Magnetic memory device and information storage method

Abstract

The invention provides a magnetic memory device and an information storage method, and the information storage method comprises the steps: generating an exchange bias field through the exchange coupling effect between an antiferromagnetic layer and a ferromagnetic free layer; the heat stability of the vertical magnetic moment is enhanced through the exchange bias field; wherein the vertical magnetic moment is a carrier for information storage; applying an external charge current to the antiferromagnetic layer to generate an out-of-plane spin polarization current; and overturning the vertical magnetic moment through the out-of-plane spin polarization current to store information. According to the invention, the thermal stability and the writing efficiency of the magnetic memory device can be greatly improved, the magnetization overturning process is simplified, the complexity and the power consumption of the system are reduced, and technical support is provided for the development of the next-generation high-density and low-power-consumption magnetic memory device.

Description

Technical Field

[0001] The present invention relates to the field of magnetic storage technologies, and particularly to spin-orbit torque (SOT) magnetic storage devices, and specifically to a magnetic storage device and a method for storing information. Background Art

[0002] Magnetic tunnel junctions composed of ferromagnetic layers with perpendicular anisotropy have great prospects in realizing high-density non-volatile storage and logic. And related research has also shown that the flipping of magnetic tunnel junctions induced by current has the advantages of high speed and low power consumption. However, if one wants to realize a high-density magnetic memory based on magnetic tunnel junctions, there are still two important problems to be solved urgently:

[0003] 1. The thermal stability of magnetic nanojunctions needs to be improved. If one wants to store information in a high-density magnetic memory for more than 10 years, the thermal stability parameter defined by the ratio of the magnetic anisotropy energy EM to the thermal energy Kt should exceed 60. However, as the size of magnetic storage devices shrinks to sub-ten nanometers, the perpendicular magnetic anisotropy weakens significantly, making it difficult to achieve stable magnetic storage at room temperature.

[0004] 2. It is necessary to achieve deterministic flipping without external field assistance. The SOT flipping of the perpendicular magnetic moment usually requires the application of an in-plane magnetic field for assistance, which increases the system complexity and power consumption, and limits the integration and application of the device. Summary of the Invention

[0005] By providing a magnetic storage device and a method for storing information, the present invention aims to solve the technical problems faced in existing spin-orbit torque magnetic storage devices, especially the problems of insufficient thermal stability and the need for in-plane magnetic field-assisted magnetization flipping when the SOT device based on the perpendicular magnetic moment shrinks to sub-ten nanometer size.

[0006] To solve at least one of the above problems existing in the prior art, in a first aspect, an embodiment of the present invention provides a magnetic storage device, including:

[0007] A ferromagnetic reference layer;

[0008] A tunneling layer, disposed in contact with one side of the ferromagnetic reference layer;

[0009] A ferromagnetic free layer, disposed in contact with the other side of the tunneling layer;

[0010] An antiferromagnetic layer, disposed in contact with the other side of the ferromagnetic free layer; and the material is an antiferromagnetic material with non-mirror symmetry.

[0011] In some embodiments of the present invention, the antiferromagnetic layer has spin-orbit coupling properties.

[0012] In some embodiments of the present invention, the carrier for information storage is a perpendicular magnetic moment.

[0013] In a second aspect, an information storage method applied to the above magnetic storage device according to an embodiment of the present invention includes:

[0014] Generating an exchange bias field through the exchange coupling effect between the antiferromagnetic layer and the ferromagnetic free layer;

[0015] Enhancing the thermal stability of the perpendicular magnetic moment through the exchange bias field; wherein the perpendicular magnetic moment is the carrier for information storage;

[0016] Applying an external charge current to the antiferromagnetic layer to generate an out-of-plane spin-polarized current;

[0017] Flipping the perpendicular magnetic moment through the out-of-plane spin-polarized current to store information.

