JP2006128453A - Magnetoresistance effect element, thin film magnetic head having the magnetoresistance effect element, head gimbal assembly having the thin film magnetic head, and magnetic disc device having the head gimbals assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an MR (magnetoresistance) effect element which shows low noise, fine detection operation by enabling an MR change rate matching a magnetic material present across interface with a nonmagnetic intermediate layer, while suppressing the magnetic distortion of a magnetizatin free layer so as not to prevent its turning into a single magnetic domain, and a thin film magnetic head using the MR effect element. <P>SOLUTION: The MR effect element has an MR lamination comprising a magnetization fixed layer whose direction of magnetization is fixed, the nonmagnetic intermediate layer overlaid on the magnetization fixed layer, and the magnetizatin free layer which is overlaid on the nonmagnetic intermediate layer and whose direction of magnetization changes in response to an applied magnetic field. The magnetizatin free layer is formed with a magnetic distortion adjusting film containing CoFe on the side opposite to the side where magnetizatin free layer is in contact with the nonmagnetic intermediate layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetoresistive (MR) effect element that detects a signal magnetic field and shows a resistance change according to the magnetic field strength, a thin film magnetic head including the MR effect element, and a head gimbal assembly (HGA) including the thin film magnetic head. And a magnetic disk drive equipped with the HGA.

  As the capacity of a hard disk drive (HDD) is reduced, a thin film magnetic head with high sensitivity and high output is required. In order to meet this demand, characteristics of a GMR head having a read head element utilizing a giant magnetoresistance (GMR) effect are being improved. On the other hand, the tunnel magnetoresistance (TMR) effect, which can be expected to have a resistance change rate more than twice the GMR effect, is attracting attention in order to cope with higher recording density. At present, development of a TMR head having a read head element using the TMR effect has been actively carried out.

In the TMR effect element for reading, a nonmagnetic intermediate layer acting as a tunnel barrier is sandwiched between a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction is variable according to an applied magnetic field. Has a structure. In this TMR element, an attempt is made to provide a high polarizability film made of a ferromagnetic material having a high polarizability on the side of the magnetization free layer in contact with the nonmagnetic intermediate layer in order to further increase the MR ratio. For example, Patent Document 1 discloses a configuration in which a ferromagnetic layer which is a magnetization free layer includes a thin CoFe high polarizability film on the tunnel barrier layer side.
Japanese Patent No. 3050189

  According to the TMR element including the high polarizability film as described above, the magnetostriction of the magnetization free layer is increased due to the characteristics of the ferromagnetic material constituting the high polarizability film. Therefore, when the layer thickness of the magnetization free layer and the film thickness of the high polarizability film are increased to some extent in order to sufficiently draw out the MR ratio increased by the presence of this high polarizability film, the internal stress and adjacent The inverse magnetostrictive effect due to external stress from the layer becomes more prominent. Due to this inverse magnetostriction effect, the magnetic anisotropy in the magnetization free layer is generally dispersed, and the magnetization free layer is prevented from becoming a single domain. As a result, inconveniences such as output noise occurring during magnetic field detection and defective element detection operations occur. As a countermeasure against this, it is also considered to use a laminated structure of such a high polarizability film and a low magnetostrictive permalloy (NiFe) film, etc., but this structure also has a sufficiently small magnetostriction enough to withstand practical use. It has become very difficult to get.

  Therefore, the object of the present invention is to reduce the magnetostriction of the magnetization free layer by preventing the magnetostriction of the magnetization free layer while preventing an MR change corresponding to the magnetic material existing at the interface with the nonmagnetic intermediate layer. An object of the present invention is to provide an MR effect element that exhibits a good detection operation with noise, a thin film magnetic head including the MR effect element, an HGA including the thin film magnetic head, and a magnetic disk device including the HGA.

  Before describing the present invention, terms used in the specification will be defined. In the element or layer structure formed on the element formation surface of the slider substrate of the thin film magnetic head, the element located on the element formation surface side with respect to the reference is defined as “lower” or “lower”. The one on the opposite side is “upper” or “upper”. Therefore, for example, the “nonmagnetic conductive layer laminated on the magnetization free layer” is a layer laminated on the layer surface opposite to the element formation surface of the magnetization free layer.

  According to the present invention, the magnetization fixed layer whose magnetization direction is fixed, the nonmagnetic intermediate layer laminated on the magnetization fixed layer, and the magnetic field laminated on the nonmagnetic intermediate layer and applied thereto MR effect including a magnetostriction adjusting film including CoFe on the side opposite to the side in contact with the nonmagnetic intermediate layer. An element is provided.

