Magnetic tunnel junction stack structure, memory, and neural network computing device

Abstract

The application provides a magnetic tunnel junction stack structure, comprising: a spin orbit moment providing layer, a first free layer, a coupling layer, a second free layer, a barrier layer and a reference layer which are sequentially stacked from bottom to top; wherein one of the first free layer and the second free layer is in-plane magnetization mode, and the other is in perpendicular magnetization mode; and the magnetization mode of the reference layer is the same as that of the second free layer. The magnetization modes of the first free layer and the second free layer are set to different magnetization modes, and the combination of the two can adapt to various applications.

Description

Technical Field

[0001] This invention relates to the field of computer storage technology, and in particular to a magnetic tunnel junction stacked structure, a memory, a neural network computing device, and a spin oscillator. Background Technology

[0002] A magnetic tunnel junction (MTJ) consists of a free layer, a barrier layer, and a reference layer. It is generally used in non-volatile memory devices. The magnetization direction of the reference layer is fixed, while the magnetization direction of the free layer is variable. When the free layer and the reference layer are parallel, the MTJ is in a low-resistance state; when they are antiparallel, it is in a high-resistance state. The change in the magnetization direction of the free layer is generally achieved through a spin-orbit moment providing layer, typically made of heavy metal (HM). When current flows through the heavy metal, the magnetic moment of the free layer is reversed by the assistance of an external magnetic field or by the addition of a magnetic bias layer.

[0003] In the process of realizing this invention, the inventors discovered at least the following technical problems in the prior art:

[0004] Currently, magnetic memories based on spin orbital moments generally require an external magnetic field and have low switching efficiency. The free layer magnetization of magnetic tunnel junctions only has two states, resulting in limited applications. Summary of the Invention

[0005] The magnetic tunneling stacked structure, memory, neural network computing device, and spin oscillator provided by this invention; by setting the magnetization mode of the first free layer and the second free layer to different magnetization modes, the combination of the two can be adapted to a variety of applications.

[0006] In a first aspect, the present invention provides a magnetic tunneling stacked structure, comprising: a spin orbital moment providing layer, a first free layer, a coupling layer, a second free layer, a barrier layer, and a reference layer stacked sequentially from bottom to top; wherein...

[0007] One of the first free layer and the second free layer is magnetized in-plane, and the other is magnetized perpendicularly;

[0008] The magnetization method of the reference layer is the same as that of the second free layer.

[0009] Optionally, the coupling layer includes:

[0010] The first coverage area covers the upper surface of the first free layer;

[0011] The second coverage area covers the region on the upper surface of the spin orbit moment providing layer other than the first free layer coverage area.

[0012] Optionally, the spin Hall angle of the coupling layer is opposite in direction to the spin Hall angle of the spin orbital moment providing layer.

[0013] Optionally, one of the coupling layer and the spin-orbit moment providing layer is made of one or more of Pt, Pd, Ir or Au, and the other is made of one or more of Ta, W or Mo.

[0014] Optionally, the materials of the first free layer, the second free layer, and the reference layer include one or more of Co, Fe, Ni, B, Pd, or Pt; the material of the barrier layer includes one or more of MgO, MgAl2O4, or Al2O3.

[0015] In a second aspect, the present invention provides a memory comprising:

[0016] As described above, any of the magnetic tunneling stacked structures; wherein the first free layer is magnetized in-plane, and the second free layer and the reference layer are magnetized perpendicularly; the saturation magnetization of the first free layer and the saturation magnetization of the second free layer satisfy the following relationship: |Ms1-Ms2| / Ms2≥20%; wherein Ms1 is the saturation magnetization of the first free layer, and Ms2 is the saturation magnetization of the second free layer;

[0017] A current source, electrically connected to the spin orbital moment, is used to provide multiple write currents, the direction of which is in-plane and perpendicular to the magnetization direction of the first free layer.

[0018] Thirdly, the present invention also provides a multi-resistive state memory, comprising:

[0019] Such as any of the magnetic tunneling stacked structures mentioned above;

[0020] A current source, electrically connected to the spin orbital moment providing layer, is used to provide various write currents.

[0021] Optionally, the first free layer is vertically magnetized, and the second free layer and the reference layer are in-plane magnetized.

