JP2000306375A - Magnetoresistance effect element and magnetic memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetoresistance effect element in which the adjustment of the coersive force of a ferromagnetic layer is superior, whose miniaturization, stability, recording density and the like are superior, which has a high magnetoresistance effect change rate and which is useful for a magnetic memory device or the like. SOLUTION: In this magnetoresistance effect element, a first antiferromagnetic layer 2, a first ferromagnetic layer 3, a nonmagnetic layer 4, a second ferromagnetic layer 5 and a second antiferromagnetic layer 6 are laminated sequentially, the layers 2, 3 and the layers 5, 6 are exhangedly coupled respectively, the magnitude of the coersive force of the layer 3 is different from the magnitude of the coercive force of the layer 5, the direction of the unidirectional anisotropy of the layer 2 is parallel to the direction of magnetization of the layer 3, and the direction of the unidirectional anisotropy of the layer 6 is parallel to the direction of magnetization of the layer 5. This magnetic memory device uses the magnetoresistance effect element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element exhibiting excellent magnetization stability and a high rate of change in magnetoresistance, and a magnetic memory element (non-volatile memory element) using the same.

[0002]

2. Description of the Related Art A magnetoresistive effect type memory element performs recording by making the magnetization direction of a magnetic layer correspond to digital information. Therefore, it does not require an external energy supply for holding records, has a simpler manufacturing process than a semiconductor memory, and does not particularly limit the material of the substrate, so that it is expected to be an inexpensive large-capacity nonvolatile memory. .

As shown in FIG. 6, the magnetoresistive memory element has a sandwich structure having a nonmagnetic layer 52 between two ferromagnetic layers 51 and 53. There are roughly two types of recording detection methods, and the roles of the respective ferromagnetic layers 51 and 53 differ according to them.

First, in one method, the two ferromagnetic layers 51 and 53 are configured to have different coercive forces, and a layer having a relatively low coercive force is a detection layer, and a layer having a relatively large coercive force is a memory layer. And In order to make the ferromagnetic layers 51 and 53 have different coercive forces, a method of using different elements or compositions or using different film thicknesses is generally used.

[0005] Recording is achieved by applying a recording magnetic field (Hw) larger than the coercive force of the memory layer and directing the magnetization of the memory layer in the direction of the recording magnetic field (Hw). For example, as shown in FIG. 7, the case where the magnetization of the memory layer 61 below the nonmagnetic layer 62 is leftward is “0”, and the case where it is rightward is “1”. However, since the coercive force of the detection layer 63 is smaller than the coercive force of the memory layer 61, the magnetization directions of both layers are parallel immediately after recording.

In the detection, a DC current of a certain magnitude is applied to the memory element and the coercive force of the detection layer 63 is larger than
This is performed by applying a magnetic field (Ha) smaller than the coercive force of the memory layer 61 and examining a change in potential due to the magnetization reversal of the detection layer 63. When the magnetization directions of both magnetic layers are parallel, the resistivity of the memory element is smaller than when the magnetization directions are antiparallel. For example, as shown in FIG.
When a detection magnetic field of + Ha is applied to the memory element in which “0” is recorded, the magnetization directions of the two magnetic layers (the memory layer 61 and the detection layer 63) become antiparallel and the potential becomes higher. The magnetization direction of the magnetic layer becomes parallel and the potential decreases. Similarly, in the memory element in which "1" is recorded, when a detection magnetic field of + Ha is applied, the magnetization directions of the two magnetic layers become parallel and the potential becomes low. Become antiparallel and the potential increases. In this detection method, the detected signal is independent of the magnetization direction of the detection layer before detection.

In another method, as shown in FIG. 9, one of two ferromagnetic layers is formed as a magnetization fixed layer 71 having a fixed magnetization direction via a nonmagnetic layer 72, and the other is formed. One is a memory layer 73, and the magnetization direction of the memory layer 73 is directed to the direction of the applied magnetic field by applying a recording magnetic field. The magnetization fixed layer 71 is formed by giving a coercive force larger than the recording magnetic field to the ferromagnetic layer.
By exchange-coupling with the antiferromagnetic layer, the magnetization reversal magnetic field in the magnetization fixed direction can be increased.