  In an MR stack composed of a magnetization fixed layer, a nonmagnetic intermediate layer, and a magnetization free layer, the MR change rate corresponding to the polarizability of the magnetic material existing at the interface with the nonmagnetic intermediate layer in the magnetization free layer is Realized. However, the magnetostriction of the magnetization free layer increases due to the characteristics of the ferromagnetic material constituting the high polarizability film, and the inverse magnetostriction effect prevents the magnetization free layer from becoming a single domain, causing output noise and detection failure. End up. On the other hand, in the present invention, the magnetization free layer has a magnetostriction adjusting film containing CoFe on the side opposite to the side in contact with the nonmagnetic intermediate layer. An MR effect element exhibiting a good detection operation with low noise can be realized by suppressing the magnetostriction of the magnetization free layer and preventing the single magnetic domain while maintaining the MR change rate suitable for the material.

The CoFe composition of the magnetostriction adjusting film is preferably Co _1−X Fe _X (0.43 ≦ X ≦ 1). When a CoFe magnetostriction adjusting film having such a composition is used, the effect of reducing the saturation magnetostriction constant λ _S of the magnetization free layer becomes more remarkable, and the single domain state of the magnetization free layer can be further stabilized. . Further, when X is 0.454 or more, this magnetostriction reducing effect reaches a high level and becomes stable. Therefore, it is more preferable that X is 0.454 or more.

The magnetization free layer preferably includes a high polarizability film on the side in contact with the nonmagnetic intermediate layer. Further, the high polarizability film is preferably a CoFe film. According to the present invention, since the magnetization free layer includes the magnetostriction adjusting film, even if a high polarizability film such as CoFe is disposed on the side in contact with the nonmagnetic intermediate layer for the purpose of improving the MR ratio, this high polarization An increase in the saturation magnetostriction constant λ _S due to the rate film can be suppressed. Therefore, an MR effect element that exhibits a good detection operation with low noise can be obtained by suppressing the magnetostriction of the magnetization free layer and preventing the formation of a single magnetic domain while improving the MR ratio.

Further, the film thickness of the high polarizability film may be 1 nm or less. Even if the film thickness of the high polarizability film is 1 nm or less, the TMR effect through the interface with the nonmagnetic intermediate layer is sufficiently maintained, and the magnetostriction reducing effect by the magnetostriction adjusting film is suppressed by suppressing the increment of the saturation magnetostriction constant λ _S. Can be made more effective.

Furthermore, it is preferable that the thickness of the magnetostriction adjusting film is equal to or greater than the thickness of the high polarizability film. By making the film thickness of the magnetostriction adjustment film equal to or greater than the film thickness of the high polarizability film, the magnetostriction reduction effect by the magnetostriction adjustment film is made more effective by suppressing at least the increment of the saturation magnetostriction constant λ _S by the high polarizability film, When the magnetostriction adjusting film made of CoFe or the like has a sufficient film thickness, the MR change rate can be improved to an original value that can be achieved by the constituent material of each film.

  The nonmagnetic intermediate layer is preferably an Al oxide film.

  Furthermore, one or two of Ta, Hf, Nb, Zr, Ti, Mo, W, Ru, Rh, Ir, Cr, Re, Cu, Pt, Au, Ag, Al, and Si are formed on the magnetization free layer. It is also preferable that at least two nonmagnetic conductive layers are laminated. By applying an exchange bias magnetic field to the magnetization free layer through the nonmagnetic conductive layer made of these materials, it becomes possible to further promote the single domain of the magnetization free layer.

  It is preferable that a current flows in a direction perpendicular to each layer surface in the magnetoresistive laminate.

  According to the present invention, there is further provided a thin film magnetic head including at least one MR effect element described above.

  According to the present invention, there is further provided an HGA comprising the above-described thin film magnetic head, a signal line to the magnetoresistive effect element of the thin film magnetic head, and a support mechanism for supporting the thin film magnetic head. .

  According to the present invention, there is further provided a magnetic disk device including at least one HGA as described above.

  According to the present invention, the MR ratio corresponding to the magnetic material existing at the interface with the nonmagnetic intermediate layer is realized, and the magnetostriction of the magnetization free layer is suppressed to prevent the single domain, thereby reducing the noise. A good detection operation can be realized.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail, referring an accompanying drawing. In the drawings, the same elements are denoted by the same reference numerals.

  FIG. 1 is a perspective view schematically showing a configuration of a main part in an embodiment of a magnetic disk apparatus according to the present invention, FIG. 2 is a perspective view showing the entire HGA according to the present invention, and FIG. 3 is a front end of the HGA. It is a perspective view of the thin film magnetic head (slider) with which the part was mounted | worn.

