SOT-MRAM device with high spin transmission efficiency and preparation method thereof

Abstract

The invention provides an SOT-MRAM device with high spin transmission efficiency and a preparation method thereof, and belongs to the field of nonvolatile memory devices. The device comprises a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction which are stacked in sequence, wherein the insertion layer is a two-dimensional material layer. The two-dimensional material is used as the insertion layer, so that the spin transmission efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of non-volatile memory devices, and particularly relates to a SOT-MRAM device with high spin transport efficiency and a preparation method thereof. BACKGROUND

[0002] With the rapid development of information technology, modern electronic devices have higher requirements for the density, speed, power consumption and durability of data storage. Traditional storage devices based on charge storage, such as DRAM, SRAM and NAND Flash, have gradually approached the physical limit and are difficult to continue to meet the growing demand for high-performance storage in emerging fields such as artificial intelligence, Internet of Things and edge computing in terms of microfabrication process, energy efficiency and service life. Therefore, exploring new non-volatile memory structures has become a key direction for the evolution of current storage chip technology.

[0003] With the increasing demand for high-performance non-volatile storage, magnetic random access memory (MRAM) as a new type of storage technology has attracted more and more attention. MRAM technology uses spin transfer torque to control the magnetization direction of magnetic material, thereby realizing data storage. Compared with traditional storage, MRAM has the advantages of high read-write speed, low energy consumption and long service life, and is particularly suitable for fields such as artificial intelligence, Internet of Things and edge computing.

[0004] In order to further improve the performance of MRAM, spin-orbit torque magnetic random access memory (SOT-MRAM) as an improved form of MRAM, uses spin-orbit coupling effect to drive the spin-orbit torque to flip the magnetic moment. Compared with the traditional magnetic field writing method, SOT-MRAM can realize data writing at lower write current and higher efficiency, thereby solving the bottleneck problem of traditional MRAM in write energy and current density.

[0005] Please refer to Figure 1 , which shows the structure of an existing SOT-MRAM, including: a SOC layer 11 (also known as a spin-orbit coupling layer) and a magnetic tunnel junction (MTJ) 12, and a bottom electrode 13 connected with the SOC layer 11 and a top electrode 14 connected with the magnetic tunnel junction 12; the magnetic tunnel junction 12 includes a magnetic free layer 121, a barrier layer 122 and a magnetic fixed layer 123 which are stacked in the SOC layer 11 in sequence, and the top electrode 14 is connected with the magnetic fixed layer 123.

[0006] The principle is: when a write current ( ) when flowing through the SOC layer 11, a spin Hall effect is generated, and the electron spin is deflected in the vertical direction, generating a transverse spin current ( ). The spin current ( ) is injected into the adjacent magnetic free layer 121, generating a spin-orbit torque (SOT) to drive the magnetization to flip. The magnetic free layer 121 is used to store data, and the direction of its magnetization (parallel or antiparallel to the magnetic fixed layer 123) determines its storage state ("0" or "1"). The barrier layer 122 is used to form a magnetic tunnel junction to achieve data reading. The magnetic fixed layer 123 is used to provide a reference magnetization direction (its magnetization direction is fixed and unchanged) for comparison with the magnetic moment of the magnetic free layer 121 to perform resistance detection. The bottom electrode 13 is used for writing (i.e., providing a write current), and the top electrode 14 is used for reading (i.e., resistance measurement of the magnetic tunnel junction).

