Magnetoresistive element

Abstract

To provide a magnetoresistive element with a large MR ratio. [Solution] The magnetoresistive element comprises a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer. The first ferromagnetic layer has a first layer and a second layer. The first layer is closer to the non-magnetic layer than the second layer. The first layer has a Heusler alloy containing Co. The second layer, unlike the Heusler alloy, has a ferromagnetic material. The first and second layers have added first atoms. The first atom is selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi. The ferromagnetic material is Co x Fe 1-x It is represented by -A. x is between 0 and 1, and A is the first atom. The first ferromagnetic layer further has a fifth layer. The first layer and the fifth layer are separated by the second layer, and the fifth layer has the Heusler alloy.

Description

[Technical Field]

[0001] This disclosure relates to a magnetoresistive element. [Background technology]

[0002] A magnetoresistive element is a device in which the resistance value changes in the stacking direction due to the magnetoresistive effect. A magnetoresistive element comprises two ferromagnetic layers and a non-magnetic layer sandwiched between them. A magnetoresistive element in which a conductor is used for the non-magnetic 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 non-magnetic layer is called a tunnel magnetoresistance (TMR) element. Magnetoresistive elements can be applied to a variety of uses, such as magnetic sensors, high-frequency components, magnetic heads, and non-volatile random access memory (MRAM).

[0003] Patent Document 1 describes a magnetic sensor equipped with a magnetoresistive element using a Heusler alloy as the ferromagnetic layer. Heusler alloys have a high spin polarization rate. Magnetic sensors containing Heusler alloys are expected to have a large output signal. On the other hand, Patent Document 1 states that Heusler alloys are difficult to crystallize unless deposited at high temperatures or on a thick substrate with a predetermined crystalline structure. Patent Document 1 also states that high temperatures for film deposition and thick substrates can cause a decrease in the output of the magnetic sensor. Patent Document 1 states that by avoiding such processes and making the ferromagnetic layer a laminated structure of an amorphous layer and a crystalline layer, the output of the magnetic sensor can be increased. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent No. 9412399 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The magnitude of the output signal of the magnetic sensor depends on the magnetoresistance change rate (MR ratio) of the magnetoresistive effect element. Generally, the higher the crystallinity of the ferromagnetic layers sandwiching the non-magnetic layer, the greater the tendency for the MR ratio to be larger. It is required to easily crystallize a Heusler alloy without using film formation at high temperatures or a thick underlayer substrate having a predetermined crystallinity, and to obtain a magnetoresistive effect element with a large MR ratio. In the magnetoresistive effect element described in Patent Document 1, the ferromagnetic layer adjacent to the non-magnetic layer is amorphous, and it is difficult to obtain a sufficiently large MR ratio.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetoresistive effect element capable of realizing a large MR ratio.

Means for Solving the Problems

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

[0008] (1) The magnetoresistive effect element according to the first aspect includes a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer. The first ferromagnetic layer has a first layer and a second layer. The first layer is closer to the non-magnetic layer than the second layer. The first layer has a Heusler alloy containing at least partially crystallized Co. The second layer has a ferromagnetic body with at least partially crystallized, different from the Heusler alloy. The first layer and the second layer have a first atom added thereto. The first atom is any one selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi.

[0009] (2) In the magnetoresistive effect element according to the above aspect, the second ferromagnetic layer may have a third layer and a fourth layer. The third layer is closer to the non-magnetic layer than the fourth layer. The third layer has a Heusler alloy containing at least partially crystallized Co. The fourth layer has a ferromagnetic body with at least partially crystallized, different from the Heusler alloy. The third layer and the fourth layer have the first atom.

[0010] (3) In the magnetoresistive element according to the above embodiment, the first ferromagnetic layer may further have a fifth layer. The first layer and the fifth layer are sandwiched between the second layer. The fifth layer has the Heusler alloy.

[0011] (4) In the magnetoresistive element according to the above embodiment, the ferromagnetic material is Co x Fe 1-x It may also be represented as -A. x is between 0 and 1 (inclusive), and A is the first atom.

[0012] (5) In the magnetoresistive element according to the above embodiment, the crystal structure of the ferromagnetic material may be a bcc structure or an fcc structure.

[0013] (6) In the magnetoresistive element according to the above embodiment, the first layer and the second layer may be adjacent to each other. In this case, the first layer and the second layer are lattice-matched, and the lattice constant of the first layer is 95% or more and 105% or less of the lattice constant of the second layer, with respect to the lattice constant of the second layer.

[0014] (7) In the magnetoresistive element according to the above embodiment, the concentration of the first atoms on the first surface of the first layer on the non-magnetic layer side may be lower than that on the second surface opposite to the first surface.

[0015] (8) In the magnetoresistive element according to the above embodiment, the concentration of the first atom in the first layer may be lower than the concentration of the first atom in the second layer.

