Magnetoresistance effect element

Abstract

To provide a magnetoresistance effect element exhibiting a large magnetoresistance change rate.SOLUTION: A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer. At least one of the first ferromagnetic layer and the second ferromagnetic layer includes a first layer and a second layer in this order from a side closer to the nonmagnetic layer, the first layer includes a crystallized Co-based Heusler alloy, the second layer is at least partially crystallized and includes a ferromagnetic element, a boron element, and an additive element. The additive element is any element selected from a group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au, the second layer is made of crystallized CoFeB-A ...(1), and A represents the additive element in a formula (1).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a magnetoresistive element. [Background technology]

[0002] A magnetoresistance effect element is an element in which the resistance value in the stacking direction changes due to the magnetoresistance effect. The magnetoresistance effect element includes two ferromagnetic layers and a nonmagnetic layer sandwiched between them. A magnetoresistance effect element in which a conductor is used for the nonmagnetic layer is called a giant magnetoresistance (GMR) element, and a magnetoresistance effect element in which an insulating layer (tunnel barrier layer, barrier layer) is used for the nonmagnetic layer is called a tunnel magnetoresistance (TMR) element. The magnetoresistance effect element can be used for various purposes such as magnetic sensors, high-frequency components, magnetic heads, and nonvolatile random access memories (MRAMs).

[0003] Patent Document 1 describes a magnetic sensor including a magnetoresistance effect element using a Heusler alloy in a ferromagnetic layer. Heusler alloys have high spin polarization, and are expected to increase the output signal of the magnetic sensor. On the other hand, Patent Document 1 describes that Heusler alloys are difficult to crystallize unless they are formed at high temperatures or on a thick base substrate with a predetermined crystallinity. Patent Document 1 describes that film formation at high temperatures or a thick base substrate can cause a decrease in the output of the magnetic sensor. Patent Document 1 describes that the output of the magnetic sensor is increased by forming the ferromagnetic layer into a laminated structure of an amorphous layer and a crystalline layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,412,399 Summary of the Invention [Problem to be solved by the invention]

[0005] The magnitude of the output signal of a magnetic sensor depends on the magnetoresistance change rate (MR ratio) of the magnetoresistance effect element. In general, the higher the crystallinity of the ferromagnetic layers sandwiching the nonmagnetic layer, the larger the MR ratio tends to be. In the magnetoresistance effect element described in Patent Document 1, the ferromagnetic layer in contact with the nonmagnetic layer is amorphous, making it difficult to obtain a sufficiently large MR ratio.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a magnetoresistance effect element capable of realizing a large MR ratio. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides the following means.

[0008] (1) A magnetoresistance effect element according to a first aspect includes a first ferromagnetic layer, a second ferromagnetic layer, and a nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer, and at least one of the first ferromagnetic layer and the second ferromagnetic layer includes a first layer and a second layer, in that order from the side closer to the nonmagnetic layer, and the first layer includes a crystallized Co-based Heusler alloy, and the second layer is at least partially crystallized and includes a ferromagnetic element, a boron element, and an additive element, and the additive element is any element selected from the group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au.

[0009] (2) In the magnetoresistive element according to the above aspect, the first ferromagnetic layer and the second ferromagnetic layer may each include the first layer and the second layer.

[0010] (3) In the magnetoresistive element according to the above aspect, the Co-based Heusler alloy may be expressed as CoYZ or Co2YZ in terms of stoichiometric composition, and the Co-based Heusler alloy may have a Co composition ratio lower than the stoichiometric composition ratio.

[0011] (4) The second layer of the magnetoresistive element according to the above aspect may be made of crystallized CoFeB-A, and the second layer may have a higher Fe content than a Co content.

[0012] (5) In the second layer of the magnetoresistive element according to the above aspect, the content of the additive element may be greater than the content of boron.

[0013] (6) In the magnetoresistive element according to the above aspect, the first layer and the second layer may be lattice-matched.

[0014] (7) The magnetoresistive element according to the above aspect may further include a boron absorption layer in contact with a surface of the second layer away from the nonmagnetic layer, and the boron absorption layer may contain any element selected from the group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au.

[0015] (8) In the magnetoresistance effect element according to the above aspect, the Co-based Heusler alloy may have an L21 structure or a B2 structure.

[0016] (9) In the magnetoresistive element according to the above aspect, the Co-based Heusler alloy is CoY α Z β wherein Y is one or more elements selected from the group consisting of Fe, Mn, and Cr, and Z is one or more elements selected from the group consisting of Si, Al, Ga, and Ge, and α+β>2 may be satisfied.

[0017] (10) In the magnetoresistive effect element according to the above aspect, a buffer layer may be provided at least either between the first ferromagnetic layer and the nonmagnetic layer or between the second ferromagnetic layer and the nonmagnetic layer, and the buffer layer may contain a NiAl alloy or Ni.

[0018] (11) In the magnetoresistive element according to the above aspect, the buffer layer may have a thickness of 0.63 nm or less.

[0019] (12) In the magnetoresistive element according to the above aspect, the nonmagnetic layer may be a metal or an alloy containing any element selected from the group consisting of Cu, Au, Ag, Al, and Cr.

[0020] (13) The magnetoresistive element according to the above aspect may further include a substrate, which is an underlayer on which the first ferromagnetic layer, the second ferromagnetic layer, and the nonmagnetic layer are stacked, and the substrate may be amorphous. Effect of the Invention

[0021] The magnetoresistive element according to the present invention exhibits a large MR ratio. [Brief description of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view of a magnetoresistive effect element according to a first embodiment. [Diagram 2] FIG. 1 is a diagram showing the crystal structure of a Heusler alloy. [Diagram 3] 1A to 1C are cross-sectional views illustrating a method for manufacturing the magnetoresistive effect element according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a magnetoresistive effect element according to a first modified example of the first embodiment. [Diagram 5] FIG. 11 is a cross-sectional view of a magnetoresistive effect element according to a second modified example of the first embodiment. [Figure 6] FIG. 11 is a cross-sectional view of a magnetoresistive effect element according to a third modified example of the first embodiment. [Figure 7] 1 is a cross-sectional view of a magnetic recording element according to Application Example 1. FIG. [Figure 8] 11 is a cross-sectional view of a magnetic recording element according to Application Example 2. FIG. [Figure 9] FIG. 11 is a cross-sectional view of a magnetic recording element according to Application Example 3. [Figure 10] 13 is a cross-sectional view of a domain wall motion element according to Application Example 4. FIG. [Figure 11] FIG. 11 is a cross-sectional view of a high-frequency device according to Application Example 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the features of the present embodiment easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and may be appropriately modified and implemented within the scope of the present invention.

