Magnetoresistive 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 Art

[0002] A magnetoresistive element is an element whose resistance value in the stacking direction changes due to the magnetoresistive effect. A magnetoresistive element includes two ferromagnetic layers and a nonmagnetic layer sandwiched therebetween. A magnetoresistive element in which a conductor is used for the nonmagnetic layer is called a giant magnetoresistance (GMR) element, and a magnetoresistive element in which an insulating layer (tunnel barrier layer, barrier layer) is used for the nonmagnetic layer is called a tunnel magnetoresistance (TMR) element. Magnetoresistive elements can be applied to various uses 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 magnetoresistive element using a Heusler alloy for the ferromagnetic layer. The Heusler alloy has a high spin polarization rate, and it is expected that the output signal of the magnetic sensor increases. On the other hand, Patent Document 1 describes that the Heusler alloy is difficult to crystallize unless it is formed on a thick under-substrate having a high temperature or a predetermined crystallinity. Patent Document 1 describes that film formation at a high temperature or a thick under-substrate can cause a decrease in the output of the magnetic sensor. Patent Document 1 describes that the output of the magnetic sensor increases by making the ferromagnetic layer have a laminated structure of an amorphous layer and a crystalline layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems 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 magnetoresistive element. Generally, the higher the crystallinity of the ferromagnetic layer sandwiching the non-magnetic layer, the larger the MR ratio tends to be. In the magnetoresistive element described in Patent Document 1, the ferromagnetic layer in contact with the non-magnetic layer is amorphous, making it difficult to obtain a sufficiently large MR ratio.

[0006] This invention has been made in view of the above circumstances, and aims to provide a magnetoresistive element that can achieve a large MR ratio. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides the following means.

[0008] (1) The magnetoresistive element according to the first embodiment comprises a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer between the first ferromagnetic layer and the second ferromagnetic layer, wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer comprises a first layer and a second layer in order from the side closest to the non-magnetic layer, the first layer comprises a crystallized Co-based Heusler alloy, and the second layer is at least partially crystallized and comprises a ferromagnetic element, a boron element and an additive element, the additive element being 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 embodiment, the first ferromagnetic layer and the second ferromagnetic layer may both comprise the first layer and the second layer.

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

[0011] (4) The second layer of the magnetoresistive element according to the above embodiment is made of crystallized CoFeB-A, and the Fe content in the second layer may be greater than the Co content.

[0012] (5) The second layer of the magnetoresistive element according to the above embodiment may contain more of the additive element than the boron content.

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

[0014] (7) In the magnetoresistive element according to the above embodiment, the second layer has a boron absorption layer in contact with the surface of the second layer that is farther from the non-magnetic 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 magnetoresistive element according to the above embodiment, the Co-based Heusler alloy may have an L21 structure or a B2 structure.

[0016] (9) In the magnetoresistive element according to the above embodiment, the Co-based Heusler alloy is Co2Y α Z β The expression is denoted as follows, where 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 element according to the above embodiment, a buffer layer is provided between the first ferromagnetic layer and the non-magnetic layer, and between the second ferromagnetic layer and the non-magnetic layer, wherein the buffer layer may contain a NiAl alloy or Ni.

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

[0019] (12) In the magnetoresistive element according to the above embodiment, the non-magnetic layer may be a metal or 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 embodiment further comprises a substrate, the substrate being a base on which the first ferromagnetic layer, the second ferromagnetic layer, and the non-magnetic layer are laminated, and the substrate may be amorphous. [Effects of the Invention]

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

[0022] [Figure 1] This is a cross-sectional view of a magnetoresistive element according to the first embodiment. [Figure 2] This is a diagram showing the crystal structure of Heusler alloy. [Figure 3] This is a cross-sectional view illustrating a method for manufacturing a magnetoresistive element according to the first embodiment. [Figure 4] This is a cross-sectional view of a magnetoresistive element according to a first modification of the first embodiment. [Figure 5] This is a cross-sectional view of a magnetoresistive element according to a second modification of the first embodiment. [Figure 6] This is a cross-sectional view of a magnetoresistive element according to a third modified example of the first embodiment. [Figure 7] This is a cross-sectional view of the magnetic recording element according to Application Example 1. [Figure 8] This is a cross-sectional view of the magnetic recording element according to Application Example 2. [Figure 9] This is a cross-sectional view of the magnetic recording element according to Application Example 3. [Figure 10] This is a cross-sectional view of the magnetic domain wall moving element according to Application Example 4. [Figure 11] This is a cross-sectional view of the high-frequency device according to Application Example 5. [Modes for carrying out the invention]

[0023] This embodiment will now be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience to clearly illustrate the features of this embodiment, and the dimensional ratios of each component may differ from those of the actual components. The materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not limited to them. It can be implemented with appropriate modifications without altering its essence.

