JP2005347512A - Magnetoresistive effect element, thin-film magnetic head, head gimbal assembly, head arm assembly, and magnetic disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain the large change of a magnetic resistance when a current is made to flow perpendicularly to the surface of each layer constituting a magnetoresistive effect element. <P>SOLUTION: The MR element 5 is provided with a nonmagnetic conductive layer 24, a free layer 25 which is arranged so that the layer 25 may adjoin one surface of the nonmagnetic conductive layer 24 and changes in the direction of magnetization in accordance with the external magnetic field, and a pinned layer 23 which is arranged so that the layer 23 may adjoin the other surface of the nonmagnetic conductive layer 24 and is fixed in the direction of magnetization. The free layer 25 has first and second magnetic layers F1 and F2 and a coupling layer 40 arranged between the magnetic layers F1 and F2. The second magnetic layer F2 is arranged nearer to the pinned layer 23 than the first magnetic layer F1, and the magnetic layers F1 and F2 are coupled with each other in an antiferromagnetic state through the coupling layer 40. The bulk scattering coefficient β of the first magnetic layer F1 has a negative value and that β of the second magnetic layer F2 has a positive value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetoresistive effect element, and a thin film magnetic head, a head gimbal assembly, a head arm assembly, and a magnetic disk apparatus having the magnetoresistive effect element.

  In recent years, with the improvement of the surface recording density of magnetic disk devices, there has been a demand for improved performance of thin film magnetic heads. As a thin film magnetic head, a reproducing head having a magnetoresistive effect element for reading (hereinafter also referred to as MR (Magnetoresistive) element) and a recording head having an inductive electromagnetic transducer for writing are laminated on a substrate. A composite thin film magnetic head having the above structure is widely used.

  As the MR element, an AMR element using an anisotropic magnetoresistive effect, a GMR element using a giant magnetoresistive effect, and a tunnel-type magnetoresistive effect are used. There are TMR elements.

  The characteristics of the reproducing head are required to be high sensitivity and high output. As a reproducing head that satisfies this requirement, GMR heads using spin-valve GMR elements have already been mass-produced. Recently, in order to cope with the further improvement of the surface recording density, development of a reproducing head using a TMR element has been advanced.

  Generally, a spin valve type GMR element includes a nonmagnetic conductive layer having two surfaces facing away from each other, a free layer disposed adjacent to one surface of the nonmagnetic conductive layer, and a non-magnetic layer. A pinned layer disposed adjacent to the other surface of the magnetic conductive layer, and an antiferromagnetic layer disposed adjacent to the surface opposite to the nonmagnetic conductive layer in the pinned layer. Yes. The free layer is a layer whose magnetization direction changes according to the signal magnetic field. The pinned layer is a ferromagnetic layer whose magnetization direction is fixed. The antiferromagnetic layer is a layer that fixes the direction of magnetization in the pinned layer by exchange coupling with the pinned layer.

  By the way, the conventional GMR head has a structure in which a current for magnetic signal detection (hereinafter referred to as a sense current) flows in a direction parallel to the surface of each layer constituting the GMR element. Such a structure is called a CIP (Current In Plane) structure. On the other hand, development of a GMR head having a structure in which a sense current is caused to flow in a direction perpendicular to the surface of each layer constituting the GMR element is underway. Such a structure is called a CPP (Current Perpendicular to Plane) structure. Hereinafter, the GMR element used for the reproducing head having the CPP structure is called a CPP-GMR element, and the GMR element used for the reproducing head having the CIP structure is called a CIP-GMR element. Note that the reproducing head using the above-described TMR element also has a CPP structure.

  The CPP-GMR element has advantages such as a smaller resistance than the TMR element and a larger output than the CIP-GMR element when the track width is reduced. Expected to have.

  Incidentally, the magnetoresistance change in the CPP-GMR element is caused by the scattering of electrons depending on the spin in the magnetic layer (hereinafter referred to as bulk scattering) and the scattering of electrons depending on the spin at the interface between two adjacent layers ( Hereinafter, it is referred to as interface scattering. The magnetoresistance change due to bulk scattering is caused by the asymmetry between the electrical conductivity of the upward spin and the electrical conductivity of the downward spin in the magnetic layer. Similarly, the magnetoresistance change due to interface scattering is caused by the asymmetry between the electrical conductivity of the upward spin and the electrical conductivity of the downward spin at the interface.

The asymmetry between the electrical conductivity of the upward spin and the electrical conductivity of the downward spin in the magnetic layer is represented by a bulk scattering coefficient β. Specifically, when the electrical conductivity of the upward spin in the magnetic layer is σ _b ↑ and the electrical conductivity of the downward spin in the magnetic layer is σ _b ↓, the bulk scattering coefficient β is expressed by the following equation: .

β = (σ _b ↑ −σ _b ↓) / (σ _b ↑ + σ _b ↓)

Similarly, the asymmetry between the electrical conductivity of the upward spin and the electrical conductivity of the downward spin at the interface is represented by the interface scattering coefficient γ. Specifically, when the electrical conductivity of the upward spin at the interface is σ _i ↑ and the electrical conductivity of the downward spin at the interface is σ _i ↓, the interface scattering coefficient γ is expressed by the following equation.

γ = (σ _i ↑ −σ _i ↓) / (σ _i ↑ + σ _i ↓)

  The larger the absolute value of the bulk scattering coefficient β, the larger the magnetoresistance change. Similarly, the larger the absolute value of the interface scattering coefficient γ, the larger the magnetoresistance change.

  The bulk scattering coefficient β depends on the material constituting the magnetic layer, and the interface scattering coefficient γ depends on the combination of the materials constituting the two adjacent layers. Non-Patent Document 1 shows the results of obtaining bulk scattering coefficient β and interface scattering coefficient γ for various materials.

  By the way, in the CPP-GMR element, unlike the CIP-GMR element, not only the contribution of interface scattering but also the contribution of bulk (volume) scattering due to conduction of electrons in the magnetic material is ignored for the magnetoresistance change. Has an effect that can not be. Therefore, in order to obtain a large magnetoresistance effect in the CPP-GMR element, it is effective to increase the thickness of the free layer, which is a magnetic layer, and use bulk scattering. However, increasing the thickness of the free layer increases the magnetization of the free layer. As a result, it is difficult to orient the magnetization direction of the free layer in the direction orthogonal to the magnetization direction of the pinned layer by the hard bias magnetic field. For this reason, when the thickness of the free layer is increased, an increase in the output voltage of the GMR element can be expected due to an increase in the thickness of the magnetic layer, but there arises a problem that the output waveform of the GMR element is significantly deteriorated.

  Therefore, for example, as shown in Patent Document 1, it has also been proposed that the free layer has a synthetic structure. This synthetic free layer has a structure in which two magnetic layers are antiferromagnetically coupled by RKKY interaction via a nonmagnetic coupling layer. In the free layer having this synthetic structure, the effective magnetization can be made smaller than that in a normal free layer having no synthetic structure. Hereinafter, of the two magnetic layers in the synthetic structure free layer, the magnetic layer far from the pinned layer is referred to as a first magnetic layer, and the magnetic layer closer to the pinned layer is referred to as a second magnetic layer.

  Patent Document 1 describes a technique in which two regions are provided in a first magnetic layer of a synthetic structure free layer. Of the two regions, the region far from the nonmagnetic coupling layer contains an element that increases specific resistance, such as Cr, and the region closer to the nonmagnetic coupling layer does not contain such an element. According to the technique described in Patent Document 1, in the CIP-GMR element, it is possible to prevent a decrease in the resistance change rate due to the sense current being shunted to the first magnetic layer, and the RKKY interaction between the two magnetic layers in the free layer The coupling magnetic field can be increased.

JP 2003-188440 A Physical Review B, The American Physical Society, USA, September 1, 1999, Vol. 60, No. 9, p. 6710-6722

  The CPP-GMR element having a synthetic structure free layer has the following inherent problems. That is, in this CPP-GMR element, the magnetization of the first magnetic layer and the magnetization of the second magnetic layer are opposite to each other. The magnetoresistance change in the CPP-GMR element is mainly a magnetoresistance change accompanying a change in the magnetization direction of the second magnetic layer. However, in the CPP-GMR element, a current flows in a direction perpendicular to the surface of each layer constituting the GMR element. For this reason, the output voltage of the CPP-GMR element depends on the combined resistance of the magnetic resistance of the second magnetic layer and the magnetic resistance of the first magnetic layer connected in series therewith. Here, when the magnetization direction of the second magnetic layer is antiparallel to the magnetization direction of the pinned layer, the magnetization direction of the first magnetic layer is parallel to the magnetization direction of the pinned layer. In general, the bulk scattering coefficients β of the first magnetic layer and the second magnetic layer are both positive values. For these reasons, the first magnetic layer has a function of reducing the magnetoresistance change of the CPP-GMR element. Therefore, conventionally, it has been difficult to increase the change in magnetoresistance of a CPP-GMR element having a synthetic structure free layer.

  The present invention has been made in view of such problems, and its object is to obtain a large change in magnetoresistance when a current is passed in a direction perpendicular to the surface of each layer constituting the magnetoresistive element. It is an object of the present invention to provide a magnetoresistive effect element and a thin film magnetic head, a head gimbal assembly, a head arm assembly, and a magnetic disk device having the magnetoresistive effect element.

  The magnetoresistive element of the present invention is disposed so as to be adjacent to one surface of the nonmagnetic conductive layer having two surfaces facing to each other and the nonmagnetic conductive layer, and has a magnetization direction according to an external magnetic field. A free layer that changes, and a pinned layer that is disposed adjacent to the other surface of the nonmagnetic conductive layer and has a fixed magnetization direction. In the present invention, the free layer has first and second magnetic layers each including a layer made of a magnetic material, and a coupling layer made of a non-magnetic material disposed between the first and second magnetic layers. The second magnetic layer is disposed closer to the pinned layer than the first magnetic layer, and the first and second magnetic layers are antiferromagnetically coupled via the coupling layer. Further, the bulk scattering coefficient of the first magnetic layer is a negative value, and the bulk scattering coefficient of the second magnetic layer is a positive value.

  In the magnetoresistive element of the present invention, the bulk scattering coefficient of the first magnetic layer in the free layer is a negative value, and the bulk scattering coefficient of the second magnetic layer in the free layer is a positive value. The change in the magnetization direction of one magnetic layer works to increase the magnetoresistance change of the magnetoresistive element.

  In the magnetoresistive element of the present invention, the absolute value of the bulk scattering coefficient of the first magnetic layer may be 0.1 or more.

  In the magnetoresistive element of the present invention, the first magnetic layer is formed of a magnetic alloy containing any one of cobalt, iron, and nickel but not containing chromium, vanadium, or manganese. And a laminate having at least one second magnetic alloy layer made of a magnetic alloy containing any one of cobalt, iron, nickel and chromium, vanadium, or manganese.