[0024] "First embodiment" 1 is a cross-sectional view of a magnetoresistance effect element according to a first embodiment. First, directions are defined. The direction in which each layer is stacked may be called the stacking direction. Also, the direction in which each layer extends, intersecting with the stacking direction, may be called the in-plane direction.

[0025] 1 includes a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a nonmagnetic layer 3. The nonmagnetic layer 3 is located between the first ferromagnetic layer 1 and the second ferromagnetic layer 2.

[0026] The magnetoresistance effect element 10 outputs a change in the relative angle between the magnetization of the first ferromagnetic layer 1 and the magnetization of the second ferromagnetic layer 2 as a change in resistance value. For example, the magnetization of the second ferromagnetic layer 2 is easier to move than the magnetization of the first ferromagnetic layer 1. When a predetermined external force is applied, the direction of the magnetization of the first ferromagnetic layer 1 does not change (is fixed), and the direction of the magnetization of the second ferromagnetic layer 2 changes. The resistance value of the magnetoresistance effect element 10 changes as the direction of the magnetization of the second ferromagnetic layer 2 changes relative to the direction of the magnetization of the first ferromagnetic layer 1. In this case, the first ferromagnetic layer 1 may be referred to as a magnetization fixed layer, and the second ferromagnetic layer 2 may be referred to as a magnetization free layer. In the following description, the first ferromagnetic layer 1 is described as a magnetization fixed layer, and the second ferromagnetic layer 2 is described as a magnetization free layer, but this relationship may be reversed.

[0027] The difference in the ease of movement between the magnetization of the first ferromagnetic layer 1 and the magnetization of the second ferromagnetic layer 2 when a certain external force is applied is caused by the difference in the coercive force between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. For example, when the thickness of the second ferromagnetic layer 2 is made thinner than that of the first ferromagnetic layer 1, the coercive force of the second ferromagnetic layer 2 becomes smaller than that of the first ferromagnetic layer 1. Also, for example, an antiferromagnetic layer may be provided on the surface of the first ferromagnetic layer 1 opposite to the nonmagnetic layer 3 via a spacer layer. The first ferromagnetic layer 1, the spacer layer, and the antiferromagnetic layer form a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a spacer layer. The first ferromagnetic layer 1 and the antiferromagnetic layer are antiferromagnetically coupled, so that the coercive force of the first ferromagnetic layer 1 is larger than that of the case without the antiferromagnetic layer. The antiferromagnetic layer is, for example, IrMn, PtMn, or the like. The spacer layer includes, for example, at least one selected from the group consisting of Ru, Ir, and Rh.

[0028] The first ferromagnetic layer 1 and the second ferromagnetic layer 2 include a ferromagnetic material. The first ferromagnetic layer 1 and the second ferromagnetic layer 2 of the magnetoresistance effect element 10 shown in FIG. 1 each have a first layer 1A, 2A and a second layer 1B, 2B. The first ferromagnetic layer 1 has, from the side closest to the nonmagnetic layer 3, a first layer 1A and a second layer 1B. The second ferromagnetic layer 2 has, from the side closest to the nonmagnetic layer 3, a first layer 2A and a second layer 2B.

[0029] For example, the first layer 1A and the second layer 1B are lattice-matched, and the first layer 2A and the second layer 2B are lattice-matched. Lattice-matched means that atoms are continuously arranged in the stacking direction at the interface between the first layer 1A and the second layer 1B and the interface between the first layer 2A and the second layer 2B. The degree of lattice matching between the first layer 1A and the second layer 1B, or the first layer 2A and the second layer 2B, is, for example, within 5%. The degree of lattice matching is the degree of deviation of the lattice constant of the second layers 1B and 2B when the lattice constant of the first layers 1A and 2A is taken as the reference. When the first layer 1A and the second layer 1B and the first layer 2A and the second layer 2B are lattice-matched, the MR ratio of the magnetoresistance effect element 10 is increased.

[0030] The first layers 1A and 2A each contain a crystallized Co-based Heusler alloy. Each of the first layers 1A and 2A is made of, for example, a Co-based Heusler alloy, and the Co-based Heusler alloy is at least partially crystallized. Each of the first layers 1A and 2A may be made of, for example, a completely crystallized Co-based Heusler alloy.

[0031] Heusler alloys are intermetallic compounds with the chemical composition XYZ or X2YZ. Ferromagnetic Heusler alloys with the X2YZ formula are called full Heusler alloys, and ferromagnetic Heusler alloys with the XYZ formula are called half Heusler alloys. Half Heusler alloys are full Heusler alloys in which some of the atoms at the X sites are vacant. Both are typically intermetallic compounds based on the bcc structure.

[0032] Fig. 2 shows an example of the crystal structure of a Heusler alloy. Fig. 2(a) to (c) show an example of the crystal structure of a full-Heusler alloy, and Fig. 2(d) to (f) show an example of the crystal structure of a half-Heusler alloy.

[0033] FIG. 2(a) is called the L21 structure. In the L21 structure, the elements in the X site, the Y site, and the Z site are fixed. FIG. 2(b) is called the B2 structure derived from the L21 structure. In the B2 structure, the elements in the Y site and the Z site are mixed, and the elements in the X site are fixed. FIG. 2(c) is called the A2 structure derived from the L21 structure. In the A2 structure, the elements in the X site, the Y site, and the Z site are mixed.

[0034] Figure 2(d) shows the C1 b It is called structure. C1 b In the structure, the elements in the X site, Y site, and Z site are fixed. b It is said to be a B2 structure derived from the C1 structure. In the B2 structure, elements in the Y site and elements in the Z site are mixed, and the element in the X site is fixed. Figure 2(f) shows the structure of the C1 bIt is called the A2 structure due to its structure. The A2 structure is a mixture of elements in the X site, Y site, and Z site.

[0035] In full-Heusler alloys, the order of crystallinity is L21>B2>A2, while in half-Heusler alloys, the order of crystallinity is C1 b The order of crystallinity is L21 structure > B2 structure > A2 structure. Although these crystal structures have different degrees of crystallinity, they are all crystals. Therefore, each of the first layers 1A and 2A has, for example, one of the crystal structures described above. The crystal structure of each of the first layers 1A and 2A is, for example, the L21 structure or the B2 structure.

[0036] Whether or not the Heusler alloy is crystallized can be determined by a transmission electron microscope (TEM) image (e.g., a high-angle scattering annular dark-field scanning transmission microscope image: HAADF-STEM image) or an electron beam diffraction image using a transmission electron beam. If the Heusler alloy is crystallized, for example, a HAADF-STEM image taken by a TEM can confirm that the atoms are regularly arranged. More specifically, a spot originating from the crystal structure of the Heusler alloy appears in the Fourier transform image of the HAADF-STEM image. If the Heusler alloy is crystallized, a diffraction spot from at least one of the (001) plane, (002) plane, (110) plane, and (111) plane can be confirmed in the electron beam diffraction image. If the crystallization can be confirmed by at least one of the means, it can be said that at least a part of the Heusler alloy is crystallized.

