Perpendicular magnetization film and perpendicular magnetization magnetoresistance effect element

Abstract

Provided are: a perpendicular magnetization film which exhibits high perpendicular magnetic anisotropy by using a Co-based alloy having a specific structure that is a physical principle different from the perpendicular magnetization of FeCoB / MgO; and a perpendicular magnetization magnetoresistance effect element. This perpendicular magnetization film comprises: a perpendicular magnetization magnetic layer; a non-magnetic layer provided at an upper part of the magnetic layer; and a base layer provided at a lower part of the magnetic layer, wherein the magnetic layer has an alloy containing Co as a main component and having a bct crystal structure, and the alloy contains the Co and Mn.

Description

Perpendicular magnetization film, perpendicular magnetization magnetoresistance effect element

[0001] This application claims priority to Japanese Patent Application No. 2024-047192, filed on March 22, 2024, the contents of which are incorporated herein by reference.

[0002] A magnetoresistive element has two magnetic layers and a non-magnetic layer sandwiched between the two magnetic layers. The resistance of the magnetoresistive element changes as the relative angle between the magnetizations of the two magnetic layers sandwiching the non-magnetic layer changes, which is known as the magnetoresistive effect. Utilizing this resistance change characteristic, magnetoresistive elements are used in a variety of applications, including magnetic sensors, high-frequency components, magnetic heads, and magnetoresistive memories.

[0003] As magnetoresistive memories become larger in capacity, there is a demand for miniaturization of magnetoresistive elements. As magnetoresistive elements become smaller, the volume of the magnetic layer decreases, and the thermal stability of magnetization decreases. For example, a perpendicular magnetization magnetoresistive element is known that uses MgO as the insulating layer material and FeCoB for the magnetic layer (see, for example, Non-Patent Document 1).

[0004] International Application Publication No. 2020 / 246553

[0005] S. Ikeda et al .,‘A perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction’ Nature Materials,Vol9,p.721(2010).S. Yuasa et al.,‘Giant tunneling magnetoresistance up to 410% at room temperature in fully epitaxial Co / MgO / Co magnetic tunnel junctions with bcc Co (001) electrodes’ Appl. Phys. Lett. 89, 042505 (2006)T. Burkert et al.,‘Calculation of uniaxial magnetic anisotropy energy of tetragonal and trigonal Fe, Co, and Ni’ Phys. Rev. B 69, 104426 (2004)

[0006] The perpendicular magnetization magnetoresistive effect element using FeCoB / MgO described in Non-Patent Document 1 utilizes perpendicular magnetization due to the interface magnetic anisotropy of FeCoB / MgO, and the FeCoB / MgO / FeCoB tunnel junction also exhibits a high TMR effect. However, although the perpendicular magnetic anisotropy constant exhibited by FeCoB / MgO is relatively large, it is considered insufficient for application to magnetoresistive memories, which have been miniaturized to several nanometers to several dozen nanometers. Attempts have been made to resolve this issue by methods such as increasing the interface magnetic anisotropy by multilayering. Materials and design guidelines that exhibit TMR equal to or greater than that of FeCoB / MgO and even greater perpendicular magnetic anisotropy are anticipated. On the other hand, there are experimental reports showing that Co / MgO with a body-centered cubic lattice (bcc) exhibits a high TMR effect, and theoretical calculations have shown that Co with a body-centered tetragonal lattice (bct, distorted bcc) exhibits perpendicular magnetic anisotropy, but this has not been experimentally verified (see, for example, Non-Patent Document 2). Furthermore, bcc Co is thermodynamically unstable, and only thin films of approximately 0.4 nanometers can be fabricated (see, for example, Non-Patent Document 2). The inventors have reported that Co-Mn-Fe / MgO, which has a magnetic layer with a bcc structure made of Co, Mn, and Fe, exhibits a high TMR effect (see, for example, Patent Document 1).

[0007] The present invention has been made in view of the above problems, and aims to provide a perpendicular magnetization film and a perpendicular magnetization magnetoresistance effect element that exhibit high perpendicular magnetic anisotropy using a Co-Mn-Fe alloy that has high magnetic anisotropy due to crystal distortion, which is a physical principle different from the perpendicular magnetization of FeCoB / MgO.

[0008] In order to solve the above problems, the present invention provides the following means.

[0009] The perpendicular magnetization film of the present invention comprises a magnetic layer with perpendicular magnetization, a non-magnetic layer above the magnetic layer, and an underlayer below the magnetic layer. The magnetic layer has an alloy with a bct crystal structure whose main component is Co. The alloy contains Co and Mn. The non-magnetic layer is preferably a (001) non-magnetic layer. The non-magnetic layer preferably contains Cr(001). The lattice size in the (001) plane of the underlayer is preferably within 1 to 1.10 times the lattice size of the alloy in the magnetic layer when the lattices are grown uniformly.

[0010] According to the present invention, it is possible to provide a perpendicular magnetization film and a perpendicular magnetization magnetoresistance effect element that exhibit high perpendicular magnetic anisotropy by using a Co-Mn-Fe alloy having a specific distortion structure that is based on a physical principle different from that of perpendicular magnetization due to the interface magnetic anisotropy of FeCoB / MgO.