  The second magnetic alloy layer may be made of a magnetic alloy containing a atomic% of iron and (100-a) atomic% of chromium, where a is 50 or more and 80 or less.

  The second magnetic alloy layer may be made of a magnetic alloy containing a atomic% of iron and (100-a) atomic% of vanadium, and a is 60 or more and 80 or less.

  The second magnetic alloy layer may be made of a magnetic alloy containing a atomic% of nickel and (100-a) atomic% of chromium, and a is 50 or more and 70 or less.

  In the magnetoresistive element of the present invention, the first magnetic layer contains 0.9 × a atomic% of cobalt, 0.1 × a atomic% of iron, and (100−a) atomic% of chromium, and a May have a layer made of a magnetic alloy having a thickness of 60 or more and 80 or less.

  In the magnetoresistive element of the invention, the first magnetic layer contains 0.9 × a atomic% of cobalt, 0.1 × a atomic% of iron, (100−a) atomic% of vanadium, and a May have a layer made of a magnetic alloy having a thickness of 60 or more and 80 or less.

  The thin film magnetic head of the present invention includes a medium facing surface facing the recording medium, a magnetoresistive element of the present invention disposed in the vicinity of the medium facing surface for detecting a signal magnetic field from the recording medium, and a magnetic signal. It comprises a pair of electrodes for flowing a detection current in a direction perpendicular to the surface of each layer constituting the magnetoresistive effect element.

  The head gimbal assembly of the present invention includes the thin film magnetic head of the present invention, and includes a slider disposed so as to face the recording medium and a suspension that elastically supports the slider. The head arm assembly of the present invention includes the thin film magnetic head of the present invention, a slider disposed so as to face the recording medium, a suspension that elastically supports the slider, and the slider in the track transverse direction of the recording medium. And a suspension attached to the arm.

  The magnetic disk device of the present invention includes the thin film magnetic head of the present invention, a slider disposed so as to face a disk-shaped recording medium that is driven to rotate, and a positioning that supports the slider and positions the recording medium. Device.

  In the magnetoresistive element, thin film magnetic head, head gimbal assembly, head arm assembly, or magnetic disk apparatus of the present invention, the bulk scattering coefficient of the first magnetic layer in the free layer is a negative value, and the second Since the bulk scattering coefficient of the magnetic layer is a positive value, the change in the magnetization direction of the first magnetic layer works to increase the magnetoresistance change of the magnetoresistive element. Thus, according to the present invention, it is possible to obtain a large change in magnetoresistance when a current is passed in a direction perpendicular to the surface of each layer constituting the magnetoresistive element.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of a thin film magnetic head and an outline of a manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 2 is a cross-sectional view showing a cross section perpendicular to the air bearing surface and the substrate of the thin film magnetic head, and FIG. 3 is a cross sectional view showing a cross section parallel to the air bearing surface of the magnetic pole portion of the thin film magnetic head.

In the method of manufacturing a thin film magnetic head according to the present embodiment, first, alumina (Al ₂ O ₃ ) is formed on a substrate 1 made of a ceramic material such as Altic (Al ₂ O ₃ .TiC) by sputtering or the like. An insulating layer 2 made of an insulating material such as 1 is formed to a thickness of 1 to 5 μm, for example. Next, a first shield layer 3 for a reproducing head made of a magnetic material such as NiFe or FeAlSi is formed in a predetermined pattern on the insulating layer 2 by plating or the like. Next, although not shown, an insulating layer made of alumina, for example, is formed on the entire surface. Next, the insulating layer is polished by chemical mechanical polishing (hereinafter referred to as CMP) until the first shield layer 3 is exposed, and the upper surfaces of the first shield layer 3 and the insulating layer are planarized.

  Next, the reproducing MR element 5 is formed on the first shield layer 3. Next, although not shown, an insulating film is formed so as to cover the two side portions of the MR element 5 and the upper surface of the first shield layer 3. The insulating film is formed of an insulating material such as alumina. Next, two bias magnetic field application layers 18 are formed so as to be adjacent to the two sides of the MR element 5 with an insulating film interposed therebetween. Next, the insulating layer 7 is formed so as to be disposed around the MR element 5 and the bias magnetic field applying layer 18. The insulating layer 7 is formed of an insulating material such as alumina.

  Next, on the MR element 5, the bias magnetic field applying layer 18 and the insulating layer 7, the second shield layer 8 of the reproducing head made of a magnetic material and serving also as the lower magnetic pole layer of the recording head is formed. The magnetic material used for the second shield layer 8 is a soft magnetic material such as NiFe, CoFe, CoFeNi, or FeN. The second shield layer 8 is formed by, for example, a plating method or a sputtering method. Instead of the second shield layer 8, a second shield layer, a separation layer made of a nonmagnetic material such as alumina formed on the second shield layer by sputtering or the like, and the separation layer And a lower magnetic pole layer formed thereon.

  Next, the recording gap layer 9 made of a nonmagnetic material such as alumina is formed on the second shield layer 8 by sputtering or the like to a thickness of 50 to 300 nm, for example. Next, in order to form a magnetic path, the recording gap layer 9 is partially etched at the center portion of a thin film coil to be described later to form a contact hole 9a.

  Next, a first layer portion 10 of a thin film coil made of, for example, copper (Cu) is formed on the recording gap layer 9 to a thickness of, for example, 2 to 3 μm. In FIG. 2, reference numeral 10 a represents a connection portion of the first layer portion 10 that is connected to a second layer portion 15 of a thin film coil to be described later. The first layer portion 10 is wound around the contact hole 9a.

  Next, an insulating layer 11 made of an organic insulating material having fluidity when heated, such as a photoresist, is formed in a predetermined pattern so as to cover the first layer portion 10 of the thin film coil and the recording gap layer 9 around the first layer portion 10. . Next, heat treatment is performed at a predetermined temperature in order to flatten the surface of the insulating layer 11. By this heat treatment, the edge portions of the outer periphery and inner periphery of the insulating layer 11 become rounded slope shapes.

  Next, in a region from the slope portion on the air bearing surface 20 side, which will be described later, of the insulating layer 11 to the air bearing surface 20 side, on the recording gap layer 9 and the insulating layer 11, a magnetic material for a recording head is used. The track width defining layer 12a of the upper magnetic pole layer 12 is formed. The top pole layer 12 is composed of the track width defining layer 12a, and a coupling portion layer 12b and a yoke portion layer 12c described later.

  The track width defining layer 12a is formed on the recording gap layer 9 and is formed on the tip portion which becomes the magnetic pole portion of the upper magnetic pole layer 12 and the slope portion on the air bearing surface 20 side of the insulating layer 11, and the yoke portion. And a connection portion connected to the layer 12c. The width of the tip is equal to the recording track width. The width of the connection part is larger than the width of the tip part.

  When the track width defining layer 12a is formed, at the same time, the connection portion layer 12b made of a magnetic material is formed on the contact hole 9a, and the connection layer 13 made of a magnetic material is formed on the connection portion 10a. The coupling portion layer 12 b constitutes a portion of the upper magnetic pole layer 12 that is magnetically coupled to the second shield layer 8.

  Next, magnetic pole trimming is performed. That is, in the peripheral region of the track width defining layer 12a, at least a part of the recording gap layer 9 and the magnetic pole portion of the second shield layer 8 on the recording gap layer 9 side is etched using the track width defining layer 12a as a mask. Thereby, as shown in FIG. 3, a trim structure in which the widths of at least a part of the magnetic pole portion of the upper magnetic pole layer 12, the magnetic gap portions of the recording gap layer 9 and the second shield layer 8 are aligned is obtained. It is formed. According to this trim structure, an increase in effective track width due to the spread of magnetic flux in the vicinity of the recording gap layer 9 can be prevented.

  Next, the insulating layer 14 made of an inorganic insulating material such as alumina is formed to a thickness of 3 to 4 μm, for example. Next, the insulating layer 14 is polished and planarized by CMP, for example, to reach the surfaces of the track width defining layer 12a, the coupling portion layer 12b, and the connection layer 13.

  Next, a second layer portion 15 of a thin film coil made of, for example, copper (Cu) is formed on the planarized insulating layer 14 to a thickness of, for example, 2 to 3 μm. In FIG. 2, reference numeral 15 a represents a connection portion of the second layer portion 15 that is connected to the connection portion 10 a of the first layer portion 10 of the thin film coil via the connection layer 13. The second layer portion 15 is wound around the connection portion layer 12b.

  Next, an insulating layer 16 made of an organic insulating material having fluidity when heated, such as a photoresist, is formed in a predetermined pattern so as to cover the second layer portion 15 of the thin film coil and the insulating layer 14 therearound. Next, heat treatment is performed at a predetermined temperature in order to flatten the surface of the insulating layer 16. By this heat treatment, the edge portions of the outer periphery and the inner periphery of the insulating layer 16 have a rounded slope shape.

  Next, a yoke portion layer 12c constituting the yoke portion of the top pole layer 12 is formed on the track width defining layer 12a, the insulating layers 14 and 16 and the coupling portion layer 12b with a magnetic material for a recording head such as permalloy. To do. The end of the yoke portion layer 12 c on the air bearing surface 20 side is disposed at a position away from the air bearing surface 20. Further, the yoke partial layer 12c is connected to the second shield layer 8 through the coupling partial layer 12b.

  Next, an overcoat layer 17 made of alumina, for example, is formed so as to cover the entire surface. Finally, the slider including the above layers is machined to form the air bearing surface 20 of the thin film magnetic head including the recording head and the reproducing head, thereby completing the thin film magnetic head.

  The thin film magnetic head manufactured in this way includes an air bearing surface 20 as a medium facing surface facing the recording medium, a reproducing head, and a recording head. The configuration of the reproducing head will be described in detail later.

  The recording head includes magnetic pole portions opposed to each other on the air bearing surface 20 side, and is magnetically coupled to the lower magnetic pole layer (second shield layer 8) and the upper magnetic pole layer 12, and the magnetic poles of the lower magnetic pole layer. And a recording gap layer 9 provided between the magnetic pole portion and the magnetic pole portion of the upper magnetic pole layer 12 and at least part of the recording gap layer 9 is disposed between the lower magnetic pole layer and the upper magnetic pole layer 12 in an insulated state. Thin film coils 10 and 15. In this thin film magnetic head, as shown in FIG. 2, the length from the air bearing surface 20 to the end of the insulating layer 11 on the air bearing surface 20 side is the throat height TH. The throat height refers to the length (height) from the air bearing surface 20 to the position where the interval between the two magnetic pole layers begins to open.