[0037] The composition of each layer constituting the magnetoresistive element can be analyzed by energy dispersive X-ray analysis (EDS). Furthermore, EDS line analysis can be used to confirm, for example, the composition distribution of each material in the film thickness direction.

[0038] The Co-based Heusler alloy is a Heusler alloy in which the X site is Co. Y is a transition metal of the Mn, V, Cr, or Ti group, or a transition metal element or a precious metal element of the Co, Fe, Ni, or Cu group, and Z is a typical element of groups III to V. The Y element is preferably one or more elements selected from the group consisting of Fe, Mn, and Cr, and the Z element is preferably one or more elements selected from the group consisting of Si, Al, Ga, and Ge.

[0039] Full Heusler alloys include, for example, Co2FeSi, Co2FeGe, Co2FeGa, Co2FeAl, and Co2FeGe. x Ga 1-x , Co2MnSi, Co2MnGe, Co2MnGa, Co2MnSn, Co2MnAl, Co2CrAl, Co2VAl, Co2Mn 1-a Fe a Al b S 1-b , etc. Examples of half-Heusler alloys are CoFeSb, NiMnSe, NiMnTe, NiMnSb, PtMnSb, PdMnSb, CoFeSb, RhMnSb, CoMnSb, IrMnSb, NiCrSb.

[0040] The Co-based Heusler alloy constituting the first layers 1A and 2A is, for example, Co2Y α Z β A Co-based full-Heusler alloy of stoichiometric composition is expressed as Co2YZ. The Co composition ratio of the Co-based Heusler alloy constituting the first layers 1A and 2A is preferably less than the stoichiometric composition ratio. In other words, when the Co-based Heusler alloy is a full-Heusler alloy, it is preferable that α+β>2 is satisfied. When the Co-based Heusler alloy is a half-Heusler alloy, the Co-based Heusler alloy constituting the first layers 1A and 2A is expressed as, for example, CoY α Z β and it is preferable that α+β>1 is satisfied.

[0041] When the Co composition ratio is relatively smaller than that of the Y site element, it is possible to avoid an antisite in which the Y site element is substituted for the X site element (the site where Co is located). The antisite fluctuates the Fermi level of the Heusler alloy. When the Fermi level fluctuates, the half-metallicity of the Heusler alloy decreases, and the spin polarization decreases. The decrease in spin polarization causes a decrease in the MR ratio of the magnetoresistance effect element 10.

[0042] Each of the second layers 1B and 2B includes a crystallized portion. Each of the second layers 1B and 2B includes an alloy including a ferromagnetic element, boron, and an additive element. The second layer may include elements other than the ferromagnetic element, boron, and additive element. Each of the second layers 1B and 2B may be made of, for example, an alloy of a ferromagnetic element, boron, and an additive element, and the ferromagnetic element, boron, and additive element are at least partially crystallized. Each of the second layers 1B and 2B may be, for example, entirely crystallized, or may be made of a ferromagnetic element, boron, and additive element.

[0043] The ferromagnetic element is at least one magnetic element selected from the group consisting of Cr, Mn, Co, Fe, and Ni, and the additive element is any element selected from the group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au.

[0044] The alloy containing a ferromagnetic element, boron, and an additive element is, for example, CoFeB-A or CoFeGaGeB-A. CoFeB-A is a CoFeB alloy to which an A element is added as an additive element. CoFeGaGeB-A is a CoFeGaGeB alloy to which an A element is added as an additive element. That is, the A element is an example of an additive element. The A element may penetrate into the crystal structure of CoFeB or may be substituted for any element of the CoFeB crystal. The A element is preferably any element selected from the group consisting of Ti, Ru, and Ta, and is particularly preferably Ta.

[0045] The element A has the property of attracting boron. Among the elements A, Ti, Ru, and Ta have particularly strong this property. As will be described in detail later, when the second layers 1B and 2B contain the element A, boron moves within the second layers 1B and 2B when heated, promoting the crystallization of the second layers 1B and 2B.

[0046] The content of the element A in the second layers 1B, 2B is, for example, greater than the content of boron. The content of the element A is, for example, 0.1 or more in the composition ratio of CoFeB-A. When a sufficient amount of the element A is present, the element A adsorbs the boron in the second layers 1B, 2B without excess or deficiency. As a result, the diffusion of boron from the second layers 1B, 2B to the first layers 1A, 2A can be suppressed. If the first layers 1A, 2A contain boron, the crystallinity of the first layers 1A, 2A decreases, which may cause a decrease in the MR ratio.

[0047] When the second layers 1B, 2B are crystallized CoFeB-A, the Fe content in the second layers 1B, 2B is, for example, greater than the Co content. When the Fe content in the second layers 1B, 2B increases, the Co element in the first layers 1A, 2A can be prevented from diffusing into the second layers 1B, 2B during annealing. Since the Co element in the first layers 1A, 2A does not diffuse from the X site, the crystal structure of the first layers 1A, 2A becomes the L21 structure, the C1 b It can be either L21 structure or B2 structure. b The B1 structure and the B2 structure have high crystallinity, and the magnetoresistance effect element 10 including the first layers 1A, 2A having these crystal structures exhibits a large MR ratio.

[0048] The nonmagnetic layer 3 is made of, for example, a nonmagnetic metal. The nonmagnetic layer 3 is, for example, a metal or alloy containing any element selected from the group consisting of Cu, Au, Ag, Al, and Cr. The nonmagnetic layer 3 contains, for example, any element selected from the group consisting of Cu, Au, Ag, Al, and Cr as a main constituent element. The main constituent element means that the proportion of Cu, Au, Ag, Al, and Cr in the composition formula is 50% or more. The nonmagnetic layer 3 preferably contains Ag, and preferably contains Ag as a main constituent element. Since Ag has a long spin diffusion length, the magnetoresistance effect element 10 using Ag exhibits a large MR ratio.

[0049] The nonmagnetic layer 3 has a thickness in the range of, for example, 1 nm to 10 nm. The nonmagnetic layer 3 inhibits magnetic coupling between the first ferromagnetic layer 1 and the second ferromagnetic layer 2.

[0050] The nonmagnetic layer 3 may be an insulator or a semiconductor. Examples of nonmagnetic insulators include Al2O3, SiO2, MgO, MgAl2O4, and materials in which a part of Al, Si, and Mg is replaced with Zn, Be, or the like. These materials have a large band gap and excellent insulating properties. When the nonmagnetic layer 3 is made of a nonmagnetic insulator, the nonmagnetic layer 3 is a tunnel barrier layer. Examples of nonmagnetic semiconductors include Si, Ge, CuInSe2, CuGaSe2, and Cu(In,Ga)Se2.

