JP2005063643A - Magnetoresistance effect type magnetic head, and magnetic recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetoresistance effect type magnetic head, and a magnetic recording and reproducing device which does not have Barkhausen noise, and the variation in reproduction characteristics is small. <P>SOLUTION: The magnetoresistance effect type magnetic head is provided with a vertical bias impression layer having a ground film consisting of ferromagnetic thin film whose crystal structure is a body-centered cubic lattice, an amorphous ferromagnetic thin film or an antiferromagnetic thin film, whose crystal structure is a body-centered cubic lattice and a hard magnetic thin film formed on the ground film. The magnetic recording and reproducing device using this magnetoresistance effect type magnetic head is also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetoresistive head and a magnetic recording / reproducing apparatus used for reproducing magnetically recorded information.

With the recent progress of miniaturization and higher density of magnetic disk devices, magnetoresistive heads (MR heads) that can obtain a high reproduction output voltage without depending on the relative speed of the disk and the head have been put into practical use. Yes. The MR head currently mounted on the magnetic disk drive uses an anisotropic magnetoresistive effect in which the electrical resistance changes depending on the angle between the direction of magnetization of the magnetic film and the direction in which the signal detection current flows. Therefore, high performance is achieved by improving the head structure and thin film material. When the surface recording density is as high as several Gb / in ^2, the MR head using the anisotropic magnetoresistive effect is expected to be insensitive, so two magnetic thin films laminated via a nonmagnetic conductive thin film A head using a giant magnetoresistive effect, in which the electrical resistance changes depending on the angle between the directions of magnetization of each other, has been studied. In any MR head, a change in electric resistance is caused by the rotation of the magnetization of the magnetoresistive film, and the domain wall motion must be suppressed in order to obtain a noise-free reproduced waveform.

  As a means for suppressing Barkhausen noise caused by domain wall motion, JP-A-2-220213 discloses a structure in which a hard magnetic thin film is laminated on a magnetoresistive effect film through a nonmagnetic underlayer in a portion other than the magnetic sensitive portion. However, JP-A-3-12511 discloses a structure in which hard magnetic thin films are arranged on both sides of a magnetoresistive film.

JP-A-2-220213

Japanese Patent Laid-Open No. 3-125311

  In order to suppress Barkhausen noise, a hard magnetic thin film used in a magnetoresistive head is required to have two magnetic characteristics. One of them is a large coercive force. Since a signal magnetic field from a recording medium and a recording magnetic field from the recording head act on the MR head, in order to have stable reproduction characteristics even under such an external magnetic field, the hard magnetic thin film is changed to a magnetoresistive effect film. A sufficiently large coercive force is required so that the longitudinal bias magnetic field that enters the magnetic field does not fluctuate. The other is that the in-plane component of magnetization is large, that is, the squareness ratio of the magnetization curve measured by applying a magnetic field in the in-plane direction is large. Of the magnetization components of the hard magnetic thin film, it is the in-film component that effectively acts as the longitudinal bias magnetic field. Therefore, the longitudinal bias magnetic field does not vary even when an external magnetic field acts. And the squareness ratio of the magnetization curve must be large.

  FIG. 15 is a view showing the structure of an MR head disclosed in Japanese Patent Laid-Open No. 2-220213. This prior art is intended to suppress Barkhausen noise of the magnetoresistive effect film 15 by a magnetic field generated from a hard magnetic thin film 26 formed on a nonmagnetic base film 251 such as Cr. Although the hard magnetic thin film 26 having a large coercive force and squareness ratio can be obtained by using the nonmagnetic base film 251, a part of the magnetic field generated from the hard magnetic thin film 26 is part of the MR element (soft magnetic thin film 13, non-magnetic thin film 13). As shown in FIG. 15, the magnetization of the magnetoresistive effect film 15 is reversed between the magnetosensitive portion and both ends thereof. become. Therefore, the magnetization state of the magnetoresistive film 15 is very unstable, and it is difficult to suppress Barkhausen noise.

  In Japanese Patent Laid-Open No. 3-125111, as shown in FIG. 16, the magnetic field generated from the hard magnetic thin film is only in one specific direction so that there is no region having the opposite magnetization component in the magnetoresistive film. A structure in which hard magnetic thin films are arranged on both sides of the MR element portion is disclosed so as to work. A laminated film composed of the soft magnetic thin film 13, the nonmagnetic conductive thin film 14, and the magnetoresistive effect film 15 (hereinafter referred to as soft magnetic thin film / nonmagnetic conductive thin film / magnetoresistance effect film) is substantially magnetosensitive. After etching so that only the portion remains, a hard magnetic thin film 26 is formed on both sides thereof, and an electrode is formed on the hard magnetic thin film 26.

  At that time, in order to maintain magnetic and electrical contact between the soft magnetic thin film / non-magnetic conductive thin film / magnetoresistance effect film and the hard magnetic thin film 26 and the electrode, the soft magnetic thin film / non-magnetic conductive It is necessary to perform etching so that the end of the thin film / magnetoresistance effect film has a gentle slope, and a part of the hard magnetic thin film 26 is formed from the soft magnetic thin film / nonmagnetic conductive thin film / magnetoresistance effect film. It will be formed on a gentle slope. However, since the crystal structure of the soft magnetic thin film 13 or the magnetoresistive effect film 15 is generally a face-centered cubic lattice, the characteristics of the hard magnetic thin film formed on these films, in particular the coercive force, are other parts. There is a problem that it is significantly deteriorated.

  In the case of a Co—Cr—Pt hard magnetic thin film or a Co—Cr hard magnetic thin film generally used as the hard magnetic thin film 26, the portion other than the soft magnetic thin film 13 or the magnetoresistive effect film 15. However, there is a problem that it is difficult to obtain a sufficiently large in-film component of magnetization, that is, a large squareness ratio. The thin film has a property of growing so that the close-packed surface of the crystal is parallel to the film surface. In the case of these hard magnetic thin films, the (001) plane is easily oriented parallel to the film surface. On the other hand, since the easy magnetization direction is the <001> direction, the magnetization is likely to be directed in a direction perpendicular to the film surface, so that the in-film component that effectively acts as a longitudinal bias magnetic field is reduced.

  These problems can be solved by providing a suitable base film and forming a hard magnetic thin film thereon. According to research on magnetic recording media, it is known that a nonmagnetic underlayer such as Cr is effective. However, if a nonmagnetic underlayer is provided on the hard magnetic thin film used in the MR head, the hard magnetic layer The magnetic exchange coupling between the thin film 26 and the soft magnetic thin film 13 and the magnetoresistive effect film 15 is cut off, and the action of stabilizing the magnetization of the end portions of the soft magnetic thin film 13 and the magnetoresistive effect film 15 is achieved. I will not work. As a result, the magnetization of these ferromagnetic thin films becomes unstable, and Barkhausen noise is likely to occur and reproduction characteristics are likely to vary.

  As described above, the problems with the MR head using the anisotropic magnetoresistive effect described in the prior art have been described. However, in the MR head using the giant magnetoresistive effect, the MR element portion has a centered crystal structure. Since it is composed of a ferromagnetic thin film having a cubic lattice, it is a common problem.

  The object of the present invention is to improve the coercive force and squareness ratio of the hard magnetic thin film, suppress the decrease in the coercive force of the hard magnetic thin film even on the ferromagnetic thin film whose crystal structure is a face-centered cubic lattice. Provided a magnetoresistive head and a magnetic recording / reproducing apparatus having no Barkhausen noise and stable reproduction characteristics by maintaining magnetic exchange coupling between the magnetic thin film and the ferromagnetic thin film constituting the MR element portion It is to be.

  The above object is to provide a magnetoresistive effect film that converts a magnetic signal into an electrical signal using the magnetoresistive effect, a pair of electrodes for causing a signal detection current to flow through the magnetoresistive effect film, and the magnetoresistive effect film. In the magnetoresistive effect type magnetic head having a longitudinal bias application layer provided for applying a longitudinal bias magnetic field to the magnetic field, a longitudinal bias application layer is formed of a base film made of a ferromagnetic thin film and a hard film formed thereon. This is achieved by forming a structure having a magnetic thin film.

  Here, a ferromagnetic thin film or an amorphous ferromagnetic thin film whose crystal structure is a body-centered cubic lattice can be used as the base film made of a ferromagnetic thin film. The above object can also be achieved by using a base film made of an antiferromagnetic thin film instead of a base film made of a ferromagnetic thin film.

  When the magnetoresistive film is a material exhibiting an anisotropic magnetoresistive effect, it is necessary to include means for applying a lateral bias magnetic field to the magnetoresistive film. A typical method is to apply a magnetoresistive film and a soft magnetic thin film provided adjacent to each other via a nonmagnetic conductive thin film.

  Further, as the magnetoresistive effect film, a first magnetic thin film and a second magnetic thin film are laminated with a nonmagnetic conductive thin film as an intermediate layer, and the magnetization directions of the first magnetic thin film are provided adjacent to each other. Fixed by an antiferromagnetic layer, the magnetization direction of the second magnetic thin film is substantially perpendicular to the magnetization direction of the first magnetic thin film without applying an external magnetic field, and It is also possible to use a magnetoresistive effect laminated film in which the electric resistance changes depending on the relative angle between the magnetization direction and the magnetization direction of the second magnetic thin film.

As a material of the hard magnetic thin film, an alloy mainly composed of Co and M ₁ (M ₁ is at least one element selected from the group consisting of Cr, Ta, Ni, Pt and Re), or Co and M ₁ An oxide-added alloy in which M ₂ (M ₂ is at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, aluminum oxide, and tantalum oxide) is added to the alloy. Typical examples include Co—Cr—Pt alloys, Co—Re alloys, Co—Cr alloys, Co—Ta—Cr alloys, Co—Ni—Pt alloys, (Co—Cr—Pt) — There are SiO ₂ alloy, (Co—Cr—Pt) —ZrO ₂ alloy, and the like.

As a material for the ferromagnetic thin film having a body-centered cubic lattice as the base film of the hard magnetic thin film, Fe—Cr alloy, Fe, Fe—Ni alloy, Fe—Co alloy, Fe—Ni— Co-based alloys or alloys in which M ₃ (M ₃ is at least one element selected from the group consisting of Si, V, Cr, Nb, Mo, Ta, and W) are used.

In the case of an Fe—Ni based alloy, Fe-0 to 25 at.% Ni, in an Fe—Co based alloy, Fe-0 to 80 at.% Co, and in an Fe—Ni—Co based alloy, Fe _100-ab Ni. when expressed in _a Co _b, a composition range of 0 ≦ a ≦ 25,0 ≦ b ≦ 80. Fe and alloys obtained by adding the above-mentioned non-magnetic elements to these Fe-based alloys have a composition range that exhibits a stable body-centered cubic structure and exhibits ferromagnetism at about 100 ° C., which is the operating environment temperature of the magnetic disk device. It can be used as a ferromagnetic underlayer. In the combination of Fe and the above additive elements, the upper limit of the addition amount is 32 at.% For Si, 48 at.% For V, 45 at.% For Cr, and 6 at.% For Nb, Mo, Ta and W. . An Fe—Cr alloy is particularly preferable, and Cr of 5 to 45 at.% Is preferable from the viewpoint of high corrosion resistance.

The material of the base film made of an amorphous ferromagnetic thin film includes Co and M ₅ (M ₅ is Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, Y, Ru, Rh, Pd, Cu, Ag. , At least one element selected from the group of Au and Pt) is used.

The material of the antiferromagnetic thin film having a body-centered cubic lattice is Cr, Mn, M ₄ (M ₄ is at least selected from the group consisting of Cu, Au, Ag, Co, Ni and platinum group elements). An alloy mainly composed of one or more elements is used.