[0016] (9) In the magnetoresistive element according to the above embodiment, the crystal structure of the Heusler alloy may be an L21 structure or a B2 structure.

[0017] (10) In the magnetoresistive element according to the above embodiment, the Co composition ratio of the Heusler alloy may be less than the stoichiometric composition ratio. The Heusler alloy is expressed as CoYZ or Co2YZ in terms of stoichiometric composition. Y is a transition metal of the Mn, V, Cr, Ti group, Co, Fe, Ni, Cu group, or noble metal element. Z is a typical element of the III to V group.

[0018] (11) In the magnetoresistive element according to the above embodiment, the Heusler alloy is composed of Co2Y α Z β It may also be written as follows: 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, satisfying α + β > 2.

[0019] (12) In the magnetoresistive element according to the above embodiment, the first atom may substitute for a part of the crystal structure of the Heusler alloy.

[0020] (13) In the magnetoresistive element according to the above embodiment, a NiAl alloy layer may be further provided between the first ferromagnetic layer and the non-magnetic layer, and between the second ferromagnetic layer and the non-magnetic layer.

[0021] (14) In the magnetoresistive element according to the above embodiment, the thickness of the NiAl alloy layer may be 0.63 nm or less.

[0022] (15) 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.

[0023] (16) The magnetoresistive element according to the above embodiment may further include a substrate. The substrate is a base on which the first ferromagnetic layer, the second ferromagnetic layer, and the non-magnetic layer are laminated, and the substrate is amorphous. [Effects of the Invention]

[0024] The magnetoresistive element according to the present invention exhibits a large MR ratio. [Brief explanation of the drawing]

[0025] [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 second embodiment. [Figure 5] This is a cross-sectional view of a magnetoresistive element according to the third embodiment. [Figure 6] This is a cross-sectional view of a magnetoresistive element according to the fourth 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]

[0026] 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.

[0027] "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 perpendicular to the stacking direction in which each layer extends is sometimes called the in-plane direction.

[0028] 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.

[0029] The magnetoresistive element 10 outputs a change in resistance or output voltage 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 magnetization of the first ferromagnetic layer 1 does not change (it remains fixed), while the direction of magnetization of the second ferromagnetic layer 2 changes. The change in the direction of magnetization of the second ferromagnetic layer 2 relative to the direction of magnetization of the first ferromagnetic layer 1 causes the resistance of the magnetoresistive element 10 to change. 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. Hereafter, 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 may be reversed.

[0030] 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 thinner than the thickness of the first ferromagnetic layer 1, the coercivity of the second ferromagnetic layer 2 is often smaller than that of the first ferromagnetic layer 1. Alternatively, for example, an antiferromagnetic layer may be placed on the side of the first ferromagnetic layer 1 opposite to the non-magnetic layer 3 side, 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. When the first ferromagnetic layer 1 and the antiferromagnetic layer are antiferromagnetically coupled, the coercivity of the first ferromagnetic layer 1 becomes greater than when there is no antiferromagnetic coupling without the antiferromagnetic layer. The antiferromagnetic layer is, for example, IrMn, PtMn, etc. The spacer layer includes, for example, at least one selected from the group consisting of Ru, Ir, and Rh.

[0031] The first ferromagnetic layer 1 contains a ferromagnetic material. The first ferromagnetic layer 1 has a first layer 1A and a second layer 1B. The first layer 1A is closer to the non-magnetic layer 3 than the second layer 1B.

[0032] The first layer 1A contains a Heusler alloy containing Co. The first layer 1A may consist of a Heusler alloy containing Co. The Heusler alloy is at least partially crystalline. The Heusler alloy may, for example, be entirely crystalline.

[0033] 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 patterns using a transmission electron beam. If a Heusler alloy is crystallized, for example, a regularly arranged state of atoms can be confirmed in the HAADF-STEM image. 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), (111), and (011) planes can be confirmed in the electron diffraction pattern. If crystallization can be confirmed by at least one of these means, it can be said that at least a portion of the Heusler alloy is crystallized.

[0034] Heusler alloys are primarily oriented (or preferentially oriented) in the (001) or (011) direction, for example. Being primarily oriented in the (001) or (011) direction means that the primary crystal orientation of the crystals constituting the Heusler alloy is in the (001) or (011) direction. For example, if a Heusler alloy consists of multiple crystal grains, the crystal orientation of each grain may differ. In this case, if the combined vector of the crystal orientation directions in any 50 crystal grains is within a range of an inclination of 25° or less with respect to the (001) direction, then it can be said that the alloy is primarily oriented in the (001) direction. The same applies to the (011) direction. Heusler alloys with aligned crystal orientations have high crystallinity, and the magnetoresistive ratio (MR) of the magnetoresistive element 10 containing this Heusler alloy is high. Furthermore, orientation directions considered equivalent to the (001) direction are also included in the (001) orientation. In other words, the (001) orientation includes the (001) orientation, the (010) orientation, the (100) orientation, and all orientation directions that are directly opposite to these.