[0011] FIG. 1 is a schematic diagram showing a cross-sectional structure of a perpendicular magnetization film according to a first embodiment; FIG. 2 is a schematic diagram showing a cross-sectional structure of a perpendicular magnetization film (number of layers: N) according to a first embodiment; FIG. 3 is a perspective view showing a magnetoresistive element according to a first embodiment; １００－ｘ Mn ｘ 1 is a diagram showing the results of a simulation of perpendicular magnetic anisotropy Kv due to strain for the perpendicular magnetization film (Co ８０ Mn ２０ ) １００－ｘ Fe ｘ1 is a diagram showing the results of a simulation of perpendicular magnetic anisotropy Kv due to strain for ". FIG. 1 is a diagram showing the relationship between perpendicular magnetic anisotropy Kv due to strain and Co concentration. FIG. 2 is a diagram showing the relationship between perpendicular magnetic anisotropy Kv due to strain and the number of layers N. FIG. 3 is a diagram showing the relationship between "perpendicular magnetic anisotropy K x film thickness t" and the number of layers N. FIG. 4 is a diagram showing a magnetization curve. FIG. 5 is a schematic diagram showing the cross-sectional structure of a perpendicular magnetization film (number of layers N = 2) of Example 5. FIG. 6 is a diagram showing the magnetization curve of Example 5. ((a) d = 0.2 nm, (b) d = 0.4 nm, (c) d = 0.6 nm, (d) d = 0.8 nm, (e) d = 1.0 nm) A longitudinal cross-sectional view of a test element of the perpendicular magnetization magnetoresistance effect element of Example 6. FIG. 7 is a diagram showing the relationship between the element resistance and in-plane magnetic field of the test element obtained in Example 6. FIG. 8 is a schematic diagram showing the cross-sectional structure of a perpendicular magnetization film (number of layers N + 1 = 5) of Example 7. FIG. 9 is a diagram showing the magnetization curve of Example 7. (a) 0.4 nm, (b) 0.6 nm, (c) 0.8 nm, (d) 1.0 nm) Schematic diagram showing the cross-sectional structure of the perpendicular magnetization film (number of layers N=2) of Example 8. Graph showing the magnetization curve of Example 9. ((a) Number of Co layers=1, (b) Number of Co layers=2, (c) Number of Co layers=3)

[0012] The present embodiment will be described in detail below with reference to the accompanying drawings. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional proportions of each component may differ from the actual proportions. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications may be made within the scope of the present invention.

[0013] (Perpendicular Magnetization Film) The perpendicular magnetization film of the present disclosure comprises a magnetic layer with perpendicular magnetization, a non-magnetic layer above the magnetic layer, and an underlayer below the magnetic layer. The magnetic layer has an alloy with a bct crystal structure whose main component is Co. The perpendicular magnetization film is characterized in that the alloy contains Co and Mn. Below, the perpendicular magnetization film of the present disclosure will be described in detail using the first to third embodiments as examples. The perpendicular magnetization film of the present disclosure is not limited by these. The three numbers in parentheses are Miller indices.

[0014] [First Embodiment] The perpendicular magnetization film of the first embodiment of the present invention comprises a magnetic layer with perpendicular magnetization, a non-magnetic layer (001) above the magnetic layer, and an underlayer below the magnetic layer. The magnetic layer has an alloy with a bct crystal structure whose main component is Co. The alloy includes Co and Mn. The alloy may further include other transition metals such as Fe and Ni. The non-magnetic layer preferably includes Cr(001). The lattice size in the (001) plane of the underlayer is preferably within 1 to 1.10 times the lattice size of the alloy in the magnetic layer when the lattices are uniformly grown. The perpendicular magnetization film of this embodiment preferably further includes a non-magnetic layer (001) 3 above the magnetic layer 2 and an underlayer 4 below the magnetic layer, as shown in FIG. 1 .

[0015] [Magnetic Layer with Perpendicular Magnetization] The magnetic layer 2 contains an alloy with a bct crystal structure distorted from a bcc crystal structure, primarily composed of Co. The magnetization direction of the magnetic layer 2 is perpendicular to the surface of the magnetic layer 2. The "alloy with a bct crystal structure" of the present invention refers to a crystal structure distorted from an alloy with a bcc (body-centered cubic lattice) structure, in which the c / a ratio is less than 1.0, where a is the crystal lattice plane parallel to the surface of the magnetic layer and c is the crystal lattice plane perpendicular to the surface of the magnetic layer. For example, the c / a ratio may be 0.98 or less, 0.95 or less, 0.93 or less, 0.90 or less, 0.88 or less, or 0.85 or less. The c / a ratio is greater than 0.50, for example, the c / a ratio may be 0.55 or greater, 0.60 or greater, 0.65 or greater, 0.70 or greater, 0.75 or greater, or 0.80 or greater. The c / a ratio of the perpendicular magnetization magnetic layer 2 of this embodiment is preferably 0.80 to 0.95, and more preferably 0.85 to 0.90. The alloy preferably contains Co at 50 at% or greater but 90 at% or less. It is more preferable that the alloy contains Co at 75 at% or greater, and even more preferable that the alloy contains Co at 80 at% or greater. It is preferable that the alloy contains Mn at 10 at% or greater but 25 at% or less. It is more preferable that the alloy contains Mn at 20 at% or less, and even more preferable that the alloy contains Mn at 15 at% or greater.