  By using a ferromagnetic thin film, an amorphous ferromagnetic thin film with a crystal structure of body-centered cubic lattice, or an antiferromagnetic thin film with a crystal structure of body-centered cubic lattice as the underlying film, the following effects may occur. it can.

  The <001> direction, which is the easy magnetization direction of the hard magnetic thin film, is tilted from the direction perpendicular to the film surface direction to the film surface direction or completely toward the film surface direction, thereby improving the coercive force and the squareness ratio. is there.

  Further, when the hard magnetic thin film is formed on a ferromagnetic thin film having a face-centered cubic structure, a crystal having a face-centered cubic lattice with small crystal magnetic anisotropy is provided in the hard magnetic thin film by providing a base film. Grain growth can be suppressed, and thus a decrease in coercive force can be suppressed. In the material of the hard magnetic thin film, it is known that there is a crystal having a face-centered cubic lattice with small crystal magnetic anisotropy in addition to a close-packed hexagonal lattice with large crystal magnetic anisotropy. When the layer on which the hard magnetic thin film is formed has a face-centered cubic lattice, the crystal structure of the face-centered cubic lattice is easily formed due to the influence of the crystal structure of the hard magnetic thin film. By using the above base film, such a decrease in coercive force can be suppressed.

  When the hard magnetic thin film is formed on a layer having a different crystal structure as shown in FIG. 16, by providing the base film, it has a uniform magnetic characteristic regardless of the difference in the lower layer. A hard magnetic thin film can be obtained.

  Further, by applying a magnetic exchange coupling between the hard magnetic thin film and the ferromagnetic thin film constituting the MR element portion, the direction of magnetization in the ferromagnetic thin film constituting the MR element portion is changed. Can be stabilized in the same direction as the direction of the longitudinal bias magnetic field generated from the magnetic field and entering the magnetosensitive portion of the MR element.

  The ferromagnetic thin film in which the crystal structure of the underlayer of the present invention is a body-centered cubic lattice has a large effect of changing the crystal orientation of the hard magnetic thin film formed on the upper layer and increasing the magnetization component in the in-plane direction. . An alloy mainly composed of Fe and Cr, which is a specific material of a ferromagnetic thin film whose crystal structure is a body-centered cubic lattice, has a stable body-centered cubic structure and is formed by a known general manufacturing method. A ferromagnetic thin film having In addition, the Fe—Cr alloy thin film having a preferable composition of Cr of 5 to 45 atomic% has practical corrosion resistance and exhibits ferromagnetism even at an environmental temperature of about 100 ° C. during operation of the magnetic disk device. This is a preferable undercoat film of the present invention.

  When a hard magnetic thin film is used for the longitudinal bias application layer of the magnetoresistive head, the intrinsic coercive force of the hard magnetic thin film must be sufficiently larger than the magnetic field acting from the outside. However, in general, when a hard magnetic thin film is formed on a magnetoresistive effect film or a Ni—Fe-based alloy thin film used as a soft magnetic thin film provided for applying a lateral bias magnetic field, the intrinsic coercive force is reduced to glass. Since it is significantly smaller than that produced on a substrate, it cannot be used as a longitudinal bias application layer. In order not to reduce the intrinsic coercive force, a means of laminating a hard magnetic thin film on a magnetoresistive film or soft magnetic thin film through a nonmagnetic layer is used, but in this case as well, Barkhausen noise is sufficiently suppressed. I can't. This is due to the fact that there is a part of the magnetoresistive effect film or soft magnetic thin film in which the magnetization is opposite to the magnetization direction of the hard magnetic thin film, so that the magnetization direction is unstable or a domain wall is generated. Therefore, if the magnetization of the magnetoresistive film or soft magnetic thin film is stabilized in the same direction as the magnetization direction of the hard magnetic thin film, Barkhausen noise can be suppressed.

  In order to stabilize the magnetization of the magnetoresistive film or soft magnetic thin film in the same direction as the magnetization direction of the hard magnetic thin film while suppressing the decrease in the intrinsic coercivity of the hard magnetic thin film, The most effective means is to form a hard magnetic thin film after forming a ferromagnetic thin film having a body-centered cubic lattice as the base film. This is because a thin film having a body-centered cubic lattice as a base film is provided as a base film, thereby suppressing the growth of crystal grains having a face-centered cubic lattice with a small crystalline magnetic anisotropy and a close-packed structure with a large crystalline magnetic anisotropy. This is to promote the growth of the hexagonal lattice. In addition, by using a ferromagnetic material for the base film, exchange coupling occurs between the magnetoresistive film or the soft magnetic thin film and the hard magnetic thin film, and the magnetization direction is stabilized in the same direction. By adopting such a configuration, the effect of the longitudinal bias magnetic field generated from the hard magnetic thin film and the effect of stabilizing the magnetization due to exchange coupling act, so the Barkhausen noise suppression effect is improved. In other words, since the effect of stabilizing the magnetization by exchange coupling acts excessively, even if the intrinsic coercive force of the hard magnetic thin film is somewhat smaller than the conventional one, the noise suppression effect equivalent to the conventional one can be obtained. The selection range of the material and the film forming conditions is widened, and the production becomes easy.

  Even if an antiferromagnetic thin film or an amorphous ferromagnetic thin film whose crystal structure is a body-centered cubic lattice is used as the base film, the same effect as described above can be obtained and Barkhausen noise can be suppressed.

  Since the magnitude of the longitudinal bias magnetic field depends on the amount of magnetic flux generated from the ferromagnetic film constituting the longitudinal bias application layer, it is generally adjusted by changing the residual magnetic flux density and film thickness of the ferromagnetic film. . In the hard magnetic thin film having the base film, the product of the product of the residual magnetic flux density and the film thickness of the hard magnetic thin film and the product of the residual magnetic flux density and the film thickness of the base film effectively acts. From the standpoint of controlling the longitudinal bias magnetic field, it is considered that the control is most easily performed when an antiferromagnetic thin film that does not generate magnetic flux from the base film is used. When the underlying film is a ferromagnetic thin film, it is considered that the smaller the residual magnetic flux density is easier to control whether the crystal structure is a body-centered cubic lattice or an amorphous structure in consideration of the variation in film thickness.

  In particular, the hard magnetic thin film described above is a Co—Pt alloy, a Co—Cr—Pt alloy, or a Ti oxide, V oxide, Zr oxide, Nb oxide, Mo oxide, Hf oxide, or Ta oxide. Of these, an alloy including at least one of a material, W oxide, Al oxide, Si oxide, and Cr oxide is preferable.

  This hard magnetic thin film is preferably composed of (Equation 1) or (Equation 2).

Co _a Cr _b Pt _c (Equation 1) or (Co _a Cr _b Pt _c ) _1-x (MO _y ) _x (Equation 2) (where x = 0.01 to 0.20, y: 0.2) 4 to 3, a: 0.5 to 0.9, b: 0 to 0.25, C: 0.03 to 0.30, M: Ti, V, Zr, Mo, Hf, Ta, W, Al, At least one of Si and Cr)
When the magnetoresistive effect film exhibits an anisotropic magnetoresistive effect, it is necessary to apply a lateral bias magnetic field to the magnetoresistive effect film, and the soft magnetic film for that purpose includes nickel-iron alloy, cobalt, nickel- One type of iron-cobalt alloy, zirconium oxide, aluminum oxide, hafnium oxide, titanium oxide, beryllium oxide, magnesium oxide, tantalum oxide, rare earth oxygen compound, zirconium nitride, hafnium nitride, aluminum nitride, titanium nitride, beryllium nitride, magnesium nitride , Silicon nitride, and one or more compounds selected from rare earth nitrogen compounds.

  The specific resistance of the soft magnetic thin film for applying a lateral bias magnetic field to the magnetoresistive effect film is preferably 70 μΩcm or more.

  The lateral bias film is preferably made of a nickel-iron-based alloy containing 78 to 84 atomic% of nickel.

  The present invention relates to a pair of longitudinal bias application layers provided on a substrate, a pair of electrodes formed on each of the permanent magnet films, and a magnetoresistive effect element film provided in contact with the longitudinal bias application layer. A magnetoresistive effect type magnetic head having an antiferromagnetic film made of nickel oxide, a two-layered ferromagnetic film, a nonmagnetic metal film, and a soft magnetic film sequentially formed from the substrate side; The longitudinal bias application layer has the above-described configuration.

  The two ferromagnetic films are preferably composed of a 70 to 95 atomic% Ni alloy layer and a Co layer or a Co alloy layer from the substrate side.

  The two-layered ferromagnetic film is preferably composed of a soft magnetic film from the antiferromagnetic side and a soft magnetic film having a larger spin-dependent scattering than the soft magnetic film.

  The present invention includes a pair of longitudinal bias application layers provided on a substrate, a pair of electrodes formed on each of the application layers, and a magnetoresistive element film provided in contact with the longitudinal bias layer. The magnetoresistive effect type magnetic head has an antiferromagnetic film, a ferromagnetic film, a nonmagnetic film, a soft magnetic film, a nonmagnetic film, a ferromagnetic film, and an antiferromagnetic film in order from the substrate side. The vertical bias application layer is laminated and has the above-described configuration.

  The amount of the compound added to the soft magnetic thin film for applying the above-mentioned lateral bias is such that the ratio of atoms excluding oxygen or nitrogen in the compound is 3 to 20% with respect to all atoms excluding oxygen and nitrogen. Is preferred. This is because when the amount of the compound is 3% or less, the increase in electric resistance is small, and when it is 20% or more, the saturation magnetic flux density is lowered and the value is not sufficient as a lateral bias film. Although the specific resistance of the lateral bias film of the present invention increases substantially in proportion to the amount of compound added, the magnetoresistive head preferably has a specific resistance of 70 μΩcm or more. This is because the output of the magnetoresistive effect type magnetic head is lowered unless the specific resistance of the lateral bias film is sufficiently larger than the specific resistance of the magnetoresistive effect film. This is because the specific resistance of the magnetoresistive effect film is 20 to 30 μΩcm, and the specific resistance of the lateral bias film is at least twice this.

  The magnetic film includes an alloy of Ni 70 to 95 atomic% and Fe 5 to 30 atomic%, or an alloy containing Co 1 to 5 atomic%, or Co 30 to 85 atomic%, Ni 2 to 30 atomic%, and Fe 2 to 50 atomic%. It is preferable to use an alloy having a face-centered cubic structure. Permalloy, permender alloy, or the like may also be used. That is, it is preferable to use a ferromagnetic material having good soft magnetic properties. This is because a good laminated structure can be formed, the soft magnetic characteristics are excellent, and a larger magnetoresistance effect is produced.

  It is preferable to use Au, Ag, or Cu for the nonmagnetic conductive film. In addition, Cr, Pt, Pd, Ru, Rh, or an alloy thereof may be used. That is, it is preferable to use a material that does not have spontaneous magnetization at room temperature and has good electron permeability.

  Further, the substrate may be a base for forming these films, and may have a function as a slider of a magnetic disk device. Examples of this material include alumina containing 5% or less of TiC, stabilized zirconia, and the like. The ceramic sintered body is preferable.

  By having such a film structure, the magnetoresistive effect element has a function of changing its electric resistance against a weak external magnetic field, and has a large effect of changing the electric resistance from 5% to 10%. . For this reason, the magnetic recording / reproducing apparatus of the present invention has a function of directly digitizing a signal recorded in an analog state at the time of reproduction, and further has an effect of increasing the recording capacity per disk area, that is, the recording density.

  In addition, as a film configuration, a flat film such as aluminum oxide or nickel oxide is formed on the substrate, or a film such as iron, titanium, tantalum, zirconium, hafnium, niobium, cobalt iron alloy or the like is formed on the substrate. May be further formed as a base. The film on the substrate has an effect of flatly forming a multilayer film on the surface thereof, and preferably has a uniform and flat film structure on the surface of the substrate, and the thickness of each film is 20 to 20 for a metal film. It is preferably about 5 to 1000 mm for a film other than 200 mm or a metal.