[0024] "First Embodiment" Figure 1 is a cross-sectional view of a magnetoresistive element according to the first embodiment. First, let's define the direction. The direction in which each layer is stacked is sometimes called the stacking direction. Also, the direction in which each layer extends, intersecting the stacking direction, is sometimes called the in-plane direction.

[0025] The magnetoresistive element 10 shown in Figure 1 comprises a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a non-magnetic layer 3. The non-magnetic layer 3 is located between the first ferromagnetic layer 1 and the second ferromagnetic layer 2.

[0026] The magnetoresistive element 10 outputs a change in resistance value based on the change in the relative angle between the magnetization of the first ferromagnetic layer 1 and the magnetization of the second ferromagnetic layer 2. The magnetization of the second ferromagnetic layer 2 is, for example, more mobile 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 (it is fixed), while the direction of the magnetization of the second ferromagnetic layer 2 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, the resistance value of the magnetoresistive element 10 changes. In this case, the first ferromagnetic layer 1 is sometimes called the fixed magnetization layer, and the second ferromagnetic layer 2 is sometimes called the free magnetization layer. In the following explanation, the first ferromagnetic layer 1 will be described as the fixed magnetization layer and the second ferromagnetic layer 2 as the free magnetization layer, but this relationship can also 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 predetermined external force is applied is due to the difference in coercivity between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. For example, if the thickness of the second ferromagnetic layer 2 is made thinner than the thickness of the first ferromagnetic layer 1, the coercivity of the second ferromagnetic layer 2 will be smaller than that of the first ferromagnetic layer 1. Alternatively, for example, an antiferromagnetic layer may be provided on the side of the first ferromagnetic layer 1 opposite to the non-magnetic 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 consists of two magnetic layers sandwiching a spacer layer. The antiferromagnetic coupling between the first ferromagnetic layer 1 and the antiferromagnetic layer increases the coercivity of the first ferromagnetic layer 1 compared to the case without the antiferromagnetic layer. The antiferromagnetic layer can be, for example, IrMn, PtMn, etc. 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 contain a ferromagnetic material. The first ferromagnetic layer 1 and the second ferromagnetic layer 2 of the magnetoresistive element 10 shown in Figure 1 each have a first layer 1A, 2A and a second layer 1B, 2B. The first ferromagnetic layer 1 has a first layer 1A and a second layer 1B, in order from the side closest to the non-magnetic layer 3. The second ferromagnetic layer 2 has a first layer 2A and a second layer 2B, in order from the side closest to the non-magnetic layer 3.

[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 matching means that at the interface between the first layer 1A and the second layer 1B, and at the interface between the first layer 2A and the second layer 2B, atoms are continuously arranged in the stacking direction. The degree of lattice matching between the first layer 1A and the second layer 1B, or between 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 constants of the second layers 1B and 2B relative to the lattice constants of the first layers 1A and 2A. 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 magnetoresistive element 10 increases.

[0030] The first layers 1A and 2A each contain a crystalline Co-based Heusler alloy. Each of the first layers 1A and 2A is, for example, made of a Co-based Heusler alloy, and at least a portion of the Co-based Heusler alloy is crystalline. Each of the first layers 1A and 2A may also consist entirely of a crystalline Co-based Heusler alloy.

[0031] Heusler alloys are intermetallic compounds with a chemical composition of XYZ or X2YZ. Ferromagnetic Heusler alloys denoted as X2YZ are called full Heusler alloys, while ferromagnetic Heusler alloys denoted as XYZ are called half Heusler alloys. Half Heusler alloys are full Heusler alloys in which some of the atoms at the X site have vacancies. In both cases, they are typically intermetallic compounds based on a bcc structure.

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

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

[0034] Figure 2(d) shows C1 b This is called structure. C1 b The structure has fixed elements in the X site, Y site, and Z site. Figure 2(e) shows C1 b This is called a structurally derived B2 structure. In a B2 structure, elements that would normally occupy the Y site and elements that would normally occupy the Z site are mixed, while the elements that would normally occupy the X site are fixed. Figure 2(f) shows C1 bThis is called a structurally derived A2 structure. In an A2 structure, elements that would normally be in the X site, Y site, and Z site are all present together.

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

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

[0037] The compositional analysis of each layer constituting a magnetoresistive element can be performed using energy-dispersive X-ray spectroscopy (EDS). Furthermore, EDS analysis allows for, for example, confirmation of the compositional distribution of each material in the film thickness direction.

