JP2003208706A - Magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of a Barkhausen noise, to suppress the formation of steps on a magnetoresistive effect element layer and a recording head placed thereon, and the concentration of stress, and to prevent the breaking of a thin magneto-resistance layer by the steps of a hard magnetic substance layer. <P>SOLUTION: The magnetoresistive effect reproducing head is provided with a magnetoresistive effect film 3 made of a ferromagnetic material thin film, which has a central sensing region 102 and an end magnetic domain control region 103, and a hard magnetic substance layer 1 made of a hard magnetic material thin film, which is overlapped with and brought into direct contact with the end magnetic domain control region 103. In order to maintain the central sensing region 102 of the magnetoresistive effect film 3 in a single magnetic domain state, a longitudinal magnetic bias is generated by a magnetic field and ferromagnetic exchange coupling. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing head for reading an information signal from a magnetic recording medium, and more particularly to a magnetoresistive effect reproducing head characterized by a bias magnetic field and a magnetic recording / reproducing apparatus using the same. Regarding

[0002]

2. Description of the Related Art In the prior art, the magnetoresistive effect (M
R) elements or magnetic read transducers called heads are disclosed. These MR elements are capable of reading data from magnetic surfaces that have a large linear recording density. The MR element utilizes the resistance change of a read element made of a magnetoresistive material to detect magnetic field signals as a function of the amount and direction of magnetic flux sensed by the element. Also, in order to operate the MR element optimally, 2
It is also disclosed that it is necessary to apply two bias fields.

MR so that the response to the magnetic flux becomes linear
A lateral bias field is typically used to bias the device. This bias magnetic field is perpendicular to the surface of the magnetic recording medium and parallel to the surface of the flat MR element.
There are various methods for applying this bias, such as shunt bias, soft bias, and soft AJ cent layer (SAL) bias (for example, USP 4,663,685).

These lateral biases cause the head to be R-
It is generated at a level sufficient to bias it into the most linear range of the H characteristic curve.

Another bias magnetic field used in the MR element is called a longitudinal bias magnetic field in the technical field, and is parallel to the surface of the magnetic recording medium and M
It is parallel to the longitudinal direction of the R element. The function of the longitudinal bias magnetic field is to suppress Barkhausen noise caused by multi-domain effect in the MR element.

In the prior art, many bias methods and devices for MR elements have been developed. However, since the recording density is increased, the recording track is made narrower,
It has become necessary to increase the linear recording density along the track. Small MR elements satisfying these requirements have not yet been realized.

A conceptual solution to these problems in the prior art can be obtained by implementing patterned longitudinal biasing, as disclosed in JP-A-60-59518 and USP 5,005,096 (JP-A-2-220213). )
It is described in. In short, the above-mentioned prior art puts an appropriate single domain state in the end region of the magnetoresistive layer (MR layer) and, as a result, induces the single domain state in the central magnetic sensitive region of the MR layer. Is. This can be achieved by creating a longitudinal bias only in the end regions of the MR layer. The longitudinal bias in this prior art is realized by ferromagnetic exchange coupling or magnetostatic coupling between the hard magnetic layer and the soft magnetic MR layer.

Japanese Unexamined Patent Publication (Kokai) No. 60-59518 discloses a method for realizing a longitudinal bias by ferromagnetic exchange coupling, in which a ferromagnetic layer having a coercive force larger than that of the MR layer is provided only in a portion where the electrode and the MR layer overlap. Have been described. The thickness of each thin film used here is 200 to 1 for the MR layer.
It is described that the ferromagnetic layer having a large coercive force is 500 to 3000 Å (50 to 300 nm).

USP 5,005,096 describes a method for realizing a longitudinal bias by magnetostatic coupling between a hard magnetic layer and an MR element. In this method, soft magnetic MR
The inherent coercive force of the hard magnetic layer exchange-coupled with the layer is substantially lost, and there is a problem in the durability of the bias, and the magnetic flux from the hard magnetic layer does not adversely affect the sensitivity profile. Therefore, the hard magnetic layer is provided parallel to the MR layer and is separated from the MR layer. actually,
A non-magnetic spacer layer is inserted between the hard magnetic thin film and the end magnetic domain control region of the MR layer to adjust the thickness of the hard magnetic thin film to the magnetic flux in the end magnetic domain control region of the MR layer and the central part of the MR layer. The magnetic flux ratio between the magnetic flux and the longitudinal magnetic flux is selected to be a desired ratio. For this purpose, a spacer layer having a thickness of 50 to 200 nm is suitable, and as a suitable non-magnetic material having conductivity, C is used.
r, W, Nb and Ta are preferred.

USP 4,663,685 (Japanese Patent Laid-Open No. 62-406)
No. 10) describes that a longitudinal bias is applied using an antiferromagnetic material (MnFe) to control magnetic domains and domain walls of the MR layer to reduce noise.

[0011]

In the case of USP 4,663,685 in which magnetic domain control is performed using an antiferromagnetic material film, MnFe is the only material that can be put to practical use due to magnetic properties such as the Neel point. However, MnFe has a problem of low corrosion resistance, and M is only M due to ferromagnetic coupling at the portion in contact with the MR film.
It does not control the magnetic domains of the R film.

The hard magnetic layer can control the magnetic domain by the ferromagnetic coupling in the contact portion and the magnetic field leaking from the hard magnetic layer. Therefore, the magnetic domain control method for the MR film using the hard magnetic layer is more versatile than that for the antiferromagnetic film, has a high magnetic domain control effect, and can be applied more freely than the antiferromagnetic film.