[0007] However, the heavy metal materials commonly used in the SOC layer 11, such as Pt and Ta, still have the problems of limited spin Hall angle and insufficient spin current injection efficiency. This not only increases the write energy consumption, but also exacerbates the risk of electromigration aging of the device. Secondly, the interface between the traditional magnetic free layer material such as CoFeB and the heavy metal often has problems such as lattice mismatch, strong scattering mechanism, and interface oxidation, which causes strong loss of spin current during injection, low spin transparency, and further limits the SOT efficiency. In addition, in order to meet the requirement of thermal stability, the magnetic free layer usually needs to have a certain thickness, which is in conflict with the trend of device miniaturization. Thinning the magnetic layer is beneficial to reducing the current density and increasing the storage density, but it sacrifices the magnetic stability, making it difficult to balance high-speed writing and data retention. These problems jointly restrict the actual write efficiency, reliability, and device integration of SOT-MRAM. SUMMARY

[0008] Therefore, the present application provides a SOT-MRAM device with high spin transport efficiency and a preparation method thereof, aiming to solve one or more of the above technical problems, thereby improving the spin transport efficiency of the SOT-MRAM device.

[0009] In a first aspect, the present application provides a SOT-MRAM device with high spin transport efficiency, comprising: a spin-orbit coupling layer, an insertion layer, and a magnetic tunnel junction stacked in sequence; wherein the insertion layer is a two-dimensional material layer.

[0010] Optionally, the insertion layer comprises a plurality of two-dimensional material layers stacked in sequence.

[0011] Optionally, when the insertion layer comprises a single two-dimensional material layer, the thickness of the insertion layer is 0.3 nm to 0.7 nm.

[0012] Optionally, when the insertion layer comprises a plurality of two-dimensional material layers, the thickness of the insertion layer is 1 nm to 5 nm.

[0013] Optionally, the two-dimensional material adopted by the two-dimensional material layer comprises: Any one of graphene, transition metal dichalcogenide, black phosphorus, MXenes, black graphene oxide, tungsten diselenide, sulfur dioxide, two-dimensional boron nitride, indium sulfide, two-dimensional molybdenum diselenide, and two-dimensional titanium nitride.

[0014] Optionally, the magnetic injection layer comprises a heavy metal material layer.

[0015] Optionally, the heavy metal material layer comprises any one of a Pt layer and a Ta layer.

[0016] Optionally, the magnetic tunnel junction comprises a magnetic free layer, a barrier layer, and a magnetic fixed layer, which are sequentially stacked on the insertion layer.

[0017] In a second aspect, the present application provides a preparation method of an SOT-MRAM device with high spin transport efficiency, comprising: preparing a spin orbit coupling layer; forming an insertion layer on the spin orbit coupling layer; wherein the insertion layer is a two-dimensional material layer; forming a magnetic tunnel junction on the insertion layer.

[0018] Optionally, the step of forming the insertion layer on the spin orbit coupling layer comprises: providing a two-dimensional material; adopting a two-dimensional transfer platform to transfer the two-dimensional material layer to the surface of the spin orbit coupling layer as the insertion layer through a dry transfer process.

[0019] The technical method provided by the present application has at least the following beneficial effects: The present application provides an SOT-MRAM device, an insertion layer is formed between the spin orbit coupling layer and the magnetic tunnel junction, and the insertion layer is a two-dimensional material layer. The unexpected technical effect is: First, the interface between the spin orbit coupling layer and the magnetic tunnel junction is regulated by the two-dimensional material, and the interface defect state is reduced.

[0020] The thickness of the two-dimensional material layer is very uniform (usually only one to several atomic layers), which makes them maintain very good interface flatness when in contact with other materials (such as a heavy metal layer). The improvement of the interface flatness can reduce the irregularity and defects of atomic arrangement, reduce the scattering caused by irregular atomic structure, and thus reduce the number of interface defect states, thereby improving the spin injection efficiency by reducing the number of defect states of the interface of the spin orbit coupling layer.

[0021] Secondly, the high surface energy and chemical stability of two-dimensional materials prevent interfacial oxidation.

[0022] Two-dimensional materials typically possess high surface energy, enabling them to form strong chemical bonds with metal layers (i.e., spin-orbit coupling layers and magnetic tunnel junctions). Graphene, for example, exhibits very strong carbon-carbon bonds and high chemical stability. When two-dimensional materials are inserted into the metal / magnetic layer interface, they effectively reduce oxidation or chemical reactions at the interface, thereby suppressing defect formation caused by interface oxidation and improving spin injection efficiency.