[0038] The Co-based Heusler alloy is a Heusler alloy in which the above X site is Co. Y is a transition metal of the Mn, V, Cr, Ti group or a transition metal element or noble metal element of the Co, Fe, Ni, Cu group, and Z is a typical element from Group III to Group 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, Co2FeGe x Ga 1-x , Co2MnSi, Co2MnGe, Co2MnGa, Co2MnSn, Co2MnAl, Co2CrAl, Co2VAl, Co2Mn 1-a Fe a Al b Si 1-b , etc. Half Heusler alloys include, for example, 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 represented, for example, by Co2Y α Z β . The stoichiometric composition Co-based full Heusler alloy is represented by 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. That is, when the Co-based Heusler alloy is a full Heusler alloy, it is preferable to satisfy α + β > 2. When the Co-based Heusler alloy is a half Heusler alloy, the Co-based Heusler alloy constituting the first layers 1A and 2A is represented, for example, by CoY α Z β , and it is preferable to satisfy α + β > 1.

[0041] If the Co composition ratio is relatively low compared to the elements at the Y site, it is possible to avoid antisite formation, where the elements at the Y site are replaced by elements at the X site (the site where Co is located). Antisite formation causes fluctuations in the Fermi level of the Heusler alloy. When the Fermi level fluctuates, the half-metallicity of the Heusler alloy decreases, and the spin polarizability decreases. The decrease in spin polarizability causes a decrease in the MR ratio of the magnetoresistive element 10.

[0042] The second layer 1B and 2B each contain crystalline portions. Furthermore, the second layer 1B and 2B each contain an alloy containing a ferromagnetic element, boron, and additive elements. The second layer may also contain elements other than the ferromagnetic element, boron, and additive elements. The second layer 1B and 2B may each consist, for example, of an alloy of a ferromagnetic element, boron, and additive elements, with at least a portion of the ferromagnetic element, boron, and additive elements being crystalline. The second layer 1B and 2B may each be, for example, entirely crystalline, or consist of a ferromagnetic element, boron, and additive elements.

[0043] The ferromagnetic element is at least one magnetic element selected from the group consisting of, for example, Cr, Mn, Co, Fe, and Ni. 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] Alloys containing ferromagnetic elements, boron, and additive elements include, for example, CoFeB-A and CoFeGaGeB-A. CoFeB-A is a CoFeB alloy with element A added as an additive element. Similarly, CoFeGaGeB-A is a CoFeGaGeB alloy with element A added as an additive element. In other words, element A is just one example of an additive element. Element A may be embedded within the crystal structure of CoFeB, or it may be substituted for any element in the CoFeB crystal. Element A is preferably one of the elements selected from the group consisting of Ti, Ru, and Ta, and is particularly preferably Ta.

[0045] Element A has the property of attracting boron. Among the elements of A, Ti, Ru, and Ta exhibit this property particularly strongly. As will be explained in more detail later, the presence of element A in the second layers 1B and 2B causes boron to move within the second layers 1B and 2B during heating, promoting the crystallization of the second layers 1B and 2B.

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

[0047] If the second layer 1B,2B is crystallized CoFeB-A, the Fe content in the second layer 1B,2B is, for example, greater than the Co content. An increased Fe content in the second layer 1B,2B suppresses the diffusion of Co elements from the first layer 1A,2A into the second layer 1B,2B during annealing. By preventing the Co elements from diffusing from the X site in the first layer 1A,2A, the crystal structure of the first layer 1A,2A becomes an L21 structure, C1 b It will be either a B2 structure or a L21 structure, or a C1 structure. b The B2 structure exhibits high crystallinity, and the magnetoresistive element 10, which has the first layers 1A and 2A of this crystalline structure, shows a large MR ratio.

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

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

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

[0051] Next, a method for manufacturing the magnetoresistive element 10 will be described. The method for manufacturing the magnetoresistive element 10 includes a film deposition step for each layer and an annealing step after film deposition. In the annealing step, the ferromagnetic element, boron, and element A crystallize.

[0052] Figure 3 is a schematic diagram illustrating the manufacturing method of the magnetoresistive element 10 according to the first embodiment. First, a substrate Sub is prepared to serve as the base for film deposition. The substrate Sub may be crystalline or amorphous. Examples of crystalline substrates include metal oxide single crystals, silicon single crystals, and sapphire single crystals. Examples of amorphous substrates include silicon single crystals with a thermal oxide film, ceramics, and quartz glass.

[0053] Next, the second layer 11B, the first layer 11A, the non-magnetic layer 13, the first layer 12A, and the second layer 12B are sequentially stacked on the substrate Sub. These layers are deposited, for example, by sputtering.

[0054] The second layers 11B and 12B are both made of an alloy containing the ferromagnetic element, boron, and element A as described above. Both the second layers 11B and 12B are amorphous after film formation. The first layers 11A and 12A are both the Co-based Heusler alloy as described above. Since the first layers 11A and 12A grow on an amorphous substrate, they grow in the (110) direction, which is their preferred direction of growth. Therefore, the first layers 11A and 12A become crystals with low crystallinity. The non-magnetic layer 13 is made of the same material as the non-magnetic layer 3 described above.