FIG. 10 is a diagram showing a state of a shifted magnetization loop of a “ferromagnetic layer / antiferromagnetic layer” film configuration in which a ferromagnetic layer and an antiferromagnetic layer are exchange-coupled. In this figure, H
ex (exchange coupling magnetic field). As can be easily seen from the figure, the coercive force of the ferromagnetic layer is H
Assuming that c, the magnetization reversal magnetic field becomes Hex ± Hc. When a magnetic field is applied in the shift direction of the magnetization loop to reverse the magnetization, a larger magnetic field is required than in the case of a single ferromagnetic layer film.

Further, when the shift amount of the magnetization loop is larger than the coercive force, that is, when Hex> Hc, FIG.
As shown in FIG. 1, when the magnetic field is zero, the magnetization is always oriented in a predetermined direction. In this way, even if the magnetization is reversed for some reason, the magnetization direction returns to its original state, and there is no need to initialize.

The detection starts from the state where no magnetic field is applied.
This is performed by applying a magnetic field having a magnitude capable of reversing the magnetization of the memory layer 73 in one of the determined directions and reading a change in the output voltage. For example, as shown in FIG. 12, if the fixed magnetization is rightward, if the magnetization direction of the memory layer 73 is “0”, it is rightward, if “1”, it is leftward, and if the detection magnetic field application direction is rightward, “ 0 ”is recorded in the memory layer 73
Since the magnetization direction of does not change even when the detection magnetic field is applied,
No change in output voltage. On the other hand, if "1" is recorded, the magnetization of the two ferromagnetic layers becomes antiparallel to parallel when the detection magnetic field is applied, so that the magnetoresistance decreases and the detection voltage decreases. However, such a detection method erases recorded information, so that rewriting is required to retain the information. Therefore, in order to avoid information erasure, it is necessary to perform detection without applying a magnetic field. In this case, the output voltage value when "0" is recorded and "1" are recorded. It is necessary to know in advance the value of the output voltage.

In order to obtain a high S / N, it is preferable that the magnetoresistance ratio is large. The rate of change in magnetoresistance varies depending on the material of the magnetic layer, the interface shape of each layer, and the like, but in the case of a spin-scattering film configuration, it also depends on the thickness of the nonmagnetic layer between the magnetic layers. This is called a shunt effect. When the thickness of the non-magnetic layer is increased, the ratio of the number of electrons flowing through the non-magnetic layer and irrespective of the magneto-resistance change increases, so that the magneto-resistance change rate decreases. Therefore, from the viewpoint of the shunt effect, it is preferable that the film thickness of the nonmagnetic layer is thin.

When a memory utilizing a change in magnetoresistance is used in a mobile information device, a high-density memory is required. In such a memory, it is necessary to reduce the cell area. Photolithography and FIB used in semiconductor processes
Can be used.

[0013]

As described above, in the spin-scattering type magnetoresistive memory element, the thickness of the nonmagnetic layer sandwiched between the ferromagnetic layers is preferably smaller from the viewpoint of the shunt effect. . However, as the thickness of the non-magnetic layer decreases, the magnetostatic coupling force acting between the ferromagnetic layers increases. This magnetostatic coupling acts in a direction to make the magnetizations of the two ferromagnetic layers parallel. Therefore, when the magnetostatic coupling force increases, the magnetization does not become antiparallel, and no change in magnetoresistance occurs.

The magnitude of the demagnetizing field of the ferromagnetic material depends on its shape. The smaller the ratio of the length of the direction of easy magnetization to the film thickness is, the larger the magnitude of the demagnetizing field is. is there. That is, if the area of the memory cell is reduced without changing the thickness of the magnetic layer of the magnetoresistive memory element, the demagnetizing field increases and the magnetization becomes unstable, making it impossible to hold or detect information. Further, even if the thickness of the magnetic layer is reduced, there is a limit in producing a magnetic layer thin film having a uniform thickness, and a sufficiently small thickness for producing a high-density memory cannot be obtained.