  In FIG. 1, reference numeral 10 denotes a plurality of magnetic disks rotating around the rotation axis of a spindle motor 11, 12 denotes an assembly carriage device for positioning a thin film magnetic head (slider) on a track of the magnetic disk 10, and 13 denotes thin film magnetics. A recording / reproducing circuit for controlling the read / write operation of the head is shown.

  The assembly carriage device 12 is provided with a plurality of drive arms 14. These drive arms 14 can be angularly swung about a pivot bearing shaft 16 by a voice coil motor (VCM) 15 and are stacked in a direction along the shaft 16. An HGA 17 is attached to the tip of each drive arm 14. Each HGA 17 is provided with a slider so as to face the surface of each magnetic disk 10. The slider floats with a predetermined gap hydrodynamically on the surface of the rotating magnetic disk 10 during a write or read operation. The magnetic disk 10, the drive arm 14, the HGA 17, and the thin film magnetic head (slider) may be singular.

  As shown in FIG. 2, the HGA is configured by fixing a slider 21 having a magnetic head element to the tip of a suspension 20 and electrically connecting one end of a wiring member 25 to a terminal electrode of the slider 21. The

  The suspension 20 includes a load beam 22, a flexure 23 having elasticity fixedly supported on the load beam 22, a base plate 24 provided at the base of the load beam 22, and a lead conductor provided on the flexure 23. And the wiring member 25 which consists of the connection pad electrically connected to the both ends is comprised mainly.

  It is obvious that the suspension structure in the HGA of the present invention is not limited to the structure described above. Although not shown, a head driving IC chip may be mounted in the middle of the suspension 20.

  As shown in FIG. 3, the thin film magnetic head (slider) in this embodiment includes a write magnetic head element and a read magnetic head element 30 stacked on each other, and four signal terminal electrodes 31 connected to these elements. , On the element formation surface 32. Reference numeral 33 denotes an air bearing surface (ABS) of the slider. In addition, the number and position of these terminal electrodes are not limited to the form of FIG. In FIG. 3, there are four terminal electrodes. However, for example, a configuration in which three electrodes are provided and the ground is grounded to the slider substrate may be employed.

  FIG. 4 is a cross-sectional view schematically showing the layer structure of the MR effect element for reading and the inductive element for writing in one embodiment of the thin film magnetic head according to the present invention. An AA line cross section perpendicular to the ABS is shown.

In FIG. 4, reference numeral 40 denotes a slider substrate forming the main part of the slider, and is made of, for example, Altic (Al ₂ O ₃ —TiC). Reference numeral 41 denotes a lower shield layer having a thickness of about 0.3 μm to about 3 μm formed on one side surface (element forming surface) when the ABS 40a of the slider substrate 40 is used as a bottom surface through a base film (not shown). For example, NiFe, NiFeCo, CoFe, FeN or FeZrN. Reference numeral 42 denotes an upper shield layer made of, for example, NiFe, NiFeCo, CoFe, FeN, or FeZrN having a thickness of about 0.3 μm to about 4 μm. The reproduction gap length, which is the distance between the upper and lower shield layers 42 and 41, is about 0.03 μm to about 1 μm. Reference numeral 44 denotes an MR laminate, which is formed between the lower shield layer 41 and the upper shield layer 42 so as to extend along the ABS 40a. Reference numeral 430 denotes an insulating layer made of Al ₂ O ₃ or the like.

Reference numeral 431 denotes an insulating layer having a thickness of about 0.1 μm to about 2.0 μm made of, for example, Al ₂ O _{3 and the} like laminated on the upper shield layer 42. The bottom pole layer 45 is laminated on the insulating layer 431, and is made of, for example, NiFe, NiFeCo, CoFe, FeN, or FeZrN having a thickness of about 0.3 μm to about 3 μm. It should be noted that the upper shield layer 42 and the lower magnetic pole layer 45 may be integrated to serve as both layers, and in this case, the insulating layer 431 is omitted. 46 is an upper magnetic pole layer having a thickness of about 0.5 μm to about 5 μm made of, for example, NiFe, NiFeCo, CoFe, FeN, or FeZrN, and 47 is a thickness of about 0.1 μm made of an organic resin such as a thermosetting resist. A coil conductive layer 49 made of, for example, Cu or NiFe, surrounded by an insulating layer 48 having a thickness of about 5 μm, 49 has a thickness of about 0.0, for example, made of Al ₂ O ₃ or DLC, etc., laminated on the lower magnetic pole layer 45. A gap layer of 03 μm to about 0.5 μm (corresponding to a recording gap length), 50 indicates an overcoat layer made of, for example, Al ₂ O ₃ .