[0035] The Heusler alloy is an intermetallic compound with a chemical composition of XYZ or X2YZ. The ferromagnetic Heusler alloy represented by X2YZ is called a full Heusler alloy, and the ferromagnetic Heusler alloy represented by XYZ is called a half Heusler alloy. The half Heusler alloy is obtained by making some of the atoms at the X site of the full Heusler alloy into vacant sites. Both the full Heusler alloy and the half Heusler alloy are typically intermetallic compounds based on the bcc structure.

[0036] Figure 2 is an example of the crystal structure of the Heusler alloy. Figures 2(a) to (c) are examples of the crystal structure of the full Heusler alloy, and Figures 2(d) to (f) are examples of the crystal structure of the half Heusler alloy.

[0037] Figure 2(a) is called the L21 structure. In the L21 structure, the elements entering the X site, the elements entering the Y site, and the elements entering the Z site are fixed. Figure 2(b) is called the B2 structure derived from the L21 structure. In the B2 structure, the elements entering the Y site and the elements entering the Z site are mixed, and the elements entering the X site are fixed. Figure 2(c) is called the A2 structure derived from the L21 structure. In the A2 structure, the elements entering the X site, the elements entering the Y site, and the elements entering the Z site are mixed.

[0038] <00…​​​​​​​​​​​​​​Crystallinity increases in the order of Structure > B2 Structure > A2 Structure. Although these crystal structures differ in their degree of crystallinity, they are all crystalline. The first layer 1A has, for example, one of the above crystal structures. The crystal structure of Heusler alloy is, for example, L21 structure or B2 structure, and the crystal structure of the first layer 1A is, for example, L21 structure or B2 structure.

[0040] Here, X is a transition metal or noble metal element from the group Co, Fe, Ni, or Cu in the periodic table; Y is a transition metal or element species of X from the group Mn, V, Cr, or Ti; and Z is a typical element from groups III to V. If the Heusler alloy contains Co, then X is Co. Y is, for example, one or more elements selected from the group consisting of Fe, Mn, and Cr, and Z is, for example, one or more elements selected from the group consisting of Si, Al, Ga, and Ge.

[0041] A Heusler alloy containing Co is a Heusler alloy in which the X site is Co. For example, a Heusler alloy containing Co is CoY. α Z β Or Co2Y α Z β These are denoted as follows: A full Heusler alloy with a stoichiometric Co group is denoted as Co2YZ. A half Heusler alloy with a stoichiometric Co group is denoted as CoYZ.

[0042] The Co composition ratio of the Heusler alloy is preferably less than the stoichiometric composition ratio. That is, if the Co-based Heusler alloy is a full Heusler alloy, it is preferable that α + β > 2. In this case, α satisfies 0.3 < α < 2.1, more preferably 0.4 < α < 2.0, and β satisfies 0.1 ≤ β ≤ 2.0. If the Co-based Heusler alloy is a half Heusler alloy, it is preferable that α + β > 1. In this case, α satisfies 0.3 < α < 2.1, more preferably 0.4 < α < 2.0, and β satisfies 0.1 ≤ β ≤ 2.0.

[0043] 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.

[0044] Co-containing full Heusler alloys include, for example, Co2FeSi, Co2FeAl, and Co2FeGe x Ga 1-x Co2MnGe x Ga 1-x , Co2MnSi, Co2MnGe, Co2MnGa, Co2MnSn, Co2MnAl, Co2CrAl, Co2VAl, Co2Mn 1-a Fe a Al b Si 1-b These are examples of half-Heusler alloys containing Co, such as CoFeSb and CoMnSb.

[0045] The first layer 1A contains a first atom. The first atom is an atom added to the first layer 1A. The first atom is selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi. Preferably, the first atom is selected from the group consisting of Al, Cr, Mn, Ni, Cu, Zn, Pd, Sn, Sb, Pt, Au, and Bi, more preferably from the group consisting of Cr, Mn, Ni, Cu, Zn, and Pd, even more preferably from the group consisting of Mn, Ni, Cu, and Zn, and particularly preferably Zn. During manufacturing, the first atom moves within the first layer 1A, which promotes the crystallization of the first layer 1A.

[0046] The first layer 1A may contain additive atoms other than the first atom. That is, the first layer 1A may contain one or more atoms selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi.

[0047] The first atom may either penetrate between the crystal lattices of the Heusler alloy or substitute for any of the atoms constituting the crystal structure of the Heusler alloy. Alternatively, part of the first atom may penetrate between the crystal lattices of the Heusler alloy, while the remaining part substitutes for any of the atoms constituting the crystal structure of the Heusler alloy. A substance in which the first atom penetrates between the crystal lattices is called an interstitial solid solution, and a substance in which some of the atoms constituting the crystal lattice are substituted with the first atom is called a substitutional solid solution. It is preferable that at least part of the first atom substitutes for any of the atoms constituting the crystal structure of the Heusler alloy. As will be described in detail later, if the size of the added atom is large enough to substitute for an atom constituting the Heusler alloy, it has a greater effect in promoting the crystallization of the first layer 1A.