[0022] Fourthly, the present invention also provides a neural network computing device, including...

[0023] Such as any of the magnetic tunneling stacked structures mentioned above; used to store corresponding weight values ​​based on multiple currents;

[0024] A current source, electrically connected to the spin orbital moment layer, is used to provide various write currents.

[0025] Fifthly, the present invention also provides a spin oscillator, comprising:

[0026] Such as any of the magnetic tunneling stacked structures mentioned above;

[0027] A current source, electrically connected to the spin-orbit moment providing layer, is used to provide current to the spin-orbit moment providing layer, the current being greater than three times the flip current of the first free layer.

[0028] The magnetic tunnel junction stacked structure provided by this invention has two free layers. Furthermore, the first and second free layers, through coupling and coordination of magnetization methods, can possess magnetization components in both the in-plane and vertical directions. That is, each free layer has magnetization components in two directions, and the magnetization components of the two free layers are flipped by different current-driven methods. This structure can achieve efficient flipping without an external magnetic field and can realize multiple states, thereby enabling the magnetic tunnel junction to have a wider range of applications. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a magnetic tunneling stacked structure according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of two magnetic moment variations in a magnetic tunnel junction stacked structure according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the magnetic moment oscillation variation of a magnetic tunnel junction stacked structure according to an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of a magnetic tunneling stacked structure according to another embodiment of the present invention;

[0033] Figure 5 This is a schematic diagram of a magnetic tunneling stacked structure according to another embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram illustrating various magnetic moment variations in a magnetic tunnel junction stacked structure according to another embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram illustrating various resistance variations in a magnetic tunnel junction stacked structure according to another embodiment of the present invention. Detailed Implementation

[0036] 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. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention provides a magnetic tunneling stacked structure, such as... Figure 1 As shown, the structure includes: a spin-orbit moment providing layer 100, a first free layer 200, a coupling layer 300, a second free layer 400, a barrier layer 500, and a reference layer 600 stacked sequentially from bottom to top; wherein, one of the first free layer 200 and the second free layer 400 is in-plane magnetized, and the other is perpendicularly magnetized; the magnetization mode of the reference layer 600 is the same as that of the second free layer 400. In this embodiment, the magnetization direction of the reference layer 600 is fixed, while the magnetization directions of the first free layer 200 and the second free layer 400 are variable. The reference layer 600 and the second free layer 400 may both be perpendicularly magnetized or both be in-plane magnetized, but the magnetization directions of the first free layer 200 and the second free layer 400 may differ. If the second free layer 400 is in-plane magnetized, then the first free layer 200 is perpendicularly magnetized; if the second free layer 400 is perpendicularly magnetized, then the first free layer 200 is in-plane magnetized. The spin orbital moment providing layer 100 allows current to pass through, and the in-plane magnetization direction of the first free layer 200 or the second free layer 400 is perpendicular to the current direction. When current passes through the spin orbital moment providing layer 100, it causes the magnetic moment of the first free layer 200 to deflect, which, through coupling, drives the magnetic moment of the second free layer 400 to deflect. Under different saturation magnetization intensities and different current conditions, the first free layer 200 and the second free layer 400 can be simultaneously flipped or multi-resistance state storage can be achieved. As an optional implementation, the materials of the first free layer 200, the second free layer 400, and the reference layer 600 include one or more of Co, Fe, Ni, B, Pd, or Pt. As an optional implementation, the material of the barrier layer 500 includes one or more of MgO, MgAl2O4, and Al2O3. As a preferred implementation, one of the coupling layer 300 and the spin orbital moment providing layer 100 is made of one or more of Pt, Pd, Ir, or Au, and the other is made of one or more of Ta, W, or Mo. Of the materials mentioned above, Pt, Pd, Ir, and Au are materials with positive spin Hall angles, while Ta, W, and Mo are materials with negative spin Hall angles.