[0023] Third, spin transport efficiency can be controlled by spin-orbit coupling of two-dimensional materials.

[0024] Strong spin-orbit coupling in two-dimensional materials can modulate the injection and transport efficiency of spin currents at interfaces. By optimizing the characteristics of spin-orbit coupling, two-dimensional materials can enable efficient spin transport at interfaces, reducing spin loss and improving injection efficiency. In particular, with the help of two-dimensional material layers with strong spin-orbit coupling, spin polarization and transport at interfaces can be enhanced, avoiding interference from interface defects and stray charges. Furthermore, because two-dimensional materials typically possess long spin relaxation times (e.g., in graphene, the electron spin retention time is extremely long), they can effectively transport spin current and prevent spin scattering and decoherence. In contrast, traditional metal interfaces often suffer from spin current loss due to interface defects, impurities, and poor spin conductivity. The long spin retention time of two-dimensional materials effectively reduces spin scattering at the interface with the metal layer. This helps improve the injection efficiency of spin current and avoids spin decoherence caused by stray charges and interface defects.

[0025] Fourth, two-dimensional materials are beneficial for reducing the influence of interface defect states and stray charges.

[0026] Two-dimensional materials possess strong charge transfer capabilities, enabling the modulation of magnetic layers and their properties through interfacial charge reconstruction. Interactions between heavy metal layers. The unique electronic structure of two-dimensional materials can effectively modulate the electron distribution between the metal and magnetic layers, avoiding charge concentration or stray phenomena and reducing the influence of interface defect states. By adjusting the charge distribution, two-dimensional materials can reduce the interference of stray charges at the interface on spin current. This charge reconstruction helps stabilize the interface electronic state, reducing local electric field fluctuations caused by interface charge inhomogeneity, thereby mitigating the scattering loss of spin current.

[0027] Two-dimensional material layers can effectively passivate interface defects through their surface chemical properties. These materials often have low defect density and high chemical stability, and can avoid charge trapping caused by defects by chemically reacting with defect atoms (such as oxygen or metal ions) at the interface.

[0028] Due to the ability of two-dimensional materials to effectively passivate interface defects, the scattering effect of defects on electrons and spin current is reduced. This reduces the spin current de-coherence rate, allowing spin information to be more stably maintained during transmission, thereby improving the efficiency of spin injection.

[0029] The fifth, two-dimensional material insertion layer can solve the problem of magnetic stability and data retention caused by thinning the magnetic layer (magnetic free layer).

[0030] Enhance magnetic stability: Through exchange coupling and exchange bias effect, two-dimensional materials help to increase the reversal energy barrier of the magnetic layer, enhancing its thermal stability.

[0031] Improve spin injection efficiency: Due to its excellent spin transport characteristics, two-dimensional materials can effectively reduce interface scattering and spin de-coherence, improving the efficiency of spin current injection.

[0032] Reduce thermal effects: Through its high thermal conductivity, two-dimensional materials can effectively disperse heat, reducing the impact of thermal fluctuations on the magnetic layer, thereby improving data retention capability.

[0033] Through the above aspects, by introducing two-dimensional materials as an insertion layer, the influence of interface defect states and stray charges can be effectively adjusted, and the injection and transport efficiency of spin current can be improved. The atomic-level flatness, high surface energy and chemical stability of two-dimensional materials can reduce the generation of interface defects; the strong spin-orbit coupling effect improves the transmission efficiency of spin current; at the same time, the charge reconstruction and defect passivation further reduce the interference of stray charges and defects on the interface to the spin current. Therefore, two-dimensional materials not only optimize the spin injection efficiency, but also effectively improve the stability of data storage. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0035] Figure 1 A structure schematic diagram of an SOT-MRAM device provided by the related art.