However, the prior art of Japanese Patent Laid-Open No. 60-59
In US Pat. No. 518 and US Pat. No. 5,005,096, a ferromagnetic film having a large coercive force is provided only in a portion where the MR layer which is soft magnetic and the electrode are overlapped with each other, and the hard magnetic layer which is exchange-coupled with the soft magnetic MR layer is unique. There is a problem in that the coercive force of is disappeared and there is a problem in the durability of the bias, and that the magnetic flux from the hard magnetic layer adversely affects the lateral sensitivity profile.

Further, conventionally, only the magnetic field leaking from one magnetic pole of the hard magnetic film is used in the MR layer, and the magnetic field leaking from the other magnetic pole is not used. In some cases, the magnetic field is penetrated into the MR layer to disturb the magnetic state. May cause recording demagnetization by affecting the medium facing the head, or may cause noise by penetrating the magnetic shield film sandwiching the MR layer from both sides or the core of the adjacent inductive recording head. Was becoming.

An object of the present invention is to provide a small MR head having low noise by providing an excellent MR element which overcomes the problems of the prior art.

The object of the present invention is, in particular, for thin MR layers.
It is to realize an MR head in which Barkhausen noise is suppressed by efficiently applying a longitudinal bias.

Another object of the present invention is to efficiently apply a longitudinal bias by using a hard magnetic material such as a permanent magnet.

[0018]

In order to achieve the above object of the present invention, the MR head of the present invention comprises an MR layer made of a thin film of a ferromagnetic material having a central magnetic sensitive region and an end magnetic domain control region. And a hard magnetic layer formed of a thin film of a hard magnetic material that is in direct contact with and overlaps with the end magnetic domain control region, in order to maintain the central magnetic sensitive region of the magnetoresistive layer in a single magnetic domain state, a magnetic field and The MR head has a structure for generating a longitudinal magnetic bias by ferromagnetic exchange coupling.

Further, preferably, at least an MR layer made of a thin film of a ferromagnetic material and a hard magnetic layer made of a thin film of a hard magnetic material in direct contact with the MR layer are provided, and the film thickness of the magnetoresistive layer. Is 5 nm or more and less than 20 nm, the thickness of the hard magnetic layer is in the range of 10 to 100 nm, and the ratio of the thickness of the hard magnetic layer to the thickness of the MR layer is 1 or more. .

Further, preferably, an MR layer made of a thin film of a ferromagnetic material having a central magnetic field sensitive region and an end magnetic domain control region and a thin film of a hard magnetic material overlapping and in direct contact with the end magnetic domain control region. In the MR head including at least the hard magnetic layer, the length of the central magnetic sensitive region is made larger than the track width (distance between inner end faces of electrodes).

More preferably, the MR layer formed of a thin film of a ferromagnetic material having a central magnetic sensitive region and an end magnetic domain control region of the present invention and a hard magnetic material that is in direct contact with the end magnetic domain control region in an overlapping manner. In the MR head having at least the hard magnetic layer composed of the thin film, the end magnetic domain control region of the MR layer is present on the hard magnetic layer.

More preferably, in the magnetoresistive head using the magnetoresistive film as the magnetosensitive film, the magnetic field leaking from the hard magnetic layer provided adjacent to the magnetoresistive film and the magnetoresistive film and the hard magnetic layer. A magnetic head for controlling magnetic domains of a magnetoresistive film by ferromagnetic coupling of layers, characterized in that a magnetic field leaking from a hard magnetic film is effectively closed in a ferromagnetic material forming the magnetic head. .

The hard magnetic layer provided in the MR head of the present invention is, for example, Co-Pt or Co-Pt-C having good corrosion resistance.
r, Co-Pt-Pd, Co-Pt-Ni or Co-
Since a Cr-Ta alloy thin film or the like can be used, a reproducing head having excellent environmental resistance can be constructed, and this is mounted on a recording device to realize a high-density magnetic recording / reproducing device.

In the prior art, the structure in which the necessary longitudinal bias is applied to the magnetoresistive layer by the ferromagnetic exchange coupling between the hard magnetic layer and the end magnetic domain control region and the magnetic field generated by the hard magnetic layer. The magnetoresistive effect element has never been known. The present invention is a prior art disclosed in JP-A-60-59.
518 publication and USP 5,005,096, soft magnetic MR
The point that a ferromagnetic film with a large coercive force is provided only in the portion where the layer and the electrode overlap, and the inherent coercive force of the hard magnetic layer exchange-coupled with the soft magnetic MR layer is substantially lost, and the durability of the bias is a problem. However, as a result of a more detailed study, it was found that the MR head of the present invention has a soft magnetic MR. Even if the hard magnetic layer is not provided only in the overlapping portion of the layer and the electrode, the soft magnetic M
Inserting a non-magnetic layer between the R layer and the hard magnetic layer, the soft magnetic M
This is based on the finding that Barkhausen noise can be suppressed without magnetostatically coupling the R layer and the hard magnetic layer. This effect is particularly effective when the MR layer is as thin as 20 nm or less.

Further, in the conventional technique, as shown in FIG.
Only the magnetic field leaking from one of the two magnetic poles is used for the magnetoresistive effect film 3 as the magnetic field 2 leaking from the permanent magnet 1 which is a hard magnetic layer provided on the MR film 3 with the insulating film 6 interposed therebetween. The magnetic field leaking from the magnetic pole is not used, and in some cases, it penetrates into the MR film 2 to disturb the magnetic state, and the magnetic domain control effect is reduced. The magnetic field leaking into the space also affects the medium facing the head, causing recording demagnetization, and penetrating into the magnetic shield film sandwiching the MR film from both sides and the core of the adjacent inductive recording head. It may cause noise.

Therefore, it is necessary to prevent the magnetic field leaking from the permanent magnet from leaking into the space.