  Next, the configuration of the reproducing head will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view showing a cross section parallel to the air bearing surface of the read head.

  In the reproducing head in the present embodiment, the first shield layer 3 and the second shield layer 8 which are arranged at a predetermined interval, and between the first shield layer 3 and the second shield layer 8 are provided. The arranged MR element 5, the insulating film 6 covering the two sides of the MR element 5 and the upper surface of the first shield layer 3, and 2 adjacent to the two sides of the MR element 5 with the insulating film 6 interposed therebetween And two bias magnetic field application layers 18. The insulating film 6 is made of alumina, for example. The bias magnetic field application layer 18 is configured using a hard magnetic layer (hard magnet), a laminate of a ferromagnetic layer and an antiferromagnetic layer, or the like. Specifically, the bias magnetic field application layer 18 is formed of, for example, CoPt or CoCrPt.

  The reproducing head in the present embodiment is a reproducing head having a CPP structure. The first shield layer 3 and the second shield layer 8 also serve as a pair of electrodes for causing a sense current to flow in a direction perpendicular to the surface of each layer constituting the MR element 5 with respect to the MR element 5. ing. A pair of electrodes may be provided above and below the MR element 5 separately from the first shield layer 3 and the second shield layer 8. The MR element 5 is a spin valve type GMR element. The resistance value of the MR element 5 changes according to an external magnetic field, that is, a signal magnetic field from a recording medium. The sense current flows in a direction perpendicular to the surface of each layer constituting the MR element 5. The resistance value of the MR element 5 can be obtained from the sense current. In this way, the information recorded on the recording medium can be reproduced by the reproducing head.

  The MR element 5 includes an underlayer 21, an antiferromagnetic layer 22, a pinned layer 23, a nonmagnetic conductive layer 24, a free layer 25, and a protective layer 26 that are sequentially stacked on the first shield layer 3. The pinned layer 23 is a layer whose magnetization direction is fixed, and the antiferromagnetic layer 22 is a layer that fixes the magnetization direction in the pinned layer 23 by exchange coupling with the pinned layer 23. The underlayer 21 is provided in order to improve the crystallinity and orientation of each layer formed thereon, and in particular to improve exchange coupling between the antiferromagnetic layer 22 and the pinned layer 23. The free layer 25 is a layer whose magnetization direction changes according to an external magnetic field, that is, a signal magnetic field from a recording medium. The protective layer 26 is a layer for protecting each layer below it.

  The thickness of the foundation layer 21 is 2 to 6 nm, for example. As the underlayer 21, for example, a stacked body of a Ta layer and a NiFeCr layer is used.

The thickness of the antiferromagnetic layer 22 is, for example, 5 to 30 nm. The antiferromagnetic layer 22 is, for example, Pt, consists Ru, Rh, Pd, Ni, Cu, Ir, and at least one M _II selected from the group consisting of Cr and Fe, the antiferromagnetic material containing Mn ing. Among these, the content of Mn is preferably 35 atomic% or more and 95 atomic% or less, and the content of the other element M _II is preferably 5 atomic% or more and 65 atomic% or less. This antiferromagnetic material exhibits antiferromagnetism without heat treatment, and exhibits non-heat treatment antiferromagnetic material that induces an exchange coupling magnetic field with the ferromagnetic material, and exhibits antiferromagnetism by heat treatment. There is a heat treatment type antiferromagnetic material. The antiferromagnetic layer 22 may be composed of either of them.

  The non-heat-treatment type antiferromagnetic material includes a Mn alloy having a γ phase, and specifically, RuRhMn, FeMn, IrMn, and the like. The heat-treated antiferromagnetic material includes a Mn alloy having a regular crystal structure, and specifically includes PtMn, NiMn, PtRhMn, and the like.

  In the pinned layer 23, the magnetization direction is fixed by exchange coupling at the interface with the antiferromagnetic layer 22. The pinned layer 23 in the present embodiment has a second pinned layer AP2, a coupling layer 30 and a first pinned layer AP1 stacked in order on the antiferromagnetic layer 22, and is a so-called synthetic pinned layer. The first pinned layer AP1 and the second pinned layer AP2 include, for example, a magnetic layer made of a ferromagnetic material containing at least Co in the group consisting of Co and Fe. In particular, the (111) plane of this ferromagnetic material is preferably oriented in the stacking direction. An additive such as B may be added to the material constituting the first pinned layer AP1 and the second pinned layer AP2. The first pinned layer AP1 and the second pinned layer AP2 are antiferromagnetically coupled, and the magnetization directions are fixed in opposite directions. The thickness of the first pinned layer AP1 is, for example, 3 to 7 nm. The thickness of the second pinned layer AP2 is, for example, 3 to 7 nm.

  Further, the first pinned layer AP1 may be constituted by a single magnetic layer, or may be constituted by a plurality of layers including a nonmagnetic layer such as a Cu layer in addition to the magnetic layer. For example, the first pinned layer AP1 may have a structure in which a CoFe layer and a Cu layer are alternately and repeatedly stacked 2 to 5 times and then a CoFe layer is stacked. In this example, the composition of CoFe constituting the CoFe layer is, for example, Co: 90 atomic%, Fe: 10 atomic%, Co: 50 atomic%, and Fe: 50 atomic%. In this way, by configuring the first pinned layer AP1 with a plurality of layers including a nonmagnetic layer such as a Cu layer in addition to the magnetic layer, the interface scattering coefficient γ is relatively small in the first pinned layer AP1. Many large interfaces can be formed. As a result, the magnetoresistance change of the MR element 5 can be increased.

  The thickness of the coupling layer 30 in the pinned layer 23 is, for example, 0.2 to 1.2 nm. The coupling layer 30 is made of a nonmagnetic material including at least one selected from the group consisting of Ru, Rh, Ir, Re, Cr, Zr, and Cu, for example. The coupling layer 30 generates antiferromagnetic exchange coupling between the first pinned layer AP1 and the second pinned layer AP2, and the magnetization of the first pinned layer AP1 and the magnetization of the second pinned layer AP2 are opposite to each other. It is for fixing. Note that the magnetization of the first pinned layer AP1 and the magnetization of the second pinned layer AP2 are opposite to each other, not only when the directions of these two magnetizations differ from each other by 180 °, but also when the directions of the two magnetizations are 180 ° ± Including the case of 20 ° difference.

  The thickness of the nonmagnetic conductive layer 24 is, for example, 1.0 to 4.0 nm. The nonmagnetic conductive layer 24 is made of, for example, a nonmagnetic conductive material containing 80 wt% or more of at least one selected from the group consisting of Cu, Au, and Ag.

  The free layer 25 in the present embodiment includes a second magnetic layer F2, a coupling layer 40, and a first magnetic layer F1 that are sequentially stacked on the nonmagnetic conductive layer 24. Each of the magnetic layers F1 and F2 includes a layer made of a magnetic material. The thickness of the coupling layer 40 is, for example, 0.2 to 1.2 nm. The coupling layer 40 is made of a nonmagnetic material including at least one selected from the group consisting of Ru, Rh, Ir, Re, Cr, Zr, and Cu, for example. Specific examples of the coupling layer 40 include a 0.4 to 0.8 nm Ru layer and a 0.6 to 0.8 nm Rh layer. The second magnetic layer F2 is disposed at a position closer to the pinned layer 23 than the first magnetic layer F1. The first and second magnetic layers F1 and F2 are antiferromagnetically coupled by the RKKY interaction via the coupling layer 40. That is, the magnetization direction of the first magnetic layer F1 and the magnetization direction of the second magnetic layer F2 are opposite to each other. However, the magnitude of the magnetization of the second magnetic layer F2 is larger than the magnitude of the magnetization of the first magnetic layer F1. Therefore, in the absence of a signal magnetic field, the magnetization direction of the second magnetic layer F2 is aligned with the direction of the bias magnetic field.

The thickness of the first magnetic layer F1 is, for example, 1.0 to 4.0 nm. The characteristics of the first magnetic layer F1 will be described in detail later. The thickness of the second magnetic layer F2 is, for example, 2.0 to 6.0 nm. The second magnetic layer F2 is made of, for example, a magnetic material containing at least Co from the group consisting of Ni, Co, and Fe. Specifically, the second magnetic layer F2 is preferably composed of Co _x Fe _y Ni _{100- (x + y)} whose (111) plane is oriented in the stacking direction. In the formula, x and y are in atomic% within the range of 70 ≦ x ≦ 100 and 0 ≦ y ≦ 25, respectively.

  The thickness of the protective layer 26 is, for example, 0.5 to 10 nm. As the protective layer 26, for example, a stacked body of a Cu layer having a thickness of 5.0 nm and a Ru layer having a thickness of 5.0 nm is used.

  Each layer constituting the MR element 5 is formed by, for example, a sputtering method. In the formation process of the MR element 5, after forming each layer constituting the MR element 5, in order to fix the magnetization direction in the pinned layer 23, annealing (heat treatment), for example, at 270 ° C. for 4 hours is performed in a magnetic field. Do. The shape of the upper surface of the MR element 5 is, for example, a square having a length of 0.1 μm and a width of 0.1 μm. It should be noted that the layer configuration of the MR element 5 may be a configuration that is upside down from the configuration shown in FIG.

  Next, the operation of the thin film magnetic head according to the present embodiment will be described. The thin film magnetic head records information on a recording medium with a recording head, and reproduces information recorded on the recording medium with a reproducing head.

  In the reproducing head, the direction of the bias magnetic field by the bias magnetic field application layer 18 is orthogonal to the direction perpendicular to the air bearing surface 20. In the MR element 5, when there is no signal magnetic field, the magnetization direction of the second magnetic layer F2 in the free layer 25 is aligned with the direction of the bias magnetic field. The magnetization direction of the first magnetic layer F1 in the free layer 25 is opposite to the magnetization direction of the second magnetic layer F2. The magnetization direction of the pinned layer 23 is fixed in a direction perpendicular to the air bearing surface 20.

  In the MR element 5, the magnetization directions of the magnetic layers F 1, F 2 in the free layer 25 change according to the signal magnetic field from the recording medium, whereby the magnetization directions of the magnetic layers F 1, F 2 and the magnetization of the pinned layer 23 are changed. The relative angle with respect to the direction changes, and as a result, the resistance value of the MR element 5 changes. The resistance value of the MR element 5 can be obtained from the potential difference between the shield layers 3 and 8 when a sense current is passed through the MR element 5 by the first and second shield layers 3 and 8. In this way, the information recorded on the recording medium can be reproduced by the reproducing head.

