Magnetic tunnel junction device and magnetic memory

Abstract

The invention provides a magnetic tunnel junction device, which comprises a net magnetic moment layer with an in-plane net magnetic moment and used for generating a first in-plane polarized spin current; the light metal layer is located on the net magnetic moment layer and used for generating an orbital flow based on the orbital Hall effect, and the first in-plane polarization spin current forms an out-plane polarization spin current after penetrating through the net magnetic moment layer / light metal layer interface; the conversion layer is located on the light metal layer and used for converting the track flow generated by the light metal layer into a second in-plane polarized spin current; and the free layer is located on the conversion layer, and the magnetic moment of the free layer realizes deterministic overturning under the combined action of spin orbit moments generated by the out-of-plane polarization spin current and the second in-plane polarization spin current. According to the invention, efficient and deterministic overturning of the vertical magnetic moment of the free layer can be realized.

Description

Technical Field

[0001] This invention relates to the field of magnetic memory design technology, and in particular to a magnetic tunnel junction device and a magnetic memory. Background Technology

[0002] Traditional spin-orbit-moment magnetic random access memory (SOT-MRAM) primarily utilizes the spin Hall effect or Rashba effect of heavy metals to convert current into spin current, which is then injected into the adjacent free layer to apply a spin-orbit moment, thereby causing the magnetic moment of the free layer to flip. Since the spin polarization direction induced by the current is parallel to the in-plane, for free layers with perpendicular magnetic anisotropy, the flip probabilities in the two directions driven by the current are equivalent. This means that an external magnetic field is required to achieve deterministic magnetic moment flipping. However, the design of an external auxiliary magnetic field introduces many problems, such as increased power consumption, difficulty in miniaturizing device size, and increased integration complexity, which is completely inconsistent with the development trend of low-power electronic devices. To overcome these difficulties, a magnetic field-free SOT-MRAM flipping scheme is needed. Summary of the Invention

[0003] In view of this, the present invention provides a magnetic tunnel junction device and a magnetic memory, which can achieve efficient and deterministic reversal of the vertical magnetic moment of the free layer without the assistance of an external magnetic field.

[0004] In a first aspect, the present invention provides a magnetic tunnel junction device, comprising: A net magnetic moment layer, having an in-plane net magnetic moment, is used to generate a first in-plane polarized spin current; A light metal layer is located on the net magnetic moment layer. The light metal layer has an orbital Hall effect and is used to generate orbital flow based on the orbital Hall effect. The first in-plane polarized spin flow forms an out-of-plane polarized spin flow after passing through the interface between the net magnetic moment layer and the light metal layer. A conversion layer, located on the light metal layer, has a strong spin-orbit coupling effect and is used to convert the orbital flow generated by the light metal layer into a second in-plane polarized spin flow. A free layer, located on the conversion layer, has a reversible vertical magnetic moment. Under the combined action of the spin orbit moments generated by the out-of-plane polarized spin current and the second in-plane polarized spin current, the magnetic moment of the free layer achieves deterministic reversal.

[0005] Optionally, the material of the net magnetic moment layer is a ferromagnetic material with in-plane magnetic anisotropy.

[0006] Optionally, the material of the net magnetic moment layer is an antiferromagnetic material, and the specific method of forming it is to apply an in-plane magnetic field when growing the antiferromagnetic material, or to perform annealing under an in-plane magnetic field after growing the antiferromagnetic material.

[0007] Optionally, the antiferromagnetic material may include at least one of IrMn alloy, PtMn alloy, FeMn alloy, and PdMn alloy.

[0008] Optionally, the thickness of the net magnetic moment layer is 3~7 nm.

[0009] Optionally, the material of the light metal layer is a 3d or 4d transition metal material with ultra-high orbital Hall conductivity.

[0010] Optionally, the thickness of the light metal layer is 1~5 nm.

[0011] Optionally, the material of the conversion layer includes at least one of tantalum (Ta), platinum (Pt), and gadolinium (Gd).

[0012] Optionally, the thickness of the conversion layer is 0.5~1nm.

[0013] In a second aspect, the present invention provides a magnetic storage device including a magnetic tunnel junction device as provided in the first aspect.