In the present invention, the magnetic field leaking from the hard magnetic layer formed in the vicinity of the MR film is introduced into the soft magnetic film or the magnetic shield film used for the bias, and the magnetic field is closed in the magnetic material. Thus, the adverse effect due to the leakage of the magnetic field from the hard magnetic layer is removed at the same time as the magnetic domain control of the MR film.
By applying this method, the effect of controlling the magnetic domains of the soft magnetic film for bias and the magnetic shield film is newly added, and this effect can reduce the noise of the head.

By injecting the magnetic field leaking from the hard magnetic layer into the soft magnetic film or the magnetic shield film used for bias, the magnetization of the soft magnetic film can be controlled by the magnetic field from the hard magnetic layer. The head output waveform is obtained. Further, in the head having a structure in which the magnetic shield film and the core of the recording induction type magnetic head are shared, the magnetization state of the core is also controlled, so that the characteristics of the recording head can be controlled to be constant.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 shows the structure of a magnetoresistive (MR) reproducing head according to the present invention.

In FIG. 1, the MR layer 3, the shunt film 4,
A magnetic head is composed of the SAL layer 105, the hard magnetic layer 1, and the electrode layer 12. The MR layer 3 includes a central magnetic sensitive area 102 for detecting an information magnetic field from the medium and a central magnetic sensitive area 10.
The second magnetic domain structure is divided into end magnetic domain control regions 103 for controlling the Barkhausen noise.

In the present invention, the MR layer 3 is biased by a method different from the methods disclosed in JP-A-60-59518 and JP-A-2-220213. That is,
Both the longitudinal bias and the lateral bias serve to bias the central magnetic sensitive region 102. Here, the longitudinal bias is parallel to the MR layer 3, and the end magnetic domain control region 10
It is generated by the hard magnetic layer 1 which is in direct contact with 3. The lateral bias is generated by the shunt film 4 and the SAL layer 105 which are parallel to the MR layer 3. Electrode layer 1
Reference numeral 2 transmits the signal detection current and the bias current to the MR layer 3 and the shunt film 4, and the output signal is detected between the inner ends of the electrode layer 12 which is an electric path for transmitting the output signal to the external electric circuit. .

In this embodiment, the MR layer 3 has a thickness of 5 to 20.
nm, the thickness of the hard magnetic layer 1 is 10 to 100 nm, and the thickness of the shunt film 4 is 10 to 40 nm.

The MR layer 3 is a Ni--Fe alloy thin film, the hard magnetic layer 106 is a Co--Pt--Cr alloy thin film, and the shunt film 4 is an Nb thin film. For the hard magnetic layer 1, a magnetic recording medium material such as a Co-Pt alloy thin film, a Co-Pt-Pd alloy thin film, a Co-Pt-Ni alloy thin film, a Co-Cr-Ta alloy thin film, or another hard magnetic material is also effective. Met. By this method, a magnetoresistive effect reproducing head having high reproducing output without Barkhausen noise could be obtained.

The thinner the MR layer 3 is, the larger the current density required for signal detection becomes.
This is preferable because the reproduction output of the signal will increase. Substantially, the film thickness capable of obtaining high reproduction output was less than 20 nm. It is considered that this is because as the thickness of the MR layer 3 becomes thinner, the amount of heat generated by the flowing current is reduced and the deterioration of the MR layer 3 due to electromigration is suppressed. However, as the thickness of the MR layer 3 becomes thinner, the number of defects increases, and pinholes and the like are more likely to occur. The practically usable film thickness was 5 nm or more.

In this embodiment, the Co-Pt-Cr hard magnetic layer 1 and the Ni-FeMR layer 3 are formed before the magnetoresistive reproducing head is manufactured.
As a result of measuring the BH curve of each of the individual thin films, the coercive force of 72 to 112 kA / m and 40 to 120 A / m was shown, while the end magnetic domains of the hard magnetic layer 1 and the MR layer 3 were measured. When the BH curve of the two-layer film portion of the control region 103 was measured, the coercive force showed an intermediate value between the values of both layers, as shown in FIG. 2, and the thickness of the hard magnetic layer 1 decreased. Accordingly, the coercive force of the two-layer film also tended to decrease. Further, the BH curve shows a smooth curve without steps, and the hard magnetic layer 1
It was confirmed that and the magnetoresistive layer 3 were ferromagnetically exchange-coupled.

Further, a Ni-Fe thin film is formed of Co-Pt-C.
It was clarified that different coercive force was exhibited when formed on the r thin film and when formed below. The curve 201 showing the case where the Ni-Fe thin film is formed under the Co-Pt-Cr thin film shows that the coercive force rapidly decreases as the Co-Pt-Cr thin film becomes thinner, while the Ni-Fe thin film is formed. The curve 202 showing the case formed above has a gradual decrease in coercive force. When the crystal state of this two-layer film is examined by an X-ray diffraction method, different crystal states are shown between the upper and lower Ni—Fe thin films, and it is speculated that this difference is reflected in the coercive force.

Further, as a preliminary study, a magnetoresistive effect element in which the shunt film 4 and the SAL layer 105 of FIG. 1 were omitted was prepared, and the longitudinal bias applied to the MR layer 3 by the hard magnetic layer 1 was measured. That is, the track width (distance between the electrode inner end faces) is 4 μm, the lateral width of the MR layer 1 is 4 μm, and M
An external AC magnetic field was applied in the vertical direction (longitudinal direction of the magnetoresistive layer) in parallel with the R layer 3, and the shift width of the magnetic field appearing in the response curve was measured.