[0051] Next, a description will be given of a method for manufacturing the magnetoresistance effect element 10. The method for manufacturing the magnetoresistance effect element 10 includes a film formation step for each layer and an annealing step after the film formation. In the annealing step, the ferromagnetic element, boron, and element A are crystallized.

[0052] 3 is a schematic diagram for explaining a method for manufacturing the magnetoresistance effect element 10 according to the first embodiment. First, a substrate Sub is prepared as a base for film formation. The substrate Sub may be crystalline or amorphous. Examples of crystalline substrates include metal oxide single crystal, silicon single crystal, and sapphire single crystal. Examples of amorphous substrates include silicon single crystal with a thermal oxide film, ceramic, and quartz glass.

[0053] Next, the second layer 11B, the first layer 11A, the nonmagnetic layer 13, the first layer 12A, and the second layer 12B are laminated in this order on the substrate Sub. These layers are formed by, for example, a sputtering method.

[0054] The second layers 11B and 12B are both made of an alloy containing the above-mentioned ferromagnetic element, boron, and element A. The second layers 11B and 12B are both amorphous after deposition. The first layers 11A and 12A are both made of the above-mentioned Co-based Heusler alloy. The first layers 11A and 12A grow on an amorphous underlayer, and therefore grow in the (110) direction in which they are more likely to grow. As a result, the first layers 11A and 12A become crystals with low crystallinity. The nonmagnetic layer 13 is made of the same material as the nonmagnetic layer 3 described above.

[0055] Next, the laminate stacked on the substrate Sub is annealed. The annealing temperature is, for example, 300° C. or less, for example, 250° C. or more and 300° C. or less.

[0056] When the stack is annealed, in the second layers 11B and 12B, boron contained in the ferromagnetic element, boron, and element A is attracted to the element A. The boron is attracted to the element A and diffuses in the second layers 11B and 12B. As the boron diffuses in the second layers 11B and 12B, it mixes with the atoms in the second layers 11B and 12B. The mixed atoms are rearranged, and the second layers 11B and 12B are crystallized.

[0057] Both of the second layers 11B and 12B have a bcc type crystal structure. In the process in which the second layers 11B and 12B each become a bcc type crystal structure, the atoms contained in the first layers 11A and 12A also rearrange. The atoms contained in the first layers 11A and 12A are influenced by the crystal structure of the adjacent second layer 11B or second layer 12B and rearrange, and the first layers 11A and 12A each crystallize. In other words, the first layers 11A and 12A are influenced by the crystallization of the second layers 11B and 12B, respectively, and become highly crystalline as they become more ordered.

[0058] As described above, by annealing the stack, the second layers 11B and 12B are crystallized to become the second layers 1B and 2B, and the first layers 11A and 12A are crystallized to become the first layers 1A and 2A. In addition, the nonmagnetic layer 13 becomes the nonmagnetic layer 3. As a result, the magnetoresistance effect element 10 shown in FIG. 1 is obtained.

[0059] As described above, by using the manufacturing method of the magnetoresistance effect element 10 according to this embodiment, the Heusler alloy can be crystallized regardless of the crystal structure of the base. Here, the manufacturing method of the magnetoresistance effect element 10 has been introduced as one step, but the above method can also be applied to a method of crystallizing a single ferromagnetic layer. For example, a crystalline Heusler alloy can be obtained by stacking a layer of an alloy containing a ferromagnetic element, boron, and element A and a ferromagnetic layer containing a Heusler alloy and heating them.

[0060] In the method for manufacturing the magnetoresistance effect element 10 according to this embodiment, the first ferromagnetic layer 1 and the second ferromagnetic layer 2 are crystallized at a low temperature of 300° C. or less. If the temperature is 300° C. or less, even if annealing is performed after other components of a magnetic head are fabricated, adverse effects on the other components (e.g., a magnetic shield) can be reduced. Therefore, there is no restriction on the timing of annealing, which facilitates the manufacture of elements such as a magnetic head.

[0061] In the magnetoresistance effect element 10 according to this embodiment, the first ferromagnetic layer 1 and the second ferromagnetic layer 2 sandwiching the nonmagnetic layer 3 are crystallized. Therefore, the first ferromagnetic layer 1 and the second ferromagnetic layer 2 exhibit high spin polarization. As a result, the magnetoresistance effect element 10 according to this embodiment exhibits a high MR ratio.

[0062] The above describes the embodiments of the present invention in detail with reference to the drawings. However, each configuration and combination thereof in each embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention.

[0063] For example, FIG. 4 is a cross-sectional view of a magnetoresistance effect element 10A according to a first modification. In the magnetoresistance effect element 10A shown in FIG. 4, only the first ferromagnetic layer 1 has a first layer 1A and a second layer 1B. Although FIG. 4 shows an example in which only the first ferromagnetic layer 1 has a first layer and a second layer, only the second ferromagnetic layer 2 may have a first layer and a second layer. In this case, the remaining ferromagnetic layer may be, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, an alloy containing these metals and at least one element selected from B, C, and N, or a Heusler alloy. For example, the composition of the remaining ferromagnetic layer is Co-Fe, Co-Fe-B.

[0064] For example, the magnetoresistance effect element may have layers other than the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the nonmagnetic layer 3.

[0065] Fig. 5 is a cross-sectional view of a magnetoresistive effect element 10B according to Modification Example 2. The magnetoresistive effect element 10B shown in Fig. 5 differs from the magnetoresistive effect element 10 shown in Fig. 1 in that it has boron absorption layers 4 and 5.

[0066] The boron absorption layers 4 and 5 are non-magnetic layers. The boron absorption layers 4 and 5 each contain boron and any element selected from the group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au. Hereinafter, Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au are the same as the above-mentioned element A. However, the element A contained in the boron absorption layers 4 and 5 does not need to be the same as the element A contained in the second layers 1B and 2B.

[0067] The boron absorption layers 4 and 5 are, for example, formed by adding boron to a metal or alloy composed of the element A. The boron absorption layers 4 and 5 preferably contain any element selected from the group consisting of Ti, Ru, and Ta among the elements A. The boron absorption layers 4 and 5 are, for example, formed by adding boron or carbon to a metal or alloy containing any element selected from the group consisting of Ti, Ru, and Ta.

[0068] The boron absorption layers 4 and 5 do not contain boron during the film formation process, for example. In other words, the boron absorption layers 4 and 5 before the annealing process are, for example, a metal or alloy of element A. As described above, element A has the property of attracting boron. The boron absorption layers 4 and 5 contain boron because element A attracts boron during annealing.