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

[0056] When the laminate is annealed, in the second layer 11B,12B, the ferromagnetic element, boron, and the boron contained in element A are attracted to element A. The boron is attracted to element A and diffuses within the second layer 11B,12B. As the boron diffuses within the second layer 11B,12B, it mixes the atoms within the second layer 11B,12B. The mixed atoms rearrange, and the second layer 11B,12B crystallizes.

[0057] Both the second layers 11B and 12B have a bcc-type crystal structure. During the process in which the second layers 11B and 12B each acquire a bcc-type crystal structure, the atoms contained within the first layers 11A and 12A also rearrange. The atoms contained within the first layers 11A and 12A are rearranged under the influence of the crystal structure of the adjacent second layer 11B or second layer 12B, and the first layers 11A and 12A each crystallize. In other words, each of the first layers 11A and 12A is influenced by the crystallization of the second layers 11B and 12B, leading to increased order and the formation of highly crystalline crystals.

[0058] As described above, by annealing the laminate, the second layers 11B and 12B crystallize to become the second layers 1B and 2B, and the first layers 11A and 12A crystallize to become the first layers 1A and 2A. In addition, the non-magnetic layer 13 becomes the non-magnetic layer 3. As a result, the magnetoresistive element 10 shown in Figure 1 is obtained.

[0059] As described above, the manufacturing method for the magnetoresistive element 10 according to this embodiment allows for the crystallization of the Heusler alloy regardless of the underlying crystal structure. Although this method is presented here as one step in the manufacturing process of the magnetoresistive element 10, it can also be applied to the crystallization of individual ferromagnetic layers. For example, a crystalline Heusler alloy can be obtained by laminating a layer of an alloy containing a ferromagnetic element, boron, and element A with a ferromagnetic layer containing a Heusler alloy and then heating them.

[0060] In the manufacturing method of the magnetoresistive element 10 according to this embodiment, the first ferromagnetic layer 1 and the second ferromagnetic layer 2 crystallize at a low temperature of 300°C or less. At 300°C or less, even if annealing is performed after other components of the magnetic head are manufactured, for example, adverse effects on other components (e.g., magnetic shield) can be reduced. Therefore, the timing of annealing is not restricted, and the manufacturing of elements such as magnetic heads becomes easier.

[0061] Furthermore, in the magnetoresistive element 10 according to this embodiment, the first ferromagnetic layer 1 and the second ferromagnetic layer 2 sandwiching the non-magnetic layer 3 are crystallized. Therefore, the first ferromagnetic layer 1 and the second ferromagnetic layer 2 exhibit high spin polarization. As a result, the magnetoresistive element 10 according to this embodiment exhibits a high MR ratio.

[0062] Although embodiments of the present invention have been described in detail above with reference to the drawings, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention.

[0063] For example, Figure 4 is a cross-sectional view of a magnetoresistive element 10A according to the first modified example. In the magnetoresistive element 10A shown in Figure 4, only the first ferromagnetic layer 1 has a first layer 1A and a second layer 1B. Although Figure 4 shows an example in which only the first ferromagnetic layer 1 has a first layer and a second layer, the second ferromagnetic layer 2 may also 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 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] Furthermore, for example, the magnetoresistive element may have layers other than the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the non-magnetic layer 3.

[0065] Figure 5 is a cross-sectional view of a magnetoresistive element 10B according to a second modified example. The magnetoresistive element 10B shown in Figure 5 differs from the magnetoresistive element 10 shown in Figure 1 in that it has boron absorption layers 4 and 5.

[0066] Boron absorption layers 4 and 5 are non-magnetic layers. Each of the boron absorption layers 4 and 5 contains boron and one of the elements selected from the group consisting of Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au. Hereafter, Ti, V, Cr, Cu, Zn, Zr, Mo, Ru, Pd, Ta, W, Ir, Pt, and Au are the same as the element A described above. However, the element A contained in 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, metals or alloys composed of element A to which boron has been added. Preferably, the boron absorption layers 4 and 5 contain any element selected from the group consisting of Ti, Ru, and Ta among element A. The boron absorption layers 4 and 5 are, for example, metals or alloys containing any element selected from the group consisting of Ti, Ru, and Ta to which boron or carbon has been added.

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

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

[0070] Figure 6 is a cross-sectional view of a magnetoresistive element 10C according to a third modified example. The magnetoresistive element 10C shown in Figure 6 differs from the magnetoresistive element 10 shown in Figure 1 in that it has buffer layers 6 and 7.