FIG. 3 shows the relationship between the longitudinal bias and the thickness ratio of the Co-Pt-Cr hard magnetic film to the Ni-FeMR film. 301
When the length of the central magnetic sensitive area is 10 μm and the MR layer is placed on top, 302 is the MR when the length of the central magnetic sensitive area is 50 μm.
When the layer is placed on top, 303 is the case where the length of the central magnetic sensitive region is 50 μm and the MR layer is placed on the bottom.

As shown in FIG. 3, the longitudinal bias is MR
It is clear that it is applied when the ratio of the thickness of the hard magnetic layer 1 to the thickness of the layer 3 is 1 or more. By using this result, the thickness of the hard magnetic layer 1 of the magnetoresistive effect reproducing head can be selected to achieve a desired longitudinal bias. It is preferable that the level of the longitudinal bias is sufficient to maintain the central magnetic sensitive region 102 of the MR layer 3 in a single magnetic domain state. Based on this result, it was found that a magnetoresistive effect reproducing head was produced and a magnetoresistive effect reproducing head free from Barkhausen noise was obtained.

As shown at 303 in FIG. 3, M
When the R layer 3 is formed on the lower side, it is difficult to obtain a sufficient bias in the element vertical direction. In this case, it became clear that the ratio of the thickness of the hard magnetic layer 1 to the thickness of the MR layer 3 should be 2 or more, preferably 3 or more. That is, when the MR layer 3 is formed on the hard magnetic layer 1, it is easier to obtain a sufficient bias with a thin hard magnetic film.

In this embodiment, the length of the central magnetic sensitive region 102 of the MR layer 3 is made longer than the track width (distance between the electrode inner end faces). This results in a magnetic domain due to a longitudinal bias. The MR output can be obtained only from the inside of the MR layer 3 which is completely controlled, and a magnetoresistive effect reproducing head without Barkhausen noise was obtained.

Generally, when the magnetoresistive effect reproducing head is used in combination with the recording inductive head, the magnetoresistive effect reproducing head and the recording inductive head do not adversely affect each other, and the position resolution of signal reproduction. In order to ensure the above, soft magnetic material layers called shield layers are formed above and below the magnetoresistive effect reproducing head. In the conventional magnetic domain control method, it depends on the distance between the hard magnetic layer and the shield layer, but since the magnetic flux generated by the hard magnetic layer is absorbed by the shield layer, the magnetostatic coupling with the magnetoresistive layer is weakened, and a sufficient longitudinal magnetic field is obtained. In some cases, it was not possible to apply a directional bias.

In the magnetic domain control method of the present invention, the hard magnetic layers 1 and M
The R layer 3 is ferromagnetically exchange-coupled, and further the hard magnetic layer 1
The magnetic fields of are combined to apply a longitudinal bias. Therefore, since the magnetic field leaking from the hard magnetic layer 1 to the outside is small, there is almost no problem of absorption of magnetic flux by the shield layer described above, and sufficient longitudinal bias should be applied to the central magnetic sensitive region 102 of the MR layer 3. I was able to.

Example 2 In FIG. 1, the direction of magnetization in the central magnetic sensitive region 102 of the MR layer 3 is such that the longitudinal magnetic field from the hard magnetic layer 1 in contact with the end magnetic domain control region 103, the hard magnetic substance. The magnetization direction of the end magnetic domain control region 103 of the MR layer 3 determined by the ferromagnetic exchange coupling between the layer 1 and the end magnetic domain control region 103 of the MR layer 3, and the lateral direction from the shunt film 4 and the SAL layer 105. It is affected by the directional bias magnetic field and the high frequency signal magnetic field coming from the medium. The magnetization in the central magnetic sensitive region 102 of the MR layer 3 is unnecessary for the longitudinal magnetic field from the hard magnetic layer 1 and the longitudinal bias generated by the ferromagnetic exchange coupling between the hard magnetic layer 1 and the MR layer 3. If it is large, the reproduction output of the signal is reduced, which is not preferable.

In FIG. 4, the track width is 4 μm and the lateral width of the MR layer 1 is 4 μm in the structure of FIG.
The results of measuring the half-value width of the response curve when a lateral alternating magnetic field is applied are shown by changing the film thickness and the length of the central magnetic sensitive region 102 of the magnetoresistive layer 3. 401 is Co
-When the thickness of the Pt-Cr layer is 80 nm. 402C
This is the case where the thickness of the o-Pt-Cr layer is 40 nm.

It is clear from FIG. 4 that the full width at half maximum does not change significantly when the length of the central magnetic sensitive region 102 of the MR layer 3 is 10 μm or more, and the influence of the film thickness of the hard magnetic layer 1 is small. Became. This is an advantage in the magnetic head manufacturing process, and the length of the central magnetic sensitive region 102 is 10 μm.
It is shown that if the thickness is set to m or more, it is not necessary to strictly control the film thickness of the MR layer 3. However, the central magnetic sensitive area 10
When 2 is long, the longitudinal bias magnetic field becomes small,
Barkhausen noise occurs easily and becomes dull.

On the other hand, the length of the central magnetic sensitive region 102 is 10
When the thickness is less than μm, the full width at half maximum increases rapidly, and the Barkhausen noise can be suppressed because the longitudinal bias magnetic field is large, but the reproduction output is lowered and the magnetic head manufacturing process is difficult.

Based on the above results, a magnetoresistive effect reproducing head having a track width of 3 μm was manufactured and mounted on a magnetic disk device to detect a recording / reproducing waveform. The result is shown in FIG. In FIG. 5, 501 is Barkhausen noise suppression rate, 50
Reference numeral 2 represents a reproduction output.

As shown by the curve 501, the length of the central magnetic sensitive region where Barkhausen noise does not occur in the reproduced waveform and the suppression rate is high is 50 μm or less. As indicated by the curve 502, the length of the central magnetic sensitive region where the required reproduction output was obtained was larger than the track width (4 μm in this case).