[0014] The magnetic tunnel junction device provided by this invention utilizes out-of-plane polarized spin current generated at the interface of the net magnetic moment layer / light metal layer to break the symmetry of the free layer magnetic moment reversal and achieve deterministic reversal of the vertical magnetic moment of the free layer. On the other hand, based on the orbital Hall effect in the light metal layer, orbital current is generated, which can provide a more efficient magnetic moment driving force by leveraging the high orbital Hall conductivity, thereby helping to improve the reversal efficiency and reduce the critical reversal current density and power consumption. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a magnetic tunnel junction device in one embodiment of the present invention; Figure 2 This is a schematic diagram of the out-of-plane polarized spin flow generation mechanism in one embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the principle of generating and converting orbital flow into in-plane spin flow in one embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the principle of free layer magnetic moment reversal in one embodiment of the present invention; Figure 5 This is a schematic diagram showing the relationship between the pulse current and the anomalous Hall resistance measured by the magnetic tunnel junction device in an embodiment of the present invention without magnetic field assistance. Figure 6 This is a schematic diagram illustrating the effect of the thickness of the light metal layer on the critical reversal current density. Figure 7 This is a schematic diagram of the structure of a magnetic tunnel junction device in another embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of this disclosure.

[0017] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0018] In the context of this disclosure, when a layer / element is referred to as being "above" another layer / element, the layer / element may be directly above the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "above" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0019] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0020] Under current technology, the over-reliance on heavy metal materials in SOT-MRAM devices limits their further development. On the one hand, the high resistivity of heavy metals makes it difficult to reduce the overall power consumption of the devices; on the other hand, the small spin Hall angle makes it difficult to meet practical requirements for switching efficiency. The high price of heavy metals also significantly increases the cost of industrial production.

[0021] This invention provides a magnetic tunnel junction device, such as... Figure 1 As shown, the magnetic tunnel junction device includes: a net magnetic moment layer 100, a light metal layer 101, a conversion layer 102, and a free layer 103, wherein, The net magnetic moment layer 100 has an in-plane net magnetic moment for generating a first in-plane polarized spin current; The light metal layer 101 is located on the net magnetic moment layer 100. The light metal layer 101 has an orbital Hall effect and is used to generate orbital flow based on the orbital Hall effect. Furthermore, the first in-plane polarized spin flow forms an out-of-plane polarized spin flow after passing through the interface between the net magnetic moment layer 100 and the light metal layer 101. The conversion layer 102 is located on the light metal layer 101. The conversion layer 102 has a strong spin-orbit coupling effect and is used to convert the orbital flow generated by the light metal layer 101 into a second in-plane polarized spin flow. The free layer 103 is located on the conversion layer 102. The free layer 103 has a reversible vertical magnetic moment. Under the combined action of the spin orbit moments generated by the out-of-plane polarized spin current and the in-plane polarized spin current, the magnetic moment of the free layer 103 achieves deterministic reversal.

[0022] In this embodiment, the stacked structure of net magnetic moment layer 100, light metal layer 101, and conversion layer 102 is used to provide spin orbit moment for free layer flipping. Therefore, the stacked structure of net magnetic moment layer 100, light metal layer 101, and conversion layer 102 can be regarded as a whole to form spin orbit moment providing layer 200.

[0023] The following is a detailed explanation of each layer.

[0024] Figure 2 This is a schematic diagram of the out-of-plane polarized spin current generation mechanism. For ease of explanation, the following coordinate system is constructed: the x-axis is the direction perpendicular to the paper and outwards, the y-axis is the direction of film extension, and the z-axis is the direction perpendicular to the film surface. The film surface of each layer is parallel to the xy plane.

[0025] like Figure 2 As shown in (a), the in-plane net magnetic moment of the net magnetic moment layer 100 is along the -x direction. When current flows through the net magnetic moment layer 100 along the -x direction, under the action of the in-plane net magnetic moment, the net magnetic moment layer 100 generates a first in-plane polarized spin current σ polarized in the -x direction. x The spin flow is injected upwards, and when the in-plane polarized spin flow σ x When passing through the interface between the net magnetic moment layer 100 and the light metal layer 101, due to the interface characteristics of the net magnetic moment layer 100 and the light metal layer 101, an interface spin orbital field is formed at the interface, and the polarized spin current σ in the first surface is generated. x It will be subject to the torque of the interface spin orbital field, which will cause the spin to precess around the direction of the spin orbital field (similar to the precession of a gyroscope). This will effectively rotate the original in-plane spin direction by 90 degrees, changing it from an in-plane direction to an out-of-plane +z direction, thus forming an out-of-plane polarized spin current σ in the +z direction. z .