  Next, features of the MR element 5 according to the present embodiment will be described. The MR element 5 according to the present embodiment is arranged so as to be adjacent to one surface of the nonmagnetic conductive layer 24 and the nonmagnetic conductive layer 24 having two surfaces facing opposite to each other, and according to an external magnetic field. It includes a free layer 25 in which the direction of magnetization changes, and a pinned layer 23 that is disposed adjacent to the other surface of the nonmagnetic conductive layer 24 and in which the direction of magnetization is fixed.

  The free layer 25 in the present embodiment is disposed between the first magnetic layer F1 and the second magnetic layer F2 each including a layer made of a magnetic material, and the first and second magnetic layers F1 and F2. And a coupling layer 40 made of a nonmagnetic material. The second magnetic layer F2 is disposed at a position closer to the pinned layer 23 than the first magnetic layer F1. The first and second magnetic layers F1 and F2 are antiferromagnetically coupled by the RKKY interaction via the coupling layer 40. The bulk scattering coefficient β of the first magnetic layer F1 is a negative value, and the bulk scattering coefficient β of the second magnetic layer F2 is a positive value. The absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is preferably 0.1 or more.

  The first magnetic layer F1 includes any one of cobalt (Co), iron (Fe), and nickel (Ni), but does not include any of chromium (Cr), vanadium (V), and manganese (Mn). A laminated body having at least one first magnetic alloy layer and at least one second magnetic alloy layer made of a magnetic alloy containing any one of cobalt, iron, nickel and chromium, vanadium, or manganese. It may be. In the case where the first magnetic layer F1 is constituted by a laminated body having one or more first magnetic alloy layers and second magnetic alloy layers, the first magnetic layer F1 and the second magnetic layer The first magnetic alloy layer is preferably in contact with the coupling layer 40 so that the layer F2 is well antiferromagnetically coupled to the layer F2 via the coupling layer 40.

  The second magnetic alloy layer may be made of a magnetic alloy containing a atomic% of iron and (100-a) atomic% of chromium, where a is 50 or more and 80 or less. The second magnetic alloy layer may be made of a magnetic alloy containing a atomic% of iron and (100-a) atomic% of vanadium, and a is 60 or more and 80 or less. The second magnetic alloy layer may be made of a magnetic alloy containing a atomic% of nickel and (100-a) atomic% of chromium, and a is 50 or more and 70 or less. The composition of these second magnetic alloy layers is derived from examples shown later.

  The first magnetic layer F1 contains 0.9 × a atomic% of cobalt, 0.1 × a atomic% of iron, and (100-a) atomic% of chromium, and a is 60 or more and 80 or less. You may have the layer which consists of magnetic alloys. The first magnetic layer F1 contains 0.9 × a atomic% of cobalt, 0.1 × a atomic% of iron, (100-a) atomic% of vanadium, and a is 60 or more and 80 or less. You may have the layer which consists of magnetic alloys. The composition of each of the above magnetic alloys is also derived from the results of Examples shown later.

  The second magnetic layer F2 may include a nonmagnetic layer such as a Cu layer in addition to the magnetic alloy layer. For example, the second magnetic layer F2 has a structure in which a CoFe layer having a thickness of 1.0 nm and a Cu layer having a thickness of 0.2 nm are alternately and repeatedly stacked four times, and the total thickness is 4.8 nm. Good. Thus, by inserting the nonmagnetic layer into the second magnetic layer F2, it is possible to form many interfaces having a relatively large interface scattering coefficient γ in the second magnetic layer F2, and as a result, the MR element 5 It is possible to increase the change in magnetoresistance.

  In the present embodiment, since the bulk scattering coefficient β of the first magnetic layer F1 is a negative value and the bulk scattering coefficient β of the second magnetic layer F2 is a positive value, the first magnetic layer F1 The change in the direction of magnetization of the MR element 5 works to increase the magnetoresistance change of the MR element 5. Thus, according to the present embodiment, a large magnetoresistance change can be obtained when a current is passed in a direction perpendicular to the surface of each layer constituting the MR element 5.

  Hereinafter, the principle of increasing the magnetoresistance change of the MR element 5 according to the present embodiment will be described in detail.

  First, with reference to FIG. 8 and FIG. 9, the change in magnetoresistance due to bulk scattering will be described. Here, as shown in FIGS. 8 and 9, the laminated body 50 including the magnetic layers 51 and 52 and the nonmagnetic conductive layer 53 disposed between the magnetic layers 51 and 52 is divided into an upward spin and a downward spin. Is considered to pass through in a direction perpendicular to the surfaces of the layers 51 to 53. The magnetic layers 51 and 52 correspond to the pinned layer 23 and the free layer 25 in the MR element 5. FIG. 8 shows a parallel state in which the magnetizations of the magnetic layers 51 and 52 are both upward. FIG. 9 shows an antiparallel state in which the magnetization of the magnetic layer 51 is upward and the magnetization of the magnetic layer 52 is downward. Here, in order to simplify the description, the electrical resistance of the nonmagnetic conductive layer 53 is ignored. 8 and 9, the upward spin is represented by the symbol e ↑, and the downward spin is represented by e ↓. 8 and 9, the magnitude of the electrical conductivity of the upward spin and the downward spin is schematically represented by the width of an arrow having a width.

First, consider a case where upward spins and downward spins pass through a magnetic layer with upward magnetization. Spin-up of the electrical conductivity sigma _b ↑ and the electrical conductivity of the down spin sigma _b ↓ is in the magnetic layer, using a bulk scattering coefficient beta, it is expressed by the following equation. Note that ρ is the specific resistance of the magnetic layer.

σ _b ↑ = (1 / 2ρ) + xβ
σ _b ↓ = (1 / 2ρ) −yβ

Considering the case of complete polarization (β = 1), σ _b ↓ = 0, so y = 1 / 2ρ. Furthermore, since σ _b ↑ + σ _b ↓ = 1 / ρ, x = 1 / 2ρ. Therefore, σ _b ↑ and σ _b ↓ of each spin are expressed by the following equations.

σ _b ↑ = (1 + β) / 2ρ
σ _b ↓ = (1-β) / 2ρ

Here, the specific resistance of the magnetic layer with respect to the upward spin is ρ ↑, and the specific resistance of the magnetic layer with respect to the downward spin is ρ ↓. Since ρ ↑ = 1 / σ _b ↑ and ρ ↓ = 1 / σ _b ↓, the following equation is obtained by modifying the above equation.

ρ ↑ = 2ρ / (1 + β) (1)
ρ ↓ = 2ρ / (1-β) (2)

  Here, in order to simplify the explanation, it is assumed that the magnetic layers 51 and 52 are made of the same material. In this case, the specific resistances ρ of the magnetic layers 51 and 52 are equal, and the bulk scattering coefficients β of the magnetic layers 51 and 52 are also equal.

  When the specific resistance of the stacked body 50 with respect to the upward spin in the parallel state shown in FIG. 8 is ρ ↑ (parallel), this is expressed by the following equation.

  ρ ↑ (parallel) = 2ρ / (1 + β) + 2ρ / (1 + β) = 4ρ / (1 + β)

  Similarly, when the specific resistance of the stacked body 50 with respect to the downward spin in the parallel state is ρ ↓ (parallel), this is expressed by the following equation.

  ρ ↓ (parallel) = 2ρ / (1-β) + 2ρ / (1-β) = 4ρ / (1-β)

  Here, the specific resistance of the stacked body 50 in the parallel state is defined as ρ (parallel). The current path in the stacked body 50 can be considered as a parallel circuit of an upward spin current path and a downward spin current path. Therefore, ρ (parallel) is expressed by the following equation.

ρ (parallel) = (ρ ↑ (parallel) × ρ ↓ (parallel)) / (ρ ↑ (parallel) + ρ ↓ (parallel))
= 2ρ

  Next, consider the antiparallel state shown in FIG. When the specific resistance of the stacked body 50 with respect to the upward spin in this antiparallel state is ρ ↑ (antiparallel), this is expressed by the following equation.

  ρ ↑ (antiparallel) = 2ρ / (1 + β) + 2ρ / (1-β)

  Similarly, when the specific resistance of the stacked body 50 with respect to the downward spin in the antiparallel state is ρ ↓ (antiparallel), this is expressed by the following equation.

  ρ ↓ (antiparallel) = 2ρ / (1-β) + 2ρ / (1 + β)

  Therefore, when the specific resistance of the laminated body 50 in the antiparallel state is ρ (antiparallel), this is expressed by the following equation.

ρ (antiparallel) = (ρ ↑ (antiparallel) × ρ ↓ (antiparallel)) / (ρ ↑ (antiparallel) + ρ ↓ (antiparallel)) = 2ρ / (1-β ² )

  Here, if Δρ = ρ (antiparallel) −ρ (parallel) is defined, Δρ is expressed by the following equation.

Δρ = 2ρ / (1-β ² ) -2ρ = 2ρβ ² / (1-β ² )

  From the above equation, it can be seen that Δρ increases as the bulk scattering coefficient β increases, and as a result, the change in magnetoresistance increases.

  Next, with reference to FIG. 10 and FIG. 11, a change in magnetoresistance due to interface scattering will be described. Here, as shown in FIGS. 10 and 11, a case is considered in which upward spins and downward spins pass through the interface 63 formed by contact of the magnetic layers 61 and 62 in a direction perpendicular to the interface 63. FIG. 10 shows a parallel state in which the magnetizations of the magnetic layers 61 and 62 are both upward. FIG. 11 shows an antiparallel state in which the magnetization of the magnetic layer 61 is upward and the magnetization of the magnetic layer 62 is downward. Here, a region in the magnetic layers 61 and 62 in which resistance due to electron scattering at the interface 63 occurs is referred to as an interface region 64. The length of the interface region 64 in the direction perpendicular to the interface 63 is defined as an interface length L. In FIG. 10 and FIG. 11, the upward spin is represented by the symbol e ↑ and the downward spin is represented by e ↓. 10 and FIG. 11, the magnitude of the electrical conductivity of the upward spin and the downward spin is schematically represented by the width of the arrow having a width.

First, consider the parallel state shown in FIG. The electrical conductivity σ _i ↑ of the upward spin at the interface and the electrical conductivity σ _i ↓ of the downward spin are expressed by the following equations using the interface scattering coefficient γ. Note that ρ _i is a specific resistance at the interface.

σ _i ↑ = (1 / 2ρ _i ) + xγ
σ _i ↓ = (1 / 2ρ _i ) −yγ

Considering the case of complete polarization (γ = 1), σ _i ↓ = 0, so y = 1 / 2ρ _i . Furthermore, since σ _i ↑ + σ _i ↓ = 1 / ρ _i , x = 1 / 2ρ _i . Therefore, σ _i ↑ and σ _i ↓ of each spin are expressed by the following equations.

