole.

A method of manufacturing a laminated film of ferromagnetic film / antiferromagnetic film / ferromagnetic film which constitutes the shield magnetic body will be described.
A sputtering method or a plating method can be used for forming the ferromagnetic film. Ferromagnetic film /
It is desirable to continuously sputter the antiferromagnetic film / ferromagnetic film. This is because the interface between the ferromagnetic film and the antiferromagnetic film needs to be clean. The exchange coupling acting at the interface is significantly deteriorated by the presence of impurity atoms. After sputtering, it is processed into a required shape by using a photolithography technique such as milling to form a magnetic head shield. When the plating method is used, a ferromagnetic layer is formed by plating on a base film made of a ferromagnetic material, and a new base film made of a ferromagnetic material is provided thereon. Further, an antiferromagnetic film is formed, and in addition, a protective film made of a ferromagnetic material is formed. The ferromagnetic underlayer film, antiferromagnetic film and ferromagnetic protective film are preferably formed by a continuous film by sputtering. This is because it is necessary to keep the interface between the ferromagnetic film and the antiferromagnetic film normal. A ferromagnetic film is further stacked on these stacked films by a plating method and patterned to form a head shield layer. The ferromagnetic protective layer formed by sputtering serves as a base film for plating, and at the same time, serves to prevent corrosion of the antiferromagnetic film in the plating bath. This is particularly important for Mn-based alloys such as FeMn and NiMn as antiferromagnetic materials.

[0025]

As is apparent from the above, when the shield magnetic film that magnetically shields the magnetoresistive effect element has a laminated structure of ferromagnetic film / antiferromagnetic film / ferromagnetic film, the magnetic domain control of the shield magnetic film is performed. It is possible to reduce changes in the intensity and distribution of the static magnetic field generated by the shield magnetic film near the reproduction gap. As a result, the bias applied to the magnetoresistive effect element is stable, and a magnetic head having good reproduction characteristics with little fluctuation in reproduction output can be obtained. Although the embodiment of the present invention has been described in detail with the magnetoresistive effect magnetic head, it can be applied to a magnetic head having a magnetic pole or a shield magnetic film using a magnetic material in view of the technical idea of the present invention. Are within the scope of implementation for those skilled in the art.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a shield magnetic film according to the present invention.

FIG. 2 is a perspective view of a magnetoresistive magnetic head according to an embodiment of the present invention.

FIG. 3 is a perspective view of a magnetoresistive head according to another embodiment of the present invention.

FIG. 4 is an end view of a magnetoresistive head according to another embodiment of the magnet of the present invention.

FIG. 5 is a conceptual diagram of magnetic interaction for explaining the principle of the present invention.

FIG. 6 shows a shield magnetic film thickness and magnetization characteristics.

FIG. 7 shows detected current vs. output fluctuation characteristics.

FIG. 8 is a magnetization distribution on the surface facing the magnetic recording medium.

FIG. 9 is a perspective view of a conventional magnetoresistive effect magnetic head.

FIG. 10 is a central cross-sectional view of a conventional magnetoresistive effect magnetic head.

FIG. 11 is a perspective view of a conventional magnetoresistive effect magnetic head.

[Explanation of symbols]

11 ferromagnetic film, 12 antiferromagnetic film, 13 ferromagnetic film,
21 MR element, 23 non-magnetic gap, 24 shield magnetic film, 25 shield magnetic film, 29 inductive magnetic head, 30 MR element, 33 shield magnetic film, 34 shield magnetic film, 35 ferromagnetic film, 36 antiferromagnetic film,
37 ferromagnetic film, 40 MR element, 41 non-magnetic gap, 44 shield magnetic film, 48 non-magnetic gap, 4
9 recording magnetic pole, 50 ferromagnetic material, 51 antiferromagnetic material, 52 magnetization, 90 induction type magnetic head.

Claims (7)

[Claims] 1. A magnetic head for recording and reproducing information on a magnetic recording medium, wherein part or all of a magnetic circuit of the magnetic head is a laminated film of a ferromagnetic film / antiferromagnetic film / ferromagnetic film. A magnetic head characterized in that 2. A magnetic head for recording / reproducing information on / from a magnetic recording medium, wherein at least one of a pair of shield magnetic films, in which magnetoresistive effect elements are opposed to each other with a nonmagnetic insulating layer interposed therebetween, is strong. A magnetic head characterized in that a part or the whole is composed of a laminated film of a magnetic film / antiferromagnetic film / ferromagnetic film. 3. A magnetic head for recording and reproducing information on a magnetic recording medium, recording by a magnetic circuit having a magnetic pole and a recording gap, and being surrounded by a pair of shield magnetic films and a non-magnetic insulating layer. A magnetic head which is reproduced by a magnetoresistive effect element, wherein a part or all of the magnetic pole or the pair of shield magnetic films is a laminated film of a ferromagnetic film / antiferromagnetic film / ferromagnetic film. 4. The magnetic head according to claim 1, wherein the laminated film of the ferromagnetic film / antiferromagnetic film / ferromagnetic film has a constant magnetization direction immediately before a reproducing operation. A magnetic head characterized in that 5. The magnetic head according to claim 1, wherein the antiferromagnetic film is made of a material whose conductivity is lower than that of the ferromagnetic film. head. 6. The magnetic head according to claim 3,
A magnetic head characterized in that the magnetic pole and the shield magnetic film are partially shared. 7. The magnetic head according to claim 6, wherein:
A magnetic head characterized in that the shared laminated film of ferromagnetic film / antiferromagnetic film / ferromagnetic film is an electrical nonconductor.