  The thin film magnetic head of the present invention comprises a combination of an inductive recording head for recording a signal on a recording medium and a magnetoresistive effect reproducing head for reproducing the signal. A magnetic film sandwich structure having a film sandwiched therebetween, and the recording head is formed between the substrate and the reproducing head.

  The present invention can reduce a decrease in sensitivity due to an increase in shape anisotropy of a magnetic film in a magnetoresistive element. This can be reduced by making the magnetic film thinner. This is because the shape anisotropy of the magnetic film is roughly proportional to its thickness. On the other hand, the total thickness of the magnetoresistive film of the present invention needs to be about 100 to 300 mm in order to prevent a decrease in output due to surface scattering, but individual magnetic films separated by a nonmagnetic film, particularly This is because even if the thickness of the soft magnetic film at the center of the film is 100 mm or less, particularly 10 to 20 mm or less, no decrease in output occurs. This action occurs because the mechanism of the magnetoresistive effect is caused by the magnetic film / nonmagnetic film / magnetic film interface.

  Further, the thickness of the magnetic film of the magnetoresistive effect element mounted in the present invention is preferably 5 to 1000 mm, particularly 10 to 100 mm. This is because the magnetic film has sufficient magnetization at room temperature and the current is effectively utilized for the magnetoresistance effect.

  The thickness of the nonmagnetic conductive film that separates the magnetic films is preferably 2 to 1000 mm. This is because the non-magnetic conductive film does not hinder the conduction of electrons, and it is particularly necessary to keep the antiferromagnetic or ferromagnetic coupling between the magnetic films sufficiently small. In the case of Cu, it is preferably about 10 to 30 mm.

  An example of the configuration of the magnetoresistive element of the present invention is formed by arranging a pair of electrodes on a film in which NiO, NiFe, Cu, NiFe, Cu, NiFe, and NiO are sequentially laminated on a substrate. Alternatively, a pair of electrodes is arranged on a film in which NiO, Co / NiFe, Cu, Co / NiFe, Cu, Co / NiFe, and NiO are sequentially stacked on a substrate.

  Alternatively, the magnetoresistive element of the present invention is formed by arranging a pair of electrodes on a film in which NiO, CoNiFe, Cu, NiFe, Cu, Co / NiFe, and NiO are sequentially laminated on a substrate. This is because these structures effectively prevent the output from being reduced by surface scattering, effectively improve the output, and make the central film thinner, making it possible to reduce the thickness of the magnetic film. This is because deterioration of the sensitivity can be prevented without lowering the output.

  The magnetic recording / reproducing apparatus of the present invention can use the magnetoresistive element as a reproducing unit in this way, and can shorten the recording wavelength recorded on the recording medium, that is, the high recording density. In addition, recording with a narrow recording track can be realized, sufficient reproduction output can be obtained, and good recording can be maintained.

  According to the present invention, the longitudinal bias application layer provided to suppress Barkhausen noise of the magnetoresistive effect type magnetic head using the anisotropic magnetoresistive effect and the giant magnetoresistive effect is provided with the ferromagnetic thin film, the amorphous By comprising a base film made of a ferromagnetic thin film or an antiferromagnetic thin film and a hard magnetic thin film formed thereon, a magnetic structure such as a magnetoresistive film or a bias film having a face-centered cubic lattice. Even if the longitudinal bias application layer is formed on the thin film, the decrease in coercive force can be suppressed. In addition, since exchange coupling occurs between the magnetoresistive film or the bias film and the hard magnetic thin film, the magnetization of these thin films becomes stable and a magnetoresistive head free from Barkhausen noise can be provided.

  In addition, according to the present invention, the permanent magnet film is formed at both ends of the magnetoresistive effect element, so that the electromagnetism conversion characteristics are stabilized and the waveform fluctuation can be reduced. Further, according to the present invention, a magnetic recording / reproducing apparatus having a large reproduction output and a high recording density can be achieved.

(Example 1)
Regarding the improvement of the magnetic properties of the hard magnetic thin film on the base film of the present invention, the case where an Fe—Cr alloy thin film having a crystal structure of a body-centered cubic lattice is used as the base film will be described. FIG. 2A shows the magnetic properties in the in-plane direction of the single layer film of the prior art Co—Cr—Pt hard magnetic thin film, and FIG. 2B shows the top of the Fe—Cr alloy thin film of the present invention. The magnetic characteristics in the in-plane direction of the Co—Cr—Pt-based hard magnetic thin film (hereinafter referred to as Fe—Cr / Co—Cr—Pt) produced in the above are compared. The thin film is prepared by sputtering, and the thickness of the Co—Cr—Pt hard magnetic thin film is 40 nm regardless of the presence or absence of the underlying film, and the thickness of the Fe—Cr alloy thin film is 10 nm. The composition of the Co—Cr—Pt hard magnetic thin film is 69 at.% Co-14 at.% Cr-17 at.% Pt, and the composition of the Fe—Cr alloy thin film is 90 at.% Fe-10 at.% Cr. is there. In the single layer film, the coercive force is 610 Oe, the product of the residual magnetic flux density and the film thickness (hereinafter referred to as the amount of magnetization) is 200 G · μm, and the ratio of the residual magnetic flux density to the saturation magnetic flux density (hereinafter referred to as the squareness ratio). Called) is 0.73. On the other hand, in Fe—Cr / Co—Cr—Pt, the coercive force is 1035 Oe, the value of magnetization is 430 G · μm, and the squareness ratio is 0.90. Here, the magnetization amount represents the magnitude of the magnetic field generated from the magnetic film, and corresponds to a longitudinal bias magnetic field applied to the magnetoresistive effect film. In order to operate the MR head stably and with high sensitivity, the magnetization amount of the longitudinal bias application layer is suitably 1 to 2.5 times the magnetization amount of the magnetoresistive effect film. In Cr / Co—Cr—Pt, a size sufficient to apply a longitudinal bias magnetic field is obtained.

  Since the optimum amount of magnetization of the MR head varies depending on the film thickness of the magnetoresistive film, the film thickness of the hard magnetic thin film may be changed in accordance with the film thickness. In addition, when the Fe—Cr alloy thin film is provided as the base film, both the coercive force and the squareness ratio are greatly improved. The coercive force is preferably large in view of the stability of the longitudinal bias magnetic field and the like, and the one having a large squareness ratio has the effect of reducing the thickness of the hard magnetic thin film.

In the case of a single layer film, the coercive force and the magnetization amount are small because the <001> direction is oriented perpendicularly to the film surface of the hard magnetic thin film crystal. FIG. 3 is an X-ray diffraction profile of a Co—Cr—Pt single layer film and a laminated film of Fe—Cr / Co—Cr—Pt. In any film, the <001> crystal axis is oriented perpendicular to the film surface, and diffraction lines from the (002) plane are observed. However, the intensity of the diffraction line is about 6 times greater in the single layer film, indicating that the degree of orientation of <001> is higher. The Co—Cr—Pt film is hexagonal and has strong magnetic anisotropy in the <001> direction. Therefore, a strong <001> orientation like a single layer film generates perpendicular anisotropy and reduces the in-plane component of magnetization. When an Fe—Cr alloy thin film is provided as a base film, the crystal structure of this film is a body-centered cubic lattice, and the <001> crystal axis is oriented perpendicular to the film surface. It is considered that the crystal orientation of the Co—Cr—Pt film changed and the <001> orientation changed.
(Example 2)
When the thickness of the base film is as thin as 5 to 20 nm, as shown in FIG. 4, both sides of the soft magnetic thin film 13 / nonmagnetic conductive thin film 14 / magnetoresistance effect film 15 are cut off so that only the signal detection region remains. When the longitudinal bias application layer 24 and the electrode film 17 are disposed, the longitudinal bias magnetic field can be applied not only to the magnetoresistive effect film 15 but also to the soft magnetic thin film 13 by the magnetic field generated from the longitudinal bias application layer 24. Barkhausen noise caused by the thin film 13 can be suppressed. In addition, since the magnetoresistive film 15 exists only in the signal detection region, a head having excellent off-track characteristics can be obtained. When the both sides of the soft magnetic thin film 13 / the nonmagnetic conductive thin film 14 / the magnetoresistive effect film 15 are cut off, the width of the soft magnetic thin film 13 located on the substrate side becomes wider than the other films.
In general, since a Ni—Fe thin film having a crystal structure of a face-centered cubic lattice is used as the soft magnetic thin film 13, the reproducing track side of the hard magnetic thin film is formed on the face-centered cubic lattice when no base film is used. In this portion, the coercive force is lowered and Barkhausen noise is generated. In addition, when a nonmagnetic thin film is used as the base film, the magnetization direction becomes unstable in a portion that is wider than the magnetoresistive film of the soft magnetic thin film, and this appears as Barkhausen noise. When a ferromagnetic thin film, an antiferromagnetic thin film, or an amorphous ferromagnetic thin film whose crystal structure is a body-centered cubic lattice is used as an underlayer, the coercive force of the hard magnetic thin film is not lowered, and the hard magnetic thin film and the soft magnetic thin film are not reduced. Since exchange coupling occurs between the thin films, the magnetization of the soft magnetic thin film is stabilized, and Barkhausen noise can be suppressed.

  In order to suppress Barkhausen noise without reducing the output, it is important to adjust the magnitude of the longitudinal bias magnetic field to an appropriate value. Considering the fluctuation of the longitudinal bias magnetic field due to the variation in film thickness, the base film 252 showing ferromagnetism is saturated by adding Ni, Co, Si, V, Cr, Nb, etc. to Fe rather than Fe thin film having a high saturation magnetic flux density. The Fe-based alloy thin film or amorphous ferromagnetic thin film with a reduced magnetic flux density can suppress fluctuations to a smaller extent. Furthermore, if the antiferromagnetic thin film has a film thickness that exhibits antiferromagnetism, a magnetic field is not generated from itself regardless of the film thickness.

  In the embodiment described here, the magnetoresistive head in which the soft magnetic thin film 13, the magnetoresistive film 15, and the electrode film 17 are arranged in order from the substrate side is shown, but it is not always necessary to arrange them in this order.

  In this embodiment, a material exhibiting an anisotropic magnetoresistance effect is used as the magnetoresistance effect film. In addition, sputtering is used to form a thin film described below.

  About 10 μm of an alumina film is formed as an insulating film 20 on the nonmagnetic substrate 10 made of ceramics, and the surface is precisely polished. About 2 μm of a Co—Hf—Ta alloy amorphous thin film is formed as the lower shield layer 111 and processed into a predetermined shape using an ion milling method. After forming an alumina film of 0.3 μm as the lower gap layer 121, the soft magnetic thin film 13 for applying a lateral bias magnetic field 13 is a Ni—Fe—Cr alloy thin film 40 nm, the nonmagnetic conductive thin film 14 is a Ta thin film 20 nm, A 30 nm thick Ni—Fe alloy thin film is sequentially formed as the magnetoresistive effect film 15, and a laminated film of a soft magnetic thin film, a nonmagnetic conductive thin film, and a magnetoresistive effect film (hereinafter referred to as soft magnetic thin film / nonmagnetic conductive thin film / (Referred to as a magnetoresistive film) into a predetermined shape. A lift-off mask material is formed at a position to be a signal detection region, and these layers are laminated under the condition that a gentle slope is formed at the end of the soft magnetic thin film / nonmagnetic conductive thin film / magnetoresistance effect film by an ion milling method. The film is etched so that only the magnetosensitive part remains. As the longitudinal bias applying layer 24, an Fe—Cr alloy thin film 10 nm which is a base film 252 whose crystal structure is ferromagnetic with a body-centered cubic lattice and a Co—Pt—Cr hard magnetic thin film 40 nm which is a hard magnetic thin film 26 are sequentially formed. Subsequently, after forming a 0.2 μm thick Au thin film to be an electrode film 17 for reading out the change in the electric resistance of the magnetoresistive effect film 15, the lift-off mask material is removed to obtain a signal detection region. Is formed. On top of this, an upper gap layer 122 made of alumina having a thickness of 0.3 μm and an upper shield layer 112 made of Ni—Fe alloy having a thickness of about 2 μm are sequentially formed. Further, after forming the insulating film 18 on the upper part, an induction type magnetic head for recording is manufactured, but the details are omitted.