σ _i ↑ = (1 + γ) / 2ρ _i
σ _i ↓ = (1-γ) / 2ρ _i

Here, it is assumed that the interface resistance with respect to the upward spin is R ↑, the specific resistance of the interface with respect to the upward spin is ρ _i ↑, the resistance of the interface with respect to the downward spin is R ↓, and the specific resistance of the interface with respect to the downward spin is ρ _i ↓. From Ohm's law, the resistances R ↑ and R ↓ are expressed by the following equations. A is the area of the interface (cross-sectional area of the interface region).

R ↑ = ρ _i ↑ ・ L / A
_{R ↓ = ρ i ↓ · L} / A

  When the above equation is modified, the following equation is obtained. R ↑ A is the interface resistance per unit area for upward spins, and R ↓ A is the interface resistance per unit area for downward spins.

R ↑ A = ρ _i ↑ ・ L
_{R ↓ A = ρ i ↓ ·} L

Here, ρ _i ↑ = 1 / σ _i ↑ = 2ρ _i / (1 + γ) and ρ _i ↓ = 1 / σ _i ↓ = 2ρ _i / (1-γ). The following equation is obtained.

R ↑ A = 2ρ _i L / (1 + γ)
R ↓ A = 2ρ _i L / (1-γ)

Further, assuming that the total resistance R of the interface is ρ _i L = RA, the above equation is modified to obtain the following equation.

R ↑ A = 2RA / (1 + γ)
R ↓ A = 2RA / (1-γ)

Here, R ^* = R / (1-γ ² ) is defined. Then, the above equation is modified to obtain the following equation.

R ↑ A = 2R ^* A (1-γ) (3)
R ↓ A = 2R ^* A (1 + γ) (4)

Next, the interface resistance of the magnetic layer 61 is R ₁ and the interface resistance of the magnetic layer 62 is R ₂ . Further, R ₁ ^* = R ₁ / (1-γ ² ) and R ₂ ^* = R ₂ / (1-γ ² ) are defined.

  When the resistance of the interface per unit area to the upward spin in the parallel state is R ↑ A (parallel), this is expressed by the following equation.

R ↑ A (parallel) = 2R ₁ ^* A (1−γ) + 2R ₂ ^* A (1−γ)

  Similarly, when the resistance of the interface per unit area to the downward spin in the parallel state is R ↓ A (parallel), this is expressed by the following equation.

R ↓ A (parallel) = 2R ₁ ^* A (1 + γ) + 2R ₂ ^* A (1 + γ)

  Therefore, when the total resistance of the interface per unit area in the parallel state is RA (parallel), this is expressed by the following equation.

RA (parallel)
= (R ↑ A (parallel) × R ↓ A (parallel)) / (R ↑ A (parallel) + R ↓ A (parallel))
= {1/2 (2R ₁ ^* A + 2R ₂ ^* A)} · 4A ² (1-γ ² ) (R ₁ ^* + R ₂ ^* ) ²

  Next, consider the antiparallel state shown in FIG. If the resistance of the interface per unit area to the upward spin in this antiparallel state is R ↑ A (antiparallel), this is expressed by the following equation.

R ↑ A (antiparallel) = 2R ₁ ^* A (1−γ) + 2R ₂ ^* A (1 + γ)

  Similarly, when the resistance of the interface per unit area to the downward spin in the antiparallel state is R ↓ A (antiparallel), this is expressed by the following equation.

R ↓ A ^{_{(antiparallel) = 2R 1 * A (1}} + γ) + 2R 2 * A (1-γ)

  Therefore, when the total resistance of the interface per unit area in the antiparallel state is RA (antiparallel), this is expressed by the following equation.

RA (anti-parallel)
= (R ↑ A (antiparallel) × R ↓ A (antiparallel)) / (R ↑ A (antiparallel) + R ↓ A (antiparallel)))
^{_{= {1/2 (2R 1 * A}} + 2R 2 * A)} · {4 (R 1 * A) 2 (1-γ 2) + 4R 1 * R 2 * A 2 (1 + γ) 2 + 4R 1 * R 2 * A ² (1-γ) ² +4 (R ₂ ^* A) ² (1-γ ² )}

  From the above, the magnetoresistance change AΔR per unit area is expressed by the following equation.

AΔR = RA (anti-parallel) -RA (parallel)
_{^{= 4 · 4γ 2 R 1 *}} R 2 * A 2/2 (2R 1 * A + 2R 2 * A)
= 4γ ² R ₁ ^* R ₂ ^* A / (R ₁ ^* + R ₂ ^* )

Here, for the sake of simplicity, assuming that the magnetic layers 61 and 62 are made of the same material, R ₁ = R ₂ . Substituting R ₁ ^* = R ₁ / (1-γ ² ), R ₂ ^* = R ₂ / (1-γ ² ) into the above equation, and further using R ₁ = R ₂ , AΔR is It is expressed by the following formula.

AΔR = 4γ ² R ₁ ^* R ₂ ^* A / (R ₁ ^* + R ₂ ^* ) = 2γ ² AR / (1-γ ² )

  From the above equation, it can be seen that the larger the interface scattering coefficient γ, the larger the magnetoresistance change AΔR per unit area.

  Next, with reference to FIGS. 12 and 13, the change in magnetoresistance in the MR element 5 according to the present embodiment will be considered. 12 and 13 show each layer constituting the MR element 5. Arrows in the layers represent the direction of magnetization. An arrow indicated by reference numeral 70 schematically represents a sense current. FIG. 12 shows a parallel state in which the magnetization of the first pinned layer AP1 and the magnetization of the second magnetic layer F2 are oriented in the same direction. FIG. 13 shows an antiparallel state in which the magnetization of the first pinned layer AP1 and the magnetization of the second magnetic layer F2 are directed in opposite directions.

  Here, in order to simplify the description, the portion of the first magnetic layer F1 that is in contact with the coupling layer 40, the second magnetic layer F2, the first pinned layer AP1, and the second pinned layer AP2 are all CoFe. It shall be comprised by. The nonmagnetic conductive layer 24 is made of Cu, and the coupling layers 30 and 40 are made of Ru. The base layer 21 and the antiferromagnetic layer 22 are collectively referred to as a buffer layer.

In the following description, the specific resistance of the second pinned layer AP2 is ρ _{CF (AP2)} , the specific resistance of the first pinned layer AP1 is ρ _{CF (AP1)} , and the specific resistance of the second magnetic layer F2 is ρ _{CF ( F2)} , the specific resistance of the first magnetic layer F1 is represented by ρ _CF , the specific resistance of the coupling layers 30 and 40 is represented by ρ _Ru , and the specific resistance of the nonmagnetic conductive layer 24 is represented by ρ _Cu . Note that the resistance of the buffer layer and the protective layer 26 is ignored.

The thickness of the second pinned layer AP2 is t _{CF (AP2)} , the thickness of the first pinned layer AP1 is t _{CF (AP1)} , the thickness of the second magnetic layer F2 is t _{CF (F2)} , the first The thickness of the magnetic layer F1 is represented by t _F1 , the thickness of the coupling layers 30 and 40 is represented by t _Ru , and the thickness of the nonmagnetic conductive layer 24 is represented by t _Cu .

The bulk scattering coefficient of the second pinned layer AP2 is β _{CF (AP2)} , the bulk scattering coefficient of the first pinned layer AP1 is β _{CF (AP1)} , and the bulk scattering coefficient of the second magnetic layer F2 is β _{CF (F2).} The bulk scattering coefficient of the first magnetic layer _F1 is represented as β _F1 .

Further, the resistance at the interface between the buffer layer and the second pinned layer AP2 is R _{Buf / CF (AP2)} , the resistance at the interface between the second pinned layer AP2 and the coupling layer 30 is R _{CF (AP2) / Ru} , and the resistance between the coupling layer 30 and the second pinned layer AP2. The resistance at the interface between the 1 pinned layer AP is R _{Ru / CF (AP1)} , the resistance at the interface between the first pinned layer AP and the nonmagnetic conductive layer 24 is R _{CF (AP1) / Cu} , and the resistance between the nonmagnetic conductive layer 24 and the second The interface resistance of the magnetic layer F2 is R _{Cu / CF (F2)} , the resistance of the interface between the second magnetic layer F2 and the coupling layer 40 is R _{CF (F2) / Ru} , and the coupling layer 40 and the first magnetic layer F1 The interface resistance is represented as R _{Ru / F1} , and the interface resistance between the first magnetic layer F1 and the protective layer 26 is represented as R _{F1 / CAP} .

Further, the interface scattering coefficient at the interface between the second pinned layer AP2 and the coupling layer 30 is γ _{CF (AP2) / Ru} , and the interface scattering coefficient at the interface between the coupling layer 30 and the first pinned layer AP is γ _{Ru / CF (AP1)} , The interface scattering coefficient at the interface between the first pinned layer AP and the nonmagnetic conductive layer 24 is γ _{CF (AP1) / Cu} , and the interface scattering coefficient at the interface between the nonmagnetic conductive layer 24 and the second magnetic layer F2 is γ _{Cu / CF ( F2)} , the interface scattering coefficient at the interface between the second magnetic layer F2 and the coupling layer 40 is γ _{CF (F2) / Ru} , and the interface scattering coefficient at the interface between the coupling layer 40 and the first magnetic layer F1 is γ _{Ru / F1} . Represent. Further, A is the cross-sectional area of the cross section of the MR element 5 parallel to the surface of each layer of the MR element 5.

As described above, the resistivity ρ ↑ of the magnetic layer with respect to the upward spin and the resistivity ρ ↓ of the magnetic layer with respect to the downward spin are expressed by the above formulas (1) and (2). Here, if defined as ρ ^* = ρ / (1-β ² ), the following equations are obtained by modifying equations (1) and (2).

ρ ↑ = 2ρ ^* (1-β)
ρ ↓ = 2ρ ^* (1 + β)

  When the thickness of the magnetic layer is t, the resistance ρ ↑ t per unit area of the magnetic layer for the upward spin and the resistance ρ ↓ t per unit area of the magnetic layer for the downward spin are respectively expressed by the following equations. The

ρ ↑ t = 2ρ ^* t (1-β) (5)
ρ ↓ t = 2ρ ^* t (1 + β) (6)

On the other hand, when R ^* = R / (1-γ ² ) is defined, the resistance AR ↑ per unit area of the interface with respect to the upward spin and the resistance AR ↓ per unit area of the interface with respect to the downward spin are respectively expressed by the following equations: It is represented by The following formula is substantially the same as the above formulas (3) and (4).

AR ↑ = 2AR ^* (1-γ) (7)
AR ↓ = 2AR ^* (1 + γ) (8)

Equations (5) to (8) are also valid when ρ, ρ ^* , t, β, R, R ^* , and γ are suffixed.