Therefore, the material used for the ferromagnetic layer of the high-density memory is preferably a material having a large uniaxial magnetic anisotropy and a sufficiently large coercive force. However, at present, such materials have not been proposed yet.

An object of the present invention is to make it possible to easily adjust the coercive force of the ferromagnetic layer, to stably maintain the magnetization direction even if the size is reduced, and to increase the recording density. An object of the present invention is to provide a magnetic memory element and a magnetoresistive element useful therefor.

A further object of the present invention is to reduce the thickness of the nonmagnetic layer formed between the ferromagnetic layers, and to provide a magnetic memory element having a high magnetoresistance ratio and a useful magnetic memory element. Another object of the present invention is to provide a simple magnetoresistive element.

[0018]

The magnetoresistive element of the present invention comprises at least a first antiferromagnetic layer, a first ferromagnetic layer,
A nonmagnetic layer, a second ferromagnetic layer, and a second antiferromagnetic layer are sequentially stacked, and the first antiferromagnetic layer, the first ferromagnetic layer, the second antiferromagnetic layer, The second ferromagnetic layers are exchange-coupled to each other, and the magnitude of the coercive force of the first ferromagnetic layer is different from the magnitude of the coercive force of the second ferromagnetic layer, and the first antiferromagnetic layer is The direction of the unidirectional anisotropy of the ferromagnetic layer is parallel to the magnetization direction of the first ferromagnetic layer, and the direction of the unidirectional anisotropy of the second antiferromagnetic layer is the direction of the second ferromagnetic layer. A magnetoresistive element characterized by being parallel to the magnetization direction of the layer.

Further, a magnetic memory element according to the present invention is a magnetic memory element using the above-described magnetoresistive element, wherein one of the first ferromagnetic layer and the second ferromagnetic layer has a smaller coercive force. Is a detection layer, and a ferromagnetic layer having a larger coercive force is a memory layer.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

FIG. 1 is a schematic sectional view illustrating the basic film configuration of the magnetic memory element of the present invention. In the figure, 1 is a substrate,
Reference numeral 2 denotes a first antiferromagnetic layer, 3 denotes a first ferromagnetic layer, 4 denotes a nonmagnetic layer, 5 denotes a second ferromagnetic layer, and 6 denotes a second antiferromagnetic layer.

The substrate 1 is generally made of Si, glass, or the like, but any material having high flatness and durability may be used, and the material is not particularly limited.

The antiferromagnetic layers (the first antiferromagnetic layer 2 and the second antiferromagnetic layer 6) include MnFe, MnIr, MnPt,
Mn-based or Cr-based antiferromagnetic materials such as MnPtCr and AlCr, and oxide antiferromagnetic materials such as NiO and α-Fe ₂ O ₃ can be used. In particular, those having a Neel point higher than the operating temperature are preferable. In particular, since a magnetic memory element using an oxide antiferromagnetic material has high insulating properties, there is no shunt of electrons in the antiferromagnetic material, and a high magnetoresistance ratio can be expected.

For the ferromagnetic layers (the first ferromagnetic layer 3 and the second ferromagnetic layer 5), Co, CoFe, Fe, NiFe or the like can be used.

As the non-magnetic layer 4, a non-magnetic metal layer such as Cu or Al ₂ O ₃ can be used.

The reversal of the unidirectional anisotropy of the antiferromagnetic layers 2 and 6 is performed through the magnetization of the exchange-coupled ferromagnetic layers 3 and 5. That is, in a state where the direction of the unidirectional anisotropy of the antiferromagnetic layers 2 and 6 and the magnetization direction of the ferromagnetic layers 3 and 5 are parallel,
When an external magnetic field is applied antiparallel to these directions, the magnetizations of the ferromagnetic layers 3 and 5 are reversed, and the magnetic moments of the atoms of the antiferromagnetic layers 2 and 6 that are exchange-coupled are also reversed. By the action, the magnetic moments of the atoms in the antiferromagnetic layers 2 and 6 are sequentially inverted, whereby the unidirectional anisotropy of the antiferromagnetic layers 2 and 6 is inverted.