At this time, the reproduction output sharply decreased when the length of the central magnetic sensitive area became smaller than the track width, and it became difficult to obtain the required reproduction output. As a result, when the length of the central magnetic sensitive region 102 of the MR layer 3 is larger than the track width, there is no Barkhausen noise, and a magnetoresistive effect reproducing head having a necessary reproducing output can be obtained.
As a result, a magnetic disk device having a recording density of 200 Mb / in ² or more could be obtained.

(Embodiment 3) Another embodiment of the present invention will be described. 6 and 7 show the configurations of two types of magnetoresistive effect reproducing heads having different electrode shapes, and FIG. 8 shows the configuration of the magnetoresistive effect reproducing head having a structure in which the hard magnetic layer 1 does not appear on the medium facing surface. Indicates. Also in these magnetoresistive effect reproducing heads, the magnetic domain control means of the present invention having the hard magnetic layer 1 in direct contact with the MR layer 3 is effective, and the MR layer 3 is effective.
By setting the ratio of the film thickness of the hard magnetic layer 1 to the film thickness of 1 or more, a magnetoresistive effect reproducing head having no Barkhausen noise and an easy manufacturing process could be obtained. In addition, 4 is a shunt film and 105 is a SAL film.

In these magnetoresistive effect reproducing heads, the formation positions of the electrode layer 12 and the hard magnetic layer 1 are shifted, and this reduces the step difference on the inner end face of the electrode layer 12, and the MR layer 3 and above it. In addition to being able to reduce the influence on the recording head layer formed on the disk, the stress concentrated on the inner end surface of the electrode portion can be reduced by forming the electrode layer 12 and the hard magnetic layer 1, and thus the Barkhausen noise can be reduced. It is now possible to obtain a magnetoresistive effect reproducing head that is less likely to generate.

In the above embodiments, the shunt film 4 and the SAL film 105 are used as the lateral bias applying means. However, the magnetoresistive effect reproducing head of the present invention can be applied to other lateral bias applying means known in the art, such as a shunt bias alone, a current bias in which an electrically insulating layer is inserted between the magnetoresistive layer and the shunt film. ,
The means called a barber pole can be used in any combination. These known lateral bias applying means follow the prior art.

(Embodiment 4) The basic structural principle of the MR element of another embodiment of the present invention is illustrated in FIG.

In this element, the hard magnetic layer 1 is formed on the same substrate adjacent to the MR 3, and the soft magnetic film 5 is provided via the shunt film 4.

The hard magnetic layer 1 is magnetized parallel to the easy axis of magnetization of the MR film 3, and the magnetic field 2 leaking from one magnetic pole of the permanent magnet film which is the hard magnetic layer penetrates into the MR film 3. The magnetic field 2 leaking from the other magnetic pole enters the soft magnetic film 5. Therefore, as compared with the conventional element shown in FIG. 9, there is effectively no magnetic field leaking into the space, and there is no effect on other magnetic materials such as the medium.

An embodiment of an MR head including the MR element shown in FIG. 10 is shown in FIG. Reference numerals 8 and 9 in FIG. 11 denote magnetic shield films, between which MR elements are formed. The material of the substrate 10 is zirconia, on which a Ni-19% Fe film is formed as a magnetic shield film 8 by a sputtering method of about 1 μm.
Alumina film 11 was formed as an insulating film on this, leaving only a necessary portion by the lithography method. The magnetic shield film 8
Although it may be implemented with a Co-based amorphous film or a Fe-based magnetic film,
The reproduction characteristics are slightly different.

The thickness of the alumina film 11 varies depending on the desired recording frequency of the magnetic head, but in the present embodiment, it is 0.1-.
0.5 μm. A Ni-19% Fe film (magnetostriction constant 5 × 10 ⁻⁷ ) having a thickness of 3-45 nm was formed thereon as the MR layer 3, and the MR element 3 was removed while leaving a necessary portion. Co-20% on both sides of this MR layer 3
After the hard magnetic layer 1 made of a Pt alloy film was vapor-deposited, fine processing was performed by the same method to form Nb as the shunt film 4 and a Co—Zr—Ta—Ru amorphous alloy as the soft magnetic film 5. CoPt
The thickness of the alloy film is 3 to 100 nm. Further, an electrode 12 for energizing the device was formed, and the alumina film 11 and the magnetic shield film 9 were attached again. Track width is 0.5 to 1
It is 0 μm. Although the film thickness is the same as the lower alumina film and the magnetic shield film 8, the film thickness may be different depending on the purpose of use of the head.

The head produced as described above was machined so that the height of the MR layer 3 was a desired dimension, for example, 1 to 10 μm to form a head, and its reproducing characteristics were evaluated.
The recording medium used for the evaluation is a CoCrTa-based or CoPtCr-based sputter medium.

As a comparative experiment, an MR head shown in FIG. 12 was prepared in which the stray magnetic field from the hard magnetic layer 1 was less likely to enter the soft magnetic film. In the example of FIG. 12, the shunt film 4 covers the hard magnetic layer 1, and the soft magnetic layer 5 is shorter than the MR film 3.

As a result of comparing the reproduction outputs of FIG. 11 and FIG. 12, the S / N ratio of the reproduction output was 3.0 for the head of FIG. 11 and 1.5 for FIG.

(Embodiment 5) Next, in the head of FIG. 11, a head having a structure in which the MR film partially overlaps the hard magnetic layer,
Also, a head having a structure in which a part of the MR film is placed under the hard magnetic layer was prototyped and the S / N was measured.

In each of these magnetic heads, there is no leakage of magnetic flux and an improvement in S / N is observed. However, as described in Example 1, the head with the MR layer placed on top shows superior characteristics. .