[0071] Buffer layers 6 and 7 are layers containing either NiAl alloy or Ni, respectively. Buffer layer 6 is a buffer layer that alleviates the lattice mismatch between the first ferromagnetic layer 1 and the non-magnetic layer 3. Buffer layer 7 is a buffer layer that alleviates the lattice mismatch between the non-magnetic 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 non-magnetic layer 3 is reduced, and the lattice mismatch between the non-magnetic 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 were 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 to this.

[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 Figure 7, the magnetic recording element 100 has a magnetic head MH and a magnetic recording medium W. In Figure 7, the direction in which the magnetic recording medium W extends is defined as the X direction, and the direction perpendicular to the X direction is defined as the Y direction. The XY plane is parallel to the main plane of the magnetic recording medium W. The direction connecting the magnetic recording medium W and the magnetic head MH, which is perpendicular to the XY plane, is defined as the Z direction.

[0078] The magnetic head MH has an air bearing surface (media-facing surface) S facing the surface of the magnetic recording medium W. The magnetic head MH moves along the surface of the magnetic recording medium W in the directions of arrows +X and -X at a position a certain distance away from the magnetic recording medium W. The magnetic head MH has a magnetoresistive element 10 that acts as a magnetic sensor and a magnetic recording section (not shown). The resistance meter 21 measures the resistance value of the magnetoresistive 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. In other words, the magnetic recording unit performs magnetic recording on the magnetic recording medium W. The magnetoresistive element 10 reads the magnetization information 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 that performs magnetic recording, and the backing layer W2 is a magnetic path (magnetic flux path) that returns the magnetic flux for writing back 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 magnetoresistive 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 on the recording layer W1 of the opposing magnetic recording medium W. For example, in Figure 7, the magnetization direction of the second ferromagnetic layer 2 is oriented in the +z direction due to the influence of the magnetization of the recording layer W1 oriented in the +z direction. In this case, the magnetization directions of the first ferromagnetic layer 1, which is a magnetization-fixed layer, and the second ferromagnetic layer 2 become parallel.

[0082] Here, the resistance when the magnetization directions of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 are parallel differs 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 in the parallel case and the resistance value in the antiparallel case, the larger the MR ratio of the magnetoresistive element 10. The magnetoresistive element 10 according to this embodiment contains a crystallized Heusler alloy and has a large MR ratio. Therefore, the magnetization information of the recording layer W1 can be accurately read out as a change in resistance value by the resistance measuring instrument 21.

[0083] There are no particular restrictions on the shape of the magnetoresistive element 10 of the magnetic head MH. 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 placed at a position away from the magnetic recording medium W.

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

[0085] As shown in Figure 8, the magnetic recording element 101 includes a magnetoresistive element 10, a power supply 22, and a measuring 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 measuring 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 magnetoresistive element 10. The current becomes spin-polarized as it passes through the first ferromagnetic layer 1, becoming a spin-polarized current. The spin-polarized current reaches the second ferromagnetic layer 2 via the non-magnetic layer 3. The magnetization of the second ferromagnetic layer 2 is reversed by the spin transfer torque (STT) caused by the spin-polarized current. 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 of the magnetoresistive element 10 in the stacking direction changes. The resistance value of the magnetoresistive element 10 in the stacking direction is read out by the measurement unit 23. In other words, the magnetic recording element 101 shown in Figure 8 is a spin transfer torque (STT) type magnetic recording element.

[0087] The magnetic recording element 101 shown in Figure 8 includes a magnetoresistive element 10 containing a crystallized Heusler alloy and having a high MR ratio, thus enabling accurate data recording.

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

[0089] As shown in Figure 9, the magnetic recording element 102 includes 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 is in contact with, for example, the second layer 1B of the first ferromagnetic layer 1. The spin-orbit torque wiring 8 extends in one direction in the in-plane direction. The power supply 22 is connected to the first and second ends of the spin-orbit torque wiring 8. The first and second ends sandwich the magnetoresistive element 10 in a plan view. The power supply 22 supplies a writing 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 the power supply 22 generates a potential difference between the first and second ends of the spin-orbit torque wiring 8, a current flows in the in-plane direction of the spin-orbit torque wiring 8. The spin-orbit torque wiring 8 has the function of generating a spin current due to the spin Hall effect when current flows. The spin-orbit torque wiring 8 includes, for example, any of the following materials that have the function of generating a spin current due to the spin Hall effect when current flows: metal, alloy, intermetallic compound, metal boride, metal carbide, metal silicide, or metal phosphide. For example, the wiring includes a non-magnetic metal with an atomic number of 39 or higher that has d electrons or f electrons in its outermost shell.

[0091] When current flows in the in-plane direction of the spin-orbit torque wiring 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 spin uneven distribution within the spin-orbit torque wiring 8 and induces a spin current in the thickness direction of the spin-orbit torque wiring 8. The spins are injected from the spin-orbit torque wiring 8 into the first ferromagnetic layer 1 by the spin current.