[0038] The magnetic tunnel junction stacked structure provided in this invention has two free layers. The first and second free layers, through coupling and coordination of magnetization methods, can possess magnetization components in both the in-plane and vertical directions. That is, each free layer has magnetization components in two directions. The magnetization components of the two free layers are flipped by different current-driven methods, enabling multiple states and thus allowing for wider applications of the magnetic tunnel junction. This structure can achieve efficient flipping without an external magnetic field and can realize multiple states, thereby enabling wider applications of the magnetic tunnel junction. In the above embodiments, the memory cells of the magnetic tunnel junction stacked structure are deposited on a substrate using traditional methods such as molecular beam epitaxy, atomic layer deposition, or magnetron sputtering, followed by traditional nanodevice fabrication processes such as photolithography and etching. The shape of the magnetic tunnel junction is elliptical, rhombic, rectangular, or polygonal. For the above embodiments, antiferromagnetic coupling can be achieved by adjusting the thickness of the coupling layer 300.

[0039] As an optional implementation method, such as Figure 4 As shown, the coupling layer 300 includes:

[0040] The first coverage area covers the upper surface of the first free layer 200;

[0041] The second coverage area covers the area on the upper surface of the spin orbit moment providing layer 100 other than the coverage area of ​​the first free layer 200.

[0042] The coupling layer 300 covers the first free layer 200 and the spin orbit moment providing layer 100, which is beneficial to improving the flipping efficiency of the first free layer 200. The antiferromagnetic coupling effect of the coupling layer 300 is preferentially used, which is superimposed with its own spin Hall effect.

[0043] As an optional implementation, in the above-described embodiment, the spin Hall angle of the coupling layer 300 is opposite in direction to the spin Hall angle of the spin orbital moment providing layer. In this embodiment, the coupling layer 300 and the spin orbital moment providing layer 100 jointly promote the magnetic moment reversal of the first free layer 200, which is equivalent to increasing the spin Hall angle and improving the reversal efficiency.

[0044] This invention also provides a memory, including: any of the magnetic tunnel junction stacked structures described above; wherein the first free layer is in-plane magnetized, and the second free layer and the reference layer are perpendicularly magnetized; the saturation magnetization of the first free layer and the saturation magnetization of the second free layer satisfy the following relationship: |Ms1-Ms2| / Ms2≥20%; wherein Ms1 is the saturation magnetization of the first free layer, and Ms2 is the saturation magnetization of the second free layer;

[0045] A current source, electrically connected to the spin orbital moment, is used to provide multiple write currents, the direction of which is in-plane and perpendicular to the magnetization direction of the first free layer.

[0046] The memory provided in this embodiment does not require an external magnetic field. Current drives the magnetic moment of the first free layer 200 to flip, which in turn drives the second free layer 400 to flip via coupling, enabling both high and low resistance states. For example... Figure 2 As shown, Figure 2 The simulation demonstrates the magnetic moment changes of the first free layer 200 and the second free layer 400 according to this embodiment. The first free layer 200 and the second free layer 400 are in their initial state of free relaxation without current. Regarding the in-plane magnetization component, when the current drives the in-plane magnetization component of the first free layer 200 from positive to negative, the in-plane magnetization component of the second free layer 400 changes from negative to positive due to antiferromagnetic action. Within a reasonable range, the in-plane antiferromagnetic effect holds regardless of the magnitudes of the saturation magnetization of the first free layer 200 and the second free layer 400. Regarding the vertical magnetization component, the greater the saturation magnetization of the first free layer 200, the smaller the influence of the antiferromagnetic effect, meaning a smaller vertical magnetization component of the first free layer 200. During the flipping process, the first free layer 200 precesses from its initial state. When the current is large enough, the precession angle is greater than the angle between the initial direction of the magnetic moment and the thin film interface, meaning the vertical magnetization component of the first free layer 200 changes from negative to positive. Therefore, the antiferromagnetic effect has a certain probability of causing the vertical magnetization component of the second free layer 400 to change from positive to negative, thus achieving the flipping. Figure 2 It is known that the magnetic moments of the first free layer 200 and the second free layer 400 are only positive and negative. The change in the resistance of the magnetic tunnel junction is mainly determined by the angle between the magnetization direction of the magnetic layer (second free layer 400) directly connected to the barrier layer 500 and the magnetization direction of the reference layer 600. Therefore, the resistance of the magnetic tunnel junction corresponds to two resistance states.