Next, the change in magnetoresistance in the MR element 5 is obtained. In the MR element 5 which is a CPP-GMR element, when the current density of the sense current is constant, the output voltage is equal to the specific resistance of the MR element 5 in the antiparallel state and the specific resistance of the MR element 5 in the parallel state. It is proportional to the product Δρ _MR t _MR of the difference Δρ _MR and the thickness t _MR of the MR element 5. Assuming that the difference between the resistance of the MR element 5 in the antiparallel state and the resistance of the MR element 5 in the parallel state is ΔR _MR , Δρ _MR t _MR is equal to AΔR _MR from Ohm's law.

By the way, in a magnetic material, it can be considered that upward spins and downward spins flow in parallel without intermingling. Therefore, the current path in the magnetic material can be considered as a parallel circuit of an upward spin current path and a downward spin current path. Therefore, AΔR _MR is a resistance AR ↑ (parallel) per unit area of the MR element 5 with respect to the upward spin in the parallel state, and a resistance AR ↓ (per unit area of the MR element 5 with respect to the downward spin in the parallel state) Resistance AR ↑ per unit area of the MR element 5 with respect to the upward spin in the anti-parallel state and anti-parallel resistance AR ↓ per unit area of the MR element 5 with respect to the downward spin in the anti-parallel state (Anti-parallel).

  AR ↑ (parallel), AR ↓ (parallel), AR ↑ (antiparallel), and AR ↓ (antiparallel) are expressed by the following equations (9) to (12).

AR ↑ (Parallel) = 2 {AR ^* _{Buf / CF (AP2)}
+ Ρ ^* _{CF (AP2)} t _{CF (AP2)} (1 + β _{CF (AP2)} )
+ AR ^* _{CF (AP2) / Ru} (1 + γ _{CF (AP2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / CF (AP1)} (1-γ _{Ru / CF (AP1)} )
+ Ρ ^* _{CF (AP1)} t _{CF (AP1)} (1-β _{CF (AP1)} )
+ AR ^* _{CF (AP1) / Cu} (1-γ _{CF (AP1) / Cu} ) + ρ _Cu t _Cu
+ AR ^* _{Cu / CF (F2)} (1-γ _{Cu / CF (F2)} )
+ Ρ ^* _{CF (F2)} t _{CF (F2)} (1-β _{CF (F2)} )
+ AR ^* _{CF (F2) / Ru} (1-γ _{CF (F2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / F1} (1 + γ _{Ru / F1} )
+ Ρ ^* _F1 t _F1 (1 + β _F1 ) + AR ^* _{F1 / CAP} } (9)

AR ↓ (Parallel) = 2 {AR ^* _{Buf / CF (AP2)}
+ Ρ ^* _{CF (AP2)} t _{CF (AP2)} (1-β _{CF (AP2)} )
+ AR ^* _{CF (AP2) / Ru} (1-γ _{CF (AP2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / CF (AP1)} (1 + γ _{Ru / CF (AP1)} )
+ Ρ ^* _{CF (AP1)} t _{CF (AP1)} (1 + β _{CF (AP1)} )
+ AR ^* _{CF (AP1) / Cu} (1 + γ _{CF (AP1) / Cu} ) + ρ _Cu t _Cu
+ AR ^* _{Cu / CF (F2)} (1 + γ _{Cu / CF (F2)} )
+ Ρ ^* _{CF (F2)} t _{CF (F2)} (1 + β _{CF (F2)} )
+ AR ^* _{CF (F2) / Ru} (1 + γ _{CF (F2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / F1} (1-γ _{Ru / F1} )
+ Ρ ^* _F1 t _F1 (1−β _F1 ) + AR ^* _{F1 / CAP} } (10)

AR ↑ (antiparallel) = 2 {AR ^* _{Buf / CF (AP2)}
+ Ρ ^* _{CF (AP2)} t _{CF (AP2)} (1 + β _{CF (AP2)} )
+ AR ^* _{CF (AP2) / Ru} (1 + γ _{CF (AP2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / CF (AP1)} (1-γ _{Ru / CF (AP1)} )
+ Ρ ^* _{CF (AP1)} t _{CF (AP1)} (1-β _{CF (AP1)} )
+ AR ^* _{CF (AP1) / Cu} (1-γ _{CF (AP1) / Cu} ) + ρ _Cu t _Cu
+ AR ^* _{Cu / CF (F2)} (1 + γ _{Cu / CF (F2)} )
+ Ρ ^* _{CF (F2)} t _{CF (F2)} (1 + β _{CF (F2)} )
+ AR ^* _{CF (F2) / Ru} (1 + γ _{CF (F2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / F1} (1-γ _{Ru / F1} )
+ Ρ ^* _F1 t _F1 (1−β _F1 ) + AR ^* _{F1 / CAP} } (11)

AR ↓ (antiparallel) = 2 {AR ^* _{Buf / CF (AP2)}
+ Ρ ^* _{CF (AP2)} t _{CF (AP2)} (1-β _{CF (AP2)} )
+ AR ^* _{CF (AP2) / Ru} (1-γ _{CF (AP2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / CF (AP1)} (1 + γ _{Ru / CF (AP1)} )
+ Ρ ^* _{CF (AP1)} t _{CF (AP1)} (1 + β _{CF (AP1)} )
+ AR ^* _{CF (AP1) / Cu} (1 + γ _{CF (AP1) / Cu} ) + ρ _Cu t _Cu
+ AR ^* _{Cu / CF (F2)} (1-γ _{Cu / CF (F2)} )
+ Ρ ^* _{CF (F2)} t _{CF (F2)} (1-β _{CF (F2)} )
+ AR ^* _{CF (F2) / Ru} (1-γ _{CF (F2) / Ru} ) + ρ _Ru t _Ru
+ AR ^* _{Ru / F1} (1 + γ _{Ru / F1} )
+ Ρ ^* _F1 t _F1 (1 + β _F1 ) + AR ^* _{F1 / CAP} } (12)

  Since the resistance AR (parallel) per unit area of the MR element 5 in the parallel state is a combined resistance of parallel resistances AR ↑ (parallel) and AR ↓ (parallel), it is expressed by the following equation.

  AR (Parallel) = (AR ↑ (Parallel), AR ↓ (Parallel)) / (AR ↑ (Parallel) + AR ↓ (Parallel))

  Similarly, the resistance AR (antiparallel) per unit area of the MR element 5 in the antiparallel state is a combined resistance of parallel resistors AR ↑ (antiparallel) and AR ↓ (antiparallel). It is expressed by a formula.

  AR (antiparallel) = (AR ↑ (antiparallel) · AR ↓ (antiparallel)) / (AR ↑ (antiparallel) + AR ↓ (antiparallel)))

The magnetoresistance change AΔR _MR of the MR element 5 is obtained by the following equation.

AΔR _MR = AR (antiparallel) -AR (parallel)
= (AR ↑ (antiparallel) · AR ↓ (antiparallel)-AR ↑ (parallel) · AR ↓ (parallel)) / (AR ↑ (parallel) + AR ↓ (parallel))

Here, AR ^* _{CF (AP2) / Ru} = AR ^* _{Ru / CF (AP1)} = AR ^* _{CF (F2) / Ru} = AR ^* _{Ru / F1} = AR ^* _{CF / Ru} . Also, AR ^* _{CF (AP1) / Cu} = AR ^* _{Cu / CF (F2)} = AR ^* _{CF / Cu} . Further, γ _{CF (AP2) / Ru} = γ _{Ru / CF (AP1)} = γ _{CF (F2) / Ru} = γ _{Ru / F1} . In addition, γ _{CF (AP1) / Cu} = γ _{Cu / CF (F2)} = γ _{CF / Cu} . When these are used, the following formulas (13) and (14) are derived from the formulas (9) to (12).

AR ↑ (Parallel) + AR ↓ (Parallel) = AR ↑ (Anti-parallel) + AR ↓ (Anti-parallel)
= 4 {AR ^* _{Buf / CF (AP2)} + ρ ^* _{CF (AP2)} t _{CF (AP2)} + 4AR ^* _{CF / Ru}
+ 2ρ _Ru t _Ru + ρ ^* _{CF (AP1)} tCF _(AP1) + 2AR ^* _{CF / Cu} + ρ _Cu t _{Cu
^{+ Ρ * CF (F2) t}} CF (F2) + ρ * F1 t F1 + AR * F1 / CAP} ... (13)

(AR ↑ (antiparallel), AR ↓ (antiparallel)-AR ↑ (parallel), AR ↓ (parallel))
= 16 (β _{CF (AP1)} ρ ^* _{CF (AP1)} t _{CF (AP1)} + γ _{CF / Cu} AR ^* _{CF / Cu}
-Β _{CF (AP2)} ρ ^* _{CF (AP2)} t _{CF (AP2)} ) × (β _{CF (F2)} ρ ^* _{CF (F2)} t _{CF (F2)}
+ Γ _{CF / Cu} AR ^* _{CF / Cu−} β _F1 ρ ^* _CF1 t _F1 ) (14)

  Here, let ¼ be the right side of equation (13) as E2 as follows.

E2 = AR ^* _{Buf / CF (AP2)} + ρ ^* _{CF (AP2)} t _{CF (AP2)} + 4AR ^* _{CF / Ru}
+ 2ρ _Ru t _Ru + ρ ^* _{CF (AP1)} tCF _(AP1) + 2AR ^* _{CF / Cu} + ρ _Cu t _Cu
+ Ρ ^* _{CF (F2)} t _{CF (F2)} + ρ ^* _F1 t _F1 + AR ^* _{F1 / CAP} (15)

  Moreover, let ¼ be the right side of equation (14) as E1 as follows.

E1 = 4 (β _{CF (AP1)} ρ ^* _{CF (AP1)} t _{CF (AP1)} + γ _{CF / Cu} AR ^* _{CF / Cu}
-Β _{CF (AP2)} ρ ^* _{CF (AP2)} t _{CF (AP2)} ) × (β _{CF (F2)} ρ ^* _{CF (F2)} t _{CF (F2)}
+ Γ _{CF / Cu} AR ^* _{CF / Cu−} β _F1 ρ ^* _CF1 t _F1 ) (16)

The magnetoresistance change AΔR _MR of the MR element 5 is obtained by the following equation.