In the present invention, the coercive force of the ferromagnetic layers 3 and 5 is determined by the thickness of the ferromagnetic layers 3 and 5, the exchange coupling force between the ferromagnetic layers 3 and 5 and the antiferromagnetic layers 2 and 6, Ferromagnetic layers 2, 6
Varies with the thickness of the film. In particular, the coercive force can be easily adjusted by appropriately selecting the film thickness of the ferromagnetic layers 3, 5 or the antiferromagnetic layers 2, 6.

FIG. 2 is a graph showing a change in coercive force depending on the thickness of the ferromagnetic layer. The sample used for this measurement is
10 nm thick NiO as antiferromagnetic layer on glass substrate
Layer, CoFe layer as ferromagnetic layer, 10 nm as protective layer
This is a film configuration in which thick SiN layers are sequentially stacked. As can be seen from this graph, the coercive force of the ferromagnetic layers 3, 5 is almost inversely proportional to the film thickness.

FIG. 3 shows a sample having the above film configuration.
5 is a graph showing a change in coercive force of the ferromagnetic layer when the thickness of the FeCo layer as the ferromagnetic layer is fixed at 5 nm and the thickness of the NiO layer as the antiferromagnetic layer is changed. As the thickness of the NiO layer increases, the coercive force of the ferromagnetic layer increases,
It can be seen that the coercive force of the ferromagnetic layer can be adjusted by changing the thickness of the iO layer. However, when the thickness of the NiO layer increases, the unidirectional anisotropy of the NiO layer does not reverse, and a shift in the direction of the magnetic field is observed in the magnetization curve or the magnetoresistance curve, which becomes asymmetric with respect to the origin. During recording, a different magnetic field of 180 ° direction is applied. However, if the magnetic field direction shifts as described above, the required magnetic field size differs depending on the magnetic field application direction, and the magnetic field size is controlled by the magnetic field direction. This is undesirable because it requires an electric circuit to perform.

FIG. 4 is a graph showing the shift amount in the direction of the magnetic field, that is, the relationship between the exchange coupling magnetic field and the thickness of the NiO film serving as the antiferromagnetic layer. The thickness of the CoFe layer, which is the ferromagnetic layer of the sample used for this measurement, was kept constant at 5 nm.

In order to reverse the unidirectional anisotropy of the antiferromagnetic layer, it is necessary to select the thickness of the antiferromagnetic layer so that exchange energy cannot be stored in the antiferromagnetic layer. However, such a film thickness differs depending on the material and structure of the antiferromagnetic layer.

FIG. 5 is a graph showing the relationship between the applied magnetic field and the rate of change in magnetoresistance in the magnetoresistance element of the present invention, and
FIG. 3 is a diagram also showing how the magnetization directions of the ferromagnetic layers 3 and 5 and the directions of unidirectional anisotropy of the antiferromagnetic layers 2 and 6 change.

The case where the applied magnetic field H satisfies H <-H ₂ is defined as an initial state. At this time, the directions of the magnetization and the unidirectional anisotropy of each of the layers 2, 3, 5, and 6 are all parallel to the direction of the applied magnetic field, as shown in FIG. From this state, increase the applied magnetic field by +
When H ₁ <H <+ H ₂ , the magnetization of the second ferromagnetic layer 5 having a relatively small coercive force is reversed, and the magnetization directions of the first ferromagnetic layer 3 and the second ferromagnetic layer 5 are changed. It becomes antiparallel and the resistivity increases. + H ₁ is represented by Hc ₂ + Hex ₂ + Hs.
Here, Hc ₂ is the original coercive force of the second ferromagnetic layer 5, Hex ₂ is the exchange coupling force acting between the second antiferromagnetic layer 6, and Hs is the two ferromagnetic layers 3, 5. Between the magnetostatic coupling forces.

When the applied magnetic field is further increased and + H ₂ <H, the magnetization of the first ferromagnetic layer 3 is inverted, and the resistivity is reduced again. + H ₂ is represented by Hc ₁ + Hex ₁ -Hs. Here, Hc ₁ is the original coercive force of the first ferromagnetic layer 3, and Hex ₁ is the exchange coupling force acting on the first antiferromagnetic layer 2.