[0018] In some embodiments of the present invention, flipping the perpendicular magnetic moment through the out-of-plane spin-polarized current includes:

[0019] Generating a spin-orbit torque in the ferromagnetic free layer through the out-of-plane spin-polarized current;

[0020] Flipping the perpendicular magnetic moment through the spin-orbit torque.

[0021] In some embodiments of the present invention, an information storage method further includes:

[0022] Making the energy of the ferromagnetic free layer in the +z direction different from the energy in the -z direction through exchange bias fields in different directions to generate different magnetic ground states.

[0023] In some embodiments of the present invention, an information storage method further includes:

[0024] Flipping the perpendicular magnetic moment through the different magnetic ground states and the spin-orbit torque.

[0025] In some embodiments of the present invention, the direction of the external charge current, the polarization direction of the out-of-plane spin-polarized current, and the direction of the exchange bias field have a one-to-one correspondence relationship.

[0026] In some embodiments of the present invention, an information storage method further includes:

[0027] Deterministically flipping the perpendicular magnetic moment by controlling the direction of the external charge current.

[0028] In some embodiments of the present invention, deterministically flipping the perpendicular magnetic moment by controlling the direction of the external charge current includes:

[0029] Changing the polarization direction of the out-of-plane spin-polarized current by controlling the direction of the applied charge current;

[0030] Changing the exchange bias field by controlling the polarization direction of the out-of-plane spin-polarized current;

[0031] Making the perpendicular magnetic moment flip deterministically by controlling the exchange bias field.

[0032] First, from the above description, a magnetic storage device provided by an embodiment of the present invention includes: a ferromagnetic reference layer; a tunneling layer, disposed in contact with the ferromagnetic reference layer on one side; a ferromagnetic free layer, disposed in contact with the other side of the tunneling layer on one side; an antiferromagnetic layer, disposed in contact with the other side of the ferromagnetic free layer; and the material is an antiferromagnetic material with non-mirror symmetry.

[0033] Second, an embodiment of the present invention also provides a method for storing information using the above magnetic storage device. The method includes: first, generating an exchange bias field through the exchange coupling effect between the antiferromagnetic layer and the ferromagnetic free layer; enhancing the thermal stability of the perpendicular magnetic moment through the exchange bias field; where the perpendicular magnetic moment is the carrier for information storage; then, applying an applied charge current to the antiferromagnetic layer to generate an out-of-plane spin-polarized current; and finally, flipping the perpendicular magnetic moment through the out-of-plane spin-polarized current to store information.

[0034] In summary, the present invention proposes a novel magnetic storage device based on an exchange bias field and an out-of-plane spin-orbit torque current, which can greatly improve the thermal stability and writing efficiency of the magnetic storage device, simplify the magnetization flipping process, and reduce the system complexity and power consumption, providing technical support for the development of the next-generation high-density and low-power magnetic storage devices. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. In the drawings:

[0036] Figure 1 Schematic diagram of an exchange bias field and an out-of-plane spin current-regulated magnetic tunnel junction of a magnetic storage device according to an embodiment of the present invention Figure 1 .

[0037] Figure 2 Schematic diagram of an exchange bias field and an out-of-plane spin current-regulated magnetic tunnel junction of a magnetic storage device according to an embodiment of the present invention Figure 2 .

[0038] Figure 3Schematic diagram of the magnetic tunnel structure of a magnetic storage device in the prior art.

[0039] Figure 4 Flow schematic of a method for storing information using the above magnetic storage device according to an embodiment of the present invention Figure 1 。

[0040] Figure 5 Flow schematic diagram of step 400 according to an embodiment of the present invention.

[0041] Figure 6 Flow schematic diagram of step 800 according to an embodiment of the present invention.