[0016] The thickness of the magnetic layer 2 may be 1 nm or more, 2 nm or more, 3 nm or more, or 10 nm or less, as long as strain can be induced. When the alloy contains Fe, it may consist essentially of only Co, Mn, and Fe, in addition to impurities. "Consisting essentially of only Co, Mn, and Fe, in addition to impurities" means that the total amount of Co, Mn, and Fe in the alloy may be 99 at% or more, 99.5 at% or more, 99.8 at% or more, 99.9 at% or more, or 100 at%.

[0017] When each component of the alloy is contained within the above range, by appropriately distorting it to form a bct crystal structure, it is possible to form the perpendicular magnetization film of this embodiment, which is metastable and has a magnetization direction perpendicular to the surface of the magnetic layer.

[0018] To induce distortion, the magnetic layer 2 includes a non-magnetic layer (001) 3 above the magnetic layer 2 and an underlayer 4 below the magnetic layer 2. In the present invention, at least the magnetic layer 2 directly above and in contact with the underlayer 4 has a bct crystal structure distorted from the bcc crystal structure. The non-magnetic layers and magnetic layers other than the magnetic layer 2 directly above and in contact with the underlayer 4 may or may not have a distorted bct crystal structure.

[0019] [Nonmagnetic Layer] The nonmagnetic layer (001) 3 is a cubic or tetragonal crystal, and may be made of Cr or V. In order to induce in-plane tensile strain, the lattice size in the (001) plane of the nonmagnetic layer (001) 3 is preferably within 1 to 1.10 times the lattice size of the alloy of the magnetic layer when the lattices are uniformly grown. The nonmagnetic layer (001) 3 is preferably a conductive material, and may be a metal or a transition metal. It is more preferable that the nonmagnetic layer (001) 3 contains Cr(001). The thickness of the nonmagnetic layer (001) 3 may be 1 nm or more, or may be 3 nm or more, or may be 10 nm or less.

[0020] [Underlayer] The underlayer 4 may be any material as long as it is made of a (001) crystal. To induce in-plane tensile strain, the lattice size in the (001) plane of the underlayer 4 is preferably within 1 to 1.10 times the lattice size of the alloy of the magnetic layer when the lattices are uniformly grown. To function as a barrier layer for the magnetoresistive element, the underlayer 4 may be made of, for example, a cubic crystal (rock salt structure, spinel structure, etc.) oxide such as MgO or Mg—Ga—O, or a nitride such as GaN, Al—Ga—N, InN, or Cr. The underlayer 4 may also be made of multiple layers made of (001). In this case, a first underlayer, for example, a Cr(001) layer, and a second underlayer, for example, an MgO(001) oxide layer, may be stacked on the first underlayer on a (001) substrate made of any material. The thickness of the underlayer 4 may be about 0.5 nm to 2 nm in the magnetoresistive element.

[0021] The perpendicular magnetization film 1 according to the present embodiment includes a non-magnetic layer (001) 3, a perpendicular magnetization magnetic layer 2, and an underlayer 4. The magnetic layer 2 comprises a bct crystal structure alloy primarily composed of Co, the alloy containing Co and Mn, and the non-magnetic layer (001) 3 contains Cr(001). The underlayer 4 functions as a barrier layer for the magnetoresistive element, and is preferably made of, for example, a cubic (rock salt structure, spinel structure, etc.) oxide such as MgO or Mg—Ga—O, or a nitride such as GaN, Al—Ga—N, or InN. Furthermore, by forming the (001) plane of the underlayer 4, the magnetic layer 2 directly above the underlayer 4 can be converted from a bcc crystal structure to a distorted bct crystal structure, and the non-magnetic layer 3 is then formed on top of this. Optionally, a layer consisting of a repeating magnetic layer and a non-magnetic layer may be stacked on the non-magnetic layer 3.

[0022] 2, the perpendicular magnetization film 1a of this embodiment includes a first non-magnetic layer (001) 3a-1 on top of the first magnetic layer 2a-1 and an underlayer 4a below the first magnetic layer 2a-1. The perpendicular magnetization film 1a may also have a laminated structure including a second magnetic layer 2a-2 (not shown) and a second non-magnetic layer (001) 3a-2 (not shown) in that order on the first non-magnetic layer (001) 2a-1. For example, as shown in FIG. 2, in an example where the number of magnetic layers is N=n, the perpendicular magnetization film 1a may have a laminated structure including an n-th magnetic layer 2a-n and an n-th non-magnetic layer (001) 3a-n in that order on the n-1-th non-magnetic layer (001) 2a-n-1 (not shown). The second magnetic layer 2a-2 has a bct crystal structure alloy mainly composed of Co, and the alloy contains Co and Mn. In the perpendicularly magnetized film 1a of this embodiment having a stacked structure, the second magnetic layer 2a-2 may be the magnetic layer 2 described above under "magnetic layer." The alloy of the second magnetic layer 2a-2 may have the same composition as the alloy of the first magnetic layer 2a-1, or may have a different composition. The second magnetic layer 2a-2 may have the same thickness as the first magnetic layer 2a-1, or may have a different thickness.