Next, when the applied magnetic field is weakened to −H ₂ <H <−H ₁ , the magnetization of the second ferromagnetic layer 5 is reversed, and the applied magnetic field is set to H <−H ₂ to restore the initial state. Return.

When the magnetoresistive element of the present invention is applied as a memory element, of the two “ferromagnetic layer / antiferromagnetic layer” exchange coupling films, the one having a relatively large coercive force is used as the memory layer.
The one having a relatively small coercive force is used as the detection layer. In FIG. 5, the coercive force of the memory layer is H ₂ and the coercive force of the detection layer is H ₁ . For example, when a magnetic field having a magnitude of H ₂ or more (recording magnetic field: Hw) is applied in the + direction, the magnetization and unidirectional anisotropy of both exchange-coupling films are oriented in the + direction, and “1” is recorded. State. When the recording magnetic field Hw is applied in the negative direction,
The magnetization and unidirectional anisotropy of both exchange-coupling films point in the-direction,
This is a state where “0” is recorded.

For example, in the state where “1” is recorded, a magnetic field having a magnitude larger than H _{1 and} smaller than H ₂ (detected magnetic field: H
When a) is applied in the + direction, no magnetization reversal occurs, and the magnetizations of the memory layer and the detection layer remain parallel, so that the resistance of the memory element shows a small value. Next, when the detection magnetic field Ha is applied in the negative direction, the magnetization and the unidirectional anisotropy of the detection layer are reversed, so that the magnetizations of the memory layer and the detection layer become antiparallel, and the resistance of the memory layer shows a large value. That is, the detection magnetic field Ha
Is continuously applied from the + direction to the − direction, the resistance value increases. Therefore, “1” can be detected by detecting the amount of change in the resistance. Similarly, when “0” is recorded, the detection magnetic field Ha is changed from the + direction to −.
When the voltage is continuously applied in the direction, the resistance value decreases, and "0" can be detected by detecting the amount of change in the resistance.

In the present invention, the ferromagnetic layer having the smaller coercive force is used as the detection layer, the ferromagnetic layer having the larger coercive force is used as the memory layer, and the first antiferromagnetic layer 2 is anisotropic in one direction. Since the direction of the property is parallel to the magnetization direction of the first ferromagnetic layer 3 and the direction of the unidirectional anisotropy of the second antiferromagnetic layer 6 is parallel to the magnetization direction of the second ferromagnetic layer 5, It is possible to increase the coercive force of the ferromagnetic layer used for the memory layer and the detection layer, to stabilize the magnetization direction even if the memory layer is miniaturized, and to make the ferromagnetic layer and the antiferromagnetic layer a film. The desired coercive force can be easily obtained by adjusting the thickness. In addition, since it is easy to increase the difference in coercive force between the memory layer and the detection layer, the antiparallel state between the magnetization of the memory layer and the magnetization of the detection layer is stable even if the thickness of the nonmagnetic layer is reduced. Obtained. Here, that the magnetization direction of the ferromagnetic layer is parallel to the direction of the unidirectional anisotropy of the antiferromagnetic layer means that the magnetization is maintained parallel under recording, reproducing, and other normal use conditions.

Although the use of the magnetoresistive element of the present invention is not particularly limited, a magnetic memory element used in the method shown in FIG. 5, particularly a spin scattering type or spin tunnel type magnetoresistive effect type memory element Very useful as.

[0040]

The present invention will be described in more detail with reference to the following examples.

<Example 1> On a glass substrate, an Ir ₃₀ Mn ₇₀ layer having a thickness of 3 nm as a first antiferromagnetic layer, a Co ₉₀ Fe ₁₀ layer having a thickness of 10 nm as a first ferromagnetic layer, and a nonmagnetic layer 2 having a thickness of 10 nm A Cu layer having a thickness of 0.2 nm, a Co ₉₀ Fe ₁₀ layer having a thickness of 2 nm as a second ferromagnetic layer, and an Ir ₃₀ Mn ₇₀ layer having a thickness of 3 nm as a second antiferromagnetic layer were sequentially laminated by sputtering without breaking vacuum. .