[0042] Figure 7 Schematic illustration of the principle of exchange bias field enhancing thermal stability and assisting deterministic magnetization reversal in the specific embodiment of the present invention Figure 1 ;

[0043] Figure 8 Schematic illustration of the principle of exchange bias field enhancing thermal stability and assisting deterministic magnetization reversal in the specific embodiment of the present invention Figure 2 ;

[0044] Figure 9 Schematic illustration of the principle of exchange bias field enhancing thermal stability and assisting deterministic magnetization reversal in the specific embodiment of the present invention Figure 3 ;

[0045] The attached drawings are all schematic diagrams, where the thicknesses of the various functional layers or regions involved are not actual sizes, and the distances between the functional regions are not actual values. Specific Embodiment

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned accompanying drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or devices. Without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0048] Detailed examples are disclosed herein. Its specific structural details and functional details are only for the purpose of describing the examples. Therefore, the present invention can be implemented in many alternative forms, and the present invention should not be construed as being limited only to the example embodiments presented herein, but should cover all variations, equivalents, and alternatives falling within the scope of the present invention.

[0049] Spintronics, as an emerging branch of electronics, utilizes the spin degree of freedom of electrons to process information. Compared with traditional charge-based electronics, it has the advantages of lower power consumption, faster speed, and non-volatility. Especially in the aspect of memory, compared with traditional charge-based storage devices, spin storage devices have the advantages of higher speed, lower power consumption, and non-volatility.

[0050] Magnetic Random Access Memory (MRAM) has become the main application direction in spin storage devices. After years of development, its information writing method has formed three types of MRAM, including Toggle-MRAM based on magnetic field writing, STT-MRAM based on spin transfer torque (STT) writing, and SOT-MRAM based on spin orbit torque (SOT) writing.

[0051] Toggle-MRAM uses an external magnetic field to flip the magnetization direction of the free layer in the storage cell, thereby achieving data writing. The storage cell of Toggle-MRAM has high stability and durability, and is suitable for application scenarios that require long-term reliability. Relying on an external magnetic field for the writing operation results in high power consumption and slow writing speed. Due to the need for complex magnetic field control, the integration and scalability are limited. STT-MRAM utilizes the spin transfer torque effect to bias the electron spin by applying a current, thereby flipping the magnetization direction of the free layer. Compared with Toggle-MRAM, STT-MRAM does not require an external magnetic field, reducing system complexity and power consumption. At the same time, STT-MRAM has a faster writing speed and better scalability. As the size of the storage cell shrinks, the writing current requirement of STT increases significantly, resulting in an increase in power consumption. In addition, the randomness during writing and the long writing delay may affect data reliability. SOT-MRAM achieves magnetization flipping through the spin orbit torque effect. By applying a current to generate a spin current in the heavy metal layer, a spin orbit torque effect is triggered in the free layer, realizing magnetic moment flipping. SOT-MRAM has an extremely fast writing speed, higher efficiency, and lower writing current. In addition, it can achieve high-frequency operation without the need for read-write separation and has excellent durability.

[0052] However, the above three types of magnetic random access memories all have the following technical problems: As the size of magnetic storage devices shrinks to sub-ten nanometers, the perpendicular magnetic anisotropy is significantly weakened, making it difficult to achieve stable magnetic storage at room temperature. In addition, all three of these magnetic random access memories need to achieve deterministic switching without external field assistance, which increases system complexity and power consumption and limits the integration and application of devices.

[0053] Based on this, an embodiment of the present invention provides a magnetic storage device. Figure 1 A schematic diagram of the magnetic storage device according to an embodiment of the present invention. As Figure 1 and Figure 2 shown ( is the out-of-plane (z-direction) polarized spin current, is the exchange bias field, and I is the applied external charge current), a magnetic storage device includes:

[0054] A ferromagnetic reference layer 1;

[0055] A tunneling layer 2, with one side attached to the ferromagnetic reference layer 1;

[0056] A ferromagnetic free layer 3, with one side attached to the other side of the tunneling layer 2;

[0057] An antiferromagnetic layer 4, attached to the other side of the ferromagnetic free layer 3; and the material is a non-mirror-symmetric antiferromagnetic material.

