Antiferromagnetic body material, two-layer film of magnetic body and insulator, tunnel magnetoresistive element, and magnetic memory

Abstract

This antiferromagnetic body material has a hexagonal crystal structure, and comprises: an antiferromagnetic layer formed of Mn3A1-xBx (0<x<0.5, A=Ga, Ge, Sn, and B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb) or (Mn1-pCrp)3GaqGerSn1-q-r (0<p<0.5, 0<q<1, 0<r<1, and 0<q+r≤1); and an insulator layer laminated on the surface of the same. Preferably, A represents at least one of Ga and Sn. In addition, preferably, B represents at least one of Mg, Al, Si, Mn, Cu, Zn, Ag, Cd, In, Sb, Au, and Tl.

Description

Antiferromagnetic materials, double-layered films of magnetic and insulator materials, tunnel magnetoresistance elements, and magnetic memories

[0001] This disclosure relates to antiferromagnetic materials, two-layer films of magnetic bodies and insulators, tunnel magnetoresistive elements, and magnetic memories. This application claims priority to U.S. Provisional Patent Application No. 63 / 529,410, filed July 28, 2023, the contents of which are incorporated herein by reference.

[0002] A magnetoresistive element is known in which an insulating layer is sandwiched between a ferromagnetic layer whose magnetization direction is variable and a ferromagnetic layer whose magnetization direction is fixed. To increase the speed of such a magnetoresistive element, Mn is used instead of the ferromagnetic material. ３ The use of an antiferromagnetic layer such as Sn has been considered (see, for example, H. Tsai, et al., “Electrical manipulation of a topological antiferromagnetic state,” Nature, volume 580, pages 608-613 (2020)).

[0003] In International Patent Application Publication No. 2022 / 220251, Mn ３ It is disclosed that by sandwiching Ta between the Sn and insulating contact layer, the roughness of the interface is suppressed and smoothed, and the read signal of the magnetic memory element is strengthened.

[0004] The ferromagnetic layer is made of Mn ３ It has been shown by X. Chen, et al., "Octupole-driven magnetoresistance in an antiferromagnetic tunnel junction," Nature 613, 490 (2023) that a tunnel magnetoresistance element can be obtained by using an antiferromagnetic layer such as Sn and sandwiching an insulating layer such as MgO between two antiferromagnetic layers.

[0005] International Patent Application Publication No. 2022 / 220251

[0006] H. Tsai, et al. , “Electrical manipulation of a topological antiferromagnetic state,” Nature, volume 580, pages 608-613 (2020) X. Chen, et al. , “Octupole-driven magnetoresistance in an antiferromagnetic tunnel junction”, Nature 613, 490 (2023)

[0007] It is therefore desirable to obtain such a tunnel magnetoresistive element that is highly heat-resistant. An object of the present invention is to obtain a tunnel magnetoresistive element and a magnetic memory that are highly heat-resistant.

[0008] According to one aspect of the present disclosure, the antiferromagnetic material is Mn ３ A １－ｘ B ｘ (0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb), or (Mn １－ｐ Cr ｐ ) ３ Ga ｑ Ge ｒ Sn １－ｑ－ｒ (0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1) and has a hexagonal crystal structure.

[0009] According to another aspect of the present disclosure, the two-layer film of a magnetic material and an insulator has a layer made of the above-mentioned ferromagnetic material and a layer made of an insulator laminated on the layer made of the ferromagnetic material.

[0010] According to yet another aspect of the present disclosure, the tunneling magnetoresistive element has a second antiferromagnetic film layer stacked on the insulator of the two-layer film.

[0011] According to yet another aspect of the present disclosure, a magnetic memory includes a plurality of the tunnel magnetoresistive elements described above.

[0012] According to the present invention, a tunnel magnetoresistive element and a magnetic memory having high heat resistance can be obtained.

[0013] A more complete understanding of the present disclosure and many of its attendant advantages will be readily obtained as it becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which: Figure 1 is a cross-sectional view of one embodiment of a bilayer film of a magnetic material and an insulator; Figure 2 is a cross-sectional view of one embodiment of a tunneling magnetoresistive element; Figure 3 is a graph of the average absolute value of the magnetic moment at each site, and Figure 4 is a graph of the Mn ３ The difference in Neel temperature (calculated value) compared to Sn (ΔT Ｎ 1 is a graph plotting the amount of element substitution (amount of element substitution) with an upper limit of 10%. FIG. 2 is a cross-sectional view illustrating the operation of a tunnel magnetoresistive element. FIG. 3 is a circuit diagram of an embodiment of a magnetic memory.