  After the element formation is completed, the longitudinal bias application layer 24 is magnetized by applying a DC magnetic field of 5 kOe in the length direction (horizontal direction in the figure) of the magnetoresistive film. Thereafter, the substrate is cut and processed into a slider to complete the production of the MR head.

  In the present embodiment, as a means for applying a lateral bias magnetic field, a method of applying by a soft magnetic thin film 13 provided adjacently via a magnetoresistive effect film 15 and a nonmagnetic conductive thin film 14 is used. This is one method for applying a lateral bias magnetic field, and other methods can be used.

  Further, although a laminated film of Fe—Cr 10 nm / Co—Cr—Pt 40 nm is used as the longitudinal bias application layer 24, this is an example of the embodiment, and the magnetization amount of the longitudinal bias application layer is the magnetoresistive effect film. As long as the amount of magnetization is about 1 to 2.5 times, this film thickness structure or these materials may not be used. The amount of magnetization can be adjusted by changing the film thickness of each of the base film 252 exhibiting ferromagnetism and the hard magnetic thin film 26 because they are ferromagnetically coupled. Furthermore, if the amount of magnetization of the longitudinal bias application layer is sufficiently large, it can be adjusted by tilting the magnetization direction from the length direction of the magnetoresistive film to the height direction (perpendicular to the paper surface). is there.

5 to 8 show the MR head (FIGS. 5 and 6) of the present invention and a non-magnetic underlayer for examining the effect of magnetic exchange coupling acting between the hard magnetic thin film and the magnetoresistive film. 8 is a comparison of the sensitivity distribution in the track direction and the magnetization distribution model of a comparative MR head (FIGS. 7 and 8) using Cr. First, the track profile measurement method will be described. In this track profile, a signal is written on a very narrow track of about 0.4 μm on the disk, and this signal is read while moving the MR head in the radial direction of the disk to obtain the reproduction output of each part of the MR head. It is a thing. Therefore, the horizontal axis in the figure is the moving distance, and the vertical axis is the reproduction output at that position. When the distribution of the MR head sensitivity in the track direction is examined by such measurement, it can be seen that the MR head reproduction sensitivity has a mountain-shaped distribution that is large at the center of the track and low at the end. The actual reproduction voltage is considered to correspond to the integration value of these signals in the track direction. In the MR head of the nonmagnetic underlayer shown in FIGS. 7 and 8, the geometrical track width (electrode spacing) is 2.8 μm, and the magnetic track width (T _WM ) is 2.4 μm. It has decreased by 4 μm. Here, the magnetic track width is defined as a width in which the output at each point in the figure is integrated in the track direction and the value of the integration curve is from 5% of the whole to 95% of the whole. Therefore, the magnetic track width corresponds to the effective track width of the MR head. The reason why the magnetic track width decreases in the MR head of the nonmagnetic underlayer is that the magnetization of the end of the magnetoresistive film is oriented in the normal direction of the disk as shown by the magnetization model in FIG. it is conceivable that. When the magnetization is directed in the normal direction as described above, the magnetization of the magnetoresistive effect film cannot be rotated according to the signal magnetic field from the medium, and as a result, the sensitivity is lowered at this portion. In this head, since there is such a dead zone at the end of the signal detection region, the reproduction voltage is low. On the other hand, in the MR head of the present invention using a ferromagnetic thin film as an underlayer (FIGS. 5 and 6), the magnetic track width (T _WM ) is 2.25 μm with respect to the geometric track width of 2.25 μm. The geometric track width and the effective track width are almost the same. This is because in the MR head of the present invention, the magnetization does not face the normal direction of the disk at the end of the magnetoresistive film, and therefore there is no dead zone as in the MR head using the nonmagnetic underlayer. As a result, it has a high output. In the magnetization distribution diagram of FIG. 6, the magnetization of the signal detection region is inclined obliquely because a lateral bias magnetic field is applied to the magnetoresistive film.

From the above results, it was found that there is a difference in the state of magnetization at the end of the signal detection region between the MR head using a nonmagnetic underlayer and the MR head of the present invention. This difference is due to the presence or absence of magnetic exchange coupling between the hard magnetic thin film and the magnetoresistive effect film and soft magnetic thin film. In the MR head of the present invention, the magnetization of the hard magnetic thin film and the magnetoresistive film is magnetically exchange-coupled via the magnetic underlayer, so that the magnetization of the ends of the magnetoresistive film and the soft magnetic thin film is hard. The direction is the same as the direction of magnetization of the magnetic thin film. In this case, since the magnetization of the hard magnetic thin film is magnetized in the track direction of the MR head, the magnetization of the magnetoresistive effect film and the soft magnetic thin film are also oriented in the track direction. On the other hand, in the case of an MR head using a nonmagnetic underlayer, there is no magnetic exchange coupling between the hard magnetic thin film, the magnetoresistive film, and the soft magnetic thin film. It is well known that an MR head is a complex laminated structure of insulating films and metal films made of ceramics, and an extremely large stress concentration tends to occur from the complex structure. Therefore, stress is likely to concentrate at the etched end, such as the end of the signal detection region. When the magnetoresistive film is subjected to stress, the magnetization is likely to be directed in the direction of the stress according to the magnetostriction (it is difficult to be directed depending on the magnetostriction). It is considered that the rotation of magnetization at the end of the signal detection region of the MR head using the nonmagnetic underlayer is caused by such stress. When the hard magnetic thin film is magnetically exchange-coupled in the end region as in the present invention, it is possible to prevent such magnetization instability that is likely to occur at the end of the signal detection region.
(Example 3)
FIG. 1 is a perspective view showing the structure of a magnetoresistive head using the anisotropic magnetoresistive effect of the present invention, and FIG. About 10 μm of an alumina film is formed as an insulating film 20 on the nonmagnetic substrate 10 made of ceramics, and the surface is precisely polished. A Co—Hf—Ta alloy amorphous thin film is formed to a thickness of about 2 μm by sputtering as the lower shield layer 111 and processed into a predetermined shape using ion milling. After forming an alumina film of 0.3 μm as the lower gap layer 121, the soft magnetic thin film 13 for applying a lateral bias magnetic field 13 is a Ni—Fe—Cr alloy thin film 40 nm, the nonmagnetic conductive thin film 14 is a Ta thin film 20 nm, A 30 nm thick Ni—Fe alloy thin film is sequentially formed as the magnetoresistive effect film 15, and the soft magnetic thin film / nonmagnetic conductive thin film / magnetoresistance effect film is processed into a predetermined shape. A lift-off mask material is formed at a position to be a signal detection region. After cleaning the surface of the magnetoresistive film by sputter etching, as the longitudinal bias applying layer 24, the Fe thin film 10nm as the underlayer film 252 showing the ferromagnetism in the body-centered cubic lattice and the Co-Pt as the hard magnetic thin film 26 are used. A Cr-based hard magnetic thin film of 32 nm is sequentially formed, and subsequently, an Au thin film serving as an electrode film 17 for reading out a change in electric resistance of the magnetoresistive effect film 15 is formed to a thickness of 0.2 μm. A sputtering method was used for film formation, and the Ar gas pressure was 5 mTorr and the substrate temperature was room temperature. Note that the coercive force of a laminated film made of a Fe thin film 10 nm and a Co—Pt—Cr hard magnetic thin film 32 nm fabricated on a glass substrate is 1200 Oe, and the ratio Br / Bs (hereinafter referred to as an angle) of the residual magnetic flux density Br and the saturated magnetic flux density Bs. The mold ratio was 0.80, and the residual magnetic flux density was 0.93T. In this embodiment, the Fe / Co—Cr—Pt laminated film is used as the longitudinal bias application layer, but this is a representative example of the longitudinal bias application layer 24 and is not particularly limited to this laminated film. Next, the signal detection region is formed by removing the lift-off mask material to which the Fe / Co—Cr—Pt laminated film as the vertical bias application layer 24 and the Au thin film as the electrode film 17 are attached. On this, an upper gap layer 122 made of alumina having a thickness of 0.3 μm and an upper shield layer 112 made of a Ni—Fe alloy having a thickness of about 2 μm are sequentially formed. Further, after forming the insulating film 18 on the upper part, an induction type magnetic head for recording is manufactured, but the details are omitted. Thereafter, the substrate is cut and processed into a slider to complete the production of the magnetoresistive head.

  The presence or absence of Barkhausen noise was examined for the magnetoresistive head manufactured as described above. For comparison, the longitudinal bias application layer is a Co—Pt—Cr hard magnetic thin film of 80 nm (no base film), the base film is a nonmagnetic Cr thin film of 10 nm, and the hard magnetic thin film is a Co—Pt—Cr hard magnetic thin film of 52 nm. The magnetoresistive head was also evaluated. The magnetic characteristics of a Co—Pt—Cr hard magnetic thin film with a thickness of 80 nm fabricated on a glass substrate are a coercive force of 450 Oe, a squareness ratio of 0.55, a residual magnetic flux density of 0.49 T, and a 10 nm The magnetic properties of a Co-Pt-Cr hard magnetic thin film with a thickness of 52 nm fabricated on a glass substrate via a Cr thin film are coercive force of 1500 Oe, squareness ratio of 0.85, and residual magnetic flux density of 0.75 T. Although the magnetic characteristics of the Fe thin film 10 nm / Co—Pt—Cr based hard magnetic thin film 32 nm are different from those of the laminated film, the product of the residual magnetic flux density and the film thickness are the same. Are considered to be approximately equal. Barkhausen noise was evaluated by observing the reproduction waveform when a recording pattern recorded at 5 kFCI on a thin film medium with a residual magnetic flux density and a magnetic film thickness of 150 G · μm was reproduced with a flying height of 0.12 μm and a sense current of 10 mA. Then, as the Barkhausen noise suppression rate, the number of heads where Barkhausen noise did not appear was compared with the observed number of heads. The barbhausen noise suppression rate of the head using the Fe thin film 10 nm / Co—Pt—Cr hard magnetic thin film 32 nm as the longitudinal bias application layer is 100%, whereas the Co—Pt—Cr hard magnetic thin film 80 nm The head was 10%, and the Cr thin film 10 nm / Co—Pt—Cr hard magnetic thin film 52 nm head was 65%. Co-Pt-Cr hard magnetic thin film 80 nm head with no underlying film has a low Barkhausen noise suppression rate because the Co-Pt-Cr hard magnetic thin film has a face-centered cubic lattice crystal structure. This is because the coercive force is small because the film is formed directly on the surface, and when an external magnetic field acts, the magnetization of the longitudinal bias application layer also moves, and the longitudinal bias magnetic field does not work effectively. In the case of a Cr thin film 10 nm / Co—Pt—Cr hard magnetic thin film 52 nm head using a non-magnetic Cr thin film as a base film, the direction of magnetization in the signal detection region is different from that of the longitudinal bias application layer as shown in FIG. The magnetic field is directed in the same direction as the longitudinal bias application layer. However, under the longitudinal bias application layer, the magnetization direction of the magnetoresistive film is opposite to the magnetization direction of the longitudinal bias application layer due to the magnetostatic action of the element end. Therefore, it is considered that a domain wall is generated in a portion where the magnetization direction is opposite in the magnetoresistive effect film, and Barkhausen noise is generated.