[0069] The boron absorption layers 4 and 5 suppress the diffusion of boron into the first layers 1A and 2A and the nonmagnetic layer 3 during annealing. When the first layers 1A and 2A contain boron, the crystallinity of the first layers 1A and 2A decreases, and the MR ratio of the magnetoresistance effect element 10 decreases. When the nonmagnetic layer 3 contains boron, the crystallinity of the nonmagnetic layer 3 decreases, and the MR ratio of the magnetoresistance effect element 10B decreases. In other words, the boron absorption layers 4 and 5 prevent boron contained in the second layers 1B and 2B from diffusing into the first layers 1A and 2A and the nonmagnetic layer 3, and suppress the decrease in the MR ratio of the magnetoresistance effect element 10B.

[0070] Fig. 6 is a cross-sectional view of a magnetoresistance effect element 10C according to Modification Example 3. The magnetoresistance effect element 10C shown in Fig. 6 differs from the magnetoresistance effect element 10 shown in Fig. 1 in that it has buffer layers 6 and 7.

[0071] The buffer layers 6 and 7 are layers containing a NiAl alloy or Ni. The buffer layer 6 is a buffer layer that reduces the lattice mismatch between the first ferromagnetic layer 1 and the nonmagnetic layer 3. The buffer layer 7 is a buffer layer that reduces the lattice mismatch between the nonmagnetic layer 3 and the second ferromagnetic layer 2.

[0072] The buffer layers 6 and 7 each have a thickness t, for example, where 0 < t ≤ 0.63 nm. If the thickness t becomes too thick, there is a risk that electrons moving from the first ferromagnetic layer 1 (or the second ferromagnetic layer 2) to the second ferromagnetic layer 2 (or the first ferromagnetic layer 1) will be spin-scattered. When the thickness t is within this range, spin scattering of the moving electrons is suppressed, the lattice mismatch between the first ferromagnetic layer 1 and the nonmagnetic layer 3 is reduced, and the lattice mismatch between the nonmagnetic layer 3 and the second ferromagnetic layer 2 is reduced. When the lattice mismatch of each layer becomes smaller, the MR ratio of the magnetoresistive effect element 10C improves. In FIG. 6, an example in which the magnetoresistive effect element 10C has both buffer layers 6 and 7 is shown, but the magnetoresistive effect element may have only at least one of the buffer layers 6 and 7.

[0073] In the above, the first to third modified examples have been shown, but these are also merely examples of the magnetoresistive effect element according to the present embodiment. For example, the characteristic configurations of the first to third modified examples may be combined respectively.

[0074] The above magnetoresistive effect elements 10, 10A, 10B, and 10C can be used in various applications. The magnetoresistive effect elements 10, 10A, 10B, and 10C can be applied to, for example, magnetic heads, magnetic sensors, magnetic memories, high-frequency filters, and the like.

[0075] Next, an application example of the magnetoresistive effect element according to the present embodiment will be described. In the following application example, the magnetoresistive effect element 10 is used as the magnetoresistive effect element, but the magnetoresistive effect element is not limited thereto.

[0076] FIG. 7 is a cross-sectional view of a magnetic recording element 100 according to Application Example 1. FIG. 7 is a cross-sectional view of the magnetoresistive effect element 10 cut along the stacking direction.

[0077] As shown in Fig. 7, the magnetic recording element 100 has a magnetic head MH and a magnetic recording medium W. In Fig. 7, one direction in which the magnetic recording medium W extends is the X direction, and a direction perpendicular to the X direction is the Y direction. The XY plane is parallel to the main surface of the magnetic recording medium W. The direction connecting the magnetic recording medium W and the magnetic head MH and perpendicular to the XY plane is the Z direction.

[0078] The magnetic head MH has an air bearing surface (air bearing surface: medium facing surface) S facing the surface of the magnetic recording medium W. The magnetic head MH moves in the directions of arrows +X and -X along the surface of the magnetic recording medium W at a position a certain distance away from the magnetic recording medium W. The magnetic head MH has a magnetoresistive effect element 10 that acts as a magnetic sensor and a magnetic recording section (not shown). A resistance measuring device 21 measures the resistance value of the magnetoresistive effect element 10 in the stacking direction.

[0079] The magnetic recording unit applies a magnetic field to the recording layer W1 of the magnetic recording medium W and determines the direction of magnetization of the recording layer W1. That is, the magnetic recording unit performs magnetic recording on the magnetic recording medium W. The magnetoresistance effect element 10 reads the information on the magnetization of the recording layer W1 written by the magnetic recording unit.

[0080] The magnetic recording medium W has a recording layer W1 and a backing layer W2. The recording layer W1 is the part where magnetic recording is performed, and the backing layer W2 is a magnetic path (path of magnetic flux) that returns the magnetic flux for writing to the magnetic head MH. The recording layer W1 records magnetic information as the direction of magnetization.

[0081] The second ferromagnetic layer 2 of the magnetoresistance effect element 10 is, for example, a magnetization free layer. Therefore, the second ferromagnetic layer 2 exposed to the air bearing surface S is affected by the magnetization recorded in the recording layer W1 of the opposing magnetic recording medium W. For example, in FIG. 7, the magnetization direction of the second ferromagnetic layer 2 is influenced by the magnetization of the recording layer W1 oriented in the +z direction, and is oriented in the +z direction. In this case, the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2, which are magnetization fixed layers, are parallel to each other.

[0082] Here, the resistance when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 are parallel is different from the resistance when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 are antiparallel. The larger the difference between the resistance value when parallel and the resistance value when antiparallel, the larger the MR ratio of the magnetoresistance effect element 10. The magnetoresistance effect element 10 according to this embodiment contains a crystallized Heusler alloy and has a large MR ratio. Therefore, the resistance measuring device 21 can accurately read out information on the magnetization of the recording layer W1 as a change in resistance value.

[0083] The shape of the magnetoresistive element 10 of the magnetic head MH is not particularly limited. For example, in order to avoid the influence of the leakage magnetic field of the magnetic recording medium W on the first ferromagnetic layer 1 of the magnetoresistive element 10, the first ferromagnetic layer 1 may be disposed at a position away from the magnetic recording medium W.

[0084] Fig. 8 is a cross-sectional view of the magnetic recording element 101 according to Application Example 2. Fig. 8 is a cross-sectional view of the magnetic recording element 101 cut along the lamination direction.

[0085] 8, the magnetic recording element 101 includes a magnetoresistive element 10, a power supply 22, and a measurement unit 23. The power supply 22 applies a potential difference in the stacking direction of the magnetoresistive element 10. The power supply 22 is, for example, a DC power supply. The measurement unit 23 measures the resistance value of the magnetoresistive element 10 in the stacking direction.