[0058] Refer to Figure 3 , which shows a magnetic memory of the prior art. Different from the magnetic memory provided by the present invention, its bottom is a heavy metal material 5, while the corresponding thin layer of the present invention is an antiferromagnetic layer.

[0059] Continue to refer to Figure 3 (Schematic diagram of the magnetic tunnel structure of a magnetic storage device in the prior art, Figure 3 in is the in-plane (y-direction) polarized spin current, ($B_x$ is the magnetic field in the x - direction, and I is the externally applied charge current). The magnetic tunnel junctions in the prior art that use in - plane spin - polarized current and operate with the help of an external magnetic field have a rapid reduction in magnetic anisotropy energy due to the reduction in size in the tunnel junctions. In the case of sub - ten - nanometers, stable storage cannot be achieved. Due to the Spin Hall effect, the current flowing through the heavy - metal layer is converted into a spin - polarized current. However, due to the high - symmetry restriction, it can only generate an in - plane spin - polarized current that exerts a torque on the magnetic moment and can be transferred to the ferromagnetic free layer to change its magnetic moment to the plane. If a definite vertical flip is desired, an additional in - plane magnetic field is required for assistance. It can be understood that the introduction of an external magnetic field greatly increases the difficulty of power consumption reduction and size miniaturization. Generally, the materials that generate in - plane spin - polarized current in this magnetic storage device are heavy metals such as platinum (Pt), iridium (Ir), etc.

[0060] Relatively, the present invention proposes a high - performance magnetic storage device that uses an antiferromagnetic layer with symmetry breaking (non - mirror symmetry) to replace the heavy - metal layer that generates in - plane spin current in the prior art, thereby realizing all - electrical control. The out - of - plane spin - polarized current generated by the antiferromagnetic layer can directly act on the vertical magnetic moment of the ferromagnetic free layer. At the same time, the exchange - coupling effect formed between it and the ferromagnetic free layer generates an exchange - bias field, which improves the thermal stability of the vertical magnetic moment. Moreover, the externally applied charge current can directly control the exchange - bias field. There is a one - to - one correspondence between the direction of the externally applied charge current, the polarization direction of the vertical spin - polarized current, and the direction of the exchange - bias field. Thus, magnetization with a definite flip without an external field can be realized, and further, the power consumption of the device can be reduced.

[0061] In some embodiments of the present invention, the material of the antiferromagnetic layer is not only an antiferromagnetic material, but also this antiferromagnetic material has spin - orbit coupling properties.

[0062] The magnetic moments (i.e., magnetic directions) of atoms or ions in the antiferromagnetic material are arranged in an ordered anti - parallel arrangement, that is, the adjacent magnetic - moment directions are opposite. This arrangement results in these materials showing zero net magnetic moment at the macroscopic scale, although each atom or ion has a magnetic moment at the microscopic scale.

[0063] The antiferromagnetic material loses its antiferromagnetic order above a certain specific temperature. When the temperature is higher than this specific temperature (Neel temperature), the material exhibits paramagnetism.

[0064] The magnetization curve of the antiferromagnetic material shows a linear relationship at low temperatures, while the magnetization intensity rises rapidly when approaching the Neel temperature.

[0065] The Spin-Orbit Coupling (SOC) property is a physical phenomenon that describes the interaction between the electron spin and the orbital angular momentum. Specifically, it reflects the coupling between the motion of an electron in an electric field (i.e., orbital motion) and its spin state.

[0066] The electron spin is the intrinsic angular momentum of an electron, which manifests as the electron having a rotational-like motion characteristic. Spin is a quantum mechanical property and usually has only two possible states: up or down. The angular momentum of an electron when it moves around the atomic nucleus. The orbital angular momentum is closely related to the motion state of the electron.

[0067] Spin-Orbit Coupling: It refers to the coupling generated between the orbital angular momentum and the spin of an electron through electromagnetic interaction, which is a relativistic effect. Specifically, when an electron moves in an electric field, the electric field observed in its own reference frame will generate a magnetic field in this reference frame, and this magnetic field acts on the electron itself, thereby causing a change in the spin state of the electron and forming a coupling effect.