[0092] The spins injected into the first ferromagnetic layer 1 impart a spin-orbit torque (SOT) to the magnetization of the first ferromagnetic layer 1. The first ferromagnetic layer 1 undergoes magnetization reversal in response to the spin-orbit torque (SOT). In this case, the first ferromagnetic layer 1 becomes the magnetization-free layer, and the second ferromagnetic layer 2 becomes the magnetization-fixed layer. As the direction of magnetization of the first ferromagnetic layer 1 and the direction of magnetization of the second ferromagnetic layer 2 change, the resistance value of the magnetoresistive element 10 in the stacking direction changes. The resistance value of the magnetoresistive element 10 in the stacking direction is read out by the measurement unit 23. In other words, the magnetic recording element 102 shown in Figure 9 is a spin-orbit torque (SOT) type magnetic recording element.

[0093] The magnetic recording element 102 shown in Figure 9 contains a crystallized Heusler alloy and is equipped with a magnetoresistive element 10 with a high MR ratio, thus enabling accurate data recording.

[0094] Figure 10 is a cross-sectional view of a magnetic domain wall moving element (magnetic domain wall moving type magnetic recording element) according to Application Example 4. The magnetic domain wall moving 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 consists of a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a non-magnetic layer 3. In Figure 10, the direction in which the first ferromagnetic layer 1 extends is defined as the X direction, the direction perpendicular to the X direction is defined as the Y direction, and the direction perpendicular to the XY plane is defined as the Z direction.

[0095] The first magnetization fixed layer 24 and the second magnetization fixed layer 25 are connected to the first and second ends of the first ferromagnetic layer 1. The first and second ends sandwich the second ferromagnetic layer 2 and the non-magnetic layer 3 in the X direction.

[0096] The first ferromagnetic layer 1 is a layer capable of magnetically recording information through changes in its 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 with the first magnetization fixed layer 24 or the second magnetization fixed layer 25 in the Z direction is fixed in one direction. For example, the magnetization at the position overlapping with the first magnetization fixed layer 24 in the Z direction is fixed in the +Z direction, and the magnetization at the position overlapping with the second magnetization fixed layer 25 in the Z direction is fixed in the -Z direction. As a result, a magnetic 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 may have a magnetic domain wall DW inside. The first ferromagnetic layer 1 shown in Figure 10 has a magnetization M of the first magnetic domain MD1. MD1 It is oriented in the +Z direction, and the magnetization M of the second magnetic domain MD2 MD2 It is oriented in the -Z direction.

[0097] The magnetic domain wall moving element 103 can record data in multiple levels or continuously depending on the position of the magnetic 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 magnetic domain wall moving element 103 when a readout 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 as the magnetic 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 It is in the same direction (parallel), and the magnetization M of the second magnetic domain MD2 MD2 This is in the opposite direction (antiparallel). When the magnetic domain wall DW moves in the +X direction, and the area of ​​the first magnetic domain MD1 in the part that overlaps with the second ferromagnetic layer 2 in a plan view from the Z direction increases, the resistance of the magnetic domain wall moving element 103 decreases. Conversely, when the magnetic domain wall DW moves in the -X direction, and the area of ​​the second magnetic domain MD2 in the part that overlaps with the second ferromagnetic layer 2 in a plan view from the Z direction increases, the resistance of the magnetic domain wall moving element 103 increases.

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

[0100] The magnetic domain wall moving element 103 shown in Figure 10 includes a magnetoresistive element 10 containing a crystallized Heusler alloy and having a large MR ratio, thus enabling accurate data recording.

[0101] Figure 11 is a schematic diagram of a high-frequency device 104 according to application example 5. As shown in Figure 11, the high-frequency device 104 has a magnetoresistive element 10, a DC power supply 26, an inductor 27, a capacitor 28, an output port 29, and wiring 30, 31.

[0102] Wiring 30 connects the magnetoresistive element 10 to the output port 29. Wiring 31 branches off from wiring 30 and goes to ground G via the inductor 27 and DC power supply 26. The DC power supply 26, inductor 27, and capacitor 28 can be of known type. The inductor 27 cuts the high-frequency component of the current and allows the invariant component to pass through. The capacitor 28 allows the high-frequency component of the current to pass through and cuts the invariant component to pass through. The inductor 27 is placed in the part where you want to suppress the flow of high-frequency current, and the capacitor 28 is placed in the part where you want to suppress the flow of DC current.