  In this embodiment, a laminated film of Fe thin film 10 nm / Co—Pt—Cr hard magnetic thin film 32 nm is used as the longitudinal bias applying layer 24. However, the underlying film is a strong structure in which the crystal structure other than the Fe thin film is a body-centered cubic lattice. A magnetic thin film, an amorphous ferromagnetic thin film, or an antiferromagnetic thin film having a body-centered cubic lattice may be used.

  Ferromagnetic thin films whose crystal structure is a body-centered cubic lattice are Fe—Ni alloys, Fe—Co alloys, Fe—Ni—Co alloys, Fe, and Si, V, Cr, Nb as additive elements to these alloys. An alloy to which one or more of Mo, Ta, and W are added can be used. When these are used as the underlayer, the thickness of the underlayer is better in order to promote crystal growth of the hard magnetic thin film and further reduce the magnetic interaction between the particles to obtain a large coercive force. On the other hand, the exchange coupling between the magnetoresistive film and the hard magnetic thin film decreases as the base film becomes thicker. Therefore, the film thickness of the base film is preferably about 5 to 20 nm, which is a film thickness at which the growth of the hard magnetic thin film is not affected by the magnetoresistive film whose crystal structure is a face-centered cubic lattice.

  The amorphous ferromagnetic thin film is one or more selected from Co, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, Y, Ru, Rh, Pd, Cu, Ag, Au, and Pt. An amorphous alloy containing an element as a main component can be used. Typical examples include a Co—Zr—Nb thin film, a Co—Zr—Ta thin film, a Co—Hf—Nb thin film, and a Co—Hf—Ta. System thin film. Comparing the coercive force of the amorphous ferromagnetic thin film / hard magnetic thin film and the body-centered cubic ferromagnetic thin film / hard magnetic thin film, when the thickness of the underlying film is 30 nm or more, the body-centered cubic ferromagnetic thin film A larger value can be obtained by using this film. However, when the amorphous ferromagnetic thin film is used, the value is about the same as or slightly smaller than the case of using the body-centered cubic lattice ferromagnetic thin film. This is because when the film thickness is about 5 to 20 nm, the crystallinity of the body-centered cubic lattice ferromagnetic thin film is inferior compared to the case where the film thickness is large, and the growth of crystal grains is not sufficient. It seems that there is not much difference. It should be noted that the amount of magnetic flux generated from the longitudinal bias application layer is equal to the Fe thin film 10 nm / Co—Pt—Cr hard magnetic thin film 32 nm, Co—Hf—Ta amorphous ferromagnetic thin film 16 nm / Co—Pt—Cr hard The Barkhausen noise suppression rate of the magnetoresistive head using the magnetic thin film of 32 nm was 100% as in the case of using the Fe thin film of 10 nm / Co—Pt—Cr hard magnetic thin film of 32 nm.

  The antiferromagnetic thin film whose crystal structure is a body-centered cubic lattice uses an alloy containing as a main component one or more elements selected from Cr, Mn, Cu, Au, Ag, Co, Ni, and platinum group elements. Can do. In the case of these antiferromagnetic thin films, antiferromagnetism is not exhibited when the thickness is thinner than about 20 nm.

  The hard magnetic thin film can be made of an alloy mainly composed of Co and one or more elements selected from Cr, Ta, Ni, Pt, and Re. Other typical Co—Pt—Cr hard magnetic thin films Among them, there are a Co—Re hard magnetic thin film, a Co—Cr hard magnetic thin film, a Co—Ta—Cr hard magnetic thin film, a Co—Ni—Pt hard magnetic thin film, and the like. An oxide-added alloy thin film obtained by adding one or more kinds of silicon oxide, zirconium oxide, aluminum oxide, and tantalum oxide to these hard magnetic alloy thin films can also be used.

  In the MR head using the anisotropic magnetoresistance effect of the present invention, the soft magnetic thin film / nonmagnetic conductive thin film / magnetoresistance effect film are formed in the same manner as in the previous embodiment, and then the soft magnetic thin film is formed. / Nonmagnetic conductive thin film / Magnetoresistance effect film is processed into a predetermined shape. A lift-off mask material is formed at a position to be a signal detection region, and an Fe—Cr alloy thin film, which is a base film 252 showing ferromagnetism having a body-centered cubic structure, and Co, which is a hard magnetic thin film 26, are formed as a longitudinal bias application layer 24. -Cr-Pt hard magnetic thin films are sequentially formed. Subsequently, after forming an Au thin film to be the electrode film 17, the signal detection region is formed by removing the lift-off mask material. The subsequent steps are the same as those in the above-described embodiment.

When a nonmagnetic film such as Cr is used as the base film, the magnetic field generated from the hard magnetic thin film circulates through the ferromagnetic thin film constituting the MR element portion under the hard magnetic thin film as shown in FIG. For this reason, the magnetization of the magnetoresistive film is opposite to each other in the magnetic sensitive part and the part other than the magnetic sensitive part. On the other hand, when a ferromagnetic underlayer is used, the magnetization of the magnetosensitive part is caused by the magnetic field generated from the longitudinal bias application layer, and the magnetization of the part other than the magnetosensitive part is caused by the magnetic field between the longitudinal bias application layer and the magnetoresistive film. Due to exchange coupling, the direction is the same as the magnetization direction of the longitudinal bias application layer. Therefore, since there is no domain wall in the magnetoresistive film, an MR head free from Barkhausen noise can be obtained.
Example 4
The present invention can also be applied to MR heads utilizing the giant magnetoresistance effect. Among the laminated film structures showing the giant magnetoresistive effect, the simplest and basic one is an antiferromagnetic layer 31 / magnetic thin film 32 / nonmagnetic conductive thin film 33 / magnetic thin film 34 as shown in FIG. This is the configuration. The direction of magnetization of the magnetic thin film 32 is fixed in a direction perpendicular to the track direction (direction perpendicular to the paper surface) by exchange interaction with the antiferromagnetic layer 31. Magnetic anisotropy is induced in the track direction in the magnetic thin film 34, and the magnetization directions of the magnetic thin film 32 and the magnetic thin film 34 are perpendicular to each other when no external magnetic field is applied. When an external magnetic field is applied, the magnetization of the magnetic thin film 34 rotates and the angle formed with the magnetization of the magnetic thin film 32 changes, thereby changing the electrical resistance. In general, an Fe—Mn antiferromagnetic film, a Ni—Mn antiferromagnetic film, a NiO antiferromagnetic film, or the like is used for the antiferromagnetic layer 31, and a Ni—Fe thin film is used for the magnetic thin films 32 and 34. As the nonmagnetic conductive thin film 33, a Cu thin film is used. The longitudinal bias magnetic field is applied to the magnetic thin film 34 whose magnetization rotates.
(Example 5)
FIG. 11 is a cross-sectional view of the vicinity of the magnetic sensing portion of an embodiment of an MR head having a magnetoresistive effect laminated film having such a film configuration. The layers up to the lower gap layer 121 are manufactured by the same method as that of the MR head using the anisotropic magnetoresistive effect. On the lower gap layer 121, the NiO antiferromagnetic thin film 100 nm as the antiferromagnetic layer 31, the Ni—Fe alloy thin film 5 nm as the magnetic thin film 32, the Cu thin film 3 nm as the nonmagnetic conductive thin film 33, and the Ni as magnetic thin film 34. After forming the Fe-based alloy thin film 12 nm, a Ta thin film 3 nm is formed as the protective film 35. The laminated film is processed into a predetermined shape, and a lift-off mask material is formed at a position to be a signal detection region. The longitudinal bias application layer 24 of the present invention, for example, the body-centered cubic structure is formed after etching so that only the magnetosensitive portion remains under the condition that a gentle slope is formed at the end of the magnetoresistive effect laminated film by ion milling. An Fe-10 at.% Cr alloy thin film 5 nm which is a base film 252 exhibiting ferromagnetism and a Co—Pt—Cr hard magnetic thin film 14 nm which is a hard magnetic thin film 26 are formed, followed by Au forming an electrode film 17. A thin film of 0.2 μm is formed. Here, the coercivity of the Fe-10 at.% Cr alloy thin film 5 nm / Co-Pt-Cr hard magnetic thin film 14 nm fabricated on the glass substrate was 1500 Oe, the squareness ratio was 0.85, and the residual magnetic flux density was 0.87 T. It was. Next, the lift-off mask material is removed to form a signal detection region, but the subsequent steps are the same as those in the above-described embodiment, and will be omitted.

  After all the thin film forming steps are completed, a magnetic exchange coupling is generated between the antiferromagnetic layer 31 and the magnetic thin film 32, and the magnetization direction of the magnetic thin film 32 is perpendicular to the track direction (perpendicular to the paper surface). Therefore, a heat treatment step for lowering the temperature while applying a DC magnetic field from a temperature higher than the Neel point of the antiferromagnetic layer is required. After the longitudinal bias application layer is magnetized in the length direction (horizontal direction in the figure) of the magnetoresistive effect laminated film, the substrate is cut and the slider is processed to complete the production of the MR head.

  For comparison, a magnetoresistive head having the same structure using a Cr thin film 5 nm / Co—Pt—Cr hard magnetic thin film 27 nm as a longitudinal bias application layer was also produced, and the Barkhausen noise suppression rate was compared. However, the head using the Fe-10 at.% Cr alloy thin film 5 nm / Co-Pt-Cr hard magnetic thin film 14 nm was 100%, whereas the Cr thin film 5 nm / Co-Pt-Cr hard magnetic thin film was used. The head using 27 nm was 70%. The magnetic properties of the Cr thin film 5 nm / Co—Pt—Cr hard magnetic thin film 27 nm prepared on the glass substrate were 1700 Oe in coercive force, 0.90 in squareness, and 0.59 T in residual magnetic flux density. .

In the present embodiment, the MR head in which the antiferromagnetic layer 31, the magnetic thin film 32, the nonmagnetic conductive thin film 33, the magnetic thin film 34, and the electrode film 17 are arranged in order from the substrate side is shown, but not necessarily arranged in this order. May be. However, when the magnetic thin film 34 / nonmagnetic conductive thin film 33 / magnetic thin film 32 / antiferromagnetic layer 31 are used, the antiferromagnetic layer 31 includes an Fe—Mn antiferromagnetic film and an Ni—Mn antiferromagnetic layer. A conductive antiferromagnetic film such as a magnetic film is preferred.
(Example 6)
Even in an MR head having a magnetoresistive layered film composed of an antiferromagnetic layer / magnetic thin film / nonmagnetic conductive thin film / magnetic thin film, as shown in FIG. 24 and the electrode 17 can be arranged.

  Also in an MR head using the giant magnetoresistive effect, the magnetization amount of the longitudinal bias application layer has a great influence on the head stability and the reproduction output. The optimum magnetization amount of the longitudinal bias application layer is about 1 to 3 times the magnetization amount of the magnetic thin film 34 or 22.

  In the above description, the ferromagnetic thin film whose crystal structure is a body-centered cubic lattice has been mainly described as the longitudinal bias application layer of the present invention. The same effect can be obtained when a ferromagnetic thin film is used.

  The material of the amorphous ferromagnetic thin film is selected from Co, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, Y, Ru, Rh, Pd, Cu, Ag, Au, and Pt. An amorphous alloy containing at least one element as a main component can be used, and representative examples include a Co—Zr—Nb thin film, a Co—Zr—Ta thin film, a Co—Hf—Nb thin film, Examples thereof include a Co—Hf—Ta-based thin film. In the case of these materials, it is produced by sputtering. However, if Co is more than 90 at.%, It will not be amorphous, and if it is less than 70 at.%, The magnetism will be lost. Is 90 at.%, And the lower limit is 70 at.%.