AΔR _MR = E1 / E2 (17)

In the molecule E1 (equation (16)) on the right side of the equation (17), a portion where the magnetization direction does not change with respect to the change of the external magnetic field (the second pinned layer AP2 and the first pinned layer AP1) ) Will appear. In the molecule E1 (formula (16)), a term related to a portion (the second magnetic layer F2 and the first magnetic layer F1) in which the magnetization direction changes with respect to the change of the external magnetic field is shown in parentheses. appear. The bulk scattering coefficient β _{CF (F2)} of the second magnetic layer F2 in the parentheses later is a positive value. Here, if the bulk scattering coefficient β _F1 of the first magnetic layer F1 in the parentheses after is also a positive value, the term [−β _F1 ρ ^* _CF1 t _F1 ] in the parentheses is a negative value. Thus, the magnetic resistance change AΔR _MR is reduced. However, in this embodiment, since the bulk scattering coefficient beta _F1 of the first magnetic layer F1 is a negative value, - the section ^{_{[β F1 ρ * CF1 t F1}} ] is a positive value, the magnetoresistance change Works to increase AΔR _MR . Therefore, according to the MR element 5 according to the present embodiment, a large magnetoresistance change can be obtained when a current is passed in a direction perpendicular to the surface of each layer constituting the MR element 5.

  Hereinafter, the result of comparing the characteristics of the example of the MR element 5 according to the present embodiment and the comparative example for comparison with this example will be described. The magnetoresistance of the MR element 5 is such that one current supply terminal and one voltage detection terminal are connected to the first shield layer 3, and the other current supply terminal and the other voltage are connected to the second shield layer 8. Measurement was performed by a four-terminal method by connecting a detection terminal.

  First, the basic composition of the MR element of the comparative example and Examples 1 to 5 is shown in the following table. In the following table, the first column and the second column indicate the layers of the MR element, the third column indicates the specific configuration of each layer, and the fourth column indicates the thickness of each layer described in the third column. (Nm). In the second column, for example, “Ru” represents a Ru layer. In addition, the vertical relationship between the layers in the third row is the same as the vertical relationship between the layers in the MR element. Since the configuration of the first magnetic layer F1 of the free layer 25 is different for each of the comparative examples and Examples 1 to 5, they are shown in another table.

  Next, the following table shows the configuration of the first magnetic layer F1 in the comparative example and Examples 1 to 5. In the following table, the first column, the third column, the fifth column, the seventh column, the ninth column, and the eleventh column indicate the configuration of the first magnetic layer F1, and the second column, the fourth column, and the sixth column. The column, the eighth column, the tenth column, and the twelfth column respectively indicate the thickness (nm) of the layers described in the left column.

The first magnetic layer F1 in the comparative example is composed of only a CoFe layer. The composition of CoFe constituting this CoFe layer is Co: 90 atomic% and Fe: 10 atomic%. The table below shows the resistance RA (Ωμm ² ), magnetoresistance change AΔR (mΩμm ² ), resistance change rate (%), and bulk scattering coefficient β of the first magnetic layer F1 in the comparative example.

The first magnetic layer F1 in Example 1 has a configuration in which a CoFe layer having a thickness of 0.5 nm, a FeCr layer having a thickness of X nm, and a CoFe layer having a thickness of 0.5 nm are stacked. The two CoFe layers correspond to the first magnetic alloy layer, and the FeCr layer corresponds to the second magnetic alloy layer. The composition of CoFe constituting the CoFe layer is Co: 90 atomic% and Fe: 10 atomic%. Here, the composition of FeCr constituting the FeCr layer is set to Fe: a atomic% and Cr: (100-a) atomic%. In the following table, RA (Ωμm ² ), magnetoresistance change AΔR (mΩμm ² ), resistance change rate (%), bulk scattering of the first magnetic layer F1 for four examples with different combinations of values of a and X The coefficient β and the magnetization (emu / cc) of the FeCr layer are shown. In any of the four examples, the bulk scattering coefficient β of the first magnetic layer F1 is a negative value. Since the magnetization of the FeCr layer decreases as the Fe ratio a in FeCr decreases, in the following example, the thickness X of the FeCr layer increases as a decreases. From the following table, it can be seen that the MR element 5 of Example 1 can increase the magnetoresistance change AΔR and the rate of resistance change compared to the MR element of the comparative example at least in the range of a to 50 or more and 80 or less. Conceivable. Therefore, when the second magnetic alloy layer is made of FeCr having a composition of Fe: a atomic% and Cr: (100-a) atomic%, a is preferably 50 or more and 80 or less. From the table below, in Example 1, it is considered that the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is 0.1 or more when a is in the range of 50 or more and 80 or less. Therefore, the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is preferably 0.1 or more.

The first magnetic layer F1 in Example 2 has a configuration in which a CoFe layer having a thickness of 0.5 nm, a FeV layer having a thickness of X nm, and a CoFe layer having a thickness of 0.5 nm are stacked. The two CoFe layers correspond to the first magnetic alloy layer, and the FeV layer corresponds to the second magnetic alloy layer. The composition of CoFe constituting the CoFe layer is Co: 90 atomic% and Fe: 10 atomic%. Here, the composition of FeV constituting the FeV layer is Fe: a atomic% and V: (100-a) atomic%. In the following table, RA (Ωμm ² ), magnetoresistance change AΔR (mΩμm ² ), resistance change rate (%), bulk scattering of the first magnetic layer F1 for four examples with different combinations of values of a and X The coefficient β and the magnetization (emu / cc) of the FeV layer are shown. In any of the four examples, the bulk scattering coefficient β of the first magnetic layer F1 is a negative value. Since the FeV layer magnetization decreases as the Fe ratio a in FeV decreases, in the following example, the thickness X of the FeV layer increases as a decreases. From the following table, it can be seen that the MR element 5 of Example 2 can increase the magnetoresistive change AΔR and the resistance change rate as compared with the MR element of the comparative example, at least in the range of a to 60 and 80. Conceivable. For this reason, when the second magnetic alloy layer is made of FeV having a composition of Fe: a atomic% and V: (100-a) atomic%, a is preferably 60 or more and 80 or less. From the table below, in Example 2, it is considered that the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is 0.1 or more when a is in the range of 60 or more and 80 or less. Therefore, the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is preferably 0.1 or more.

The first magnetic layer F1 in Example 3 has a configuration in which a CoFe layer having a thickness of X nm, a NiCr layer having a thickness of 0.5 nm, and a CoFe layer having a thickness of X nm are stacked. The two CoFe layers correspond to the first magnetic alloy layer, and the NiCr layer corresponds to the second magnetic alloy layer. The composition of CoFe constituting the CoFe layer is Co: 90 atomic% and Fe: 10 atomic%. Here, the composition of NiCr constituting the NiCr layer is Ni: a atomic% and Cr: (100-a) atomic%. In the following table, RA (Ωμm ² ), magnetoresistance change AΔR (mΩμm ² ), resistance change rate (%), bulk scattering of the first magnetic layer F1 for four examples with different combinations of values of a and X The coefficient β and the magnetization (emu / cc) of the first magnetic layer F1 are shown. In any of the four examples, the bulk scattering coefficient β of the first magnetic layer F1 is a negative value. Since the magnetization of the first magnetic layer F1 decreases as the Ni ratio a in NiCr decreases, in the following example, the thickness X of the CoFe layer increases as a decreases. As can be seen from the table below, in the MR element 5 of Example 3, the magnetoresistance change AΔR and the resistance change rate can be increased as compared with the MR element of the comparative example, at least in the range where a is 50 or more and 70 or less. Conceivable. Therefore, when the second magnetic alloy layer is made of NiCr having a composition of Ni: a atomic% and Cr: (100-a) atomic%, a is preferably 50 or more and 70 or less. Further, from the table below, in Example 3, it is considered that the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is 0.1 or more when a is in the range of 50 or more and 70 or less. Therefore, the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is preferably 0.1 or more.

The first magnetic layer F1 in Example 4 is configured by a CoFeCr layer having a thickness of X nm. Here, the composition of CoFeCr constituting the CoFeCr layer is Co: 0.9 × a atomic%, Fe: 0.1 × a atomic%, and Cr: (100-a) atomic%. In the following table, RA (Ωμm ² ), magnetoresistance change AΔR (mΩμm ² ), resistance change rate (%), bulk scattering of the first magnetic layer F1 for four examples with different combinations of values of a and X The coefficient β and the magnetization (emu / cc) of the first magnetic layer F1 are shown. Since the CoFeCr layer magnetization decreases as the CoFe ratio a in CoFeCr decreases, in the following example, the thickness X of the CoFeCr layer increases as a decreases. From the table below, it is considered that in the MR element 5 of Example 4, the bulk scattering coefficient β of the first magnetic layer F1 becomes a negative value at least in the range of 40 to 80. Further, from the table below, in the MR element 5 of Example 4, the magnetoresistance change AΔR and the resistance change rate can be increased compared to the MR element of the comparative example in at least a within the range of 60 to 80. It is considered possible. In Example 4, when a is in the range of 60 or more and 80 or less, the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is considered to be 0.1 or more.

The first magnetic layer F1 in Example 5 is configured by a CoFeV layer having a thickness of X nm. Here, the composition of CoFeV constituting the CoFeV layer is Co: 0.9 × a atom%, Fe: 0.1 × a atom%, and V: (100−a) atom%. In the following table, RA (Ωμm ² ), magnetoresistance change AΔR (mΩμm ² ), resistance change rate (%), bulk scattering of the first magnetic layer F1 for four examples with different combinations of values of a and X The coefficient β and the magnetization (emu / cc) of the first magnetic layer F1 are shown. Since the CoFeV layer magnetization decreases as the CoFe ratio a in CoFeV decreases, in the following example, the thickness X of the CoFeV layer increases as a decreases. From the table below, in the MR element 5 of Example 5, it is considered that the bulk scattering coefficient β of the first magnetic layer F1 becomes a negative value at least in the range of 40 to 80. Further, from the table below, in the MR element 5 of Example 5, the magnetoresistance change AΔR and the resistance change rate can be increased as compared with the MR element of the comparative example in at least a within the range of 60 to 80. It is considered possible. In Example 5, when a is in the range of 60 to 80, the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is considered to be 0.1 or more.

  Here, as in Examples 1 to 3, the second magnetic alloy layer in the case where the first magnetic layer F1 is formed of a laminate including the first magnetic alloy layer and the second magnetic alloy layer. Consider the thickness. In the free layer 25 having the synthetic structure, the first magnetic layer F1 and the second magnetic layer F2 need to be well antiferromagnetically coupled via the coupling layer 40. The magnitude of the coupling between the first magnetic layer F1 and the second magnetic layer F2 depends on the state of the interface between the first magnetic layer F1 and the coupling layer 40 and the interface between the second magnetic layer F2 and the coupling layer 40. Depends on state. Here, as the thickness of the second magnetic alloy layer in the first magnetic layer F1 increases, the roughness of the surface on the coupling layer 40 side in the first magnetic layer F1 increases. For this reason, there is a limit to increasing the thickness of the second magnetic alloy layer. The upper limit of the thickness of the second magnetic alloy layer is about twice the thickness of the first magnetic alloy layer in contact with the coupling layer 40. Taking Examples 1 and 2 as an example, the upper limit of the thickness of the FeCr layer or FeV layer as the second magnetic alloy layer is twice the thickness of the CoFe layer as the first magnetic alloy layer, which is 0.5 nm. About 1.0 nm. In this case, the lower limit of the magnetization of the FeCr layer or the FeV layer is about 700 (emu / cc).