In order to make the magnetization reversal of the ferromagnetic layer steep, a DC magnetic field of about 6 kA / m is applied in parallel with the detection and recording magnetic field application direction during the formation of each layer, and the in-plane uniaxial magnetic anisotropy is applied. Induced.

Example 2 On a glass substrate, a 5 nm thick Ni ₅₀ O ₅₀ layer as a first antiferromagnetic layer, a 3 nm thick Co ₉₀ Fe ₁₀ layer as a first ferromagnetic layer, and a 2 nm thick nonmagnetic layer .2
nm thick Cu layer and 3 nm thick Co as a second ferromagnetic layer.
₉₀ Fe ₁₀ layer, 10 nm thick Ni as the second antiferromagnetic layer
_{The 50} O ₅₀ layers were sequentially stacked by sputtering without breaking vacuum. During the film formation of each layer, a DC magnetic field was applied in the same manner as in Example 1 to induce in-plane uniaxial magnetic anisotropy.

Example 3 On a glass substrate, a 15 nm thick Ni ₅₀ O ₅₀ layer as a first antiferromagnetic layer, a 10 nm thick Co ₉₀ Fe ₁₀ layer as a first ferromagnetic layer, and a 2 nm thick Al
The layers were sequentially stacked, and then oxygen gas was introduced into the chamber to oxidize the Al layer to form a nonmagnetic oxide layer. After the inside of the chamber was sufficiently evacuated again, a 10 nm thick Co ₉₀ Fe ₁₀ layer was formed as a second ferromagnetic layer, and a 5 nm thick Ni ₅₀ O ₅₀ layer was formed as a second antiferromagnetic layer. During the film formation of each layer, a DC magnetic field was applied in the same manner as in Example 1 to induce in-plane uniaxial magnetic anisotropy.

The spin tunnel film thus obtained is
It was processed to a size of 0.8 μm square by a focused ion beam processing device. Thereafter, an electrode was formed so that a voltage could be measured by passing a current between the first magnetic layer and the second magnetic layer, to obtain a magnetic memory element.

Comparative Example 1 On a glass substrate, a 10-nm thick Co ₉₀ Fe ₁₀ layer as a first ferromagnetic layer, a 2.2-nm thick Cu layer as a non-magnetic layer, and a 5-nm thick as a second ferromagnetic layer. Co ₉₀ Fe ₁₀ layer, 50 nm thick Ir as antiferromagnetic layer
₃₀ Mn ₇₀ layers were sequentially stacked by sputtering without breaking vacuum. During the film formation of each layer, a DC magnetic field was applied in the same manner as in Example 1 to induce in-plane uniaxial magnetic anisotropy.

Comparative Example 2 A 3 nm thick Co ₉₀ Fe ₁₀ layer as a first ferromagnetic layer, a 2.2 nm thick Cu layer as a nonmagnetic layer, and a 3 nm thick as a second ferromagnetic layer on a glass substrate. Ni ₈₀ O ₂₀ layers were sequentially laminated by sputtering without breaking vacuum. In addition, during the formation of each layer,
A DC magnetic field was applied in the same manner as described above to induce in-plane uniaxial magnetic anisotropy.

Comparative Example 3 A 3 nm thick Co ₉₀ Fe ₁₀ layer as a first ferromagnetic layer, a 5 nm thick Cu layer as a nonmagnetic layer, and a 3 nm thick N layer as a second ferromagnetic layer were formed on a glass substrate.
The i ₈₀ O ₂₀ layer, were sequentially laminated by sputtering without breaking the vacuum. During the film formation of each layer, a DC magnetic field was applied in the same manner as in Example 1 to induce in-plane uniaxial magnetic anisotropy.