[0047] When the saturation magnetization of the first free layer 200 and the saturation magnetization of the second free layer 400 satisfy the following relationship: |Ms1-Ms2| / Ms2<20%, the antiferromagnetic effect on the first free layer 200 is more obvious, making the vertical magnetization component of the first free layer 200 larger. During the flipping process, the first free layer 200 starts to precess from the initial state, and the maximum precession angle is smaller than the angle between the initial direction of the magnetic moment and the thin film interface. That is, the first free layer 200 cannot flip the vertical magnetization direction, and therefore cannot make the vertical magnetization component of the second free layer 400 flip through the coupling effect.

[0048] This invention also provides a multi-resistive state memory, comprising:

[0049] Such as any of the magnetic tunneling stacked structures mentioned above;

[0050] A current source, electrically connected to the spin orbital moment, provides multiple write currents, enabling the memory to exhibit multiple resistive states and perform multi-resistive-state storage, thereby increasing storage density. The magnetic tunnel junction stacked structure provided in this embodiment has two free layers. The first and second free layers, through coupling and coordination of magnetization methods, can have magnetization components in both the in-plane and vertical directions. That is, each free layer has magnetization components in two directions. The magnetization components of the two free layers are flipped through different current-driven mechanisms, enabling multiple states and thus allowing for wider applications of the magnetic tunnel junction. This structure can achieve efficient flipping without an external magnetic field and can realize multiple states, thereby enabling the magnetic tunnel junction to have a wider range of applications.

[0051] As an optional implementation method, such as Figure 5 As shown, the first free layer is magnetically magnetized vertically, while the second free layer and the reference layer are magnetically magnetized in-plane. Figure 6 As shown, Figure 6 The simulation demonstrates the magnetic moment changes of the first free layer 200 and the second free layer 400 according to this embodiment. The principle is similar. For the perpendicular magnetization components of the first free layer 200 and the second free layer 400, since the first free layer 200 is perpendicularly magnetized, its perpendicular magnetization component is very large. From the initial state, the maximum precession angle is smaller than the angle between the initial direction of the magnetic moment and the thin film interface. Therefore, the perpendicular magnetization component of the first free layer 200 does not flip, and thus cannot cause the perpendicular magnetization component of the second free layer 400 to flip through coupling. For the in-plane magnetization components of the first free layer 200 and the second free layer 400, the in-plane magnetization component of the first free layer 200 can flip. Simultaneously, based on the antiferromagnetic coupling effect of the coupling layer, it can also drive the in-plane magnetization component of the second free layer 400 to flip. In summary, the magnetic moment of the first free layer 200 remains essentially unchanged, while different current magnitudes result in different deflection angles of the second free layer 400, achieving a balance between magnetic anisotropy, spin orbital moment, and coupling. The reference layer 600 is in-plane magnetized with a fixed magnetization direction. The resistance of the magnetic tunnel junction is mainly determined by the angle between the magnetization direction of the second free layer 400 and the magnetization direction of the reference layer 600. Different angles correspond to different resistances. Figure 6 The difference in in-plane magnetization components of the 400 Å magnetic moment in the second free layer. For example... Figure 7 As shown in the diagram, the magnetic tunnel junction exhibits different resistance values ​​under different write currents, thus enabling a multi-resistance storage method.

[0052] This invention also provides a neural network computing device, including...

[0053] Such as any of the magnetic tunneling stacked structures mentioned above; used to store corresponding weight values ​​based on multiple currents;

[0054] A current source, electrically connected to the spin orbital moment layer, is used to provide various write currents.

[0055] In the aforementioned neural network computing device, since each storage cell of each magnetic tunnel junction stacked structure has multiple resistance states, the resistance states can be mapped to weight values. During neural network computation, it is unnecessary to convert weight values ​​to binary for storage; one storage cell can store one weight. When using a weight, reading from a single storage cell is sufficient, eliminating the binary conversion process and thus improving neural network computation efficiency. In this embodiment, the magnetic tunnel junction can exhibit multiple resistance states through multiple directions of the magnetic moment of the first free layer 200 or the second free layer 400, thereby enabling the storage of multiple storage states.