[0086] When a potential difference is generated between the first ferromagnetic layer 1 and the second ferromagnetic layer 2 by the power supply 22, a current flows in the stacking direction of the magnetoresistance effect element 10. The current is spin polarized when passing through the first ferromagnetic layer 1, and becomes a spin polarized current. The spin polarized current reaches the second ferromagnetic layer 2 through the nonmagnetic layer 3. The magnetization of the second ferromagnetic layer 2 is reversed by receiving a spin transfer torque (STT) caused by the spin polarized current. The resistance value in the stacking direction of the magnetoresistance effect element 10 changes as the relative angle between the magnetization direction of the first ferromagnetic layer 1 and the magnetization direction of the second ferromagnetic layer 2 changes. The resistance value in the stacking direction of the magnetoresistance effect element 10 is read by the measuring unit 23. That is, the magnetic recording element 101 shown in FIG. 8 is a spin transfer torque (STT) type magnetic recording element.

[0087] The magnetic recording element 101 shown in FIG. 8 includes a crystallized Heusler alloy and is provided with a magnetoresistance effect element 10 having a large MR ratio, and therefore can accurately record data.

[0088] Fig. 9 is a cross-sectional view of the magnetic recording element 102 according to Application Example 3. Fig. 9 is a cross-sectional view of the magnetic recording element 102 cut along the stacking direction.

[0089] As shown in FIG. 9, the magnetic recording element 102 has a magnetoresistive element 10, a spin orbit torque wiring 8, a power supply 22, and a measurement unit 23. The spin orbit torque wiring 8 contacts, for example, the second layer 1B of the first ferromagnetic layer 1. The spin orbit torque wiring 8 extends in one in-plane direction. The power supply 22 is connected to a first end and a second end of the spin orbit torque wiring 8. The first end and the second end sandwich the magnetoresistive element 10 in a planar view. The power supply 22 passes a write current along the spin orbit torque wiring 8. The measurement unit 23 measures the resistance value of the magnetoresistive element 10 in the stacking direction.

[0090] When a potential difference is generated between the first and second ends of the spin orbit torque wire 8 by the power supply 22, a current flows in the in-plane direction of the spin orbit torque wire 8. The spin orbit torque wire 8 has a function of generating a spin current by the spin Hall effect when a current flows. The spin orbit torque wire 8 includes, for example, any of a metal, an alloy, an intermetallic compound, a metal boride, a metal carbide, a metal silicide, and a metal phosphide that has a function of generating a spin current by the spin Hall effect when a current flows. For example, the wire includes a non-magnetic metal having an atomic number of 39 or more and having d electrons or f electrons in the outermost shell.

[0091] When a current flows in the in-plane direction of the spin orbit torque wire 8, the spin Hall effect occurs due to spin orbit interaction. The spin Hall effect is a phenomenon in which moving spins are bent in a direction perpendicular to the direction of current flow. The spin Hall effect creates a localized distribution of spins in the spin orbit torque wire 8, inducing a spin current in the thickness direction of the spin orbit torque wire 8. Spins are injected from the spin orbit torque wire 8 into the first ferromagnetic layer 1 by the spin current.

[0092] The spins injected into the first ferromagnetic layer 1 apply a spin orbit torque (SOT) to the magnetization of the first ferromagnetic layer 1. The first ferromagnetic layer 1 undergoes magnetization reversal upon receiving the spin orbit torque (SOT). In this case, the first ferromagnetic layer 1 becomes a magnetization free layer, and the second ferromagnetic layer 2 becomes a magnetization fixed layer. The resistance value in the stacking direction of the magnetoresistance effect element 10 changes as the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 change. The resistance value in the stacking direction of the magnetoresistance effect element 10 is read by the measuring unit 23. That is, the magnetic recording element 102 shown in FIG. 9 is a spin orbit torque (SOT) type magnetic recording element.

[0093] The magnetic recording element 102 shown in FIG. 9 includes a crystallized Heusler alloy and is provided with a magnetoresistance effect element 10 with a large MR ratio, and therefore can accurately record data.

[0094] 10 is a cross-sectional view of a domain wall motion element (domain wall motion type magnetic recording element) according to application example 4. The domain wall motion element 103 has a magnetoresistive effect element 10, a first magnetization fixed layer 24, and a second magnetization fixed layer 25. The magnetoresistive effect element 10 is made up of a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a non-magnetic layer 3. In FIG. 10, the direction in which the first ferromagnetic layer 1 extends is the X direction, the direction perpendicular to the X direction is the Y direction, and the direction perpendicular to the XY plane is the Z direction.

[0095] The first magnetization pinned layer 24 and the second magnetization pinned layer 25 are connected to a first end and a second end of the first ferromagnetic layer 1. The first end and the second end sandwich the second ferromagnetic layer 2 and the nonmagnetic layer 3 in the X direction.

[0096] The first ferromagnetic layer 1 is a layer capable of magnetically recording information by changing the internal magnetic state. The first ferromagnetic layer 1 has a first magnetic domain MD1 and a second magnetic domain MD2 inside. The magnetization of the first ferromagnetic layer 1 at a position overlapping the first magnetization fixed layer 24 or the second magnetization fixed layer 25 in the Z direction is fixed in one direction. The magnetization of the position overlapping the first magnetization fixed layer 24 in the Z direction is fixed in the +Z direction, for example, and the magnetization of the position overlapping the second magnetization fixed layer 25 in the Z direction is fixed in the -Z direction, for example. As a result, a domain wall DW is formed at the boundary between the first magnetic domain MD1 and the second magnetic domain MD2. The first ferromagnetic layer 1 can have a domain wall DW inside. The first ferromagnetic layer 1 shown in FIG. 10 has a magnetization M of the first magnetic domain MD1. MD1 is oriented in the +Z direction, and the magnetization M of the second magnetic domain MD2 MD2 is oriented in the -Z direction.

[0097] The domain wall motion element 103 can record data in multiple values ​​or continuously depending on the position of the domain wall DW of the first ferromagnetic layer 1. The data recorded in the first ferromagnetic layer 1 is read out as a change in the resistance value of the domain wall motion element 103 when a read current is applied.