  Next, the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 will be considered. From Examples 1 to 3, it can be seen that the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is preferably 0.1 or more. However, even when the absolute value of the bulk scattering coefficient β of the first magnetic layer F1 is 0.1 or more, as in the case where a is 40 in Examples 4 and 5, the change in magnetoresistance compared to the comparative example. In some cases, AΔR and the rate of change in resistance are small. This is presumably because the magnetization of the first magnetic layer F1 is too small and the function as the synthetic structure free layer 25 is not sufficiently exhibited. Therefore, as in Examples 4 and 5, when the first magnetic layer F1 is formed of a CoFeCr layer or a CoFeV layer, the composition of CoFeCr or CoFeV has a preferable range.

  Hereinafter, a head gimbal assembly and a magnetic disk device according to the present embodiment will be described. First, the slider 210 included in the head gimbal assembly will be described with reference to FIG. In the magnetic disk device, the slider 210 is arranged to face a magnetic disk that is a disk-shaped recording medium that is driven to rotate. The slider 210 includes a substrate 211 mainly composed of the substrate 1 and the overcoat layer 17 in FIG. The base body 211 has a substantially hexahedral shape. One of the six surfaces of the substrate 211 faces the magnetic disk. An air bearing surface 20 is formed on this one surface. When the magnetic disk rotates in the z direction in FIG. 4, an air flow passing between the magnetic disk and the slider 210 causes a lift in the slider 210 in the lower direction in the y direction in FIG. 4. The slider 210 floats from the surface of the magnetic disk by this lifting force. The x direction in FIG. 4 is the track crossing direction of the magnetic disk. Near the end of the slider 210 on the air outflow side (lower left end in FIG. 4), the thin film magnetic head 100 according to the present embodiment is formed.

  Next, the head gimbal assembly 220 according to the present embodiment will be described with reference to FIG. The head gimbal assembly 220 includes a slider 210 and a suspension 221 that elastically supports the slider 210. The suspension 221 is, for example, a leaf spring-shaped load beam 222 formed of stainless steel, a flexure 223 that is provided at one end of the load beam 222 and is joined to the slider 210 to give the slider 210 an appropriate degree of freedom. And a base plate 224 provided at the other end of the beam 222. The base plate 224 is attached to an arm 230 of an actuator for moving the slider 210 in the track crossing direction x of the magnetic disk 262. The actuator has an arm 230 and a voice coil motor that drives the arm 230. In the flexure 223, a part to which the slider 210 is attached is provided with a gimbal part for keeping the posture of the slider 210 constant.

  The head gimbal assembly 220 is attached to the arm 230 of the actuator. A structure in which the head gimbal assembly 220 is attached to one arm 230 is called a head arm assembly. Further, a head gimbal assembly 220 attached to each arm of a carriage having a plurality of arms is called a head stack assembly.

  FIG. 5 shows a head arm assembly according to the present embodiment. In this head arm assembly, a head gimbal assembly 220 is attached to one end of the arm 230. A coil 231 that is a part of the voice coil motor is attached to the other end of the arm 230. A bearing portion 233 attached to a shaft 234 for rotatably supporting the arm 230 is provided at an intermediate portion of the arm 230.

  Next, an example of the head stack assembly and the magnetic disk device according to the present embodiment will be described with reference to FIGS. FIG. 6 is an explanatory view showing a main part of the magnetic disk device, and FIG. 7 is a plan view of the magnetic disk device. The head stack assembly 250 has a carriage 251 having a plurality of arms 252. A plurality of head gimbal assemblies 220 are attached to the plurality of arms 252 so as to be arranged in the vertical direction at intervals. A coil 253 that is a part of the voice coil motor is attached to the carriage 251 on the side opposite to the arm 252. The head stack assembly 250 is incorporated in a magnetic disk device. The magnetic disk device has a plurality of magnetic disks 262 attached to a spindle motor 261. Two sliders 210 are arranged for each magnetic disk 262 so as to face each other with the magnetic disk 262 interposed therebetween. Further, the voice coil motor has permanent magnets 263 arranged at positions facing each other with the coil 253 of the head stack assembly 250 interposed therebetween.

  The head stack assembly 250 and the actuator excluding the slider 210 correspond to the positioning device in the present invention, and support the slider 210 and position it relative to the magnetic disk 262.

  In the magnetic disk device according to the present embodiment, the slider 210 is moved with respect to the magnetic disk 262 by the actuator so that the slider 210 is positioned with respect to the magnetic disk 262. The thin film magnetic head included in the slider 210 records information on the magnetic disk 262 by the recording head, and reproduces information recorded on the magnetic disk 262 by the reproducing head.

  The head gimbal assembly, the head arm assembly, and the magnetic disk device according to the present embodiment have the same effects as the thin film magnetic head according to the above-described present embodiment.

  In addition, this invention is not limited to the said embodiment, A various change is possible. For example, in the present invention, the pinned layer 23 is not limited to the synthetic pinned layer.

  In each embodiment, a thin film magnetic head having a structure in which a reproducing head is formed on the substrate side and a recording head is stacked thereon has been described. However, the stacking order may be reversed.

  When used as a read-only device, the thin film magnetic head may be configured to include only the reproducing head.

It is sectional drawing which shows a cross section parallel to the air bearing surface of the reproducing head in one embodiment of this invention. 1 is a cross-sectional view showing a cross section perpendicular to an air bearing surface and a substrate of a thin film magnetic head according to an embodiment of the invention. It is sectional drawing which shows the cross section parallel to the air bearing surface of the magnetic pole part of the thin film magnetic head which concerns on one embodiment of this invention. It is a perspective view which shows the slider contained in the head gimbal assembly which concerns on one embodiment of this invention. It is a perspective view which shows the head arm assembly which concerns on one embodiment of this invention. It is explanatory drawing for demonstrating the principal part of the magnetic disc apparatus based on one embodiment of this invention. 1 is a plan view of a magnetic disk device according to an embodiment of the present invention. It is explanatory drawing for demonstrating the magnetoresistive change by bulk scattering. It is explanatory drawing for demonstrating the magnetoresistive change by bulk scattering. It is explanatory drawing for demonstrating the magnetoresistive change by interface scattering. It is explanatory drawing for demonstrating the magnetoresistive change by interface scattering. It is explanatory drawing for demonstrating the magnetoresistive change in MR element which concerns on one embodiment of this invention. It is explanatory drawing for demonstrating the magnetoresistive change in MR element which concerns on one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Insulating layer, 3 ... 1st shield layer, 5 ... MR element, 7 ... Insulating layer, 8 ... 2nd shield layer, 9 ... Recording gap layer, 10 ... 1st layer part of thin film coil , 12 ... Upper magnetic pole layer, 15 ... Second layer portion of thin film coil, 17 ... Overcoat layer, 18 ... Bias magnetic field application layer, 20 ... Air bearing surface, 21 ... Underlayer, 22 ... Antiferromagnetic layer, 23 ... Pinned layer, 24 ... nonmagnetic conductive layer, 25 ... free layer, 40 ... coupling layer, F1 ... first magnetic layer, F2 ... second magnetic layer.

Claims (12)

A nonmagnetic conductive layer having two faces facing away from each other;
A free layer disposed adjacent to one surface of the nonmagnetic conductive layer, the direction of magnetization changing according to an external magnetic field;
A pinned layer disposed adjacent to the other surface of the nonmagnetic conductive layer and having a fixed magnetization direction;
The free layer has first and second magnetic layers each including a layer made of a magnetic material, and a coupling layer made of a non-magnetic material disposed between the first and second magnetic layers,
The second magnetic layer is disposed closer to the pinned layer than the first magnetic layer;
The first and second magnetic layers are antiferromagnetically coupled via the coupling layer,
The bulk scattering coefficient of the first magnetic layer is a negative value,
2. The magnetoresistive element according to claim 1, wherein the bulk scattering coefficient of the second magnetic layer is a positive value.   2. The magnetoresistive element according to claim 1, wherein an absolute value of a bulk scattering coefficient of the first magnetic layer is 0.1 or more.   The first magnetic layer includes any one of cobalt, iron, and nickel, but does not include chromium, vanadium, or manganese. The first magnetic alloy layer includes any one of cobalt, iron, and nickel. 3. The magnetoresistive effect element according to claim 1, wherein the magnetoresistive effect element comprises a laminate having at least one second magnetic alloy layer made of a magnetic alloy containing any one of chromium, vanadium, and manganese.   4. The magnetic material according to claim 3, wherein the second magnetic alloy layer is made of a magnetic alloy containing a atomic% of iron and (100-a) atomic% of chromium, and a is 50 or more and 80 or less. Resistive effect element.   4. The magnetism according to claim 3, wherein the second magnetic alloy layer is made of a magnetic alloy containing a atomic% of iron and (100-a) atomic% of vanadium, and a is 60 or more and 80 or less. Resistive effect element.   4. The magnetic material according to claim 3, wherein the second magnetic alloy layer is made of a magnetic alloy containing a atom% of nickel and (100−a) atom% of chromium, and a is 50 or more and 70 or less. Resistive effect element.   The first magnetic layer includes 0.9 × a atom% cobalt, 0.1 × a atom% iron, (100-a) atom% chromium, and a is 60 or more and 80 or less. The magnetoresistive effect element according to claim 1, further comprising a layer made of the same.   The first magnetic layer includes 0.9 × a atomic% cobalt, 0.1 × a atomic% iron, (100-a) atomic% vanadium, and a is 60 or more and 80 or less. The magnetoresistive effect element according to claim 1, further comprising a layer made of the same. A medium facing surface facing the recording medium;
The magnetoresistive effect element according to any one of claims 1 to 8, which is disposed in the vicinity of the medium facing surface in order to detect a signal magnetic field from the recording medium,
And a pair of electrodes for flowing a current for detecting a magnetic signal in a direction perpendicular to the surface of each layer constituting the magnetoresistive effect element. Thin film magnetic head. A slider including the thin film magnetic head according to claim 9 and arranged to face a recording medium;
A head gimbal assembly comprising a suspension for elastically supporting the slider. A slider including the thin film magnetic head according to claim 9 and arranged to face a recording medium;
A suspension for elastically supporting the slider;
An arm for moving the slider in a direction across the track of the recording medium, and the suspension is attached to the arm. A slider including the thin film magnetic head according to claim 9 and disposed so as to face a disk-shaped recording medium driven to rotate.
A magnetic disk drive comprising: a positioning device that supports the slider and positions the slider relative to the recording medium.

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