  FIG. 13 shows a Co—Cr—Pt single layer film and a Co—Zr—Nb thin film 20 nm, which is a specific example of an amorphous ferromagnetic thin film, as a base film, and a Co—Cr—Pt hard magnetism thereon. 2 is an X-ray diffraction profile of Co—Zr—Nb / Co—Cr—Pt in which thin films are stacked. Looking at the profile of Co—Zr—Nb / Co—Cr—Pt, a broad diffraction line due to the Co—Zr—Nb thin film and a diffraction line from the (002) plane of Co—Cr—Pt are observed. It can be seen that the Cr-Pt thin film has the <001> crystal axis oriented perpendicular to the film surface. The intensity of the Co—Cr—Pt (002) diffraction line of Co—Zr—Nb / Co—Cr—Pt was measured using the Co—Cr—Pt monolayer film and the Fe—Cr / Co—Cr—Pt shown in FIG. Compared to the Co-Cr-Pt single layer film, it is about 1/3 smaller than that for Fe-Cr / Co-Cr-Pt, but about twice as large. These indicate that the orientation degree of <001> in Co—Zr—Nb / Co—Cr—Pt is lower than that of a single layer film and higher than that of Fe—Cr / Co—Cr—Pt. Yes. Since Co—Cr—Pt has strong magnetic anisotropy in the <001> direction, the smaller the intensity of the Co—Cr—Pt (002) diffraction line, the greater the in-film magnetization component. By using a Co—Zr—Nb-based amorphous ferromagnetic thin film as a base film, the magnetic properties of the hard magnetic thin film can be improved, although not as much as when using an Fe—Cr-based ferromagnetic thin film.

The material of the antiferromagnetic thin film whose crystal structure is a body-centered cubic lattice is mainly composed of Cr, Mn, and at least one element selected from Cu, Au, Ag, Co, Ni and platinum group elements. Alloys can be used. A preferable composition range in the antiferromagnetic material is 30 ≦ c ≦ 70, 0 ≦ d ≦ 30, where X is (Cr _100-c Mn _c ) _100-d X _d where the additive element is X. The composition has the maximum exchange coupling action. As for the film thickness, anti-ferromagnetism is not exhibited when the film thickness is thinner than 20 nm. Therefore, a film thickness larger than this is necessary. The effect of improving the magnetic properties of the hard magnetic thin film is almost the same as the case of using a ferromagnetic thin film whose crystal structure is a body-centered cubic lattice.

When this antiferromagnetic thin film is used as a base film, it is desirable to perform heat treatment in a DC magnetic field in order to align the magnetization direction of the antiferromagnetic thin film with the length direction of the magnetoresistive effect film. Here, when the magnetoresistive film is an MR head using the giant magnetoresistive effect, an antiferromagnetic layer 31 is provided to fix the direction of magnetization of the magnetic thin film 32 as shown in FIG. In addition, since the magnetization direction of the antiferromagnetic layer 31 and the magnetization direction of the antiferromagnetic thin film that is the base film of the longitudinal bias application layer are different, materials having different blocking temperatures are used, respectively, or under the longitudinal bias application layer. It is necessary to select a composition in which exchange coupling occurs without applying heat treatment as the anti-strength thin film that is the base film.
(Example 7)
FIG. 14 is a diagram showing a schematic structure of an embodiment of a magnetic disk device to which the MR head of the present invention is applied. Here, an embodiment in which the MR head of the present invention is applied to a magnetic disk device as a magnetic recording / reproducing device is shown, but the MR head of the present invention is also applied to a magnetic recording / reproducing device such as a magnetic tape device, for example. Clearly it is possible.

  The schematic structure of this magnetic disk device will be described. As shown in FIG. 9, the magnetic disk device includes a spindle 202, a plurality of magnetic disks 204 a, 204 b, 204 c, 204 d, and 204 e stacked at equal intervals around the spindle 202, and a motor 203 that drives the spindle 202. And. Furthermore, a movable carriage 206, a group of magnetic heads 205a, 205b, 205c, 205d, and 205e held by the carriage 206, a magnet 208 and a voice coil 207 that constitute a voice coil motor 213 that drives the carriage 206, and And a base 201 for supporting the same. In addition, a voice coil motor control circuit 209 that controls the voice coil motor 213 according to a signal sent from a host device 212 such as a magnetic disk control device is provided. Also, the data sent from the host device 212 corresponds to the writing method of the magnetic disk 204a, etc., and a function to convert the data to be passed through the magnetic head, and the data sent from the magnetic disk 204a, etc. are amplified, A write / read circuit 210 having a function of converting into a digital signal is provided, and the write / read circuit 210 is connected to a host device 212 via an interface 211.

Next, the operation when reading data from the magnetic disk 204d in this magnetic disk device will be described. An instruction of data to be read is given from the host device 212 to the voice coil motor control circuit 209 via the interface 211. With the control current from the voice coil motor control circuit 209, the voice coil motor 213 drives the carriage 206, and the magnetic heads 205a, 205b, 205c, The groups 205d and 205e are moved at high speed and accurately positioned.
This positioning is performed by the servo information read together with the data on the magnetic disk 204d read by the magnetic head 205d and a signal related to the position provided to the voice coil motor control circuit 209. The motor 203 supported by the base 201 rotates a plurality of magnetic disks 204a, 204b, 204c, 204d, and 204e attached to the spindle 202. Next, the designated predetermined magnetic disk 204d is selected in accordance with the signal from the write / read circuit 210, the head position of the designated area is detected, and then the data signal of the magnetic head 205d is read. This reading is performed when the magnetic head 205d connected to the write / read circuit 210 exchanges signals with the magnetic disk 204d. The read data is converted into a predetermined signal and sent to the host device 212.

Here, the operation when reading data from the magnetic disk 204d has been described, but the same applies to other magnetic disks. FIG. 14 shows a magnetic disk device including five magnetic disks, but the number is not necessarily five.
(Example 8)
Even in a magnetoresistive head having a magnetoresistive laminated film composed of an antiferromagnetic layer / magnetic thin film / nonmagnetic conductive thin film / magnetic thin film, both sides of the magnetoresistive laminated film are cut off as shown in FIG. A structure in which the bias application layer 24 and the electrode film 17 are disposed can be employed. Also in this case, by using the magnetic underlayer 252 for the longitudinal bias application layer, the magnetization of the magnetic thin film 32 on the substrate side can be stabilized and Barkhausen noise can be suppressed.

In the above embodiment, the magnetoresistive head is shown in which the antiferromagnetic layer 31 / magnetic thin film 32 / nonmagnetic conductive thin film 33 / magnetic thin film 34 and electrode film 17 are arranged in this order from the substrate side. It is not necessary to arrange. However, when the magnetic thin film 34 / nonmagnetic conductive thin film 33 / magnetic thin film 32 / antiferromagnetic layer 31 are used, the antiferromagnetic layer 31 is preferably a conductive antiferromagnetic film.
Example 9
FIG. 18 shows the structure of the magnetoresistive head of this embodiment. First, a soft magnetic thin film 13, a nonmagnetic conductive thin film 14, and a magnetoresistive effect film 15 were sequentially formed. As the magnetoresistive effect film 15, 80 at.% NiFe was used. Thereafter, a stencil-like photoresist was formed on the central active region. Subsequently, the soft magnetic thin film 13, the nonmagnetic conductive thin film 14, and the magnetoresistive film 15 in the region not masked by the resist material were removed by ion milling. At this time, the substrate 45 was rotated while maintaining an appropriate angle with respect to the ion beam, thereby forming a taper 45 having a widening end. Next, a longitudinal bias application layer 24 and an electrode film 17 comprising a hard magnetic thin film 26 forming an end passive region and a base film 252 showing ferromagnetism of a body-centered cubic lattice were attached. The Co _0.82 Cr _0.09 Pt _0.09 film or Co _0.80 Cr _0.08 Pt _0.09 (ZrO ₂ ) _0.03 film was used as the hard magnetic thin film 26, and the Fe—Cr alloy of Example 2 was used as the base film 252 exhibiting ferromagnetism. The hard magnetic thin film 26 and the underlayer 252 exhibiting ferromagnetism were formed by RF sputtering, and the ZrO ₂ concentration in the CoCrPt film was adjusted by disposing a ZrO ₂ chip on the target. The film thickness of the hard magnetic film 26 is chosen bias field Co _0.82 Cr _0.09 Pt _0.09 membrane and Co _0.80 Cr ₀ to give the central active region. ₀₈ Pt _0.09 (ZrO _2), respectively 50nm to be the same at _0.03 membrane, the 52nm . The permanent magnet film and the electrode film adhered on the stencil were removed together with the stencil by lift-off. The soft magnetic thin film 13 applies a lateral bias magnetic field 44 to the magnetoresistive effect film 15, and the longitudinal bias application layer 24 applies a longitudinal bias magnetic field 46 to the magnetoresistive effect film 15. The longitudinal bias application layer is formed thinner than the total thickness of the soft magnetic thin film 13, the nonmagnetic conductive thin film 14 and the magnetoresistive effect film 15 after the magnetoresistive effect film 15 is formed in a predetermined shape. The taper is formed so as not to remain in the portion and to remain at the end of the magnetoresistive film 15. Further, the electrode film 8 is then formed, and a taper is formed at the contact portion with the magnetoresistive film 15. 121 is an alumina lower gap layer having a thickness of 0.4 μm, 111 is a lower shield layer made of a NiFe alloy of about 2 μm, and 20 is an alumina insulating film formed on the surface of the substrate 12 to a thickness of 10 μm and polished. This is for smoothing the surface of the nonmagnetic substrate 10. The nonmagnetic substrate 10 is a TiC-containing alumina sintered body. The nonmagnetic conductive thin film 14 is a 200 mm Ta film. The magnetoresistive effect film 15 is made of an 80 at.% Ni—Fe alloy having a thickness of 400 mm.

As a result of measuring the electro-magnetic conversion characteristics of these heads, Co _0.80 Cr _0.08 Pt _0.09 (ZrO ₂ ) _0.03 was compared with the head using the Co _0.82 Cr _0.09 Pt _0.09 film that had an output fluctuation of 20% and a waveform fluctuation of 10%. In the head using the film, the output fluctuation could be reduced within 5% and the waveform fluctuation within 5%. Therefore, it was confirmed that the effect of suppressing BHN and waveform fluctuation is enhanced by using the Co _0.80 Cr _0.08 Pt _0.09 (ZrO ₂ ) _0.03 film for the hard magnetic thin film 26.

  The central active region has an MR film, a soft magnetic thin film 13 that is a soft bias film for applying a lateral bias, and a nonmagnetic conductive thin film 14 that separates the two magnetic films. The end passive region is composed of a longitudinal bias applying layer 24 that applies a longitudinal bias to the central active region. The end junction region has two tapers in the central active region.

The hard magnetic film 7 applies a longitudinal bias to the central active region by a leakage magnetic field from the permanent magnet film and a coupling magnetic field in a junction region between the permanent magnet film and the central active region. The permanent magnet film needs to apply a magnetic field to the central active region stably with respect to the magnetic field from the magnetic medium in order to suppress BHN. For this purpose, a coercive force of the permanent magnet film is required to be 1000 Oe or more.
(Example 10)
FIG. 19 is a perspective view of the magnetoresistive head of this embodiment.

  The present embodiment has the same structure as that of the ninth embodiment, but differs in the laminated structure of the magnetoresistive head film. On the lower gap layer 121 made of alumina, an antiferromagnetic layer 31 made of NiO having a thickness of 50 nm, an 80 at.% Ni—Fe alloy film 54 having a thickness of 1 nm and a Co film having a thickness of 1 nm as the magnetic thin film 32. 45, a nonmagnetic conductive thin film 56 and a soft magnetic thin film 13 for applying a lateral bias made of a NiFe alloy having a thickness of 5 nm are formed from Cu having a thickness of 2 nm.