  The tip portions of the lower magnetic pole layer 45 and the upper magnetic pole layer 46 constitute pole portions 45a and 46a facing each other with a gap layer 49 therebetween, and writing is performed in these pole portions 45a and 46a. Back gap portions are provided on the opposite sides of the lower magnetic pole layer 45 and the upper magnetic pole layer 46 constituting the yoke portion from the pole portions 45a and 46a, and are coupled to each other so as to complete the magnetic circuit. The coil conductive layer 47 is formed on the insulating layer 48 so as to spiral around the coupling portion of the yoke portion.

  FIG. 5 is a cross-sectional view schematically showing the layer structure of the MR multilayer 44 in one embodiment of the thin film magnetic head according to the present invention, and shows a cross section taken along the line BB as seen from the ABS 10a direction of FIG.

  In FIG. 5, 440 is a lower metal layer, 441 is an antiferromagnetic layer, 442 is a magnetization fixed layer, 443 is a nonmagnetic intermediate layer serving as a tunnel barrier, 444 is a magnetization free layer, and 445 is an upper metal layer. . Here, the lower metal layer 440 is formed on the lower shield layer 41 serving as a lower electrode, and electrically connects the MR multilayer 44 to the lower shield layer 41. Further, the upper metal layer 445 electrically connects the MR laminate 44 to the upper shield layer 42 by forming the upper shield layer 42 serving as an upper electrode thereon. Therefore, in this embodiment, when the magnetic field is detected, the current flows between the upper and lower electrodes in a direction perpendicular to each layer surface in the MR stack. The insulating layer 430 is formed so as to surround the periphery of the MR stack 44.

  The antiferromagnetic layer 441 may have a base film made of NiFe or NiCr not shown on the interface side with the lower metal layer 440. In the magnetization fixed layer 442 stacked on the antiferromagnetic layer 441, a first ferromagnetic film 442a, a nonmagnetic film 442b, and a second ferromagnetic film 442c are sequentially formed from the antiferromagnetic layer 441 side. They have a so-called synthetic ferri structure. An exchange bias magnetic field is applied to the first ferromagnetic film 442a by exchange coupling with the antiferromagnetic layer 441, and thereby the magnetization of the entire magnetization fixed layer 442 is stably fixed.

  The magnetization free layer 444 laminated on the nonmagnetic intermediate layer 443 has a configuration in which a high polarizability film 444a, a soft magnetic film 444b, and a magnetostriction adjustment film 444c are sequentially formed and stacked from the nonmagnetic intermediate layer 443 side. It has become. The magnetization free layer 444 changes the magnetization direction in response to the applied signal magnetic field, but forms a ferromagnetic tunnel coupling with the magnetization fixed layer 442 using the nonmagnetic intermediate layer 443 as a tunnel barrier. Therefore, when the magnetization direction of the magnetization free layer 444 changes in response to the signal magnetic field, the tunnel current increases or decreases due to fluctuations in the state density of the up and down spin bands of the magnetization free layer 444, and as a result, the electrical resistance value of the MR stack Changes. By measuring this amount of change, a weak signal magnetic field can be detected. The magnetostriction adjusting film 444c in the magnetization free layer 444 suppresses the magnetostriction of the magnetization free layer 444 while maintaining the MR change rate corresponding to the high polarizability film 444a existing at the interface with the nonmagnetic intermediate layer, thereby freeing magnetization. The layer 444 has a function of maintaining a single domain state. Here, the high polarizability film 444a is not always necessary and can be omitted. When omitted, an MR change rate equivalent to the soft magnetic film 444b existing at the interface with the nonmagnetic intermediate layer is realized. The functions and effects of the magnetostriction adjusting film 444c and the high polarizability film 444a will be described in detail later.

  Although not shown, a layer made of a hard magnetic material instead of an insulating material is provided at the position of the insulating layer 430 in FIG. 5, and a thin insulation is further provided between the layer of the hard magnetic material and the MR laminate 44. A bias magnetic field by a hard bias method may be applied to the magnetization free layer 444 by interposing a layer. Alternatively, an in-stack bias stack in which a bias nonmagnetic layer, a bias ferromagnetic layer, and a bias antiferromagnetic layer are sequentially stacked between the magnetostriction adjusting film 444c and the upper metal layer 445, and the like. Biasing means may be provided. These bias means apply an exchange bias magnetic field to the magnetization free layer 444 to further promote the single domain of the magnetization free layer 444.

  6A to 6C are cross-sectional views showing a part of the process of forming the MR laminated body in one embodiment of the thin film magnetic head according to the present invention. Like FIG. 5, from the direction of the ABS 10a in FIG. A cross section taken along line B-B is shown.