[0098] The ratio of the first magnetic domain MD1 to the second magnetic domain MD2 in the first ferromagnetic layer 1 changes when the domain wall DW moves. The magnetization M2 of the second ferromagnetic layer 2 is, for example, the magnetization M of the first magnetic domain MD1. MD1 The magnetization M of the second magnetic domain MD2 is in the same direction (parallel) as MD2 The direction is opposite (anti-parallel to) that of the first magnetic domain MD1. When the domain wall DW moves in the +X direction and the area of ​​the first magnetic domain MD1 at the portion overlapping with the second ferromagnetic layer 2 in plan view from the Z direction becomes larger, the resistance value of the domain wall motion element 103 becomes lower. Conversely, when the domain wall DW moves in the -X direction and the area of ​​the second magnetic domain MD2 at the portion overlapping with the second ferromagnetic layer 2 in plan view from the Z direction becomes larger, the resistance value of the domain wall motion element 103 becomes higher.

[0099] The domain wall DW moves when a write current is applied in the X direction of the first ferromagnetic layer 1 or when an external magnetic field is applied. For example, when a write current (e.g., a current pulse) is applied in the +X direction of the first ferromagnetic layer 1, electrons flow in the -X direction opposite to the current, and the domain wall DW moves in the -X direction. When a current flows from the first magnetic domain MD1 to the second magnetic domain MD2, electrons spin-polarized in the second magnetic domain MD2 are polarized by the magnetization M of the first magnetic domain MD1. MD1 The magnetization of the first magnetic domain MD1 is reversed. MD1 When the magnetization is reversed, the domain wall DW moves in the -X direction.

[0100] The domain wall motion element 103 shown in FIG. 10 includes a crystallized Heusler alloy and is provided with a magnetoresistance effect element 10 having a large MR ratio, and therefore data can be recorded accurately.

[0101] 11 is a schematic diagram of a high-frequency device 104 according to Application Example 5. As shown in FIG. 11, the high-frequency device 104 includes the magnetoresistance effect element 10, a DC power supply 26, an inductor 27, a capacitor 28, an output port 29, and wirings 30 and 31.

[0102] The wiring 30 connects the magnetoresistance effect element 10 and the output port 29. The wiring 31 branches off from the wiring 30 and leads to the ground G via the inductor 27 and the DC power supply 26. The DC power supply 26, the inductor 27, and the capacitor 28 can be publicly known. The inductor 27 cuts the high-frequency components of the current and passes the constant components of the current. The capacitor 28 passes the high-frequency components of the current and cuts the constant components of the current. The inductor 27 is disposed in a portion where it is desired to suppress the flow of high-frequency current, and the capacitor 28 is disposed in a portion where it is desired to suppress the flow of DC current.

[0103] When an AC current or an AC magnetic field is applied to the ferromagnetic layer included in the magnetoresistance effect element 10, the magnetization of the second ferromagnetic layer 2 precesses. The magnetization of the second ferromagnetic layer 2 oscillates strongly when the frequency of the high-frequency current or high-frequency magnetic field applied to the second ferromagnetic layer 2 is close to the ferromagnetic resonance frequency of the second ferromagnetic layer 2, and does not oscillate much at frequencies far from the ferromagnetic resonance frequency of the second ferromagnetic layer 2. This phenomenon is called the ferromagnetic resonance phenomenon.

[0104] The resistance value of the magnetoresistance effect element 10 changes due to the vibration of the magnetization of the second ferromagnetic layer 2. A DC power supply 26 applies a DC current to the magnetoresistance effect element 10. The DC current flows in the stacking direction of the magnetoresistance effect element 10. The DC current flows through the wiring 30, 31 and the magnetoresistance effect element 10 to the ground G. The potential of the magnetoresistance effect element 10 changes according to Ohm's law. A high-frequency signal is output from an output port 29 in response to the change in potential (change in resistance value) of the magnetoresistance effect element 10.

[0105] The high-frequency device 104 shown in FIG. 11 includes a magnetoresistance effect element 10 that contains a crystallized Heusler alloy and has a large change range in resistance value, and therefore can transmit a high-frequency signal with a large output. EXAMPLES

[0106] Example 1 As Example 1, a magnetoresistance effect element 10 shown in FIG. 1 was fabricated. The first ferromagnetic layer 1 and the second ferromagnetic layer 2 are respectively composed of first layers 1A and 2A and second layers 1B and 2B. The first layers 1A and 2A are crystallized Co-based Heusler alloys with a composition ratio of Co2FeGa 0.5 Ge 0.5 The second layers 1B and 2B are crystallized CoFeB-A, with a composition ratio of (Co 0.4 Fe 0.4 B 0.2 ) 0.9 Ta 0.1 The nonmagnetic layer 3 was made of Ag.

[0107] The magnetoresistance effect element 10 according to Example 1 was fabricated by the following procedure. First, the second layer 1B, the first layer 1A, the nonmagnetic layer 3, the first layer 2A, and the second layer 2B having the above composition were formed in this order on an amorphous substrate by sputtering. After the formation, the first layers 1A and 2A were crystalline with low crystallinity, and the second layers 1B and 2B were amorphous.

[0108] Next, the laminated body was annealed. The annealing was performed for 10 hours at 300° C. The second layers 1B and 2B were crystallized by the annealing, and the crystallinity of the first layers 1A and 2A was improved with the crystallization of the second layers 1B and 2B.

[0109] The MR ratio and RA (sheet resistance) of the magnetoresistance effect element 10 thus fabricated were measured. The MR ratio was measured by monitoring the voltage applied to the magnetoresistance effect element 10 with a voltmeter while sweeping a magnetic field from the outside to the magnetoresistance effect element 10 while a constant current was flowing in the stacking direction of the magnetoresistance effect element 10. The resistance value was measured when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 were parallel, and when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 were antiparallel, and the MR ratio was calculated from the obtained resistance values ​​using the following formula. The MR ratio was measured at 300K (room temperature). MR ratio (%)=(R AP -R P ) / R P ×100 R P is the resistance value when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 are parallel, and R AP is the resistance value when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 are antiparallel.

[0110] RA is the resistance R when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 are parallel. P and the area A of the magnetoresistance effect element 10 in the in-plane direction.

[0111] The magnetoresistive effect element 10 according to Example 1 has an MR ratio of 11% and an RA of 0.08 Ω·μm 2 It was.

[0112] Example 2 In Example 2, the composition of the first layers 1A and 2A is Co2FeGa 0.6 Ge 0.8 The only difference from Example 1 is that the Co-based Heusler alloy constituting the first layers 1A and 2A according to Example 2 has a Co composition ratio that is lower than the stoichiometric composition ratio.

[0113] The magnetoresistive effect element 10 according to Example 2 has an MR ratio of 14% and an RA of 0.09 Ω·μm 2 It was.

[0114] Example 3 In Example 3, the composition of the second layers 1B and 2B was (Co 0.2 Fe 0.6 B 0.2 ) 0.9 Ta 0.1 The only difference from Example 1 is that the Fe content is greater than the Co content in the second layers 1B and 2B according to Example 3.