FIG. 13 shows a head having a structure in which the MR layer 3 is placed on the hard magnetic layer 1. Soft magnetic film 4 and hard magnetic layer 1
Although the bonding structure of No. 1 is different from that of FIG. 11, a high S / N value of this head was obtained.

In the above-mentioned embodiments, the same components are designated by the same numbers, and their explanations are omitted.

In the head having the structure shown in FIGS. 10 and 11, the magnetic field from the hard magnetic layer 1 penetrates in the easy axis of magnetization of the soft magnetic film 5 for applying the bias magnetic field. Not only that, the magnetic domains or the magnetization state of the bias magnetic field applying soft magnetic film 5 can be controlled. The bias film 5 must always apply a constant magnetic field to the MR film 3,
For this purpose, it is necessary to make the magnetic permeability of the entire soft magnetic film for applying a bias magnetic field constant. The magnetic permeability is always constant when the magnetic domain of the soft magnetic film is single, but is not constant when the magnetic domain is multi-domain or when the dispersion of magnetization is large and unstable. Therefore,
Magnetic flux can be introduced into the soft magnetic film to stabilize the reproducing characteristics of the magnetic head.

Example 6 FIG. 14 shows another example having the same effect. In this element, the hard magnetic layer 1 is formed on the same plane adjacent to the MR film 3 and the insulating film 6 is formed. The soft magnetic film 5 is installed therethrough. 12 is an electrode. The hard magnetic layer 1 is magnetized parallel to the easy axis of magnetization of the MR film 3, and the magnetic field leaking from one magnetic pole of the hard magnetic layer is MR.
The magnetic field penetrating the film 3 and leaking from the other magnetic pole is the soft magnetic film 5.
Break into. Therefore, similarly to the example shown in FIG. 10, the magnetic field leaking into the space is not effective, and there is no influence on other magnetic materials such as the medium. In addition, 8 is a lower shield, 9 is an upper shield, and 10 is a substrate.

The S / N ratio of this head was as high as that of the embodiment of FIG.

15 and 16 are examples in which the shape of the soft magnetic layer 5 is changed, and the S / N of this head has the same high value as in the example of FIG.

(Embodiment 7) FIG. 17 shows an example in which the leakage magnetic field from the magnetic pole of the hard magnetic layer 1 provided for controlling the magnetic domain of the MR film 3 is guided to the magnetic shield film 8. Similarly, there is effectively no magnetic field leaking into space, and there is no effect on other magnetic materials such as the medium. S / N of this head
Also, a high value similar to that of the example of FIG. 11 was obtained. In the embodiment shown in FIG. 17, the soft magnetic film for bias is not provided, but even if the soft magnetic film is provided, the effect of controlling the magnetization state of the magnetoresistive effect film is the same. Further, in the head having this structure, the magnetic flux is introduced into the magnetic shield film 8 to control the magnetic domain, so that the magnetic shield effect is increased, and the reproduced waveform on the magnetic domain controlled side is steep and the variation is reduced. Therefore, in the example of the head in which the magnetic domains of the magnetic shield films on both sides were controlled by the hard magnetic layer, the reproduction waveform was steep and the left-right symmetry was improved.

In the above-described embodiments and drawings, the same components are designated by the same reference numerals.

Next, points to be noted in the present invention will be described.

When the magnetic domain of the MR film is controlled by using the hard magnetic layer, the value of the magnetostriction constant of the MR film becomes a problem. That is, the multi-domain structure of the MR film that causes the distortion of the output waveform of the MR head depends on the value of the magnetostriction constant, and when the magnetostriction constant is very large, the hard magnetic layer cannot be used to form the single domain structure. .

In the MR head having the structure of the present invention, the influence of the magnetostriction constant of the MR film was changed to Ni-19% Fe of the Ni-Fe system magnetoresistive film.
When the magnetostriction constant was investigated in the range of + 5 × 10 ⁻⁶ to −5 × 10 ⁻⁶ with the composition in the vicinity, the occurrence frequency of the output waveform distortion of the MR head was as shown in FIG. It was found that it was very low in the range of 10 ^-6 to -3 × 10 ^-6 , but increased rapidly beyond this range. Therefore, the magnetostriction constant of the MR film used in the MR head having the magnetic domain control structure of the present invention is
In the range +3 × 10 ^-6 to -3 × 10 ^-6 or at least +4 × 10
A range of ^-6 to -4 x 10 ^-6 is desirable.

The same was true for the Co-Ni and Ni-Fe-Co MR films.

The MR head of the present invention uses an ultra-thin MR film of Ni-Fe system or the like. As is well known, the magnetization state such as the magnetic domain structure or the magnetic domain wall structure greatly differs depending on the film thickness. . When the film thickness exceeds 35 nm, the magnetic domain structure of the MR film becomes relatively stable, and when it exceeds 70 to 80 nm, it becomes unstable again. Below 35 nm, the thinner the film thickness, the more unstable the magnetization state becomes. The magnetic domain control effect of the present invention is particularly remarkable when the film thickness is 35 nm or less.

The reduction of the film thickness is advantageous in escaping the heat generation of the MR film due to the energization. As a result, the allowable current value increases and the output of the head increases with the decrease of the film thickness. Therefore, it is desirable that the film thickness is thin, but if the film thickness is 5 nm or less, the continuity of the film deteriorates, and it is not possible to form a high-quality film of a practical level by an ordinary thin film forming method. Therefore, the optimum range of the MR film in the MR head having the structure of the present invention is 5 nm or more, and a remarkable effect is obtained particularly in the range of 5 to 35 nm.