[0014] When amounts, concentrations, or other values ​​or parameters are given herein as ranges, and / or when the description includes a list of upper and lower limits, this is understood to specifically disclose all integers and fractions within the given range, and all ranges formed from any pair of any upper and lower limits, regardless of whether a narrower range is separately disclosed. When a range of numerical values ​​is recited herein, unless otherwise specified, the range is intended to include all integers and fractions within the range, as well as its endpoints. As an example, the range of 1 to 10 fully describes and includes the independent subranges 3.4 to 7.2, as well as the listing of values ​​1, 4, 6, and 10.

[0015] In an embodiment of the present disclosure, in a tunnel magnetoresistive element having an insulating layer sandwiched between a plurality of antiferromagnetic layers, the antiferromagnetic layers are made of Mn ３ A １－ｘ B ｘ (0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb), or (Mn １－ｐ Cr ｐ ) ３ Ga ｑ Geｒ Sn １－ｑ－ｒ By forming a layer having a hexagonal crystal structure of (0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1), a tunnel magnetoresistive element with relatively high heat resistance can be obtained. Therefore, when this tunnel magnetoresistive element is used in a magnetic memory, a magnetic memory with relatively high heat resistance can be obtained.

[0016] The antiferromagnetic material and embodiments of each element will be described below.

[0017] [Antiferromagnetic Material, Double-Layered Film of Magnetic Material and Insulator, and Tunneling Magnetoresistance Element] Figure 1 is a cross-sectional view showing one embodiment of a double-layered film of a magnetic material and an insulator. An insulator layer 12 is stacked on an antiferromagnetic material layer 11.

[0018] 2 is a cross-sectional view showing one embodiment of a tunnel magnetoresistive element. An insulator layer 12 is laminated on an antiferromagnetic layer 11, and a second antiferromagnetic layer 13 is further laminated on the insulator layer 12.

[0019] In the disclosed double-layered film of a magnetic material and an insulator and the tunnel magnetoresistance element, the material of the antiferromagnetic layer 11 and the second antiferromagnetic layer 13 is Mn having a hexagonal crystal structure. ３ A １－ｘ B ｘ (0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb), or (Mn １－ｐ Cr ｐ ) ３ Ga ｑ Ge ｒ Sn １－ｑ－ｒ(0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1). A is more preferably at least one of Ga and Sn, and B is more preferably at least one of Mg, Al, Si, Mn, Cu, Zn, Ag, Cd, In, Sb, Au, and Tl. x is preferably 0<x<0.5, and more preferably 0.15<x<0.25. p is preferably 0<p<0.5, and more preferably 0.15<p<0.25. q is preferably 0.2<q<0.8, and more preferably 0.4<q<0.6. r is preferably r<0.5.

[0020] The materials of the antiferromagnetic layer 11 and the second antiferromagnetic layer 13 may be the same or different. These crystals have cluster magnetic octupole spin polarization, and the net spin polarization defined by the magnetic octupole can be rotated by applying a magnetic field or passing a current.

[0021] The thicknesses of the antiferromagnetic layer 11 and the second antiferromagnetic layer 13 are each independently, for example, 0.5 nm to 40 nm, preferably 0.5 nm to 30 nm, and more preferably 0.5 nm to 20 nm. The thickness of the insulator layer 12 is, for example, 0.5 nm to 5 nm, preferably 0.5 nm to 4 nm, and more preferably 1 nm to 3 nm. By making each layer have such a thickness, the resistance value can be adjusted to a value appropriate for device application.

[0022] The inventors of the present disclosure have found, by performing simulations as described below, that the thermal stability can be improved by using a specific material for the antiferromagnetic layer.