[0023] In the perpendicular magnetization film of this embodiment having a laminated structure, the second non-magnetic layer (001) 3a-1 can be the non-magnetic layer 3 described above under "Non-magnetic Layer." The second non-magnetic layer (001) 3a-2 can have the same composition as the first non-magnetic layer (001) 3a-1, or a different composition. The second non-magnetic layer (001) 3a-2 can have the same thickness as the first non-magnetic layer (001) 3a-1, or a different thickness.

[0024] When the perpendicular magnetization film 1a of this embodiment includes two or more perpendicular magnetization magnetic layers according to this embodiment, for example, when it includes N layers, it may have a layer structure of "underlayer / perpendicular magnetization magnetic layer-1 / non-magnetic layer-1 / perpendicular magnetization magnetic layer-2 / non-magnetic layer-2 / ... / perpendicular magnetization magnetic layer-N / non-magnetic layer-N." The perpendicular magnetization film of this embodiment may include two or more perpendicular magnetization magnetic layers according to this embodiment, three or more layers, four or more layers, five or more layers, or six or more layers.

[0025] "Perpendicular Magnetization Characteristics of Perpendicular Magnetization Film of This Embodiment" As shown in Example 1 below, the perpendicular magnetization film of this embodiment has a maximum magnetization of approximately 4 MJ / m ３ A perpendicular magnetic anisotropy Kv due to the strain of the CoMnFe alloy can be obtained. If the thickness can be maintained while the film is strained, magnetic anisotropy due to the strain can be exhibited, and superiority can be found over conventional materials that use interfacial magnetic anisotropy. As a result of experiments, the perpendicular magnetization film of this embodiment was observed to have an increase in perpendicular magnetic anisotropy Kv close to the theoretical prediction of Example 1 at a composition close to that of a Co alloy with a bcc structure, as shown in FIG. 7 of Example 2. It is believed that a metastable Co alloy with a bct structure (for example, in the case of a CoMnFe alloy, a = 2.99 Å, c / a = 0.88) was obtained.

[0026] Second Embodiment The perpendicular magnetization film of the second embodiment has the same layer structure as the perpendicular magnetization film of the first embodiment shown in FIG. 1. Except for the following description, the configuration and aspects are the same as those of the first embodiment. The configuration and aspects described in the first embodiment can be incorporated herein. Unlike the nonmagnetic layer (001) 3 of the first embodiment, the nonmagnetic layer 3 of the perpendicular magnetization film of the second embodiment only needs to contain Ru. In this case, the nonmagnetic layer does not need to be (001) oriented. The perpendicular magnetization magnetic layer 2 and underlayer 4 included in the perpendicular magnetization film of the second embodiment are the same as the perpendicular magnetization magnetic layer of the first embodiment. The perpendicular magnetization film of the second embodiment may have the same multilayer structure as the perpendicular magnetization film of the first embodiment shown in FIG. 2. However, if the nonmagnetic layer of the perpendicular magnetization film of the second embodiment contains Ru, the nonmagnetic layer does not need to be (001) oriented. Similarly, if the first nonmagnetic layer 3a-1 to the n-th nonmagnetic layer 3a-n also contain Ru, the nonmagnetic layer does not need to be (001) oriented. The second non-magnetic layer 3a-2 of the second embodiment may have the same composition as the first non-magnetic layer 3a-1, or may have a different composition. The second non-magnetic layer 3a-2 may have the same thickness as the first non-magnetic layer 3a-1, or may have a different thickness. For example, it is preferable that they are the same Ru layer. The first magnetic layer 2a-1 to the n-th magnetic layer 2a-n of the second embodiment are the same as the magnetic layers of the first embodiment. The alloy of the second magnetic layer 2a-2 of the second embodiment may have the same composition as the alloy of the first magnetic layer 2a-1, or may have a different composition. The second magnetic layer 2a-2 may have the same thickness as the first magnetic layer 2a-1, or may have a different thickness.

[0027] [Nonmagnetic Layer 3] The nonmagnetic layer 3 of the second embodiment does not need to have a (001) orientation, as in the first embodiment. If the nonmagnetic layer 3 of the second embodiment is not a (001) nonmagnetic layer, the range of materials available for selection is broader, which is expected to be advantageous in terms of other physical properties such as stability, productivity, etc. The film thickness of the nonmagnetic layer 3 may be, for example, 0.04 nm or more, 0.1 nm or more, and preferably 0.2 nm or more. 0.6 nm or more is more preferable. 0.8 nm or more is even more preferable. A thickness of the above or greater allows for effective coupling with the magnetic layer 2. The film thickness of the nonmagnetic layer 3 may also be, for example, 2.0 nm or less, 1.8 nm or less, preferably 1.4 nm or less, and more preferably 1.2 nm or less. A thickness of the above or less does not hinder the miniaturization of elements. The nonmagnetic layer 3 of the second embodiment preferably contains Ru, and more preferably is a layer of Ru alone.