  As shown in FIG. 6A, first, a 2 μm-thick lower electrode / lower shield layer 41 made of, for example, NiFe is plated on an insulating layer (not shown) formed on a slider substrate (not shown). Then, a lower metal layer 440 having a thickness of 5 nm made of, for example, Ta, Hf, Nb, Zr, Ti, Mo, or W, and a thickness of 2 nm made of, for example, NiFe or NiCr are formed thereon. A ground film 441a, a 15 nm thick antiferromagnetic layer 441 made of, for example, PtMn, NiMn, IrMn, RuRhMn, etc., a 2 nm thick first ferromagnetic film 442a made of, for example, CoFe, and the like, for example, Ru, Rh, Ir A non-magnetic film 442b having a thickness of 0.8 nm made of Cr, Re, Cu or the like, a second ferromagnetic film 442c having a thickness of 3 nm made of CoFe or the like, and Al A non-magnetic intermediate layer 443 having a thickness of 0.6 nm made of an Al oxide film obtained by oxidizing a metal film made of oxygen in an atmosphere in which oxygen is introduced into a vacuum apparatus, and a high polarizability having a thickness of 1 nm made of, for example, CoFe. From a film 444a, a soft magnetic film 444b made of NiFe or the like, for example, a magnetostriction adjusting film 444c made of CoFe or the like, for example, and a film such as Ta, Hf, Nb, Zr, Ti, Mo or W The upper metal layer 445 having a thickness of 16 nm is sequentially formed by sputtering or the like.

  Although not shown, as described above, when an in-stack bias stack is provided between the magnetostrictive adjustment film 444c and the upper metal layer 445, for example, Ta, Hf, Nb, Zr, Ti, Mo, W, Ru, Rh, Ir, Cr, Re, Cu, Pt, Au, Ag, Al, Si, etc., 1 nm thick nonmagnetic layer, eg, CoFe A 5 nm bias ferromagnetic layer and a 7 nm thick bias antiferromagnetic layer made of, for example, IrMn are sequentially stacked by sputtering or the like.

Next, as shown in FIG. 6B, a photoresist pattern 60 is formed thereon by exposing and developing, for example, a lift-off photoresist layer. Thereafter, the region 62 indicated by the oblique lines in FIG. 6B is removed by an ion milling method using obliquely incident ions 61 using the photoresist pattern 60 as a mask. Thereafter, an insulating film made of, for example, Al ₂ O ₃ is formed thereon by a sputtering method or the like, and an insulating layer 430 is formed as shown in FIG. 6C by a lift-off method that peels off the photoresist pattern 60. Is done. Further, an upper electrode / upper shield layer 42 made of NiFe or the like and having a thickness of 2 μm is formed thereon by a method such as plating.

Although not shown, when the hard bias means is provided at the position of the insulating layer 430 as described above, after the ion milling process by the oblique incidence, first, the thickness 5 made of, for example, Al ₂ O _{3 is used.} An insulating film of ˜15 nm is formed by sputtering, and then a hard magnetic layer made of, for example, CoPt or CoCrPt is laminated. Thereafter, a hard bias means is formed on the insulating layer 430 by a lift-off method for removing the photoresist pattern 60.

  The materials and film thicknesses of the respective films constituting the antiferromagnetic layer 441, the magnetization fixed layer 442, the nonmagnetic intermediate layer 443, and the magnetization free layer 444 in the present embodiment are not limited to those described above, and various materials can be used. And film thickness are applicable. Further, in the magnetization fixed layer 442, in addition to the three-layer structure including three films, a single-layer structure including a ferromagnetic film or a multilayer structure having other layers can be employed. Further, in the magnetization free layer 444, in addition to the three-layer structure, a two-layer structure in which the high polarizability film 444a does not exist or a multilayer structure of four or more layers can be employed.

  Hereinafter, the effect of the magnetostriction adjusting film 444c on the magnetostriction of the magnetization free layer 444 will be described.

In the MR laminate including the above-described high polarizability film, the magnetostriction of the magnetization free layer increases due to the characteristics of the ferromagnetic material constituting the high polarizability film. Therefore, when the layer thickness of the magnetization free layer and the film thickness of the high polarizability film are increased to some extent in order to sufficiently draw out the MR ratio increased by the presence of this high polarizability film, the internal stress and adjacent The inverse magnetostrictive effect due to external stress from the layer becomes more prominent. Due to this inverse magnetostriction effect, the magnetic anisotropy in the magnetization free layer is generally dispersed, and the magnetization free layer is prevented from becoming a single domain. As a result, inconveniences such as output noise occurring during magnetic field detection and defective element detection operations occur. Therefore, in the MR multilayer, the λ _{S of the} magnetization free layer must be designed to be as small as possible in order to make the magnetization free layer a single magnetic domain and perform stable magnetic field detection.