[0048] The first surface S1 of the first layer 1A on the non-magnetic layer 3 side may have a lower concentration of first atoms than the second surface S2 on the opposite side of the first surface S1. This configuration prevents abrupt changes in the concentration of first atoms and suppresses electron scattering at the interface between the first ferromagnetic layer 1 and the non-magnetic layer 3.

[0049] The second layer 1B contains a ferromagnetic material different from that of the first layer 1A. The second layer 1B contains a ferromagnetic material different from that of the Heusler alloy in the first layer 1A. The second layer 1B is at least partially crystalline. The second layer 1B may, for example, be entirely crystalline.

[0050] The crystal structure of the second layer 1B is, for example, a bcc structure or an fcc structure. When the second layer 1B has a bcc structure or an fcc structure, the first layer 1A is more likely to crystallize as a bcc structure. As a result, the crystallinity of the first layer 1A increases, and the MR ratio of the magnetoresistive element 10 increases.

[0051] The second layer 1B contains the first atom described above. The second layer 1B may also contain one or more atoms selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi.

[0052] The ferromagnetic material contained in the second layer 1B is, for example, Cox Fe 1-x It is represented by -A. x is between 0 and 1, and A is the first atom. The first atom may be embedded in the crystal structure of CoFe, or it may be substituted for any element of the CoFe crystal. Preferably, at least a portion of the first atom is substituted for any atom constituting the crystal structure of the ferromagnetic material contained in the second layer 1B.

[0053] The concentration of the first atom in the second layer 1B is higher than, for example, the concentration of the first atom in the first layer 1A. That is, the concentration of the first atom in the first layer 1A is lower than, for example, the concentration of the first atom in the second layer 1B. A lower concentration of the first atom in the first layer 1A increases the crystallinity of the first layer 1A.

[0054] The second layer 1B is adjacent to, for example, the first layer 1A. Other layers may be placed between the second layer 1B and the first layer 1A. When the first layer 1A and the second layer 1B are adjacent, it is preferable that the first layer 1A and the second layer 1B are lattice-matched. Lattice matching between the first layer 1A and the second layer 1B means that at the interface between the first layer 1A and the second layer 1B, atoms are continuously arranged in the stacking direction. The degree of lattice matching between the first layer 1A and the second layer 1B is, for example, within 5%. The degree of lattice matching is the degree of deviation of the lattice constant of the first layer 1A with respect to the lattice constant of the second layer 1B. With respect to the lattice constant of the second layer 1B, the lattice constant of the first layer 1A is, for example, 95% to 105% of the lattice constant of the second layer 1B. When the first layer 1A and the second layer 1B are lattice-matched, the MR ratio of the magnetoresistive element 10 increases.

[0055] The second ferromagnetic layer 2 contains a ferromagnetic material. The second ferromagnetic layer 2 has a third layer 2A and a fourth layer 2B. The third layer 2A is closer to the non-magnetic layer 3 than the fourth layer 2B.

[0056] The third layer 2A contains a Heusler alloy containing Co. The third layer 2A may consist of a Heusler alloy containing Co. The third layer 2A may consist of the same material as the first layer 1A. The Heusler alloy in the third layer 2A is at least partially crystallized, and may be entirely crystallized.

[0057] The third layer 2A contains the first atom. The first atom is added to the third layer 2A. The third layer 2A may also contain other added atoms besides the first atom. The third layer 2A may contain one or more atoms selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi.

[0058] The first atom may either penetrate between the crystal lattices of the Heusler alloy constituting the third layer 2A, or it may substitute for any of the atoms constituting the crystal structure of the Heusler alloy, or a portion may penetrate between the crystal lattices of the Heusler alloy and the remaining portion may substitute for any of the atoms constituting the crystal structure of the Heusler alloy.

[0059] The first surface S3 of the third layer 2A on the non-magnetic layer 3 side may have a lower concentration of first atoms than the second surface S4 on the opposite side of the first surface S3.

[0060] The fourth layer 2B contains a ferromagnetic material different from that of the third layer 2A. The fourth layer 2B contains a ferromagnetic material different from that of the Heusler alloy in the third layer 2A. The fourth layer 2B is at least partially crystalline. The fourth layer 2B may, for example, be entirely crystalline. The crystalline structure of the fourth layer 2B is, for example, a bcc structure or an fcc structure.

[0061] The fourth layer 2B contains the first atom described above. The fourth layer 2B may also contain one or more atoms selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi.

[0062] The ferromagnetic material contained in the fourth layer 2B is, for example, Co x Fe 1-x It is represented by -A. x is between 0 and 1, and A is the first atom. The first atom may be embedded in the crystal structure of CoFe, or it may be substituted for any element of the CoFe crystal. Preferably, at least a portion of the first atom is substituted for any atom constituting the crystal structure of the ferromagnetic material contained in the fourth layer 2B.