[0068] In some embodiments of the present invention, the carrier for information storage is a perpendicular magnetic moment.

[0069] As can be seen from the above description, a magnetic storage device provided by an embodiment of the present invention includes: a ferromagnetic reference layer; a tunneling layer, one side of which is attached to the ferromagnetic reference layer; a ferromagnetic free layer, one side of which is attached to the other side of the tunneling layer; an antiferromagnetic layer, which is attached to the other side of the ferromagnetic free layer; and the material is an antiferromagnetic material with non-mirror symmetry.

[0070] The magnetic storage device proposed by the present invention uses an antiferromagnetic layer with symmetry breaking to replace the heavy metal layer that generates in-plane spin current in the prior art, thereby realizing a high-performance magnetic storage device with all-electric control. The out-of-plane spin-polarized current generated by the antiferromagnetic layer can directly act on the perpendicular magnetic moment of the ferromagnetic free layer. At the same time, the exchange coupling effect formed between it and the ferromagnetic free layer generates an exchange bias field, which improves the thermal stability of the perpendicular magnetic moment. Moreover, an external charge current can directly control the exchange bias field, and there is a one-to-one correspondence between the directions of the external charge current and the perpendicular spin-polarized current and the direction of the exchange bias field. Thus, magnetization deterministic flipping without an external field can be achieved, and further the power consumption of the device can be reduced.

[0071] Next, refer to Figure 4 , an embodiment of the present invention also provides a method for storing information using the above magnetic storage device. The method includes:

[0072] Step 100: Generate an exchange bias field through the exchange coupling effect between the antiferromagnetic layer and the ferromagnetic free layer;

[0073] Step 200: Enhance the thermal stability of the perpendicular magnetic moment through the exchange bias field; wherein, the perpendicular magnetic moment is the carrier of information storage;

[0074] Step 300: Apply an external charge current to the antiferromagnetic layer to generate an out-of-plane spin-polarized current;

[0075] Step 400: Flip the perpendicular magnetic moment through the out-of-plane spin-polarized current to store information.

[0076] As can be seen from the above description, the embodiments of the present invention also provide a method for storing information using the above magnetic storage device, and the method includes: generating an exchange bias field through the exchange coupling effect between the antiferromagnetic layer and the ferromagnetic free layer; enhancing the thermal stability of the perpendicular magnetic moment through the exchange bias field; wherein, the perpendicular magnetic moment is the carrier of information storage; applying an external charge current to the antiferromagnetic layer to generate an out-of-plane spin-polarized current; flipping the perpendicular magnetic moment through the out-of-plane spin-polarized current to store information. The present invention has the following beneficial effects:

[0077] First, improve thermal stability: By introducing the exchange bias field, the thermal stability of the perpendicular magnetic moment is enhanced, enabling the device to achieve stable storage even at the sub-ten-nanometer scale.

[0078] Next, simplify the structure of the magnetic storage device and reduce power consumption: The spin-orbit torque generated by the out-of-plane spin current in the present invention realizes magnetization reversal without the assistance of an in-plane magnetic field, simplifies the system design, and significantly reduces the power consumption during the writing process.

[0079] Finally, improve the writing speed: The application of the out-of-plane spin-orbit torque greatly improves the speed of magnetization reversal, making the writing operation more efficient and suitable for high-speed storage application scenarios.

[0080] For Step 100 and Step 200, the exchange coupling effect between the antiferromagnetic layer and the ferromagnetic free layer will generate an additional effective magnetic field (exchange bias field) in the Figure 1 shown system, increase the energy barrier between the two magnetic moment directions, and thus enhance the thermal stability of the perpendicular magnetic moment (when the magnetic moment is perpendicular to the film plane), realizing stable storage at the sub-ten-nanometer scale.