7A to 7C show the relationship between the configuration of the magnetization free layer 444 in the MR multilayer 44 and the saturation magnetostriction constant λ _S. Here, the saturation magnetostriction constant λ _S is measured by applying a predetermined magnetic field to the Al oxide layer / magnetization free layer / upper metal layer formed on the strip-shaped substrate and optically measuring the generated deflection. It was conducted.

In FIG. 7A, the magnetization free layer 444 includes a Co ₃₀ Fe ₇₀ film having a thickness of 1 nm on the side in contact with the nonmagnetic intermediate layer 443 made of an Al oxide film, and a Ni ₈₂ Fe film having a thickness of 2 nm is further formed thereon. _The structure is provided with ₁₈ films. Λ _S of this magnetization free layer was 1.23 × 10 ⁻⁵ . In this configuration, as shown in FIG. 7B, when the Co ₃₀ Fe ₇₀ film in contact with the nonmagnetic intermediate layer 443 was thickened to 2 nm, λ _S increased to 2.33 × 10 ⁻⁵ . That is, λ _S increases as the thickness of the Co ₃₀ Fe ₇₀ film in contact with the nonmagnetic intermediate layer 443 increases.

However, in this configuration, as shown in FIG. 7C, the Co ₃₀ Fe ₇₀ film and the Ni ₈₂ Fe ₁₈ film are interchanged, and the Ni ₈₂ Fe ₁₈ film is provided at a position in contact with the nonmagnetic intermediate layer 443. Compared with the structure of FIG. 7 (B), λ _S was reduced by about 30% to 1.62 × 10 ⁻⁵ even though the material composition and film thickness constituting each film were exactly the same.

From the above results, it can be seen that λ _{S of the} magnetization free layer is lowered by disposing a high polarizability film such as a Co ₃₀ Fe ₇₀ film on the side opposite to the side in contact with the nonmagnetic intermediate layer 443.

Then, lambda not only _S, the configuration of the MR stack 44 in consideration of the MR ratio, described effect of magnetostriction adjusting film 444c.

8A and 8B show the relationship between the configuration of the magnetization free layer 444 in the MR stack 44 and the λ _S and MR change rates.

In FIG. 8A, the magnetization free layer 444 includes a Co ₃₀ Fe ₇₀ film having a thickness of 2 nm on the side in contact with the nonmagnetic intermediate layer 443 made of an Al oxide film, and a Ni ₈₂ Fe film having a thickness of 2 nm is further formed thereon. _The structure is provided with ₁₈ films. When the λ _S of the magnetization free layer was measured in the MR laminated body having this configuration, it showed a slightly large value of 2.33 × 10 ⁻⁵ . The MR change rate was 20.71%.

Here, in such an MR laminated body, it is considered to reduce magnetostriction without impairing the MR change rate. As described above, the MR change rate can be increased by providing a ferromagnetic high polarizability film on the side of the magnetization free layer 444 in contact with the nonmagnetic intermediate layer 443. That is, the polarizability of the ferromagnetic material film present at the interface between the magnetization free layer 444 and the nonmagnetic intermediate layer 443 defines the outline of the TMR effect of this MR multilayer. Therefore, it is necessary to provide a Co ₃₀ Fe ₇₀ film, which is a ferromagnetic high polarizability film, on the side of the magnetization free layer 444 in contact with the nonmagnetic intermediate layer 443 in order to maintain and improve the MR ratio.

On the other hand, as described above, λ _S of the magnetization free layer 444 is lowered by disposing the high polarizability film on the side opposite to the side in contact with the nonmagnetic intermediate layer 443. Therefore, as shown in FIG. 8B, 1 nm of the 2 nm thick Co ₃₀ Fe ₇₀ film in the configuration of FIG. 8A is left on the side in contact with the nonmagnetic intermediate layer 443, and the remaining 1 nm is left. The magnetostriction adjusting film 444c is arranged on the opposite side of the magnetization free layer 444 from the side in contact with the nonmagnetic intermediate layer 443.

In the MR laminated body having this configuration, the MR change rate was measured and found to be 20.72%, which was almost the same value as the configuration of FIG. This is because the high polarizability Co ₃₀ Fe ₇₀ film is maintained as the high polarizability film 444a at the interface between the magnetization free layer 444 and the nonmagnetic intermediate layer 443 and the ferromagnetic material film constituting the entire magnetization free layer 444. And the effect of maintaining each thickness. That is, it can be seen that the MR change rate can be maintained even if the thickness of the CoFe film as the high polarizability film 444a is 1 nm. Furthermore, even if the film thickness is actually 1 nm or less, if the interface with the nonmagnetic intermediate layer is similarly formed, it is clear that a predetermined sufficient MR change rate is exhibited. On the other hand, when λ _S of the magnetization free layer 444 was measured, it was 1.13 × 10 ^−5, which was about 52% lower than the configuration of FIG. This is because the λ _S reduction effect obtained by arranging the high polarizability film on the side opposite to the side in contact with the nonmagnetic intermediate layer 443 as the magnetostriction adjusting film 444c, which is discussed in FIGS. It is understood that this is a supporting result. At this time, it is obvious that the thickness of the CoFe film as the magnetostriction adjusting film 444c is preferably as large as possible in order to suppress an increase in magnetostriction due to the high polarizability film 444a made of CoFe.