[0028] [Magnetic Layer 2] The magnetic layer 2 of the second embodiment has the same composition as the magnetic layer 2 of the first embodiment. In the second embodiment, the orientation of the nonmagnetic layer on the magnetic layer 2 of the second embodiment does not have to be (001). For example, a nonmagnetic layer 3 containing Ru is provided. In particular, when the nonmagnetic layer 3 of the second embodiment is not a (001) nonmagnetic layer, it is believed that it is the underlayer 4 below the magnetic layer 2 that induces strain in the magnetic layer 2 of the second embodiment.

[0029] [Third Embodiment] The perpendicular magnetization film of the third embodiment has the same layer structure as the perpendicular magnetization film of the second embodiment. Except for the following description, the configuration and aspects are the same as those of the second embodiment. The configuration and aspects described in the second embodiment can be used here. In the multilayer structure (N layers) of the perpendicular magnetization film of the third embodiment, the second magnetic layer 2a-2 to the Nth magnetic layer 2a-n are different from those of the second embodiment. The second magnetic layer 2a-2 to the Nth magnetic layer 2a-n of the third embodiment have a different composition from that of the first magnetic layer 2a-1.

[0030] [Second magnetic layer 2a-2 to Nth magnetic layer 2a-n] The thickness of the second magnetic layer 2a-2 may be the same as or different from that of the first magnetic layer 2a-1. The thickness of the second magnetic layer 2a-2 is preferably the same as that of the first magnetic layer 2a-1. The Nth magnetic layers 2a-n other than the second magnetic layer 2a-2 may be the same as or different from the second magnetic layer 2a-2, but are preferably the same. The second magnetic layer 2a-2 is preferably a Co layer.

[0031] (Magnetoresistive effect element) A magnetoresistive effect element according to one embodiment of the present invention has a perpendicular magnetization film according to any of the above-described embodiments, an underlayer of the perpendicular magnetization film as a barrier layer, and a reference magnetic layer disposed on the barrier layer side. The perpendicular magnetization film is a free magnetic layer. The reference magnetic layer is a magnetic layer whose magnetization direction is substantially fixed. The reference magnetic layer includes a magnetic alloy that exhibits a high TMR effect, such as Co—Mn—Fe or Fe—Co—B, directly below the barrier layer, and may include a perpendicular magnetization magnetic multilayer film below it, or an L1 ０ It may contain ordered alloys. ０ An "ordered alloy" is an alloy having a face-centered cubic structure in which each metal is regularly stacked on a monoatomic basis. ０ As an ordered alloy, for example, L1 ０Examples of the magnetoresistive effect element of this embodiment include an ordered FePt alloy. As shown in FIG. 3, an example of the magnetoresistive effect element of this embodiment is a magnetoresistive effect element 10 having a reference magnetic layer 11, a free magnetic layer 12, and a non-magnetic layer 13. The reference magnetic layer 11 has a substantially fixed magnetization direction and forms a reference layer. The free magnetic layer 12 has a variable magnetization direction and forms a free layer. The reference magnetic layer 11 and the free magnetic layer 12 are made of ferromagnetic materials. The free magnetic layer 12 is made of the perpendicular magnetization film of this embodiment described above. The magnetization direction of the reference magnetic layer 11 may be parallel to the surface of the magnetic layer (in-plane magnetization) or perpendicular to the surface of the magnetic layer (perpendicular magnetization). The reference magnetic layer 11 may be made of a known bcc (body-centered cubic) structure alloy containing Co as the main component and Co and Mn. The bcc alloy preferably contains 50 at% to 90 at% Co and 10 at% to 40 at% Mn. It may also contain 35 at% or less Fe. The reference magnetic layer 11 may be made of the well-known FeCoB alloy, which is mainly composed of Co.

[0032] The non-magnetic layer 13 is disposed between the reference magnetic layer 11 and the free magnetic layer 12 and serves as a barrier layer. The non-magnetic layer 13 is preferably made of the same material as the underlayer 4 of the perpendicular magnetization film of the present embodiment described above.

[0033] Next, the operation will be described. The magnetoresistive element 10 has an excellent tunnel magnetoresistance ratio because the free magnetic layer 12 is made of the perpendicular magnetization film of the above-described embodiment. The magnetoresistive element 10 can be manufactured by depositing the reference magnetic layer 11, the free magnetic layer 12, and the non-magnetic layer 13 by, for example, sputtering. When the reference magnetic layer 11 is also made of an alloy containing Co as a main component and Co and Mn, the magnetoresistive element 10 can be mass-produced and put into practical use by depositing all layers, including the free magnetic layer 12 containing the alloy, by sputtering.

[0034] The present invention has been described in detail above using several embodiments as examples, but the present invention is not limited to the above embodiments and modifications, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims.

[0035] Example 1 "Simulation of perpendicular magnetic anisotropy" The perpendicular magnetic anisotropy film of this embodiment is "Co １００－ｘ Mn ｘ " and "(Co ８０ Mn ２０ ) １００－ｘ Fe ｘ The perpendicular magnetic anisotropy of " was verified through simulation.