Further, as the antiferromagnetic film, an oxide NiO that does not corrode in the manufacturing process as compared with the conventional material FeMn was used, thereby achieving high reliability in the mass production process. The output of the head is determined by the product of the current flowing through the head and the resistance change amount of the spin valve film, and the antiferromagnetic film itself does not contribute to the resistance change. Therefore, by using NiO, which is an insulating material, as the antiferromagnetic film, the input current can efficiently contribute to the resistance change, and high magnetic field sensitivity can be obtained. As described above, in this embodiment, a recording density of about 5 Gb / in ² can be realized.

Further, a high reproduction output can be obtained by forming a film in which an oxide is dispersed in a NiFe alloy in the same manner as in the ninth embodiment on the soft magnetic thin film 13 in the present embodiment.
(Example 11)
FIG. 20 is a perspective view of the magnetoresistive head of this embodiment.

  The bias films 27 and 28 made of an antiferromagnetic material apply anisotropy to the magnetic film 21 by exchange coupling. The longitudinal bias application layer has the same configuration as that of the fourth embodiment. The easy magnetization direction of the magnetic film 22 sandwiched between the nonmagnetic conductive films 14 is applied by induction of uniaxial anisotropy. This is achieved by applying a magnetic field in a predetermined direction during the growth of the magnetic film. The embodiment in this figure is an example in which the application of anisotropy is realized by exchange coupling and induced magnetic anisotropy, and they are orthogonal to each other in the film plane. By increasing the anisotropy of the magnetic film 21 and decreasing the anisotropy of the magnetic film 22 compared to the magnitude of the magnetic field to be sensed, the magnetization of the magnetic film 21 is substantially fixed with respect to the external magnetic field, Only the magnetization of the magnetic film 22 reacts greatly to the external magnetic field. Further, with respect to the magnetic field to be sensed in the direction of the arrow 60, the magnetization of the magnetic film 21 changes to an easy axis excitation state in which the magnetization and the external magnetic field are parallel due to the anisotropy 61, and conversely to the anisotropy of the magnetic film 22. Therefore, it is in the state of difficult axis excitation in which the magnetization and the external magnetic field are perpendicular. This effect makes the above response even more remarkable, and realizes a state in which the element is driven by hard axis excitation by rotation with respect to the external magnetic field, and noise accompanying excitation by domain wall motion. And can be operated at high frequency.

  The film constituting the magnetoresistive effect element of this example was produced by a high frequency magnetron sputtering apparatus. At the time of film formation, a magnetic field of approximately 50 oersted is applied in parallel to the substrate using two pairs of electromagnets orthogonal to each other in the substrate surface to provide uniaxial anisotropy and to change the direction of the exchange coupling bias of the nickel oxide film. Induced in the direction of

  The induction of anisotropy was performed by applying a magnetic field in the direction to be induced when each magnetic film was formed by two pairs of electromagnets attached in the vicinity of the substrate. Alternatively, heat treatment in a magnetic field was performed near the Neel temperature of the antiferromagnetic film after the multilayer film was formed, and the direction of the antiferromagnetic bias was induced in the direction of the magnetic field.

  The performance of the magnetoresistive effect element was evaluated by patterning the film into a strip shape and forming an electrode. At this time, the direction of uniaxial anisotropy of the magnetic film and the current direction of the element were made parallel. The electrical resistance is measured as the rate of change in magnetoresistance by passing a constant current between the electrode terminals, applying a magnetic field in the direction perpendicular to the current direction in the plane of the element, and measuring the electrical resistance of the element as the voltage between the electrode terminals. did.

It is the figure showing the resistance change rate with respect to the magnetic field of the element of the structure which has a NiO film | membrane upper and lower expressed with sample No. 1 of Table 1. FIG. This corresponds to the use of NiO films for the bias films 27 and 28, Ni ₈₀ Fe ₂₀ alloy thin films for the magnetic films 21 and 22, and Cu films for the nonmagnetic conductive films. That is, the effect of the magnetic film strongly induced in the direction of the magnetic field is detected as a loop on the left half of the curve. The other effect of the magnetic film that is not strongly induced appears as a steep resistance change near the center. Since the reproduction output of the magnetoresistive effect element according to the present invention corresponds to the resistance change rate and the sensitivity corresponds to the small saturation magnetic field, it can be seen that the element output of the present invention is large and the sensitivity is high. .

  Similar effects were also obtained in the case where Ag and Au were added to Cu as the nonmagnetic conductive film and in the case where a multilayer film was formed with Ag and Au.

  In the NiO / NiFe / Cu / NiFe film in which the thickness of the Cu film is changed, the strength of the magnetic coupling oscillates between the antiferromagnetism and the ferromagnetism with a period of about 10Å along with the thickness of Cu. In order to obtain a magnetoresistive element having high sensitivity to a magnetic field, it is essential to make this magnetic coupling approximately zero. When Cu is used as the nonmagnetic conductive film, the magnetic coupling between the magnetic films can be made zero by setting the thickness in the range of 11 to 22 mm. In this way, for the first time, it is possible to obtain a magnetoresistive effect element having a large sensitivity, that is, a highly sensitive magnetoresistive element in response to a weak external magnetic field of several Oersteds.

  When Co is added to the NiFe magnetic film, the rate of change in resistance is improved from about 4% to 5.5% of NiFe alone. This indicates that the addition of Co in addition to NiFe improves the magnetoresistance effect of the laminated film.

  Table 1 shows an example of characteristics of magnetoresistive elements produced by changing the configuration of the magnetoresistive film. The film structure is such that the left side of the paper is sequentially laminated on the base side on the right side.

In Table 1, the characteristics of the element are represented by the resistance change rate and the saturation magnetic field. The reproduction output as an element corresponds to the magnitude of the resistance change rate, and the sensitivity corresponds to the magnitude of the saturation magnetic field. As is apparent from the results in Table 1, the magnetoresistive elements (No. 1 to 5) of the present invention have a resistance change rate of 4% or more and good magnetic characteristics, and the conventional laminated film (No. 6, Compared to 7), the resistance change rate is excellent. In particular, Sample Nos. 1, 2, and 4 show a good magnetic field sensitivity of about 10 oersted saturation field and a high output of 6 to 7% resistance change rate.
(Example 12)
FIG. 21 is a conceptual view of a recording / reproducing separated type head in which a recording head is formed in addition to the magnetoresistive effect type magnetic head element described in the first to eleventh embodiments. The recording / reproducing separation type head includes a reproducing head using the element of the present invention, an inductive recording head, and a shield portion for preventing the reproducing head from being confused by a leakage magnetic field. Although mounting with a recording head for horizontal magnetic recording is shown here, the magnetoresistive element of the present invention may be combined with a head for vertical magnetic recording and used for vertical recording. The head is formed with a reproducing head composed of the lower shield layer 111, the magnetoresistive element 60 and the electrode 40, and the upper shield layer 112 on the substrate 50, and a recording head composed of the lower magnetic film 84, the coil 41, and the upper magnetic film 83. Do it. The head writes a signal on the recording medium and reads the signal from the recording medium. By forming the sensing portion of the reproducing head and the magnetic gap of the recording head in such a manner that they overlap each other on the same slider, positioning can be performed simultaneously on the same track. This head was processed into a slider and mounted on a magnetic recording / reproducing apparatus.

The magnetoresistive effect element 60 and the electrode 40 are formed on the substrate 50 that also serves as the head slider 90, and these are positioned on the recording medium 91 for reproduction. The recording medium 91 rotates, and the head slider 90 moves relative to the recording medium 91 in opposition with a height of 0.2 μm or less or in contact. By this mechanism, the magnetoresistive element 60 is set at a position where the magnetic signal recorded on the recording medium 91 can be read from the leakage magnetic field. The magnetoresistive effect element 60 is composed of a film in which a plurality of magnetic films and nonmagnetic conductive films are alternately stacked, and a bias film, particularly an antiferromagnetic film. The present invention is characterized by strong anisotropy in the direction of the arrow 61 perpendicular to the surface 63 facing the recording medium, in a part of the laminated film, desirably every other of the laminated magnetic films. Is to fix the magnetization approximately in this direction. Further, the other magnetic film applies a relatively weak anisotropy in the direction perpendicular to the arrow 61 in the film surface of the magnetoresistive effect film, that is, in the direction of the arrow 62, and induces its magnetization in this direction. . With such a configuration, a signal magnetically recorded on the recording medium reaches the magnetoresistive effect element 60 as a leakage magnetic field 64 on the medium, and an arrow according to its component, particularly a component in the film surface of the magnetoresistive effect film. Magnetization rotates from the direction of 62 as indicated by an arrow 65, and the angle formed by the magnetization directions of the two adjacent magnetic films via the nonmagnetic conductive film changes to produce a magnetoresistive effect. obtain. The part of the magnetoresistive effect element that senses the signal is the part of the magnetoresistive effect element 60 through which the current flows, that is, the part sandwiched between the electrodes 40. The width 42 in the direction parallel to the surface of the recording medium 91 is recorded. It is narrower than the track width 44, and in particular, the ratio thereof is 0.8 or less to prevent cross-talk between adjacent tracks due to displacement of each other.
(Example 13)
FIG. 21 shows another embodiment in which the configuration of the recording head and the reproducing head is reversed in the magnetic recording / reproducing apparatus of the twelfth embodiment. A recording head composed of lower and upper magnetic films 83 and 84 and a coil 41 for applying magnetomotive force to these and a lower shield layer 111 are formed on the substrate 50, and then the magnetoresistive effect element 60, the electrode 40, and the upper shield layer are formed. 112. In other words, a magnetoresistive film that is relatively sensitive to the structure is formed on the recording head later to eliminate the stress and thermal effects associated with the recording head fabrication, and to facilitate alignment with the recording head, thereby reproducing the magnetic recording This will improve the system in the track width direction of the equipment and improve productivity.

FIG. 3 is a partial cross-sectional view of the magnetoresistive head of the present invention. The figure which compares the magnetic characteristic of the hard magnetic thin film which used the single layer hard magnetic thin film and the ferromagnetic thin film which has the body centered cubic structure of this invention for the base film. The figure which compares the X-ray profile of the hard magnetic thin film which used the single layer hard magnetic thin film and the ferromagnetic thin film which has the body centered cubic structure of this invention for the base film. FIG. 4 is a cross-sectional view of the vicinity of a magnetic sensing portion of an embodiment of an MR head using the anisotropic magnetoresistance effect of the present invention. The figure which shows the sensitivity distribution of the track direction of MR head which used the ferromagnetic thin film which has a body centered cubic structure of this invention for the base film. The figure which shows the magnetization model of this invention. The figure which shows the distribution of the sensitivity of the track direction of the conventional MR head using Cr foundation | substrate. The figure which shows the conventional magnetization model using Cr base | substrate. Sectional drawing of the magnetosensitive part vicinity of other embodiment of MR head using the anisotropic magnetoresistive effect of this invention. The figure which shows the film | membrane structure of a magnetoresistive effect laminated film. FIG. 3 is a cross-sectional view of the vicinity of an MR head magnetic sensing portion using the anisotropic magnetoresistance effect of the present invention. Sectional drawing of the magnetosensitive part vicinity of other embodiment of MR head using the magnetoresistive effect laminated film of this invention. The figure which compares the X-ray profile of the hard-magnetic thin film of a single layer, and the hard-magnetic thin film which used the amorphous ferromagnetic thin film of this invention for the base film. 1 is a diagram showing a magnetic disk device of an embodiment using an MR head of the present invention. The figure which shows the film | membrane structure of MR head of a prior art. The figure which shows the film | membrane structure of another another prior art MR head. FIG. 3 is a cross-sectional view of the vicinity of a magnetic sensing portion of an embodiment of an MR head using the magnetoresistive effect laminated film of the present invention. The perspective view of the magnetic sensing part of the magnetoresistive effect type magnetic head of this invention. The perspective view of the magnetic sensing part of the magnetoresistive effect type magnetic head of this invention. The perspective view of the magnetic sensing part of the magnetoresistive effect type magnetic head of this invention. 1 is a perspective view of a thin film magnetic head having a reproducing magnetoresistive magnetic head and a recording induction magnetic head of the present invention. FIG. 1 is a perspective view of a thin film magnetic head having a reproducing magnetoresistive magnetic head and a recording induction magnetic head of the present invention. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Nonmagnetic board | substrate, 13 ... Soft magnetic thin film, 14, 33, 56 ... Nonmagnetic conductive thin film, 15 ... Magnetoresistance effect film, 17 ... Electrode film, 18, 20 ... Insulating film, 24 ... Longitudinal bias application layer, 26 ... Hard magnetic thin film, 31 ... Antiferromagnetic layer, 32, 34 ... Magnetic thin film, 35 ... Protective film, 36 ... Track width direction, 45 ... Co film, 51 ... Magnetization of soft magnetic thin film, 52 ... Magnetoresistive film 53 ... Magnetization of hard magnetic thin film, 54 ... 80 at.% Ni-Fe alloy film, 60 ... Magnetoresistive element, 83 ... Upper magnetic film, 84 ... Lower magnetic film, 111 ... Lower shield layer, 112 ... Upper part Shield layer, 121 ... lower gap layer, 122 ... upper gap layer, 201 ... base, 202 ... spindle, 203 ... motor, 204a, 204b, 204c, 204d, 204e ... magnetic disk, 205a, 205b, 20 5c, 205d, 205e ... magnetic head, 206 ... carriage, 207 ... voice coil, 208 ... magnet, 209 ... voice coil motor control circuit, 210 ... write / read circuit, 211 ... interface, 212 ... host device, 213 ... voice coil Motor, 251... Nonmagnetic underlayer, 252.