[0023] (Simulation Method) In order to search for an antiferromagnetic material with improved thermal stability (higher Neel temperature), simulation was carried out in the following three steps: (1) Antiferromagnetic material Mn with a hexagonal crystal structure ３ Using X (X = Ga, Ge, Sn) as a base material, (i) a material in which X is partially replaced with another element, and (ii) a material in which Mn is partially replaced with another element and Ga, Ge, and Sn are combined in any ratio instead of X (Mn, Y). ３(1) Search for materials whose Neel temperature is higher than the standard material for two types of materials (Ga-Ge-Sn). (2) Search for materials whose magnetic state below the Neel temperature is equivalent to that of the standard material. (3) Search for materials whose structure can be stably maintained.

[0024] The following explains each of these in order: (1) Mn with a hexagonal crystal structure ３ Using X (X = Ga, Ge, Sn) as a base material, (i) a material in which X is partially substituted with any element, and (ii) a material in which Mn is partially substituted with any element Y, and Ga, Ge, and Sn are combined in any ratio instead of X (Mn, Y). ３ (Ga-Ge-Sn), and search for materials with higher Neel temperatures than the standard materials.

[0025] The elements to be substituted are 70 types of elements with atomic numbers 11 (Na) to 83 (Bi) in the periodic table, excluding rare gas elements, and the substitution amount is up to 50%. ３ Ga, Mn ３ Ge, Mn ３ Using the experimental value of Sn, and not considering the change in lattice constant due to element substitution, (Mn, Y) in (ii) ３ For (Ga-Ge-Sn), the crystal structure is determined by linear approximation from experimental values ​​according to the compounding ratio of Ga, Ge, and Sn. The Neel temperature calculated based on first-principles calculations for the crystal structure determined above is used as the reference Mn ３ A material system that increases the value above that of (Ga—Ge—Sn) is selected as a candidate for search. The specific calculation method is as follows.

[0026] First-principles calculations for the randomly substituted systems were carried out using the coherent potential approximation (CPA). For each doping system, a classical spin Hamiltonian was constructed as follows: Here, J ｉｊ (n ｉ , n ｊ ) is the exchange coupling constant between the i-th and j-th elements up to the cutoff length 2a (a is the lattice constant), and s ｉ（，ｊ）is the normalized classical spin moment at the i(,j)th site. The type dependence of the coupling constants for atoms n_i and n_j was calculated based on first-principles calculations (implemented in the AkaiKKR code (http: / / kkr.issp.u-tokyo.ac.jp / jp / )) using the Korringa-Kohn-Rostoker (KKR) Green's function method for paramagnetic local moment disorder and the Liechtenstein equation (A.I. Liechtenstein, et al. Magn. Mater. 67, 65 (1987)). In this calculation, the atom-sphere approximation and the Perdew, Becke, and Erzenhof (PBE) generalized gradient approximation parametrization were used. For the 4f states of rare-earth elements, the so-called open-core approximation was adopted.

[0027] Native Monte Carlo (MC) simulations were performed using the above Hamiltonian to determine the Néel temperature from the peak of the magnetic heat capacity. Each MC simulation was performed for 5-10 atomic configurations constructed with different random number sequences, with 100,000 MC steps for relaxation and 100,000 MC steps for magnetization calculation.

[0028] As an example, the results shown in Figure 3 are obtained. In Figure 3, the horizontal axis represents the average absolute value of the magnetic moment of each site, and the vertical axis represents the Mn ３ The difference in Neel temperature (calculated value) compared to Sn (ΔT Ｎ ) are plotted with the upper limit of the element substitution amount being 10%. ３ Sn, Mn ３ Ge, Mn ３ The area above the horizontal line corresponds to the search material. For example, Sn-System (Mn ３ In the region where elements are substituted based on Sn, ΔT Ｎ >0 corresponds to the search material.

[0029] (2) Search for materials whose magnetic state below the Neel temperature is equivalent to that of the reference material. For the material system obtained in (1) above, the magnetic structure below the Neel temperature is calculated by Monte Carlo calculation, and the original Mn ３Select one that has a similar cluster magnetic octupole polarization as X (X=Ga, Ge, Sn).

[0030] (3) Search for materials that can exist stably in the structure. For the material system obtained in (2) above, the KKR-CPA method, which incorporates the Full Potential method, is used to examine the energy stability of the alloy based on the convex hull of the formation energy. Mn, which is already known to be stable experimentally, ３ When compared with Ge substitution or Ga substitution of Sn in Sn, one that is energetically stable to the same extent is selected.