[0115] The magnetoresistive effect element 10 according to Example 3 has an MR ratio of 13% and an RA of 0.07 Ω·μm 2 It was.

[0116] Example 4 In Example 4, the composition of the first layers 1A and 2A is Co2FeGa 0.6 Ge 0.8 The composition of the second layers 1B and 2B is (Co 0.2 Fe 0.6 B 0.2 ) 0.9 Ta 0.1 The only difference from Example 1 is that the Co-based Heusler alloy constituting the first layers 1A and 2A in Example 4 has a Co composition ratio lower than the stoichiometric composition ratio, and the second layers 1B and 2B have an Fe content higher than the Co content.

[0117] The magnetoresistive effect element 10 according to Example 4 has an MR ratio of 16% and an RA of 0.08 Ω·μm 2 It was.

[0118] Example 5 In Example 5, the composition of the first layers 1A and 2A is Co2FeGa 0.6 Ge 0.8 The composition of the second layers 1B and 2B is (Co 0.2 Fe 0.65 B 0.15 ) 0.85 Ta 0.15 The only difference from Example 1 is that the Co-based Heusler alloy constituting the first layers 1A and 2A according to Example 5 has a Co composition ratio lower than the stoichiometric composition ratio, and the second layers 1B and 2B have a Fe content higher than the Co content. Moreover, Example 5 has a higher Ta content than Examples 1 to 4.

[0119] The magnetoresistive effect element 10 according to Example 5 has an MR ratio of 18% and an RA of 0.11 Ω·μm 2 It was.

[0120] Example 6 In Example 6, the composition of the first layers 1A and 2A is Co2FeGa 0.6 Ge 0.8 The composition of the second layers 1B and 2B is (Co 0.39 Fe 0.19 Ga 0.12 Ge 0.15 B 0.15 ) 0.85 Ta 0.15 The only difference from Example 1 is that the Co-based Heusler alloy constituting the first layers 1A and 2A and the (Co 0.39 Fe 0.19 Ga 0.12 Ge 0.15 B 0.15 ) 0.85 Ta 0.15 The Co composition ratio is less than the stoichiometric composition ratio.

[0121] The magnetoresistive effect element 10 according to Example 6 has an MR ratio of 21% and an RA of 0.13 Ω·μm 2 It was.

[0122] Comparative Example 1 In Comparative Example 1, the composition of the second layers 1B and 2B was (Co 0.4 Fe 0.4 B0.2 ) 0.93 Ta 0.07 This is different from Example 1. Because the Ta content in the second layers 1B and 2B was low, the mixing of atoms in the second layers 1B and 2B was insufficient, and the second layers 1B and 2B remained amorphous. Although the first layers 1A and 2A in Comparative Example 1 were crystallized, the crystallinity was inferior to that of Example 1.

[0123] The magnetoresistive effect element 10 according to Comparative Example 1 has an MR ratio of 5% and an RA of 0.08 Ω·μm 2 It was.

[0124] Comparative Example 2 In Comparative Example 2, the composition of the second layers 1B and 2B was (Co 0.4 Fe 0.4 B 0.2 ) 0.93 Ta 0.07 This is different from Example 2. Because the Ta content in the second layers 1B and 2B was low, the mixing of atoms in the second layers 1B and 2B was insufficient, and the second layers 1B and 2B remained amorphous. Although the first layers 1A and 2A in Comparative Example 1 were crystallized, the crystallinity was inferior to that of Example 2.

[0125] The magnetoresistive effect element 10 according to Comparative Example 2 has an MR ratio of 7% and an RA of 0.08 Ω·μm 2 It was.

[0126] The results of Examples 1 to 6 and Comparative Examples 1 and 2 are summarized in Table 1 below.

[0127] [Table 1] [Explanation of symbols]

[0128] 1...first ferromagnetic layer, 1A, 2A, 11A, 12A...first layer, 1B, 2B, 11B, 12B...second layer, 2...second ferromagnetic layer, 3, 13...non-magnetic layer, 4, 5...boron absorption layer, 6, 7...buffer layer, 8...spin orbit torque wiring, 10, 10A, 10B, 10C...magnetoresistance effect element, 21...resistance measuring device, 22...power supply, 23...measuring unit, 24...first magnetization fixed layer, 25...second magnetization fixed layer, 26...DC power supply, 27...inductor, 28...capacitor, 29...output port, 30, 31...wiring, 100, 101, 102...magnetic recording element, 103...domain wall motion element, 104...high frequency device, DW...domain wall, MD1...first magnetic domain, MD2...second magnetic domain, Sub...substrate

Claims

1. a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer between the first ferromagnetic layer and the second ferromagnetic layer; At least one of the first ferromagnetic layer and the second ferromagnetic layer includes a first layer and a second layer in this order from the side closer to the nonmagnetic layer, the first layer includes a crystallized Co-based Heusler alloy; the second layer is at least partially crystallized and contains a ferromagnetic element, a boron element, and an additive element; The additive element is any element selected from the group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au, The second layer is made of crystallized CoFeB-A... (1), A magnetoresistive element, wherein in formula (1), A is the additive element.

2. The magnetoresistive element according to claim 1 , wherein the first ferromagnetic layer and the second ferromagnetic layer each comprise the first layer and the second layer.

3. The Co-based Heusler alloy has a stoichiometric composition of CoYZ or Co ２ It is written as YZ.

3. The magnetoresistance effect element according to claim 1, wherein the Co-based Heusler alloy has a Co composition ratio lower than the stoichiometric composition ratio.

4. 4. The magnetoresistance effect element according to claim 1, wherein the first layer and the second layer are lattice-matched.

5. a boron absorption layer in contact with a surface of the second layer farther from the nonmagnetic layer; The magnetoresistance effect element according to any one of claims 1 to 4, wherein the boron absorption layer contains any element selected from the group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au.

6. The Co-based Heusler alloy is L2 １ 6. The magnetoresistance effect element according to claim 1, which has a B1 structure or a B2 structure.

7. The Co-based Heusler alloy is ２ Y α Z β It is written as The Y is one or more elements selected from the group consisting of Fe, Mn, and Cr, The Z is one or more elements selected from the group consisting of Si, Al, Ga, and Ge, 7. The magnetoresistance effect element according to claim 1, wherein α+β>2 is satisfied.

8. 8. The magnetoresistance effect element according to claim 1, wherein the non-magnetic layer is a metal or an alloy containing any element selected from the group consisting of Cu, Au, Ag, Al and Cr.

9. Further comprising a substrate; the substrate is a base on which the first ferromagnetic layer, the second ferromagnetic layer, and the nonmagnetic layer are laminated, 9. The magnetoresistance effect element according to claim 1, wherein the substrate is amorphous.

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