[0063] The concentration of the first atom in layer 4, 2B is higher than, for example, the concentration of the first atom in layer 3, 2A. That is, the concentration of the first atom in layer 3, 2A is lower than, for example, the concentration of the first atom in layer 4, 2B.

[0064] The fourth layer 2B is adjacent to, for example, the third layer 2A. Other layers may be placed between the fourth layer 2B and the third layer 2A. When the third layer 2A and the fourth layer 2B are adjacent, it is preferable that the third layer 2A and the fourth layer 2B are lattice-matched.

[0065] The non-magnetic layer 3 is sandwiched between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. The non-magnetic layer 3 has a thickness of, for example, 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.

[0066] 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. Metals or alloys containing these elements have excellent conductivity and reduce the area resistance (hereinafter referred to as RA) of the magnetoresistive element 10. The non-magnetic layer 3 contains, for example, any atom selected from the group consisting of Cu, Au, Ag, Al, and Cr as the main constituent atoms. The main constituent atoms mean 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 atom. Because Ag has a long spin diffusion length, the magnetoresistive element 10 using Ag exhibits a large MR ratio.

[0067] 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.

[0068] The magnetoresistive element 10 may have layers other than the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the non-magnetic layer 3 described above. For example, the first ferromagnetic layer 1 may have a base layer on the side opposite to the non-magnetic layer 3, and the second ferromagnetic layer 2 may have a cap layer on the side opposite to the non-magnetic layer 3. The base layer and the cap layer enhance the crystal orientation of the first ferromagnetic layer 1 and the second ferromagnetic layer 2. The base layer and the cap layer may contain, for example, Ru, Ir, Ta, Ti, Al, Au, Ag, Pt, or Cu.

[0069] Next, a method for manufacturing the magnetoresistive element 10 will be described. Figure 3 is a cross-sectional view illustrating the method for manufacturing the magnetoresistive element 10 according to the first embodiment.

[0070] First, a substrate Sub is prepared to serve as the base for film deposition. The substrate 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, glass, ceramics, and quartz. In this embodiment, the magnetoresistive element 10 allows for arbitrary selection of the substrate Sub, as the first layer 1A and the third layer 2A crystallize even when the substrate Sub is amorphous.

[0071] Next, the second layer 11B, the first layer 11A, the non-magnetic layer 13, the third layer 12A, and the fourth layer 12B are sequentially stacked on the substrate Sub. These layers are deposited, for example, by sputtering. The second layer 11B corresponds to the second layer 1B and is made of the same material as the second layer 1B. The second layer 11B is made of, for example, Co x Fe1-x -A. The first layer 11A corresponds to the first layer 1A and is, for example, a Heusler alloy containing Co. The first layer 11A does not need to contain the first atom immediately after deposition. The non-magnetic layer 13 corresponds to the non-magnetic layer 3 and is made of the same material as the non-magnetic layer 3. The third layer 12A corresponds to the third layer 2A and is, for example, a Heusler alloy containing Co. The third layer 12A does not need to contain the first atom immediately after deposition. The fourth layer 12B corresponds to the fourth layer 2B and is made of the same material as the fourth layer 2B. The fourth layer 12B is, for example, Co x Fe 1-x -A is the case.

[0072] The second layer 11B is amorphous after deposition. The first layer 11A grows on an amorphous substrate, and therefore grows in the direction that is most favorable for its growth (011). As a result, the first layer 11A becomes either a crystalline or amorphous material with low crystallinity after deposition. Similarly, the third layer 12A becomes either a crystalline or amorphous material with low crystallinity after deposition. The fourth layer 12B is amorphous after deposition.

[0073] 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.

[0074] The first atom contained in the second layer 11B diffuses into the first layer 11A by annealing. Similarly, the first atom contained in the fourth layer 12B diffuses into the third layer 12A by annealing. As the first atom diffuses within the first layer 11A or the third layer 12A, it mixes the atoms within those layers. The mixed atoms rearrange, causing the first layer 11A and the third layer 12A to crystallize.

[0075] Furthermore, the crystallization of the first layer 11A proceeds simultaneously with the orderly arrangement of the second layer 11B, and the crystallization of the third layer 12A proceeds simultaneously with the orderly arrangement of the fourth layer 12B. Orderly arrangement means that amorphous material crystallizes, or that already crystallized atoms rearrange themselves. When the first layer 11A and the second layer 11B are adjacent, the first layer 11A rearranges under the influence of the second layer 11B. Similarly, when the third layer 12A and the fourth layer 12B are adjacent, the third layer 12A rearranges under the influence of the fourth layer 12B. In other words, the first layer 11A crystallizes under the influence of the orderly arrangement of the second layer 11B, resulting in a crystal with high crystallinity. Similarly, the third layer 12A crystallizes under the influence of the orderly arrangement of the fourth layer 12B, resulting in a crystal with high crystallinity.