[0081] For Step 300 and Step 400, applying an external charge current generates an out-of-plane spin-polarized current through the antiferromagnetic layer. This out-of-plane spin-polarized current generates a perpendicular spin-orbit torque in the ferromagnetic free layer, and this spin-orbit torque acts on the perpendicular magnetic moment in the ferromagnetic free layer, causing it to flip, thereby realizing the writing operation of information.

[0082] An out-of-plane spin-polarized current refers to a situation where the spin polarization direction carried in the current is perpendicular to the surface of the thin film or material. The spin-orbit torque refers to the torque generated by the coupling between the spin and orbital degrees of freedom.

[0083] See Figure 5 , in some embodiments of the present invention, the flipping of the perpendicular magnetic moment by the out-of-plane spin-polarized current in step 400 includes:

[0084] Step 401: Generating a spin-orbit torque in the ferromagnetic free layer through the out-of-plane spin-polarized current;

[0085] Step 402: Flipping the perpendicular magnetic moment through the spin-orbit torque.

[0086] In step 401 and step 402, the out-of-plane spin-polarized current generates a perpendicular spin-orbit torque in the free layer. This spin-orbit torque acts on the perpendicular magnetic moment in the ferromagnetic free layer, causing it to flip.

[0087] In some embodiments of the present invention, a method for storing information further includes:

[0088] Making the energy of the ferromagnetic free layer in the +z direction different from that in the -z direction through exchange bias fields in different directions to generate different magnetic ground states.

[0089] In some embodiments of the present invention, a method for storing information further includes:

[0090] Flipping the perpendicular magnetic moment through the different magnetic ground states and the spin-orbit torque.

[0091] Due to the utilization of the auxiliary effect of the exchange bias field, the perpendicular magnetic moment can maintain stability at higher temperatures, and at the same time, no additional in-plane magnetic field assistance is required.

[0092] In some embodiments of the present invention, a method for storing information further includes:

[0093] Making the perpendicular magnetic moment perform a deterministic flip by controlling the direction of the applied charge current.

[0094] The introduction of the exchange bias field will make the energies of the +z and -z magnetization directions different, so different exchange bias fields in different directions correspond to different magnetization ground states, and a flip of the determined magnetization direction can be achieved under the action of the out-of-plane spin-orbit torque.

[0095] In some embodiments of the present invention, the direction of the applied charge current, the polarization direction of the out-of-plane spin-polarized current, and the direction of the exchange bias field have a one-to-one correspondence relationship.

[0096] It can be understood that precisely due to this correspondence relationship, deterministic flipping of magnetization can be achieved without an external magnetic field, thereby reducing the power consumption of magnetic storage devices.

[0097] In some embodiments of the present invention, a method for storing information further includes:

[0098] Controlling the direction of the applied charge current to cause deterministic flipping of the perpendicular magnetic moment.

[0099] See Figure 6 , in some embodiments of the present invention, the above-mentioned controlling the direction of the applied charge current to cause deterministic flipping of the perpendicular magnetic moment includes:

[0100] Step 801: Controlling the direction of the applied charge current to change the polarization direction of the out-of-plane spin-polarized current;

[0101] Step 802: Controlling the polarization direction of the out-of-plane spin-polarized current to change the exchange bias field;

[0102] Step 803: Controlling the exchange bias field to cause deterministic flipping of the perpendicular magnetic moment.

[0103] In steps 801 to 803, since the introduction of the exchange bias field causes a difference in energy between the two magnetization directions, there will be a corresponding magnetization ground state for each determined field direction. Therefore, the direction of the exchange bias field can be changed by regulating the direction of the applied charge current. That is, the perpendicular magnetic moment direction is directly linked to the polarization direction of the out-of-plane spin-polarized current through the exchange bias field, and deterministic flipping of the magnetic moment can be achieved by changing the current direction.