When the shunt bias method and the soft magnetic film are used as the biasing means, the ratio R of the currents flowing through the MR film and the shunt + soft magnetic film (the current of the magnetoresistive film is 1) is 0.
It is preferably between 2 and 1.3. If it is 0.2 or less, even if a metal film having a high electric resistance is used for the shunt, the distance between the soft magnetic film and the MR film becomes too close, and the structure of the present invention in which the MR film and the soft magnetic film form a closed magnetic path is not established, and the MR It becomes impossible to control the magnetic domains of the film and the soft magnetic film at the same time. 0.2
In that case, the effect of suppressing the output waveform was not sufficient.

On the other hand, if 1.3 or more, the shunt bias and the bias magnetic field due to the soft magnetic film become too strong, and the MR
The output decreases because the membrane current decreases relatively. Therefore, R is preferably between 0.2 and 1.3. The Ni-Fe MR film has a specific resistance of 15 to 30 μΩcm, the shunt film satisfying the above R has a specific resistance of 20 to 80 μΩcm, and the soft magnetic film has a specific resistance of 80 to 150 μΩcm.

As a shunt film satisfying these, Nb, T
i, Ta, V, Mo, W, Hf and their alloys such as Nb-15% T
CoTaZ as a soft magnetic film using i alloy, Nb-5Ru alloy, etc.
In an example using an amorphous alloy such as r or CoNbZr or a crystalline alloy film such as CoNiFe system or Sendust, the MR film has a current density of 5 × 10 ⁶ to 3 × 10 ⁷ A / cm ² and an output waveform symmetry of A head of 5% or less was obtained.

Al ₂ O ₃ is formed as an insulating film on the MR head.
Was recorded by a sputtering method, and the recording / reproducing characteristics were measured with a composite magnetic head with an inductive recording head formed on it, and as a result, as described above, there was no distortion and a high S / N ratio output was obtained. It was Further, as a result of measuring the recording / reproducing characteristics of the composite type magnetic head which also serves as the magnetic shield film of the MR head and the core film of the inductive head for recording, an output having no distortion and a high S / N ratio was obtained.

The method of the present invention can be applied not only to the magnetic domain control of the MR film but also to the shield film and the core film. Figure 1
Reference numeral 9 indicates a magnetic domain of the shield film which is controlled by installing hard magnetic layers 10 on both ends of the shield films 8 and 9, and the magnetic domain of the shield film is stable, so that the magnetic domain wall of the shield film is suddenly moved. Such noise disappears, and the way in which off-track noise enters is also constant.

It is possible to control the magnetization state of the MR film of the MR head as well as the magnetization states of the soft magnetic film for applying the bias magnetic field and the shield film, so that the magnetic field leaking from the hard magnetic layer effectively becomes a space in the medium direction. The magnetic field does not enter the portion where application of the leakage magnetic field from the hard magnetic layer is unnecessary, and the magnetic characteristics of the entire head are stabilized. As a result, the distortion of the output waveform of the head is completely removed, and other noise is significantly reduced. Therefore, it is possible to provide a magnetic head having optimum characteristics for a high density magnetic recording device.

[0084]

According to the present invention, it is possible to provide a magnetoresistive effect (MR) element having a structure which does not require the insertion of a non-magnetic layer and therefore has a simplified element forming process. Another effect of the present invention is that the height of the portion where the hard magnetic layer is formed in contact with the end magnetic domain control region can be reduced, and the magnetoresistive effect (MR) element layer and subsequent It is possible to prevent a step from being formed in the stacked recording heads and concentration of stress. This effect is extremely effective particularly when the end magnetic domain control region of the magnetoresistive layer is formed on the hard magnetic layer, and the thin magnetoresistive layer is used to form the stepped portion (the central magnetic sensitive region) of the hard magnetic layer. And a magnetic recording / reproducing apparatus using the same, which can effectively prevent breakage at the boundary between the edge magnetic domain control region and the end magnetic domain control region. You can

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a magnetoresistive (MR) reproducing head configuration exemplified in a first embodiment of the present invention.

FIG. 2 is a diagram showing two end magnetic domain control regions of a hard magnetic layer and a magnetoresistive layer in the MR reproducing head exemplified in Example 1 of the present invention.
The figure which shows the influence of the film thickness of a hard magnetic material layer which acts on the coercive force of a layer film part.

FIG. 3 is a diagram showing the effect of the thickness of the hard magnetic layer on the thickness of the magnetoresistive layer, which affects the longitudinal bias in the MR reproducing head illustrated in Example 1 of the present invention.

FIG. 4 is a diagram showing the influence of the length of the central magneto-sensitive region of the magnetoresistive layer on the half-value width of resistance change in the MR reproducing head exemplified in Example 2 of the present invention.

FIG. 5 is a graph showing the relationship between the length of the central magnetic field, reproduction output, and Barkhausen noise.

FIG. 6 is a perspective view showing an example of the configuration of an MR reproducing head having a different electrode layer shape.

FIG. 7 is a perspective view showing an example of the configuration of an MR reproducing head having a different electrode layer shape.

FIG. 8 is an M of a structure in which a hard magnetic layer does not appear on the medium facing surface.
FIG. 3 is a perspective view showing an example of the configuration of an R reproducing head.

FIG. 9 is a cross-sectional view of a conventional magnetoresistive head in which magnetic domains of the magnetoresistive film are controlled by a permanent magnet film.

FIG. 10 is a sectional view showing an embodiment of the present invention.

FIG. 11 is a sectional view showing an embodiment of the present invention.

FIG. 12 is a sectional view showing an embodiment of the present invention.

FIG. 13 is a sectional view showing an embodiment of the present invention.

FIG. 14 is a sectional view showing an embodiment of the present invention.

FIG. 15 is a sectional view showing an embodiment of the present invention.