Claims (28)

  A magnetoresistive film that converts a magnetic signal into an electrical signal using the magnetoresistive effect, a pair of electrodes that cause a signal detection current to flow through the magnetoresistive film, and a longitudinal bias magnetic field that is applied to the magnetoresistive film In a magnetoresistive effect type magnetic head having a longitudinal bias application layer, the longitudinal bias application layer comprises: a base film made of a ferromagnetic thin film; and a hard magnetic thin film formed on the base film made of the ferromagnetic thin film. A magnetoresistive head having a magnetoresistance effect.   2. The magnetoresistive head according to claim 1, wherein the base film made of the ferromagnetic thin film is a ferromagnetic thin film having a crystal structure of a body-centered cubic lattice.   2. A magnetoresistive head according to claim 1, wherein the base film made of the ferromagnetic thin film is an amorphous ferromagnetic thin film.   A magnetoresistive film that converts a magnetic signal into an electrical signal using the magnetoresistive effect, a pair of electrodes that cause a signal detection current to flow through the magnetoresistive film, and a longitudinal bias magnetic field that is applied to the magnetoresistive film In the magnetoresistive effect type magnetic head having a longitudinal bias application layer, the longitudinal bias application layer is formed on an underlayer made of an antiferromagnetic thin film and a hard magnetic thin film formed on the underlayer made of the antiferromagnetic thin film And a magnetoresistive effect type magnetic head.   5. The magnetoresistive head according to claim 4, wherein the base film made of the antiferromagnetic thin film is an antiferromagnetic thin film having a crystal structure of a body-centered cubic lattice.   6. The magnetism according to claim 1, wherein the magnetoresistive film is made of a ferromagnetic layer exhibiting an anisotropic magnetoresistive effect, and includes means for applying a lateral bias magnetic field to the magnetoresistive film. Resistance effect type magnetic head.   7. The magnetoresistive effect type magnetic head according to claim 6, wherein the transverse bias magnetic field is applied by a soft magnetic thin film provided adjacent to the magnetoresistive effect film via a nonmagnetic conductive thin film.   The magnetoresistive film is formed by laminating a first magnetic thin film and a second magnetic thin film with a nonmagnetic conductive thin film as an intermediate layer, and the magnetization direction of the first magnetic thin film is provided adjacently. The magnetization direction of the second magnetic thin film is fixed by the ferromagnetic layer, and the magnetization direction of the first magnetic thin film is substantially perpendicular to the magnetization direction of the first magnetic thin film without applying an external magnetic field. 6. A magnetoresistive effect magnetic head according to claim 1, wherein the magnetoresistive effect is a magnetoresistive effect laminated film in which the electric resistance varies depending on the relative angle between the direction of the magnetic field and the direction of magnetization of the second magnetic thin film. The hard magnetic thin film is an alloy whose main component is Co and M ₁ (M ₁ is at least one element selected from the group consisting of Cr, Ta, Ni, Pt and Re), or an alloy composed of Co and M ₁ 9. An oxide-added alloy to which M ₂ (M ₂ is at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, aluminum oxide and tantalum oxide) is added. The magnetoresistive effect type magnetic head described.   The ferromagnetic thin film whose crystal structure is a body-centered cubic lattice is an Fe, Fe-Ni alloy, an Fe-Co alloy, or an Fe-Ni-Co alloy. The magnetoresistive effect type magnetic head according to any one of the above. The ferromagnetic thin film whose crystal structure is a body-centered cubic lattice is Fe, Fe-Ni alloy, Fe-Co alloy, or Fe-Ni-Co alloy, and M ₃ (M ₃ is Si, V, Cr, 10. The magnetoresistive head according to claim 2, wherein the magnetoresistive head is an alloy to which at least one element selected from the group of Nb, Mo, Ta and W is added.   12. The magnetoresistive head according to claim 11, wherein the ferromagnetic thin film whose crystal structure is a body-centered cubic lattice is an alloy mainly composed of Fe and Cr.   The magnetoresistive head according to claim 12, wherein the alloy mainly composed of Fe and Cr is Cr 5 to 45 atomic%. The base film made of the antiferromagnetic thin film is mainly composed of Cr, Mn, and M ₄ (M ₄ is at least one element selected from the group consisting of Cu, Au, Ag, Co, Ni, and platinum group elements). The magnetoresistive head according to any one of claims 4 to 9, wherein the magnetoresistive head is an alloy.   A magnetoresistive film that converts a magnetic signal into an electrical signal using the magnetoresistive effect, a pair of electrodes that cause a signal detection current to flow through the magnetoresistive film, and a longitudinal bias magnetic field that is applied to the magnetoresistive film A magnetoresistive head having a longitudinal bias application layer, wherein the longitudinal bias application layer is a laminated film having an amorphous ferromagnetic thin film and a hard magnetic thin film. . The amorphous ferromagnetic thin film is made of Co and M ₅ (M ₅ is a group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, Y, Ru, Rh, Pd, Cu, Ag, Au, and Pt. 16. The magnetoresistive head according to claim 15, wherein the magnetoresistive head is an amorphous alloy mainly composed of at least one selected element. A magnetoresistive film whose electrical resistance changes with a magnetic field, a lateral bias film made of a soft magnetic film that applies a lateral bias magnetic field to the magnetoresistive film, and the lateral bias film and the magnetoresistive film are magnetically separated. A separation film made of a non-magnetic film; a longitudinal bias application layer that applies a longitudinal bias magnetic field to the magnetoresistive film provided in contact with both ends of the magnetoresistive film, the lateral bias film, and the separation film; In a magnetoresistive effect type magnetic head having a pair of electrodes for passing a current through a resistance effect film, the longitudinal bias application layer is formed of a ferromagnetic thin film, an antiferromagnetic thin film, or an amorphous ferromagnetic thin film. A base film and a hard magnetic thin film formed on the base film,
The soft magnetic film for applying a lateral bias magnetic field to the magnetoresistive effect film is one of nickel-iron alloy, cobalt, nickel-iron-cobalt alloy, zirconium oxide, aluminum oxide, hafnium oxide, titanium oxide, and beryllium oxide. , Magnesium oxide, tantalum oxide, rare earth oxygen compound, zirconium nitride, hafnium nitride, aluminum nitride, titanium nitride, beryllium nitride, magnesium nitride, silicon nitride, and one or more compounds selected from rare earth nitrogen compounds A magnetoresistive effect type magnetic head.   18. The magnetoresistive head according to claim 17, wherein a specific resistance of the soft magnetic film for applying a lateral bias magnetic field to the magnetoresistive film is 70 μΩcm or more.   19. The magnetoresistive head according to claim 18, wherein the lateral bias film is made of a nickel-iron alloy having 78 to 84 atomic% of nickel.   A magnetoresistive effect type magnetic head having a pair of longitudinal bias application layers provided on a substrate, a pair of electrodes, and a magnetoresistive effect element film provided in contact with the longitudinal bias application layer. An antiferromagnetic film made of nickel oxide, two layers of a ferromagnetic film, a nonmagnetic metal film, and a soft magnetic film are sequentially formed from the substrate side, and the longitudinal bias application layer is formed of a ferromagnetic thin film and an antiferromagnetic thin film. And a hard magnetic thin film formed on the base film, and a magnetoresistive effect type magnetic head.   21. The two-layered ferromagnetic film according to claim 20, wherein the iron alloy layer and Co layer or Co alloy layer containing Ni 70 to 95 atomic% from the substrate side, and the soft magnetic film from the iron alloy layer or the substrate side. A magnetoresistive head comprising a Co layer or Co alloy layer and the iron alloy layer.   23. The magnetoresistive head according to claim 20, wherein the two ferromagnetic films are composed of a soft magnetic film from the antiferromagnetic film side and a magnetic film having a spin-dependent scattering larger than that of the soft magnetic film.   A magnetoresistive effect type magnetic head having a pair of longitudinal bias application layers provided on a substrate, a pair of electrodes, and a magnetoresistive effect element film provided in contact with the longitudinal bias application layer. Is an antiferromagnetic film, a ferromagnetic film, a nonmagnetic film, a soft magnetic film, a nonmagnetic film, a ferromagnetic film, and an antiferromagnetic film sequentially stacked from the substrate side, and the longitudinal bias application layer is a ferromagnetic thin film. A magnetoresistive head having a base film made of any one of an antiferromagnetic thin film and an amorphous ferromagnetic thin film, and a hard magnetic thin film formed on the base film.   The antiferromagnetic film is nickel oxide, the substrate-side ferromagnetic film includes an iron alloy layer and a Co layer containing 70 to 95 atomic% of Ni, the soft magnetic film is the iron alloy layer, and the latter ferromagnetic film is 24. The magnetoresistive head according to claim 23, comprising a Co layer and the iron alloy layer from the substrate side.   The ferromagnetic film is an alloy of 70 to 95 atomic percent of Ni, 5 to 30 atomic percent of Fe and 1 to 5 atomic percent of Co, or an alloy of 30 to 85 atomic percent of Co, 2 to 30 atomic percent of Ni and 2 to 50 atomic percent of Fe. Item 25. The magnetoresistive head of item 24.   25. The magnetoresistive head according to claim 24, wherein the nonmagnetic film is one of Au, Ag, and Cu.   A magnetoresistive element having a longitudinal bias application layer having a magnetic recording medium for recording information, a base film made of a ferromagnetic thin film, and a hard magnetic thin film formed on the base film made of the ferromagnetic thin film A magnetic head for reading or writing the information, actuator means for moving the magnetic head to a predetermined position on the magnetic recording medium, transmission / reception of the information by reading or writing of the magnetic head, and movement of the actuator means And a control means for controlling the magnetic recording / reproducing apparatus. A magnetoresistive element having a longitudinal bias application layer having a magnetic recording medium for recording information, a base film made of an antiferromagnetic thin film, and a hard magnetic thin film formed on the base film made of the antiferromagnetic thin film A magnetic head for reading or writing the information, actuator means for moving the magnetic head to a predetermined position on the magnetic recording medium, transmission / reception of the information by reading or writing the magnetic head, and the actuator means And a control means for controlling the movement of the magnetic recording / reproducing apparatus.

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