[0031] From the above simulation calculations, in the tunnel magnetoresistive element, the material of the antiferromagnetic layer 11 and the second antiferromagnetic layer 13 is Mn ３ A １－ｘ B ｘ (0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb), or (Mn １－ｐ Cr ｐ ) ３ Ga ｑ Ge ｒ Sn １－ｑ－ｒ It was found that when the conditions are (0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1), the thermal stability of magnetism (Neel temperature) improves and the material can exist in a stable state in terms of energy.

[0032] In one embodiment of the present disclosure, the Neel temperature (calculated value) of the antiferromagnetic layer is Mn ３ Its Neel temperature is 10K higher than the calculated Neel temperature of Sn. ３ The Neel temperature (calculated value) of Sn is about 420K.

[0033] In one embodiment of the present disclosure, an antiferromagnetic layer (i.e., Mn ３ A １－ｘ B ｘ (0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb), or (Mn １－ｐ Crｐ ) ３ Ga ｑ Ge ｒ Sn １－ｑ－ｒ (0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1)) is below the Neel temperature and is the standard for finding materials through simulation calculations. ３ It has the same cluster magnetic octupole polarization as X (X = Ga, Ge, Sn).

[0034] In one embodiment of the present disclosure, the energy difference between the tetragonal structure and the hexagonal structure of the antiferromagnetic layer with the same composition is Mn ３ Sn or Mn ３ It has a value smaller than that of Ga.

[0035] In one embodiment of the present disclosure, the insulating layer and the two antiferromagnetic layers are in direct contact with each other. In another embodiment, one or more additional layers are interposed between the insulating layer and the antiferromagnetic layer. The additional layers disposed between the antiferromagnetic layer and the insulating layer are not particularly limited as long as they can be formed by known film formation methods such as sputtering or epitaxial growth (MBE, MOCVD, etc.). In this case, examples of the one or more additional layers include layers containing Ta or Ru.

[0036] [Method of Manufacturing Double-Layered Film of Magnetic Material and Insulator and Tunneling Magnetoresistance Element] The double-layered film of magnetic material and insulator and the tunneling magnetoresistance element can be manufactured by the following procedure: (1) creating an antiferromagnetic layer 11, (2) laminating an insulator layer 12 on the antiferromagnetic layer 11, and (3) laminating a second antiferromagnetic layer 13 on the insulator layer 12. This will be explained in detail below.

[0037] (1) Preparation of Antiferromagnetic Layer 11 The antiferromagnetic layer 11 can be prepared by depositing the material of the present disclosure on a substrate that will serve as an electrode by known deposition methods such as sputtering, epitaxial growth (MBE, MOCVD, etc.). When sputtering is used, for example, Mn ３ A １－ｘ B ｘ(0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb), or (Mn １－ｐ Cr ｐ ) ３ Ga ｑ Ge ｒ Sn １－ｑ－ｒ (0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1) and use the same material.

[0038] Examples of the material of the substrate that serves as the electrode (substrate electrode layer) include W, Pt, and Ta, and the thickness thereof is typically 1 nm to 20 nm, preferably 1 nm to 5 nm.

[0039] (2) Lamination of the insulator layer 12 on the antiferromagnetic layer 11 Next, the insulator layer 12 is formed on the antiferromagnetic layer 11 by a known film formation method such as sputtering. When using sputtering, a target material may be a metal oxide, nitride, oxynitride, or the like. Reactive sputtering in an oxygen or nitrogen atmosphere may also be used.

[0040] (3) Stacking of the second antiferromagnetic layer 13 on the insulator layer 12 Next, the antiferromagnetic layer 13 can be formed by depositing the material of the present disclosure on the insulator layer 12 by a known deposition method such as epitaxial growth (MBE, MOCVD, etc.).

[0041] When sputtering is used, the same target materials as those for the antiferromagnetic layer 11 can be used.

[0042] 4 is a cross-sectional view showing one embodiment of a tunneling magnetoresistive element. An insulator layer 12 and a second antiferromagnetic layer 13 are stacked in this order on the surface of an antiferromagnetic layer 11 on a substrate electrode layer 10. Examples of materials for the substrate electrode layer 10 include spin current generating materials such as W, Pt, and Ta.