[0036] The simulations were performed using the SPR-KKR method incorporating the coherent potential method (see Non-Patent Document 1 and Non-Patent Document 2). The magnetic anisotropy was calculated using the magnetic torque method (see Non-Patent Document 3). Non-Patent Documents 1 to 3 are incorporated herein by reference. [Non-Patent Document 1] P. Soven, Phys. Rev. B 156, 809 (1967). [Non-Patent Document 2] H. Ebert, D. Kodderitzsch, and J. Minar, Rep. Prog. Phys. 74, 096501 (2011). [Non-Patent Document 3] J. B. Staunton, L. Szunyogh, A. Buruzs, B. L. Gyorffy, S. Ostanin, and L. Udvardi Phys. Rev. B 74, 144411 (2006).

[0037] "Structure of perpendicular magnetization film to be simulated" To simplify the calculation, calculations are performed for the case where the lattice constant is changed in the bulk.

[0038] "Simulation calculation results" As shown in Figures 4 and 5, calculations were performed when the lattice constant was changed in the bulk, and the maximum energy density was 4 MJ / m ３ A perpendicular magnetic anisotropy Kv due to strain of 1 meV / atom ≒ 13.8 MJ / m was obtained. Furthermore, if strain can be achieved while maintaining the thickness, superiority over conventional materials using interface magnetic anisotropy can be found. ３ is.

[0039] Example 2 "Relationship between perpendicular magnetic anisotropy and composition" An experiment was conducted on the results of Example 1. As the perpendicular magnetization film of this embodiment, a schematic diagram of the layer structure of the perpendicular magnetization film of this example is shown in Figure 2 (when the number of layers N=1).

[0040] "Manufacturing method" An MgO (001) single crystal substrate was used as the underlayer / substrate, and a 40 nm thick Cr (001) layer was laminated as the underlayer. １００－ｘ (FeMn) ｘ (x=7, 8, 9, 10, 12, 14, 17, 23) thin film CoMnFe alloy layer and a 3 nm thick Cr layer as the non-magnetic layer were deposited by sputtering to manufacture test elements. The perpendicular magnetic anisotropy Kv due to strain was evaluated using the test elements with each composition manufactured above. The results are shown in FIG. 6. For comparison, the calculation results from Example 1 are also listed. The method for evaluating the perpendicular magnetic anisotropy Kv due to strain is as follows.

[0041] <Perpendicular magnetic anisotropy K due to strain ｖ Measurement method and conditions > Measurement equipment: Vibrating sample magnetometer Measurement conditions: With the vibrating sample magnetometer, measurements were taken by applying a magnetic field in the in-plane direction and perpendicular to the plane. A maximum magnetic field of 2 T was applied perpendicular to the plane. The saturation magnetic field H evaluated by applying a magnetic field in the direction of hard magnetization ｓ and the saturation magnetization M measured by applying a magnetic field in the easy direction of magnetization. ｓ From this, the perpendicular magnetic anisotropy Kv due to strain was evaluated using the following formula:

[0042]

[0043] Here, when the hard axis of magnetization is perpendicular to the film surface, H ｓ <0, and when the hard axis is in the film plane, H ｓ >0 (see Non-Patent Document 1).

[0044] (Example 3) "Relationship with the number of layers" When the composition of the CoMnFe alloy layer is (Co ８０ Mn １０ Fe １０), the thickness t of the CoMnFe alloy layer was 1 nm, and the number of layers was 2 to 6. Except for this, the test elements were manufactured in the same manner as in Example 2 (FIG. 2). The results are shown in FIG. 7. In addition, the perpendicular magnetic anisotropy K×film thickness t was calculated, and the relationship between "perpendicular magnetic anisotropy K×film thickness t" and the number of layers N was evaluated. K was evaluated using the following formula:

[0045]

[0046] The results are shown in Figure 8.

[0047] (Example 4) "Relationship with the number of layers" When the composition of the CoMnFe alloy layer is (Co ８４ Mn ８ Fe ８ ) Test elements were manufactured in the same manner as in Example 3. The magnetic anisotropy Kv and perpendicular magnetic anisotropy K due to strain were evaluated in the same manner as in Example 2. The results are shown in Figures 7 and 8. Furthermore, the Kerr rotation angle in each magnetic field was measured using the test elements of each composition manufactured above. The results are shown in Figure 9. The method and conditions for measuring the Kerr rotation angle are as follows.

[0048] <Method and conditions for measuring the Kerr rotation angle> Measurement device: Polar magneto-optical effect measurement device Measurement conditions: A magnetic field of up to 2T is applied in the direction perpendicular to the film surface

[0049] (Discussion of Examples 1 to 4) From the results of Examples 1 to 4, it was confirmed theoretically and experimentally that the perpendicular magnetization film of this embodiment exhibits magnetic anisotropy based on a different physical principle from that of a conventional FeCoB / MgO perpendicular magnetization film that uses interface magnetic anisotropy, in which MgO is typically used as the insulating layer material and FeCoB is used for the magnetic layer. In the case of a conventional FeCoB / MgO perpendicular magnetization film that uses interface magnetic anisotropy, it is known that joining FeCoB to MgO and performing an appropriate heat treatment will exhibit perpendicular magnetization due to so-called interface magnetic anisotropy. Therefore, unlike the conventional FeCoB / MgO using interface magnetic anisotropy, the perpendicular magnetization film of this embodiment has been confirmed, for example, from the results of the layer number relationships shown in Examples 3 and 4, that even if there is no MgO layer in the layer in contact with CoMnFe-2, as in MgO / CoMnFe-1 / Cr-1 / CoMnFe-2 / Cr-2 / ..., the perpendicular magnetic anisotropy Kv due to strain increases with an increase in the number of layers.