[0103] When an alternating current or alternating magnetic field is applied to the ferromagnetic layer contained in the magnetoresistive 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 near the ferromagnetic resonance frequency of the second ferromagnetic layer 2, and oscillates little 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 of the magnetoresistive element 10 changes due to the vibration of the magnetization of the second ferromagnetic layer 2. The DC power supply 26 applies a DC current to the magnetoresistive element 10. The DC current flows in the stacking direction of the magnetoresistive element 10. The DC current flows through the wiring 30, 31 and the magnetoresistive element 10 to ground G. The potential of the magnetoresistive element 10 changes according to Ohm's law. A high-frequency signal is output from the output port 29 in response to the change in the potential (change in resistance) of the magnetoresistive element 10.

[0105] The high-frequency device 104 shown in Figure 11 contains a crystallized Heusler alloy and is equipped with a magnetoresistive element 10 that has a large range of resistance variation, thus enabling it to emit high-frequency signals with a large output. [Examples]

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

[0107] The magnetoresistive element 10 according to Example 1 was fabricated by the following procedure. First, the second layer 1B, the first layer 1A, the non-magnetic layer 3, the first layer 2A, and the second layer 2B were sequentially deposited on an amorphous substrate by sputtering using the sputtering method. After deposition, the first layers 1A and 2A were crystalline with low crystallinity, while the second layers 1B and 2B were amorphous.

[0108] Next, the laminated structure was annealed. The annealing was performed at 300°C for 10 hours. The annealing caused the second layers 1B and 2B to crystallize, and along with the crystallization of the second layers 1B and 2B, the crystallinity of the first layers 1A and 2A also improved.

[0109] The MR ratio and RA (surface resistance) of the fabricated magnetoresistive element 10 were measured. The MR ratio was measured by monitoring the applied voltage to the magnetoresistive element 10 with a voltmeter while sweeping a magnetic field across the magnetoresistive element 10 with a constant current flowing in the stacking direction of the magnetoresistive element 10. The resistance values ​​were 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. 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 This 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 This 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 This was determined by the product of the in-plane areas A of the magnetoresistive element 10.

[0111] The magnetoresistive ratio (MR) of the magnetoresistive element 10 in Example 1 is 11%, and the resistance (RA) is 0.08 Ω·μm 2 That was the case.

[0112] (Example 2) Example 2 is a case where the composition of the first layer 1A,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 in Example 2 has a Co composition ratio less than the stoichiometric composition ratio.

[0113] The magnetoresistive ratio (MR) of the magnetoresistive element 10 in Example 2 is 14%, and the resistance (RA) is 0.09 Ω·μm. 2 That was the case.

[0114] (Example 3) Example 3 is a case where the composition of the second layer 1B, 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 second layers 1B and 2B in Example 3 have a higher Fe content than Co content.

[0115] The magnetoresistive ratio (MR) of the magnetoresistive element 10 in Example 3 is 13%, and the resistance (RA) is 0.07 Ω·μm. 2 That was the case.

[0116] (Example 4) Example 4 is a case where the composition of the first layer 1A,2A is Co2FeGa 0.6 Ge 0.8 The composition of the second layer 1B, 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 less than the stoichiometric composition ratio, and the second layers 1B and 2B have a Fe content greater than the Co content.

[0117] The magnetoresistive ratio (MR) of the magnetoresistive element 10 in Example 4 is 16%, and the resistance (RA) is 0.08 Ω·μm. 2 That was the case.

[0118] (Example 5) Example 5 is a case where the composition of the first layer 1A,2A is Co2FeGa 0.6 Ge 0.8 The composition of the second layer 1B, 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 in Example 5 has a Co composition ratio less than the stoichiometric composition ratio, and the second layers 1B and 2B have a Fe content greater than the Co content. In addition, Example 5 has a higher Ta content compared to Examples 1 to 4.

[0119] The magnetoresistive ratio (MR) of the magnetoresistive element 10 in Example 5 is 18%, and the resistance (RA) is 0.11 Ω·μm. 2 That was the case.

[0120] (Example 6) Example 6 is a case where the composition of the first layer 1A,2A is Co2FeGa 0.6 Ge 0.8 The composition of the second layer 1B, 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) of the second layers 1B and 2B in Example 6. 0.39 Fe 0.19 Ga 0.12 Ge 0.15 B 0.15 ) 0.85 Ta 0.15 In this case, the Co composition ratio is less than the stoichiometric composition ratio.

[0121] The magnetoresistive ratio (MR) of the magnetoresistive element 10 in Example 6 is 21%, and the resistance (RA) is 0.13 Ω·μm. 2 That was the case.

[0122] (Comparative Example 1) Comparative Example 1 has a composition of the second layer 1B, 2B which is (Co 0.4 Fe 0.4 B0.2 ) 0.93 Ta 0.07 This is different from Example 1 in that the Ta content in the second layers 1B and 2B is low. Since the mixing of atoms in the second layers 1B and 2B is not sufficient, the second layers 1B and 2B remained amorphous. Also, although the first layers 1A and 2A in Comparative Example 1 were crystallized, their crystallinity was inferior to that of Example 1.