Next, the relationship between the composition of the CoFe film used as the magnetostriction adjusting film 444c and λ _S will be described. The CoFe film changes in polarizability depending on the composition, and according to the present inventors, the polarizability tends to improve in a region where the Fe composition ratio is high, although it depends on the quality of the CoFe film.

  FIGS. 9A and 9B show configurations of two different magnetization free layers 444 for clarifying the influence of the composition of the magnetostriction adjusting film 444c on the magnetostriction.

9A includes a 1 nm thick CoFe film, a 2 nm thick Co ₃₀ Fe ₇₀ film, and a 2 nm thick film having various Fe composition ratios from the non-magnetic intermediate layer 443 made of an Al oxide film. A thick Ni ₈₂ Fe ₁₈ film is sequentially laminated. On the other hand, the magnetization free layer 444 in FIG. 9B has a thickness of 1 nm having a Co ₃₀ Fe ₇₀ film having a thickness of 2 nm, a Ni ₈₂ Fe ₁₈ film having a thickness of 2 nm, and various Fe composition ratios from the nonmagnetic intermediate layer 443 side. In the magnetization free layer 444 of FIG. 9A, a 1 nm thick CoFe film having various Fe composition ratios from the side in contact with the nonmagnetic intermediate layer 443 to the side in contact therewith Is moved to the opposite side. Here, by changing the Fe composition ratio of the CoFe film having a thickness of 1 nm, the saturation magnetostriction constant λ _SA of the magnetization free layer in FIG. 9A and the saturation magnetostriction constant λ _SB of the magnetization free layer in FIG. It was measured. At this time, the larger the difference Δλ _S = λ _SA −λ _SB is, the higher the magnetostriction reducing effect of the configuration of FIG. 9B is compared to the configuration of FIG. 9A.

FIG. 10A shows the relationship between the Fe composition ratio of the CoFe film and the magnetostriction of the magnetization free layer 444 in each configuration of FIGS. 9A and 9B. Further, FIG. 10 (B) shows the relationship between the Fe composition ratio and [Delta] [lambda] _S of the CoFe film. In addition, Table 1 shows actual measurement values in these relationships.

10A, the horizontal axis represents the side of the magnetization free layer 444 that is in contact with the nonmagnetic intermediate layer 443 (FIG. 9A) or the side opposite to the side that is in contact with the nonmagnetic intermediate layer 443 (FIG. 9B). )), And the vertical axis represents λ _SA and λ _SB at each Fe composition ratio of the CoFe film. According to FIG. 10 (A), λ _SA is monotonously increased as the Fe composition ratio increases, Fe composition ratio becomes 2 × ^{10 -5} or more values at 15 atomic% or more. On the other hand, λ _SB increases almost monotonically until the Fe composition ratio increases to reach 35.6 atomic%, but then reaches a peak even if the Fe composition ratio increases, and is relatively low at about 1 × 10 ⁻⁵ units. It remains small.

In FIG. 10B, the horizontal axis represents the same Fe composition ratio as in FIG. 10A, and the vertical axis represents Δλ _S at each Fe composition ratio. According to FIG. 10 (B), Δλ _S shows a remarkable increase in the composition ratio above the inflection point, with the Fe composition ratio being 43 atomic%. Actually, Δλ _S reaches a large value of 5-6 × 10 ⁻⁶ when the Fe composition ratio is 45.4 atomic% or more. From this result, the magnetostriction reducing effect of the configuration shown in FIG. 9B becomes significant when the Fe composition ratio of the CoFe film is 43 atomic% or more, and is high when the Fe composition ratio is 45.4 atomic% or more. It can be seen that it reaches and stabilizes. Here, since the CoFe film provided on the side opposite to the side in contact with the nonmagnetic intermediate layer 443 in FIG. 9B corresponds to a magnetostriction adjusting film, the CoFe film as the magnetostriction adjusting film has an Fe composition ratio. Is preferably 43 atomic% or more, and more preferably, the Fe composition ratio is 45.4 atomic% or more.

  In addition, it is clear that the above results are not limited to the composition and film thickness of each film described above, and other components constituting the MR laminated body such as the magnetization fixed layer are also limited to the above-described form. Obviously it is not.