[0043] The net spin polarization direction of the first antiferromagnetic layer is preferably perpendicular to the antiferromagnetic layer 11, but may be tilted. In this tunnel magnetoresistive element, the electrical resistance changes depending on the relative angle between the spin polarization direction of the antiferromagnetic layer 11 and the spin polarization direction of the second antiferromagnetic layer 13. Therefore, by rotating the spin polarization direction of the antiferromagnetic layer 11, it is possible to switch between a low resistance state and a high resistance state. Such a tunnel magnetoresistive element can function as a memory cell by using the difference in resistance value before and after switching as memory information.

[0044] For example, when a current is passed through the substrate electrode layer 10 in a layer-parallel direction (for example, the direction of the horizontal dashed arrow in FIG. 4 ), a spin current is generated in a direction perpendicular to the current due to spin-orbit interaction (spin Hall effect), generating a magnetic torque in the antiferromagnetic layer 11. Changing the direction of the current through the substrate electrode layer 10 causes a rotation of the spin polarization direction in the antiferromagnetic layer 11.

[0045] As explained above, the antiferromagnetic layer 11 and the second antiferromagnetic layer 13 may be made of the same material or different materials. From the viewpoint of increasing the difference between the low resistance state and the high resistance state, it is preferable that the spin polarization direction of the antiferromagnetic layer 11 and the spin polarization direction of the second antiferromagnetic layer 13 are oriented in parallel planes. That is, if the spin polarization direction of the antiferromagnetic layer 11 is approximately perpendicular to the layer direction, it is preferable that the spin polarization direction of the second antiferromagnetic layer 13 is also approximately perpendicular to the layer direction. If the spin polarization direction of the first antiferromagnetic layer 11 is approximately parallel to the layer direction, it is preferable that the spin polarization direction of the second antiferromagnetic layer 13 is also approximately parallel to the layer direction.

[0046] In the tunnel magnetoresistive element of the present disclosure, a TMR ratio can be obtained up to a relatively high temperature by using a specific material for the insulating layer depending on the plane orientation of the surface of the antiferromagnetic layer.

[0047] [Magnetic Memory] A magnetic memory can be configured by using multiple tunneling magnetoresistive elements as memory cells. This magnetic memory can have a known configuration. For example, the magnetic memory structures described in U.S. Patent Application Publication Nos. 2022 / 0149269 and 2019 / 0267540 can be used. The descriptions of U.S. Patent Application Publication Nos. 2022 / 0149269 and 2019 / 0267540 regarding the structure of the magnetic resistive memory are incorporated herein by reference.

[0048] 5 is a circuit diagram showing one embodiment of wiring of memory cells constituting a part of the magnetic memory of the present disclosure. Memory cells such as those shown in FIG. 5 are arranged in a matrix and driven.

[0049] In each memory cell, an insulating layer 12 and a second antiferromagnetic layer 13 are laminated in this order on the surface of an antiferromagnetic layer 11 laminated on a substrate electrode layer 10, thereby forming a tunneling magnetoresistive element. The operation of this tunneling magnetoresistive element is the same as that described for the tunneling magnetoresistive element.

[0050] Two power supply electrodes 15 are provided on the substrate electrode layer 10, and the power supply electrodes 15 are connected to the sources of transistors 19, respectively. The gates of the transistors 19 are connected to a word line 17, and the drains of the two transistors 19 are connected to a first write bit line 18 and a second write bit line 18′, respectively. The second antiferromagnetic layer 13 is connected to a read bit line 16 via an electrode 14.

[0051] Here, when switching data by changing the resistance value, in order to achieve one data state, the first write bit line 18 is set to H level and the second write bit line 18' is set to L level. Then, by setting the word line 17 to H level, a current flows in the substrate electrode layer 10 from the first write bit line 18 to the second write bit line 18', and the spin polarization of the antiferromagnetic layer 11 becomes a state corresponding to this current, which becomes one data state.