[0076] As described above, by annealing the laminate, the first layer 11A crystallizes to become the first layer 1A, the second layer 11B crystallizes to become the second layer 1B, the third layer 12A crystallizes to become the third layer 2A, and the fourth layer 12B crystallizes to become the fourth layer 2B. 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.

[0077] 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 ferromagnetic layer containing first atoms with a ferromagnetic layer containing a Heusler alloy and heating them.

[0078] 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 have been 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.

[0079] Furthermore, in the magnetoresistive element 10 according to this embodiment, the first layer 1A and the second layer 1B, which sandwich the non-magnetic layer 3, are crystallized. Since the first layer 1A and the second layer 1B contain crystallized Heusler alloy, they exhibit a high spin polarization rate. In other words, the magnetoresistive element 10 according to this embodiment exhibits a high MR ratio.

[0080] "Second Embodiment" Figure 4 is a cross-sectional view of a magnetoresistive element 11 according to the second embodiment. The magnetoresistive element 11 has a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a non-magnetic layer 3. The magnetoresistive element 11 differs from the magnetoresistive element 10 according to the first embodiment in that the first ferromagnetic layer 1 has a fifth layer 1C. In the magnetoresistive element 11 according to the second embodiment, components similar to those in the magnetoresistive element 10 according to the first embodiment are denoted by the same reference numerals and their description is omitted.

[0081] The first ferromagnetic layer 1 comprises a first layer 1A, a second layer 1B, and a fifth layer 1C. The first layer 1A and the fifth layer 1C are separated by the second layer 1B. The fifth layer 1C contains the same Heusler alloy as the first layer 1A. The first ferromagnetic layer 1 can also be considered to contain a ferromagnetic material different from the Heusler alloy corresponding to the second layer 1B within the Heusler alloy. The fifth layer 1C contains a first atom.

[0082] The magnetoresistive element 11 according to the second embodiment exhibits the same effects as the magnetoresistive element 10 according to the first embodiment. Furthermore, if a second layer 1B containing first atoms that promote crystallization is present inside the Heusler alloy, the first atoms diffuse from the second layer 1B to the first layer 1A and fifth layer 1C during annealing. If a diffusion source that diffuses the first atoms is present in the center of the thickness direction of the first ferromagnetic layer 1, the crystallization of the first ferromagnetic layer 1 is further promoted. Therefore, the magnetoresistive element 10 according to the second embodiment exhibits a high MR ratio.

[0083] "Third Embodiment" Figure 5 is a cross-sectional view of a magnetoresistive element 12 according to the third embodiment. The magnetoresistive element 12 has a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a non-magnetic layer 3. The magnetoresistive element 12 differs from the magnetoresistive element 10 according to the first embodiment in that the second ferromagnetic layer 2 is a single layer. In the magnetoresistive element 12 according to the third embodiment, components similar to those in the magnetoresistive element 10 according to the first embodiment are denoted by the same reference numerals and their description is omitted.

[0084] The second ferromagnetic layer 2 according to the third embodiment may be a Heusler alloy or a ferromagnetic layer other than a Heusler alloy. If the second ferromagnetic layer 2 contains a Heusler alloy, the same material as the first ferromagnetic layer 1 can be used. If the second ferromagnetic layer 2 is a ferromagnetic layer other than a Heusler alloy, the second ferromagnetic layer 2 includes, 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, or an alloy containing these metals and at least one element from B, C, and N. The second ferromagnetic layer 2 is, for example, Co-Fe or Co-Fe-B.

[0085] The second ferromagnetic layer 2 according to the third embodiment may be either a magnetized free layer or a magnetized fixed layer. The second ferromagnetic layer 2 may be located closer to the substrate Sub than the first ferromagnetic layer 1, or it may be located further away from the substrate Sub than the first ferromagnetic layer 1.

[0086] The magnetoresistive element 12 according to the third embodiment provides the same effects as the magnetoresistive element 10 according to the first embodiment.

[0087] "Fourth Embodiment" Figure 6 is a cross-sectional view of a magnetoresistive element 13 according to the fourth embodiment. The magnetoresistive element 13 has a first ferromagnetic layer 1, a second ferromagnetic layer 2, a non-magnetic layer 3, a NiAl layer 4, and a NiAl layer 5. The magnetoresistive element 13 differs from the magnetoresistive element 10 according to the first embodiment in that it has NiAl layers 4 and 5. In the magnetoresistive element 13 according to the fourth embodiment, components similar to those in the magnetoresistive element 10 according to the first embodiment are denoted by the same reference numerals and their description is omitted.

[0088] The NiAl layers 4 and 5 are layers each containing a NiAl alloy. The NiAl layer 4 is a buffer layer that relaxes the lattice mismatch between the first ferromagnetic layer 1 and the non-magnetic layer 3. The NiAl layer 5 is a buffer layer that relaxes the lattice mismatch between the non-magnetic layer 3 and the second ferromagnetic layer 2.