[0026] Since precession only occurs when the incident carriers are polarized, the out-of-plane polarized spin flow σ zThis only occurs if one of the layers has a net in-plane magnetic moment. That is, a net magnetic moment layer 100 is required to provide the initial in-plane polarization. The first in-plane polarized spin current σ... x The polarization direction is consistent with the direction of the net magnetic moment in the plane.

[0027] Similarly, such as Figure 2 As shown in (b), the in-plane net magnetic moment of the net magnetic moment layer 100 is along the -x direction. When current flows through the net magnetic moment layer 100 along the +x direction, it still generates the first in-plane polarized spin current σ polarized in the -x direction. x The spin flow is injected upwards, and when the in-plane polarized spin flow σ x When passing through the interface between the net magnetic moment layer 100 and the light metal layer 101, due to the change in current direction, the torque of the interface spin orbital field reverses, causing the in-plane polarized spin current σ to generate an out-of-plane polarized spin current σ polarized in the -z direction. z .

[0028] It should also be noted that if the in-plane net magnetic moment of the net magnetic moment layer 100 is reversed along the +x direction, when a current flows in the -x direction, an out-of-plane polarized spin current polarized in the -z direction will eventually be formed. When a current flows in the +x direction, an out-of-plane polarized spin current polarized in the +z direction will eventually be formed. That is, the polarization direction of the out-of-plane polarized spin current is determined by both the direction of the in-plane net magnetic moment and the direction of the current.

[0029] In one embodiment, the material of the net magnetic moment layer 100 can be a ferromagnetic material with in-plane magnetic anisotropy, such as CoFeB, NiFe, etc.

[0030] In another embodiment, the net magnetic moment layer 100 can be made of an antiferromagnetic material, including at least one of IrMn alloy, PtMn alloy, FeMn alloy, and PdMn alloy. The net magnetic moment layer 100 is formed by applying an in-plane magnetic field during the growth of the antiferromagnetic material, or by annealing the antiferromagnetic material under an in-plane magnetic field after its growth, which also induces an in-plane net magnetic moment on the surface of the antiferromagnetic material. Regardless of whether the net magnetic moment layer uses a ferromagnetic or antiferromagnetic material, the working mechanism is the same.

[0031] In one implementation, the thickness of the net magnetic moment layer 100 is 3~7nm.

[0032] Figure 3 A schematic diagram illustrating the principle of orbital flow generation and its conversion into in-plane spin flow. (See diagram below.) Figure 3As shown in (a), when current flows through the light metal layer 101 in the -x direction, the light metal layer 101 generates a counterclockwise orbital current based on the orbital Hall effect. Since the orbital current cannot directly interact with the magnetic moment, in this embodiment of the invention, a conversion layer 102 with strong spin-orbit coupling is inserted. The orbital current flows upward through the conversion layer 102, which converts the counterclockwise orbital current into a second-plane polarized spin current σ polarized in the +y direction. y The second-plane internal polarized spin current σ y It is further injected into the free layer 103 and acts on the free layer magnetic moment.

[0033] like Figure 3 As shown in (b), when current flows through the light metal layer 101 in the +x direction, the light metal layer 101 generates a clockwise orbital flow based on the orbital Hall effect. The conversion layer 102 has a strong spin-orbit coupling effect, which converts the clockwise orbital flow into a second-plane polarized spin flow σ polarized in the -y direction. y .

[0034] In one embodiment, the light metal layer 101 is made of a 3d or 4d transition metal material with ultra-high orbital Hall conductivity, such as Cr, Ru, Ti, Mn, V, Zr, Cu, etc., and its thickness can be between 1 and 5 nm. The conversion layer 102 is required to have strong spin-orbit coupling, and its material can be a heavy metal, such as tantalum (Ta) or platinum (Pt), or a rare metal, such as gadolinium (Gd), but is not limited thereto. The thickness of the conversion layer 102 is between 0.5 and 1 nm.

[0035] In addition, current will also flow through the conversion layer 102. Under the strong spin-orbit coupling, it will also generate an in-plane polarized spin current (referred to as the third in-plane polarized spin current in this application). After being injected into the free layer 103, it will generate a spin-orbit moment, which will act on the magnetic moment of the free layer.