[0052] To switch this data, the first write bit line 18 is set to L level and the second write bit line 18' is set to H level. Then, by setting the word line 17 to H level, a current flows in the substrate electrode layer 10 from the second write bit line 18' to the first write bit line 18, changing the spin polarization of the antiferromagnetic layer 11 and switching the data.

[0053] When reading data stored in a memory cell, either the first write bit line 18 or the second write bit line 18' is set to H level and the other is opened. Then, by setting the read bit line 16 to L level and the word line 17 to H level, a current flows from the first write bit line 18 and the second write bit line 18' to the read bit line 16, and by measuring the magnitude of this current, it is possible to determine whether the memory cell is in a high resistance state or a low resistance state and obtain the data written in the memory cell.

[0054] In one embodiment of the magnetic memory, memory cells such as those shown in FIG. 4 are arranged in a matrix, and predetermined write and read operations are performed by controlling the levels of the write bit line, read bit line, and word line by a controller.

[0055] In the magnetic memory of this embodiment, a read signal can be obtained at a relatively high temperature by using a specific material for the antiferromagnetic layer depending on the plane orientation of the surface of the antiferromagnetic layer.

[0056] Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

[0057] The double-layered film of the present invention, made of an antiferromagnetic material, a magnetic material and an insulator, can be used as a tunnel magnetoresistive element and a magnetic memory.

[0058] 10 substrate electrode layer, 11 antiferromagnetic layer, 12 insulator layer, 13 second antiferromagnetic layer, 14 electrode, 15 power supply electrode, 19 transistor, 17 word line, 18 first write bit line, 18' second write bit line, 16 read bit line

Claims

1. It has a hexagonal crystal structure and is ３ A １－ｘ B ｘ (0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, As, Ru, Ag, Cd, In, Sb, Os, Au, Hg, Tl, Pb), or (Mn １－ｐ Cr ｐ ) ３ G ｑ Ge ｒ Sn １－ｑ－ｒ (0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1).

2. The antiferromagnetic material according to claim 1, wherein A is at least one of Ga and Sn.

3. An antiferromagnetic material according to claim 1 or 2, wherein B is at least one of Mg, Al, Si, Mn, Cu, Zn, Ag, Cd, In, Sb, Au, and Tl.

4. An antiferromagnetic material according to any one of claims 1 to 3, wherein 0<x<0.5, 0<p<0.5, 0.2<q<0.8, and r<0.

5.

5. A bilayer film of a magnetic material and an insulator, comprising a layer made of the ferromagnetic material according to any one of claims 1 to 4 and a layer made of an insulator laminated on the layer made of the ferromagnetic material.

6. A tunnel magnetoresistance element comprising a double-layered film of a magnetic material and an insulator as claimed in claim 5, and a second antiferromagnetic film layer laminated on the insulator of the double-layered film.

7. A magnetic memory comprising a plurality of tunnel magnetoresistance elements according to claim 6.

8. It has a hexagonal crystal structure and is ３ A １－ｘ B ｘ (0<x<0.5, A=Ga, Ge, Sn, B=Mg, Al, Si, P, Mn, Ni, Cu, Zn, Ru, Ag, Cd, In, Os, Au, Hg, Tl), or (Mn １－ｐ Cr ｐ ) ３ G ｑ Ge ｒ Sn １－ｑ－ｒ (0<p<0.5, 0<q<1, 0<r<1, 0<q+r≦1).

9. The antiferromagnetic material according to claim 8, wherein A is at least one of Ga and Sn.

10. The antiferromagnetic material according to claim 8 or 9, wherein B is at least one of Mg, Al, Si, Mn, Cu, Zn, Ag, Cd, In, Au, and Tl.

11. The antiferromagnetic material according to any one of claims 8 to 10, wherein 0<x<0.5, 0<p<0.5, 0.2<q<0.8, and r<0.

5.

12. A bilayer film of a magnetic body and an insulator, comprising a layer made of the ferromagnetic material according to any one of claims 8 to 11 and a layer made of an insulator laminated on the layer made of the ferromagnetic material.

13. A tunnel magnetoresistance element comprising a double-layered film of a magnetic material and an insulator as claimed in claim 12, and a second antiferromagnetic film layer laminated on the insulator of the double-layered film.

14. A magnetic memory comprising a plurality of tunnel magnetoresistance elements according to claim 13.

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