[0089] The NiAl layers 4 and 5 each have, for example, a thickness t where 0 < t ≦ 0.63 nm. If the thickness t becomes too large, 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. By having the thickness t 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 13 improves.

[0090] Here, an example in which the magnetoresistive effect element 13 has both the NiAl layer 4 and the NiAl layer 5 has been shown, but it may have only one of them.

[0091] The magnetoresistive effect element 13 according to the fourth embodiment exhibits the same effects as the magnetoresistive effect element 10 according to the first embodiment.

[0092] Although several embodiments have been described in detail with reference to the drawings above, each configuration and their combinations in each embodiment are examples, and additions, omissions, substitutions, and other changes of the configuration are possible without departing from the spirit of the present invention.

[0093] The above magnetoresistive effect elements 10, 11, 12, and 13 can be used for various applications. The magnetoresistive effect elements 10, 11, 12, and 13 can be applied to, for example, magnetic heads, magnetic sensors, magnetic memories, high-frequency filters, and the like.

[0094] Next, we will describe examples of applications of the magnetoresistive element according to this embodiment. Note that while the magnetoresistive element 10 is used in the following examples, the magnetoresistive element is not limited to this.

[0095] Figure 7 is a cross-sectional view of the magnetic recording element 100 according to Application Example 1. Figure 7 is a cross-sectional view of the magnetoresistive element 10 cut along the stacking direction.

[0096] 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.

[0097] The magnetic head MH has an air bearing surface (media-facing surface) S that faces the surface of the magnetic recording medium W. The magnetic head MH moves along the surface of the magnetic recording medium W in the +X direction or the -X direction 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] The spin-orbit torque wiring 8 is in contact with, for example, the first ferromagnetic layer 1. The spin-orbit torque wiring 8 extends in one direction in the in-plane direction. In Application Example 3, the first ferromagnetic layer 1 is a magnetization-free layer, and the second ferromagnetic layer 2 is a magnetization-fixed layer.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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). 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 102 shown in Figure 9 is a spin-orbit torque (SOT) type magnetic recording element.

[0114] 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.

[0115] 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.

[0116] 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 when viewed from the Z direction.

[0117] 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 The magnetization M of the second magnetic domain MD2 is oriented in the +Z direction. MD2 It is oriented in the -Z direction.

[0118] 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.

[0119] 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 MD2MD2 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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]

[0127] (Example 1) As Example 1, a magnetoresistive element 10 shown in Figure 1 was fabricated. First, Cr and Ag were sequentially deposited as underlayers on a silicon substrate. Next, (Co0.5 Fe 0.5 ) 0.9 Mg 0.1 A film was formed. Mg corresponds to the first atom. Next, as the first layer 1A, the composition ratio was Co2FeGa 0.5 Ge 0.5 A Heusler alloy containing Co was deposited. Next, Ag was deposited as a non-magnetic layer 3. Then, as the third layer 2A, a Co2FeGa 0.5 Ge 0.5 A Heusler alloy containing Co was deposited. Then, as the fourth layer 2B, (Co 0.5 Fe 0.5 ) 0.9 Mg 0.1 The film was deposited. Immediately after deposition, the first layer 1A and the third layer 2A were amorphous.

[0128] Next, the laminated structure was annealed. The annealing was performed at 300°C for 10 hours. The first layer 1A and the third layer 2A crystallized as a result of the annealing. In addition, the crystallinity of the second layer 1B and the fourth layer 2B improved along with the crystallization of the first layer 1A and the third layer 2A. Furthermore, compositional analysis of the first layer 1A and the third layer 2A after annealing was performed, and it was confirmed that Mg was present as the primary atom in the first layer 1A and the third layer 2A.

[0129] 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 PThis 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.

[0130] 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.

[0131] The magnetoresistive ratio (MR) of the magnetoresistive element 10 in Example 1 is 10.8%, and the resistance (RA) is 0.06 Ω·μm. 2 That was the case.

[0132] (Examples 2-15) Examples 2-15 differ from Example 1 in that the first atom was changed. The MR ratio and RA of the magnetoresistive element 10 were measured using the same procedure as in Example 1. Furthermore, compositional analysis of the first layer 1A and the third layer 2A after annealing was performed to confirm that the first atom was present in the first layer 1A and the third layer 2A. In Example 2, the first atom was Al. In Example 3, the first atom was Cr. In Example 4, the first atom was Mn. In Example 5, the first atom was Ni. In Example 6, the first atom was Cu. In Example 7, the first atom was Zn. In Example 8, the first atom was Pd. In Example 9, the first atom was Cd. In Example 10, the first atom was In. In Example 11, the first atom was Sn. In Example 12, the first atom was Sb. In Example 13, the first atom was Pt. In Example 14, the first atom was Au. In Example 15, the first atom was Bi.