[0104] To further illustrate the solution, the present invention also provides a specific implementation manner of a magnetic storage device, including the following content:

[0105] The present invention aims to solve the key problems faced in existing spin-orbit torque magnetic storage devices, especially the problems of insufficient thermal stability and the need for in-plane magnetic field-assisted magnetization flipping when the perpendicular magnetic moment-based SOT device is scaled down to sub-ten-nanometer dimensions.

[0106] First, the present invention proposes a novel magnetic storage device based on the exchange bias field and the out-of-plane spin-orbit torque current. Second, the present invention is committed to improving the thermal stability and writing efficiency of the storage device, simplifying the magnetization flipping process, and reducing system complexity and power consumption, providing technical support for the development of the next generation of high-density and low-power magnetic storage devices.

[0107] First, provide the storage cell structure during the above magnetic storage. The storage cell uses a perpendicular magnetic moment as the carrier for information storage. Next, introduce an exchange bias field. Through the exchange coupling between the antiferromagnetic layer and the ferromagnetic free layer, enhance the stability of the perpendicular magnetic moment, improve the thermal stability of the storage cell, and ensure its stable operation at room temperature and higher temperatures.

[0108] Based on the above storage cell structure, the present invention also proposes a new writing mechanism. Specifically, utilize the spin-orbit torque generated by the out-of-plane spin current to induce the flipping of the magnetic moment in the ferromagnetic free layer.

[0109] See Figure 1 , which is a magnetic tunnel junction based on out-of-plane spin current and exchange bias field. Without changing the materials used for the ferromagnetic reference layer, tunneling layer, and ferromagnetic free layer, replace the heavy metal material with an antiferromagnetic material with low symmetry and strong spin-orbit coupling (SOC). Because of the symmetry breaking, the spin-polarized current generated by the spin Hall effect has a component in the out-of-plane direction, which can directly act on the perpendicular magnetic moment of the free layer.

[0110] Next, see Figure 7 , Figure 8 and Figure 9 . For a system without an exchange bias field, and the energies of the two magnetic moment ground state directions are the same. There is no definite flipping direction during the flipping process, and the energy barrier is the perpendicular magnetic anisotropy energy barrier of the material ( ), which will rapidly decrease with the size scaling and cannot stably store information. Because the exchange coupling between the antiferromagnetic layer and the ferromagnetic free layer will generate an additional effective magnetic field ( ) in this system, introducing an additional energy barrier ( ), increasing the energy barrier between the two magnetic moment ground state directions ( ), to enhance the thermal stability of the perpendicular magnetic moment and achieve stable storage at sub-ten-nanometer scale.

[0111] Also, because the introduction of the exchange bias field makes the energies of the two magnetization directions different, there will be a corresponding magnetization ground state for each definite field direction. During the magnetic moment flipping process, the in-plane magnetic moment flips towards the direction with lower magnetic moment ground state energy, thus realizing assisted deterministic magnetization flipping. Therefore, by controlling the direction of the applied charge current, the direction of the exchange bias field and the polarization direction of the out-of-plane spin-polarized current can be changed. The perpendicular magnetic moment direction is directly related to the polarization direction of the out-of-plane spin-polarized current through the exchange bias field, that is, the deterministic flipping of the magnetic moment can be achieved by changing the current direction.

[0112] Different from the prior art which requires in-plane magnetic fields to assist magnetization reversal, the present invention directly acts on the perpendicular magnetic moment through out-of-plane spin current and the exchange bias field between the free layer and the antiferromagnetic material, achieving deterministic reversal of perpendicular magnetization. This innovation not only simplifies the device structure but also significantly reduces the power consumption of the write operation.

[0113] As can be seen from the above description, the specific embodiment of the present invention also provides a method for storing information using the above magnetic storage device. The method includes: generating an exchange bias field through the exchange coupling between the antiferromagnetic layer and the ferromagnetic free layer; enhancing the thermal stability of the perpendicular magnetic moment through the exchange bias field, where the perpendicular magnetic moment is the carrier for information storage; applying an external charge current to the antiferromagnetic layer to generate an out-of-plane spin-polarized current; and controlling the polarization direction of the out-of-plane spin-polarized current to reverse the perpendicular magnetic moment for information storage.