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

[0124] (Comparative Example 2) In Comparative Example 2, the composition of the second layers 1B and 2B is (Co 0.4 Fe 0.4 B 0.2 ) 0.93 Ta 0.07 This is different from Example 2 in that the Ta content in the second layers 1B and 2B is low. Since the mixing of atoms in the second layers 1B and 2B is not sufficient, the second layers 1B and 2B remained amorphous. Also, although the first layers 1A and 2A in Comparative Example 1 were crystallized, their crystallinity was inferior to that of Example 2.

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

[0126] The results of Examples 1 to 6 and the results of 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…Magnetoresistive effect element, 21…Resistance meter, 22…Power supply, 23…Measurement 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…Magnetic domain wall moving element, 104…High-frequency device, DW…Magnetic domain wall, MD1…First magnetic domain, MD2…Second magnetic domain, Sub…Substrate

Claims

1. It comprises 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 comprises a first layer and a second layer in order from the side closest to the non-magnetic layer, The first layer contains a crystallized Co-based Heusler alloy, The second layer is at least partially crystalline and contains an alloy comprising a ferromagnetic element, a boron element, and an additive element. The alloy containing the ferromagnetic element, the boron element, and the additive element is CoFeB-A or CoFeGaGeB-A, In the above-mentioned CoFeB-A and the above-mentioned CoFeGaGeB-A, element A is one of the elements selected from the group consisting of Ti, Ru, and Ta. In the second layer, the content of element A is greater than the content of element boron. A magnetoresistive element in which the first layer and the second layer are lattice-matched.

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

3. The aforementioned Co-based Heusler alloy has a stoichiometric composition of CoYZ or Co ２ It is written as YZ, The magnetoresistive element according to claim 1 or 2, wherein the Co-based Heusler alloy has a Co composition ratio less than the stoichiometric composition ratio.

4. The second layer has a boron absorption layer in contact with the surface of the second layer that is farther from the non-magnetic layer, The magnetoresistive element according to claim 1 or 2, 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.

5. The aforementioned Co-based Heusler alloy is L2 １ A magnetoresistive element according to claim 1 or 2, wherein the element has a structure or a B2 structure.

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

7. The magnetoresistive element according to claim 1 or 2, wherein the non-magnetic layer is a metal or alloy containing any element selected from the group consisting of Cu, Au, Ag, Al, and Cr.

8. It further has a substrate, The substrate is a base on which the first ferromagnetic layer, the second ferromagnetic layer, and the non-magnetic layer are laminated. The magnetoresistive element according to claim 1 or 2, wherein the substrate is amorphous.

9. 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 comprises a first layer and a second layer in order from the side closest to the non-magnetic layer, The first layer contains a crystallized Co-based Heusler alloy, The second layer is at least partially crystalline and contains an alloy comprising a ferromagnetic element, a boron element, and an additive element. The alloy containing the ferromagnetic element, the boron element, and the additive element is CoFeB-A or CoFeGaGeB-A, In the above-mentioned CoFeB-A and the above-mentioned CoFeGaGeB-A, element A is one of the elements selected from the group consisting of Ti, Ru, and Ta. In the second layer, the Fe content is greater than the Co content. A magnetoresistive element in which the first layer and the second layer are lattice-matched.

10. The magnetoresistive element according to claim 9, wherein both the first ferromagnetic layer and the second ferromagnetic layer comprise the first layer and the second layer.

11. The Co-based Heusler alloy is expressed as CoYZ or Co2YZ in terms of its stoichiometric composition, The magnetoresistive element according to claim 9 or 10, wherein the Co-based Heusler alloy has a Co composition ratio less than the stoichiometric composition ratio.

12. The second layer has a boron absorption layer in contact with the surface of the second layer that is far from the nonmagnetic layer, The magnetoresistive element according to claim 9 or 10, 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.

13. The magnetoresistive element according to claim 9 or 10, wherein the Co-based Heusler alloy has an L21 structure or a B2 structure.

14. The Co-based Heusler alloy is represented as Co 2 Y α Z β, The aforementioned Y is one or more elements selected from the group consisting of Fe, Mn, and Cr. The aforementioned Z is one or more elements selected from the group consisting of Si, Al, Ga, and Ge. A magnetoresistive element according to claim 9 or 10, satisfying α + β > 2.

15. The magnetoresistive element according to claim 9 or 10, wherein the non-magnetic layer is a metal or alloy containing any element selected from the group consisting of Cu, Au, Ag, Al, and Cr.

16. Further comprising a substrate, The substrate is a base on which the first ferromagnetic layer, the second ferromagnetic layer, and the non-magnetic layer are laminated. The magnetoresistive element according to claim 9 or 10, wherein the substrate is amorphous.

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