[0036] Therefore, in this embodiment, the ultra-high orbital Hall conductivity and low intrinsic longitudinal resistance of the light metal layer are utilized to reduce the critical switching current density and device power consumption, while simultaneously improving the switching efficiency. The diffusion length of the orbital angular momentum of the light metal layer is much higher than that of the spin angular momentum of the heavy metal layer, which can further enhance the orbital information transmission efficiency and increase the integration density. Moreover, the spin-orbit moments generated by the conversion of the orbital current in the light metal layer and the third-plane polarized spin current generated by the conversion layer itself jointly act on the free layer magnetic moment, improving the switching efficiency.

[0037] Based on the above principles, the free layer flipping machine is manufactured as follows: refer to Figure 4 , Figure 4 A schematic diagram of the free-layer magnetic moment direction reversal mechanism, as shown below. Figure 4 As shown in (a), the initial direction of the free layer magnetic moment is vertically downward. When the current flows along the -x direction through the net magnetic moment layer 100 and the light metal layer 101, the polarized spin current σ in the second plane polarized in the +y direction... y The spin orbital moment injected into free layer 103 acts on the free layer magnetic moment, causing it to flip from its initial vertical downward direction to a horizontal direction. The out-of-plane polarized spin current σ in the +z direction... z Injected into the free layer 103, the resulting spin orbital moment acts on the free layer magnetic moment, providing something like an "equivalent vertical magnetic field," breaking the flip symmetry, achieving a deterministic flip of the free layer's vertical magnetic moment, and further flipping the magnetic moment to vertically upward.

[0038] like Figure 4 As shown in (b), the initial direction of the free layer magnetic moment is vertically upward. When the current flows along the +x direction through the net magnetic moment layer 100 and the light metal layer 101, the polarized spin current σ in the second plane polarized in the -y direction... y The spin orbital moment injected into free layer 103 acts on the free layer magnetic moment, causing it to flip from its initial vertical upward direction to a horizontal direction. The out-of-plane polarized spin current σ in the -z direction is... z Injected into the free layer 103, the resulting spin orbital moment acts on the free layer magnetic moment, providing an "equivalent vertical magnetic field", breaking the flip symmetry, realizing the deterministic flip of the free layer vertical magnetic moment, and further flipping the magnetic moment to vertically downward.

[0039] Similarly, according to the above-described reversal mechanism, if the in-plane net magnetic moment of the net magnetic moment layer 100 is reversed, the reversal of the free layer magnetic moment will also be reversed accordingly. That is, when the in-plane net magnetic moment is in the +x direction, if the current is in the -x direction, the free layer magnetic moment will reverse from vertically upward to vertically downward. If the current is in the +x direction, the free layer magnetic moment will reverse from vertically downward to vertically upward.

[0040] Figure 5 This is a schematic diagram showing the relationship between the pulse current and the anomalous Hall resistance measured in a magnetic tunnel junction device according to an embodiment of the present invention without magnetic field assistance. Figure 5 As shown, the horizontal axis represents the pulsed current applied to the spin-orbit moment providing layer 200, and the vertical axis represents the normalized anomalous Hall resistance value. By measuring the magnitude of the anomalous Hall resistance, the relationship between the magnetic moments of the free layer and the reference layer can be reflected. When the free layer and the reference layer are aligned parallel, a low-resistance state is exhibited; when the free layer and the reference layer are aligned antiparallel, a high-resistance state is exhibited. Therefore, it can be seen that the magnetic tunnel junction device provided in this embodiment can achieve a change in resistance state without magnetic field assistance, that is, it can achieve deterministic reversal without magnetic field assistance.

[0041] The magnetic tunnel junction device provided in this invention is a highly efficient magnetic tunnel junction device that achieves deterministic reversal of the vertical magnetic moment without the assistance of an external magnetic field, based on orbital current enhancement. It utilizes out-of-plane polarized spin current generated at the interface of the net magnetic moment layer / light metal layer to provide an "equivalent vertical magnetic field," breaking the symmetry of the free layer magnetic moment reversal and achieving deterministic reversal of the free layer's vertical magnetic moment. Furthermore, the orbital current generated by the orbital Hall effect in the light metal layer can leverage the high orbital Hall conductivity to provide a more efficient magnetic moment driving force, further improving reversal efficiency and reducing the critical reversal current density and power consumption. Compared to existing technologies, the magnetic tunnel junction device of this invention can achieve highly efficient and deterministic reversal of the free layer's vertical magnetic moment without applying any external auxiliary magnetic field.