Comparative Example 4 A 10 nm thick Co ₉₀ Fe ₁₀ layer and a 2 nm thick A were formed on a glass substrate as a first ferromagnetic layer.
One layer was sequentially laminated, and then oxygen gas was introduced into the chamber to oxidize the Al layer to form a nonmagnetic oxide layer. After the inside of the chamber was sufficiently evacuated again, a Ni ₈₀ O ₂₀ layer having a thickness of 10 nm was formed as a second ferromagnetic layer. During the film formation of each layer, a DC magnetic field was applied in the same manner as in Example 1 to induce in-plane uniaxial magnetic anisotropy. Using the spin tunnel film thus obtained, a magnetic memory element was prepared in the same manner as in Example 1.

Table 1 summarizes the magnetic field range in which the magnetization is antiparallel and the rate of change in magnetoresistance for the magnetic memory elements of Examples 1 to 3 and Comparative Examples 1 to 4. Here, the magnetoresistance ratio was measured by a four-terminal method.

[0051]

[Table 1]

[0052]

As described above, in the magnetic memory element of the present invention, the coercive force of the ferromagnetic layer can be easily adjusted, and the magnetization direction can be stabilized even if the size of the magnetic memory element is reduced. Magnetic memory having a high recording density can be provided. Further, the thickness of the nonmagnetic metal layer formed between the ferromagnetic layers can be reduced, and a magnetic memory element having a high magnetoresistance ratio can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a basic film configuration of a magnetic memory element of the present invention.

FIG. 2 is a graph showing a change in coercive force depending on the thickness of a ferromagnetic layer.

FIG. 3 is a graph showing a change in coercive force of a ferromagnetic layer with respect to a thickness of an antiferromagnetic layer.

FIG. 4 is a graph showing a change of an exchange coupling magnetic field with respect to a film thickness of an antiferromagnetic material.

FIG. 5 is a graph showing the relationship between the applied magnetic field and the rate of change in magnetoresistance in the magnetoresistive element of the present invention, and the change in the magnetization direction of the ferromagnetic layer and the direction of unidirectional anisotropy of the antiferromagnetic layer. FIG.

FIG. 6 is a cross-sectional view illustrating a basic film configuration of a conventional magnetic memory element.

FIG. 7 is a diagram illustrating a magnetization direction after recording of a conventional magnetic memory element.

FIG. 8 is a diagram illustrating a conventional method for detecting a magnetic memory element.

FIG. 9 is a diagram illustrating a magnetization direction after recording of a conventional magnetic memory element.

FIG. 10 is a diagram illustrating a magnetization loop of an exchange coupling film of a ferromagnetic layer and an antiferromagnetic layer.

FIG. 11 is a diagram illustrating a magnetization loop of an exchange coupling film of a ferromagnetic layer and an antiferromagnetic layer.

FIG. 12 is a diagram illustrating a conventional method for detecting a magnetic memory element.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 first antiferromagnetic layer 3 first ferromagnetic layer 4 nonmagnetic layer 5 second ferromagnetic layer 6 second antiferromagnetic layer 51, 53 ferromagnetic layer 52 nonmagnetic layer 61 memory layer 62 Nonmagnetic layer 63 Detection layer 71 Fixed magnetization layer 72 Nonmagnetic layer 73 Memory layer

Claims (2)

[Claims] At least a first antiferromagnetic layer, a first ferromagnetic layer, a nonmagnetic layer, a second ferromagnetic layer, and a second antiferromagnetic layer are sequentially stacked, and The ferromagnetic layer and the first ferromagnetic layer, and the second antiferromagnetic layer and the second ferromagnetic layer are exchange-coupled, respectively, and the coercive force of the first ferromagnetic layer is large. And the magnitude of the coercive force of the second ferromagnetic layer is different, and the direction of unidirectional anisotropy of the first antiferromagnetic layer is parallel to the magnetization direction of the first ferromagnetic layer. A magnetoresistive element, wherein the direction of the unidirectional anisotropy of the second antiferromagnetic layer is parallel to the magnetization direction of the second ferromagnetic layer. 2. A magnetic memory element using the magnetoresistive element according to claim 1, wherein the first ferromagnetic layer and the second ferromagnetic layer have a smaller coercive force. Is a detection layer, and a ferromagnetic layer having a larger coercive force is a memory layer.