[0114] The present invention aims to solve the key problems faced in existing spin-orbit torque magnetic storage devices, especially the insufficient thermal stability and the need for in-plane magnetic field-assisted magnetization reversal when the perpendicular magnetic moment-based SOT devices are scaled down to sub-ten-nanometer dimensions. The present invention can improve the thermal stability and write efficiency of the storage device, simplify the magnetization reversal process, and reduce system complexity and power consumption, providing technical support for the development of the next-generation high-density and low-power magnetic storage devices.

[0115] In the description of this specification, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0116] Descriptions with reference to terms such as "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. The order of steps involved in each embodiment is used to schematically illustrate the implementation of the present invention, and the order of steps is not limited and can be adjusted appropriately as needed.

[0117] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0118] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key point of each embodiment is to illustrate the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the description of the method embodiment. In the description of this specification, descriptions with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic representations of the above terms do not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without conflict, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0119] The above is only the embodiments of the embodiments of this specification and is not used to limit the embodiments of this specification. For those skilled in the art, various changes and modifications can be made to the embodiments of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the embodiments of this specification shall be included within the scope of the claims of the embodiments of this specification.

Claims

1. A magnetic storage device, characterized in that, Comprising: A ferromagnetic reference layer; A tunneling layer, disposed in contact with one side of the ferromagnetic reference layer; A ferromagnetic free layer, disposed in contact with the other side of the tunneling layer; An antiferromagnetic layer, disposed in contact with the other side of the ferromagnetic free layer; and the material is an antiferromagnetic material with non-mirror symmetry.

2. The magnetic storage device according to claim 1, wherein The antiferromagnetic layer has spin-orbit coupling properties.

3. The magnetic storage device according to claim 1, characterized in that, The carrier of information storage is the perpendicular magnetic moment.

4. A method for storing information in a magnetic storage device according to any one of claims 1 to 3, characterized in that, Comprising: Generating an exchange bias field through the exchange coupling effect between the antiferromagnetic layer and the ferromagnetic free layer; Enhancing the thermal stability of the perpendicular magnetic moment through the exchange bias field; wherein, the perpendicular magnetic moment is the carrier of information storage; Applying an external charge current to the antiferromagnetic layer to generate an out-of-plane spin-polarized current; Flipping the perpendicular magnetic moment through the out-of-plane spin-polarized current to store information.

5. The method for storing information according to claim 4, wherein Flipping the perpendicular magnetic moment through the out-of-plane spin-polarized current includes: Generating a spin-orbit torque in the ferromagnetic free layer through the out-of-plane spin-polarized current; Flipping the perpendicular magnetic moment through the spin-orbit torque.

6. The method for storing information according to claim 5, wherein Further comprising: Making the energy of the ferromagnetic free layer in the +z direction different from the energy in the -z direction through exchange bias fields in different directions to generate different magnetic ground states.

7. The method for storing information according to claim 6, wherein Further comprising: Flipping the perpendicular magnetic moment through the different magnetic ground states and the spin-orbit torque.

8. The method for storing information according to claim 6, wherein The direction of the external charge current, the polarization direction of the out-of-plane spin-polarized current and the direction of the exchange bias field are in a one-to-one correspondence relationship.

9. The method for storing information according to claim 8, wherein Further comprising: Deterministically flipping the perpendicular magnetic moment by controlling the direction of the external charge current.

10. The method for storing information according to claim 9, wherein The deterministically flipping the perpendicular magnetic moment by controlling the direction of the external charge current includes: Changing the polarization direction of the out-of-plane spin-polarized current by controlling the direction of the external charge current; Changing the exchange bias field by controlling the polarization direction of the out-of-plane spin-polarized current; Deterministically flipping the perpendicular magnetic moment by controlling the exchange bias field.

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