[0056] This invention also provides a spin oscillator, comprising:

[0057] Such as any of the magnetic tunneling stacked structures mentioned above;

[0058] A current source, electrically connected to the spin-orbit moment providing layer, is used to supply current to the spin-orbit moment providing layer, the current being greater than three times the flipping current of the first free layer. Figure 3 As shown, Figure 3 To demonstrate the simulation results according to this embodiment, when a sufficiently large current is continuously applied (e.g., more than three times the magnetization reversal current), the magnetic moments of the first free layer 200 and the second free layer 400 change. As shown in the figure, both the magnetic moments of the first free layer 200 and the second free layer 400 exhibit oscillation phenomena. The magnetic moment oscillation amplitude of the second free layer 400 is larger, resulting in a stronger signal that is more easily received. Therefore, this structure can be applied to microwave oscillators.

[0059] 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 tunneling stacked structure, characterized in that, include: The spin orbital moment providing layer, first free layer, coupling layer, second free layer, barrier layer, and reference layer are stacked sequentially from bottom to top; among them, One of the first free layer and the second free layer is magnetized in-plane, and the other is magnetized perpendicularly; the magnetization directions of the first free layer and the second free layer are variable; The magnetization method of the reference layer is the same as that of the second free layer; The first and second free layers, through coupling and magnetization, possess magnetization components both in-plane and in the vertical direction. When current flows through the spin orbital moment supply layer, it causes the magnetic moment of the first free layer to deflect, which in turn drives the magnetic moment of the second free layer to deflect. The magnetization components of the first and second free layers are flipped through different current-driven methods to form multiple states. The direction of the current is in-plane and perpendicular to the magnetization direction of the first free layer. The resistance of a magnetic tunnel junction is determined by the angle between the magnetization direction of the second free layer and the magnetization direction of the reference layer. Different angles correspond to different in-plane magnetization components of the magnetic moment of the second free layer.

2. The magnetic tunneling stacked structure according to claim 1, characterized in that, The coupling layer includes: The first coverage area covers the upper surface of the first free layer; The second coverage area covers the region on the upper surface of the spin orbit moment providing layer other than the first free layer coverage area.

3. The magnetic tunneling stacked structure according to claim 2, characterized in that, The spin Hall angle of the coupling layer is opposite in direction to the spin Hall angle of the spin orbit moment providing layer.

4. The magnetic tunneling stacked structure according to claim 2, characterized in that, The material of one of the coupling layer and the spin orbital moment providing layer includes one or more of Pt, Pd, Ir or Au, and the material of the other includes one or more of Ta, W or Mo.

5. The magnetic tunneling stacked structure according to claim 1, characterized in that, The materials of the first free layer, the second free layer, and the reference layer include one or more of Co, Fe, Ni, B, Pd, or Pt; the material of the barrier layer includes one or more of MgO, MgAl2O4, or Al2O3.

6. A memory, characterized in that, include: Any of the magnetic tunneling stacked structures as described in claims 1-5; wherein the first free layer is magnetized in-plane, and the second free layer and the reference layer are magnetized perpendicularly; the saturation magnetization of the first free layer and the saturation magnetization of the second free layer satisfy the following relationship: |Ms1-Ms2| / Ms2≥20%; wherein Ms1 is the saturation magnetization of the first free layer, and Ms2 is the saturation magnetization of the second free layer; A current source, electrically connected to the spin orbital moment, is used to provide multiple write currents, the direction of which is in-plane and perpendicular to the magnetization direction of the first free layer.

7. A multi-resistive state memory, characterized in that, include: Any of the magnetic tunneling stacked structures as described in claims 1-5; A current source, electrically connected to the spin orbital moment layer, is used to provide various write currents.

8. The multi-resistive state memory according to claim 7, characterized in that, The first free layer is magnetized vertically, while the second free layer and the reference layer are magnetized in-plane.

9. A neural network computing device, characterized in that, include A current source, electrically connected to the spin-orbit moment layer, is used to provide various write currents; The magnetic tunnel junction stacked structure as described in any of claims 1-5; used to store corresponding weight values ​​according to the various write currents.

10. A spin oscillator, characterized in that, include: Any of the magnetic tunneling stacked structures as described in claims 1-5; A current source, electrically connected to the spin-orbit moment providing layer, is used to provide current to the spin-orbit moment providing layer, the current being greater than three times the flip current of the first free layer.

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