FIG. 16 is a sectional view showing an embodiment of the present invention.

FIG. 17 is a sectional view showing an example of the present invention.

FIG. 18 is a graph showing the relationship between magnetostriction constant and waveform distortion.

FIG. 19 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Hard magnetic layer 2 ... Leakage magnetic field 3 ... Magnetoresistive film 4 ... Shunt membrane 5 ... Soft magnetic film 11 ... Insulating film 7 ... Magnetic shield film 8 ... Magnetic shield film 9 ... Magnetic shield film 102 ... Central magnetic field 103 ... Edge magnetic domain control region

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[Procedure amendment]

[Submission date] December 20, 2002 (2002.12.
20)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title of invention Magnetic head

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

1. A magnetoresistive effect film, and a pair of hard magnetic layers which are ferromagnetically exchange-coupled with an end portion of the magnetoresistive effect film and which are formed on the same plane as a central magnetic sensitive region of the magnetoresistive effect film. A body layer and a pair of electrodes formed on the pair of hard magnetic layers, and the length in the track width direction of the central magnetosensitive region of the magnetoresistive film is equal to that of the pair of electrodes. A magnetic head characterized in that it is longer than the distance between the inner end faces of the electrodes.

2. The magnetic head according to claim 1, wherein the length of the central magnetic sensitive region is 10 μm or more.

3. The magnetic head according to claim 1, wherein the magnetoresistive effect film has a thickness of 5 nm or more and 20 n or less.
the thickness of the hard magnetic material thin film is in the range of 10 to 100 nm, and the ratio of the thickness of the hard magnetic material thin film to the thickness of the magnetoresistive effect film is 1 or more. Characteristic magnetic head.

4. The magnetic head according to claim 1, wherein the ratio of the film thickness of the hard magnetic material thin film to the film thickness of the magnetoresistive effect film is 2 or more.

5. The magnetic head according to claim 4, wherein the ratio of the film thickness of the hard magnetic material thin film to the film thickness of the magnetoresistive film is 3 or more.

6. The magnetic head according to claim 1, wherein the hard magnetic material thin film is Co—P.
t, Co-Pt-Cr, Co-Pt-Pd, Co-Pt
A magnetic head containing a material of either -Ni or Co-Cr-Ta alloy.

7. The magnetic head according to any one of claims 1 to 6, wherein the magnetoresistance as a member constituting a closed magnetic circuit together with the magnetoresistive film by introducing a magnetic flux from the hard magnetic film A magnetic head comprising a soft magnetic material layer arranged parallel to an effect film.

8. The magnetic head according to claim 7, wherein the soft magnetic layer disposed in parallel with the magnetoresistive film is a magnetic shield layer.

Continued front page    (72) Inventor Yuu Yuto             1-280, Higashikoigokubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. (72) Inventor Noboru Shimizu             1-280, Higashikoigokubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. (72) Inventor Naoki Koyama             1-280, Higashikoigokubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. F-term (reference) 5D034 BA03 BA04 BA12 BB08 CA04                       CA08

Claims (11)

[Claims] 1. A magnetoresistive effect film comprising a thin film of a ferromagnetic material having a central magnetic sensitive region and an end magnetic domain control region, and a thin film of a hard magnetic material overlapping and directly in contact with the end magnetic domain control region. And a hard magnetic material layer for maintaining a central magnetic field sensitive region of the magnetoresistive film in a single domain state, thereby generating a longitudinal magnetic bias by a magnetic field and ferromagnetic exchange coupling. Effect playhead. 2. A magnetoresistive effect reproducing head according to claim 1, wherein the magnetoresistive effect film has a pair of electrodes for supplying a current, and the length of the central magnetic sensitive region is larger than the distance between the electrodes. 3. The magnetoresistive effect reproducing head according to claim 1, wherein the length of the central magnetic sensitive region is 10 μm or more. 4. The film thickness of the magnetoresistive film is 5 nm or more,
It is less than 20 nm, the thickness of the hard magnetic layer is in the range of 10 to 100 nm, and the ratio of the thickness of the hard magnetic layer to the thickness of the magnetoresistive film is 1 or more. The magnetoresistive effect reproducing head according to any one of claims 1 to 3. 5. The magnetoresistive effect reproducing head according to claim 1, wherein an end magnetic domain control region of the magnetoresistive effect film is present on the hard magnetic layer. 6. The hard magnetic layer is made of Co-Pt, Co-Pt-
Cr, Co-Pt-Pd, Co-Pt-Ni or Co
The magnetoresistive effect reproducing head according to any one of claims 1 to 5, which comprises a -Cr-Ta alloy thin film. 7. A magnetoresistive film, a pair of electrode films for flowing a detection current through the magnetoresistive film, and a pair of hard magnetic films for controlling magnetic domains of the magnetoresistive film. The gap between the pair of hard magnetic films is wider than the gap between the pair of electrode films, and the magnetoresistive effect of applying a magnetic field from the hard magnetic film to the magnetoresistive film sandwiched between the electrode films. Mold head. 8. The magnetoresistive head according to claim 7, wherein the magnetoresistive film is laminated directly on the hard magnetic film, and the electrode film is laminated on the magnetoresistive film. 9. A magnetoresistive head according to claim 7, further comprising a member which forms a closed magnetic circuit together with the magnetoresistive film by introducing magnetic flux from the hard magnetic film. 10. The magnetoresistive effect head according to claim 9, wherein the member forming the closed magnetic path is a soft magnetic material layer arranged substantially parallel to the magnetoresistive film. 11. The magnetoresistive head according to claim 9, wherein the member forming the closed magnetic path is a magnetic shield layer arranged substantially parallel to the magnetoresistive film.