[0050] (Example 5) "Relationship with thickness of non-magnetic layer" As shown in Figure 10, test elements were manufactured in the same manner as in Example 4, except that the number of layers N was 2 and the thickness of the non-magnetic layer Cr was d = 0.2 nm, 0.4 nm, 0.6 nm, 0.8 nm, or 1.0 nm. Using the test elements of each composition manufactured above in the same manner as in Example 4, the Kerr rotation angle in each magnetic field was measured. The results are shown in Figure 11.

[0051] (Considerations on Example 5) From the results of Example 5, it can be seen that as the thickness of Cr increases, Kv increases and perpendicular magnetization becomes more stable. Furthermore, at least in Example 5, the thickness of Cr is preferably 0.4 nm or more, and more preferably 0.6 nm or more.

[0052] Example 6 A magnetoresistive element 10 was manufactured by sputtering, in which the free layer was an alloy of the perpendicular magnetization film of this embodiment and the reference layer was a Co—Mn—Fe alloy with a bcc structure. As shown in Fig. 12, 40 nm of Cr(001) was deposited on an MgO(001) substrate, followed by the deposition of a 4 nm-thick reference magnetic layer 11 (reference layer) made of a Co—Mn—Fe thin film, and then the perpendicular magnetization film of this embodiment with a six-layer structure was deposited by sputtering. The perpendicular magnetization film of this embodiment having a six-layer structure includes a non-magnetic layer 13 (underlayer of the perpendicular magnetization film of this embodiment) made of a 2 nm thick MgO film, a free magnetic layer 12 (magnetic layer of the perpendicular magnetization film of this embodiment) made of a 1 nm thick bct-structured Co-Mn-Fe(001) film, and a 40 nm thick Cr layer (non-magnetic layer of the perpendicular magnetization film of this embodiment). The film was formed by sputtering with a six-layer structure such as MgO / Co-Mn-Fe(001) / Cr(001) / [Co-Mn-Fe(001) / Cr(001)]×4 layers / Co-Mn-Fe(001) / Cr(001). After film formation, a heat treatment (anneal) was performed at a predetermined temperature up to 300° C. for 1 hour to manufacture a test element of the magnetoresistance effect element 10. The composition of the reference magnetic layer 11 of this embodiment is Co ６６ Mn １７ Fe １７ The composition of the free magnetic layer 12 in this example is Co ８０ Mn １０ Fe １０ The element resistance was measured using each test element by the following method, and the measurement results are shown in FIG.

[0053] <Method for Measuring Element Resistance> Apparatus: DC four-terminal magnetoresistance prober The element resistance was measured by the DC four-terminal method at room temperature with an applied voltage of 10 mV.

[0054] (Discussion of Example 6) The results of Example 6 show that perpendicular magnetization film characteristics can be obtained even in the element form, demonstrating that it can be applied to magnetoresistive elements. Because a metal is used for the non-magnetic layer, even if the number of layers is increased, the resistance of the entire element does not increase, and this is thought to be an advantage over conventional materials that use interfacial magnetic anisotropy at this time.

[0055] Example 7 Example of the Second Embodiment Manufacturing Method As shown in FIG. 14, an MgO (001) single crystal substrate was used as the base / substrate 15c, and a 40 nm thick Cr (001) layer was laminated as the base layer 14c. In order, a 2 nm thick MgO (001) layer was laminated as the base layer 14c, and a 1 nm thick "Co" layer was laminated as the first perpendicular magnetization magnetic layer 2c-1. ８0 Mn 10 Fe 10 a CoMnFe alloy layer made of a thin film, a Ru layer having a thickness t ((a) t=0.4 nm; (b) t=0.6 nm; (c) t=0.8 nm; (d) t=1.0 nm) as the first non-magnetic layer 3c-1, and a 1 nm thick "Co ８0 Mn 10 Fe 10 A thin CoMnFe alloy layer was formed by sputtering. Then, a multilayer film consisting of N layers, from the second non-magnetic layer 3c-2 / / third perpendicular magnetization magnetic layer 2c-3 to the Nth non-magnetic layer 3c-n / / Nth perpendicular magnetization magnetic layer 2c-n, was formed on top of the CoMnFe alloy layer. A 3-nm-thick Cr layer was then formed on top of the Nth non-magnetic layer 3c-t to fabricate the test element of this example. The second non-magnetic layer 3c-2 to the Nth non-magnetic layer 3c-n have the same components and thicknesses as the first non-magnetic layer 3c-1. The third non-magnetic layer 3c-3 to the Nth perpendicular magnetization magnetic layer 2c-n have the same components and thicknesses as the second perpendicular magnetization magnetic layer 2c-2. Furthermore, the Kerr rotation angle was measured in each magnetic field using each test element fabricated as described above, using the same method as in Example 5. The results are shown in FIG. 15.