[0042] Figure 6 This is a schematic diagram illustrating the effect of the thickness of the light metal layer on the critical switching current density. (Example:) Figure 6 As shown, in this embodiment of the invention, the material of the light metal layer 101 is selected as the light metal Cr, and the material of the conversion layer 102 is selected as Ta. The influence of orbital current on performance was demonstrated by changing the thickness of the Cr layer. The horizontal axis represents the thickness of the Cr layer, and the vertical axis represents the critical switching current density. It can be seen from the figure that the critical switching current density decreases with increasing Cr layer thickness. When the Cr layer thickness increases to 5 nm, the critical switching current density reaches a minimum of approximately 1.0. 10 7 The critical flip current density decreased by approximately 35% compared to the pure heavy metal Ta sample without a Cr layer, with an ampere / cm². This result demonstrates that the strong orbital Hall conductivity in light metals can effectively reduce the critical flip current density and improve the flip efficiency. Figure 6 The four curves were measured under different external magnetic fields.

[0043] In one embodiment, such as Figure 7 As shown, the magnetic tunnel junction device further includes a barrier layer 104, a reference layer 105, a pinning layer 106, and a protective layer 107 stacked above the free layer 103. The stacked structure formed by the free layer 103, barrier layer 104, reference layer 105, pinning layer 106, and protective layer 107 can be referred to as the magnetic tunnel junction stack layer 201. The materials of each layer of the magnetic tunnel junction stack layer 201 can be selected according to the prior art, and will not be described in detail in this application.

[0044] On the other hand, another embodiment of the present invention provides a magnetic memory including the magnetic tunnel junction device in the above embodiments.

[0045] The above description does not provide detailed explanations of the technical aspects of each layer's patterning and etching. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A magnetic tunnel junction device, characterized in that, include: A net magnetic moment layer, having an in-plane net magnetic moment, is used to generate a first in-plane polarized spin current; A light metal layer is located on the net magnetic moment layer. The light metal layer has an orbital Hall effect and is used to generate orbital flow based on the orbital Hall effect. The first in-plane polarized spin flow forms an out-of-plane polarized spin flow after passing through the interface between the net magnetic moment layer and the light metal layer. A conversion layer, located on the light metal layer, has a strong spin-orbit coupling effect and is used to convert the orbital flow generated by the light metal layer into a second in-plane polarized spin flow. A free layer, located on the conversion layer, has a reversible vertical magnetic moment. Under the combined action of the spin orbit moments generated by the out-of-plane polarized spin current and the second in-plane polarized spin current, the magnetic moment of the free layer achieves deterministic reversal.

2. The magnetic tunnel junction device according to claim 1, characterized in that, The material of the net magnetic moment layer is a ferromagnetic material with in-plane magnetic anisotropy.

3. The magnetic tunnel junction device according to claim 1, characterized in that, The material of the net magnetic moment layer is an antiferromagnetic material, and its specific formation method is as follows: an in-plane magnetic field is applied when the antiferromagnetic material is grown, or after the antiferromagnetic material is grown, annealing is performed under an in-plane magnetic field.

4. The magnetic tunnel junction device according to claim 3, characterized in that, The optional antiferromagnetic materials include at least one of IrMn alloy, PtMn alloy, FeMn alloy, and PdMn alloy.

5. The magnetic tunnel junction device according to claim 1, characterized in that, The thickness of the net magnetic moment layer is 3~7nm.

6. The magnetic tunnel junction device according to claim 1, characterized in that, The material of the light metal layer is a 3d or 4d transition metal material with ultra-high orbital Hall conductivity.

7. The magnetic tunnel junction device according to claim 1, characterized in that, The thickness of the light metal layer is 1~5nm.

8. The magnetic tunnel junction device according to claim 1, characterized in that, The material of the conversion layer includes at least one of tantalum (Ta), platinum (Pt), and gadolinium (Gd).

9. The magnetic tunnel junction device according to claim 1, characterized in that, The thickness of the conversion layer is 0.5~1nm.

10. A magnetic storage device, characterized in that, Includes the magnetic tunnel junction device as described in any one of claims 1 to 9.

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