  All the embodiments described above are illustrative of the present invention and are not intended to be limiting, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

1 is a perspective view schematically showing a configuration of a main part in an embodiment of a magnetic disk device according to the present invention. FIG. It is a perspective view showing the whole HGA by this invention. It is a perspective view of the thin film magnetic head with which the tip part of HGA was equipped. FIG. 3 is a cross-sectional view schematically showing a layer configuration of an MR effect element for reading and an inductive element for writing in an embodiment of a thin film magnetic head according to the present invention. 1 is a cross-sectional view schematically showing a layer configuration of an MR multilayer body in an embodiment of a thin film magnetic head according to the present invention. It is sectional drawing which shows the one part process which forms MR laminated body in one Embodiment of the thin film magnetic head by this invention. It is a figure which shows the relationship between the structure of the magnetization free layer in MR laminated body, and a saturation magnetostriction constant (lambda) _S. It is a figure which shows the relationship between the structure of the magnetization free layer in MR laminated body, (lambda) _S, and MR change rate. It is a figure which shows the structure of two different magnetization free layers for clarifying the influence of the composition of the magnetostriction adjustment film | membrane with respect to a magnetostriction. FIG. 10 is a diagram showing the relationship between the Fe composition ratio of the CoFe film and λ _S of the magnetization free layer 444 and the difference ΔλS in each configuration of FIGS. 9A and 9B.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic disk 11 Spindle motor 12 Assembly carriage apparatus 13 Recording / reproducing circuit 14 Drive arm 15 Voice coil motor (VCM)
16 Pivot bearing shaft 17 Head gimbal assembly (HGA)
20 Suspension 21 Slider 22 Load beam 23 Flexure 24 Base plate 25 Wiring member 30 Magnetic head element 31 Signal terminal electrode 32 Element formation surface 33 Air bearing surface (ABS)
40 Slider substrate 41 Lower shield layer 42 Upper shield layer 430, 431 Insulating layer 44 MR laminate 440 Lower metal layer 441 Antiferromagnetic layer 441a Underlayer 442 Fixed magnetic layer 442a First ferromagnetic film 442b Nonmagnetic film 442c Second Ferromagnetic film 443 nonmagnetic intermediate layer 444 magnetization free layer 444a high polarizability film 444b soft magnetic film 444c magnetostriction adjustment film 445 upper metal layer 45 lower pole layer 46 upper pole layer 47 coil conductive layer 48 insulating layer 49 gap layer 50 over Coat layer 60 Photoresist pattern 61 Incident ions 62 Region to be removed

Claims (12)

  Magnetization fixed layer in which the magnetization direction is fixed, a nonmagnetic intermediate layer laminated on the magnetization fixed layer, and a magnetization that is laminated on the nonmagnetic intermediate layer and whose magnetization direction is variable according to the applied magnetic field A magnetoresistive stack including a free layer, and the magnetization free layer includes a magnetostriction adjusting film containing CoFe on a side opposite to a side in contact with the nonmagnetic intermediate layer. Resistive effect element. 2. The magnetoresistive element according to claim 1, wherein a CoFe composition of the magnetostriction adjusting film is Co _1-X Fe _X (0.43 ≦ X ≦ 1).   3. The magnetoresistive element according to claim 1, wherein the magnetization free layer includes a high polarizability film on a side in contact with the nonmagnetic intermediate layer.   The magnetoresistive effect element according to claim 3, wherein the high polarizability film is a CoFe film.   The magnetoresistive effect element according to claim 3 or 4, wherein a film thickness of the high polarizability film is 1 nm or less.   6. The magnetoresistive effect element according to claim 3, wherein a film thickness of the magnetostrictive adjustment film is equal to or greater than a film thickness of the high polarizability film.   The magnetoresistive element according to claim 1, wherein the nonmagnetic intermediate layer is an Al oxide film.   One or two of Ta, Hf, Nb, Zr, Ti, Mo, W, Ru, Rh, Ir, Cr, Re, Cu, Pt, Au, Ag, Al, and Si on the magnetization free layer The magnetoresistive effect element according to any one of claims 1 to 7, wherein a nonmagnetic conductive layer comprising the above is laminated.   The magnetoresistive effect element according to claim 1, wherein a current flows in a direction perpendicular to each layer surface in the magnetoresistive laminate.   A thin film magnetic head comprising at least one magnetoresistive element according to any one of claims 1 to 9.   11. A head gimbal assembly comprising: the thin film magnetic head according to claim 10; a signal line to the magnetoresistive effect element of the thin film magnetic head; and a support mechanism for supporting the thin film magnetic head.   A magnetic disk drive comprising at least one head gimbal assembly according to claim 11.

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