[0056] (Example 8) "Example of the Third Embodiment" "Manufacturing Method" As shown in FIG. 16, an MgO (001) single crystal substrate was used as the base / substrate 15d, and a 40 nm thick Cr (001) layer was laminated as the base layer 14d. In order, a 2 nm thick MgO (001) layer was laminated as the base layer 4d, and a 1 nm thick "Co" layer was laminated as the first perpendicular magnetization magnetic layer 2d-1. ８０ Mn １０ Fe １０A thin CoMnFe alloy layer and a 0.8 nm thick Ru layer were deposited by sputtering as the first non-magnetic layer 3d-1. A 1 nm thick Co layer was then deposited by sputtering on top of that as the second perpendicularly magnetized magnetic layer 2d-2. Then, multilayer films were deposited on top of that, from the second non-magnetic layer 3d-2 / / third perpendicularly magnetized magnetic layer 2d-3 to the Nth non-magnetic layer 3d-n / / Nth perpendicularly magnetized magnetic layer 2d-n, with the number of Co layers M = "N-1" (FIG. 17: (a) M = 1 layer; (b) M = 2 layers; (c) M = 3 layers). A 3 nm thick Cr layer was then deposited on top of that as the non-magnetic layer 3d-t, and the test elements of this example were manufactured. The second non-magnetic layer 3d-2 to the fourth non-magnetic layer 3d-4 have the same components and the same thickness as the first non-magnetic layer 3d-1, and the third perpendicular magnetization magnetic layer 2d-3 to the fourth perpendicular magnetization magnetic layer 2d-4 have the same components and the same thickness as the second perpendicular magnetization magnetic layer 2d-2. Furthermore, using each of the test elements manufactured as above, the Kerr rotation angle in each magnetic field was measured in the same manner as in Example 5. The results are shown in Figure 17.

[0057] 1, 1a, 1b, 1c, 1d... Perpendicular magnetization film 2, 2a-1, 2a-n, 2b-1, 2b-2, 2c-1, 2c-2, 2d-1, 2d-2... Magnetic layer 3... Nonmagnetic layer, nonmagnetic layer (001) 3a-1, 3a-n, 3b-1, 3b-2... Nonmagnetic layer (001) 3c-1, 3c-2, 3c-t, 3d-1, 3d-t...Nonmagnetic layer 4, 4a, 4b, 4c, 4d...Underlayer (001) 11...Magnetoresistive element 10...Magnetoresistive element 11, 11a...Reference magnetic layer 12, 12a...Free magnetic layer 13, 13a...Nonmagnetic layer (001) 14, 14a, 14c, 14d...base layer (001) 15, 15a, 15c, 15d...substrate

Claims

1. A perpendicular magnetization film comprising a magnetic layer with perpendicular magnetization, a non-magnetic layer on top of the magnetic layer, and an underlayer on bottom of the magnetic layer, wherein the magnetic layer has an alloy with a bct crystal structure containing Co as the main component, and the alloy contains Co and Mn.

2. The perpendicular magnetization film according to claim 1, wherein the non-magnetic layer on top of the magnetic layer is a (001) non-magnetic layer.

3. The perpendicular magnetization film according to claim 2, wherein the nonmagnetic layer contains Cr(001).

4. The perpendicular magnetization film according to claim 1, wherein the nonmagnetic layer contains Ru.

5. A perpendicular magnetization film according to claim 1, wherein the lattice size in the (001) plane of the underlayer is within 1 to 1.10 times the lattice size of the alloy of the magnetic layer when grown with a uniform lattice.

6. A perpendicular magnetization film according to claim 1, wherein said alloy contains 75 at % to 90 at % of said Co and 10 at % to 25 at % of said Mn.

7. The perpendicular magnetization film according to claim 6, wherein said alloy further contains Fe in an amount of 25 at % or less.

8. The perpendicular magnetization film according to claim 1, wherein the underlayer comprises any one of MgO, Mg--Ga--O, GaN, Al--Ga--N, and Cr as an underlayer (001).

9. A perpendicular magnetization film according to claim 1, characterized in that it has a laminated structure further including a second magnetic layer and a second non-magnetic layer in that order on the non-magnetic layer.

10. The perpendicular magnetization film according to claim 9, wherein the second magnetic layer and the second non-magnetic layer have the same composition as the magnetic layer and the non-magnetic layer, respectively.

11. The perpendicular magnetization film according to claim 9, wherein the second magnetic layer and the second non-magnetic layer have compositions different from the magnetic layer and the non-magnetic layer, respectively.

12. The perpendicular magnetization film according to claim 11, wherein the second non-magnetic layer is a Co layer.

13. A perpendicular magnetization film according to claim 2, characterized in that it has a laminated structure further including a second magnetic layer and a second non-magnetic layer (001) in that order on the non-magnetic layer (001).

14. The perpendicular magnetization film according to claim 13, wherein the second magnetic layer and the second non-magnetic layer (001) have the same composition as the magnetic layer and the non-magnetic layer (001), respectively.

15. A magnetoresistive effect element comprising: a perpendicular magnetization film according to any one of claims 1 to 14; and a reference magnetic layer disposed on the underlayer side of said perpendicular magnetization film, wherein said perpendicular magnetization film is a free magnetic layer, and said reference magnetic layer is a magnetic layer whose magnetization direction is substantially fixed.

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