[0133] (Example 16) Example 16 differs from Example 1 in that the fabricated magnetoresistive element is the magnetoresistive element 11 shown in Figure 4. The fifth layer 1C is the same as the first layer 1A (Co 0.5 Fe 0.5 ) 0.9 Zn 0.1 The MR ratio and RA of the magnetoresistive element 10 were measured under the same conditions as in Example 1. Furthermore, a compositional analysis of the fifth layer 1C after annealing was performed, and it was confirmed that Zn was present as the first atom in the fifth layer 1C.

[0134] (Example 17) Example 17 differs from Example 1 in that the fabricated magnetoresistive element was the magnetoresistive element 13 shown in Figure 6. In Example 17, NiAl was deposited to a thickness of 0.24 nm between the first ferromagnetic layer 1 and the non-magnetic layer 3, and between the second ferromagnetic layer 2 and the non-magnetic layer 3. The MR ratio and RA of the magnetoresistive element 10 were measured under the same conditions as in Example 7.

[0135] (Comparative Example 1) Comparative Example 1 differs from Example 1 in that the first layer 1A and the third layer 2A were not made with the first atom, Mg. In other words, none of the magnetoresistive element, first layer 1A, second layer 1B, third layer 2A, and fourth layer 2B of Comparative Example 1 contain the first atom. The MR ratio and RA of the magnetoresistive element 10 were measured under the same conditions as in Example 1.

[0136] Table 1 shows the measurement results for Examples 1 to 17 and Comparative Example 1.

[0137] [Table 1] [Explanation of Symbols]

[0138] 1…First ferromagnetic layer, 1A…First layer, 1B…Second layer, 1C…Fifth layer, 2…Second ferromagnetic layer, 2A…Third layer, 2B…Fourth layer, 3…Non-magnetic layer, 4…NiAl layer, 5…NiAl layer, 8…Spin-orbit torque wiring, 10…Magnetoresistive element, 21…Resistance meter, 22…Power supply, 23…Measurement unit, 26…DC power supply, 27…Inductor, 28…Capacitor, 29…Output port, 30,31…Wiring, 100,101,102…Magnetic recording element, 103…High-frequency device

Claims

1. It comprises a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer. The first ferromagnetic layer comprises a first layer and a second layer. The first layer is closer to the non-magnetic layer than the second layer, The first layer has a Heusler alloy containing Co, Unlike the Heusler alloy, the second layer has a ferromagnetic material. The first layer and the second layer each have the added first atom, The first atom is selected from the group consisting of Mg, Al, Cr, Mn, Ni, Cu, Zn, Pd, Cd, In, Sn, Sb, Pt, Au, and Bi. The ferromagnetic material is Co ｘ Fe １－ｘ - Represented by A, x is between 0 and 1, and A is the first atom. The first ferromagnetic layer further comprises a fifth layer, The first layer and the fifth layer are separated by the second layer, The fifth layer is a magnetoresistive element having the Heusler alloy.

2. The aforementioned second ferromagnetic layer has a third layer and a fourth layer, The third layer is closer to the non-magnetic layer than the fourth layer, The third layer has a Heusler alloy containing at least a portion of crystallized Co, Unlike the Heusler alloy, the fourth layer has at least a portion of a crystalline ferromagnetic material. The magnetoresistive element according to claim 1, wherein the third layer and the fourth layer have the first atom.

3. The magnetoresistive element according to claim 1, wherein the crystal structure of the ferromagnetic material is a bcc structure or an fcc structure.

4. The first layer and the second layer are adjacent to each other. The first layer and the second layer are grid-matched, The magnetoresistive element according to claim 1, wherein, with respect to the lattice constant of the second layer, the lattice constant of the first layer is 95% or more and 105% or less of the lattice constant of the second layer.

5. The magnetoresistive element according to claim 1, wherein the first surface of the first layer on the non-magnetic layer side has a lower concentration of the first atoms than the second surface on the opposite side of the first surface.

6. The magnetoresistive element according to claim 1, wherein the concentration of the first atom in the first layer is lower than the concentration of the first atom in the second layer.

7. The crystal structure of the aforementioned Heusler alloy is L2 １ A magnetoresistive element according to claim 1, wherein the element has a B2 structure or a B2 structure.

8. The aforementioned Heusler alloy has the compositional formula 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, satisfying α + β > 2.

9. The magnetoresistive element according to claim 1, wherein the first atom substitutes for a part of the crystal structure of the Heusler alloy.

10. The magnetoresistive element according to claim 1, further comprising a NiAl alloy layer in at least one of the spaces between the first ferromagnetic layer and the non-magnetic layer, and between the second ferromagnetic layer and the non-magnetic layer.

11. The magnetoresistive element according to claim 10, wherein the thickness of the NiAl alloy layer is 0.63 nm or less.

12. The magnetoresistive element according to claim 1, 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.

13. 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, wherein the substrate is amorphous.

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