[0036] Figure 2 A structure schematic diagram of an SOT-MRAM device provided by an embodiment of the present application.

[0037] Figure 3 A preparation method flowchart of an SOT-MRAM device provided by an embodiment of the present application.

[0038] Figure 4 A result graph of the spin Hall effect of the structure provided by an embodiment of the present application. A result graph of the spin Hall effect of the structure provided by an embodiment of the present application.

[0039] Figure 5 A result graph of the spin Hall effect of the structure provided by an embodiment of the present application. A result graph of the spin Hall effect of the structure provided by an embodiment of the present application.

[0040] Figure 6 A result graph of the spin Hall effect of the structure provided by an embodiment of the present application. A result graph of the spin Hall effect of the structure provided by an embodiment of the present application.

[0041] Figure 7 A result graph of the spin Hall effect of the structure provided by an embodiment of the present application. A result graph of the spin Hall effect of the structure provided by an embodiment of the present application. A result graph of the spin Hall effect of the structure provided by an embodiment of the present application.

[0042] Figure 8 A result graph of the spin Hall effect of the structure provided by an embodiment of the present application. A result graph of the spin Hall effect of the structure provided by an embodiment of the present application.

[0043] The reference signs are as follows: 11: spin orbit coupling layer; 12: magnetic tunnel junction; 121: magnetic free layer; 122: potential barrier layer; 123: magnetic fixed layer; 13: bottom electrode; 14: top electrode; 15: insertion layer. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0045] Related definition explanations: Lattice mismatch: lattice mismatch refers to the inconsistency of the lattice structures of two materials (such as CoFeB (magnetic free layer) and heavy metal material (spin orbit coupling layer)) at the atomic scale. Even if their lattice constants (the side length of a unit lattice) are similar, the arrangement, direction and shape of the lattice may deviate.

[0046] The impact of lattice mismatch on spin transport efficiency: Spin current injection depends on electron transport and spin retention capabilities. When the spin current passes through the interface of a spin-orbit coupling layer (heavy metal) / magnetically free layer (magnetic metal layer), electrons need to cross this interface into the other material. This process is affected by lattice matching. When the lattice structure is mismatched (lattice fit is poor), the electron propagation path at the interface is perturbed, leading to enhanced electron scattering. Especially near the interface, the momentum direction of electrons may be disrupted, resulting in spin loss and affecting spin transport efficiency. Due to lattice mismatch, electron scattering is more intense, especially in the laterally propagating spin direction. Scattering not only affects electron charge transport but also disrupts their spin states, leading to spin current loss and further affecting spin transport efficiency.

[0047] Scattering mechanism: Scattering refers to the process by which electrons interact with lattice defects, impurities, and other electrons, changing their propagation direction and momentum.

[0048] There are two main scattering mechanisms: elastic scattering and inelastic scattering.

[0049] Elastic scattering: Elastic scattering does not change the energy of the electron, but it may change its propagation direction. During swirling injection, elastic scattering causes electrons to deviate in direction, leading to spin randomization. This is because, during scattering, the electron's spin direction may no longer align with its direction of motion, resulting in the decay of the spin current.

[0050] Inelastic scattering: Inelastic scattering not only changes the direction of electrons but can also alter their energy. For example, the interaction of electrons with phonons or other excited states can lead to a change in spin direction. This change has a more pronounced effect on spin current than elastic scattering because inelastic scattering increases the dissipation of spin current, resulting in greater spin loss.

[0051] Different types of scattering can cause spin loss during the injection of spin flow, especially near the interface between the spin-orbit coupling layer and the magnetic free layer, where this effect is more pronounced. Scattering enhances the spin randomization process, leading to losses in the spin flow.

[0052] Interfacial oxidation: Interfacial oxidation refers to the oxidation that occurs at the interface when a metal comes into contact with air or other oxygen sources. Oxide layer. The oxide layer alters the electrical conductivity, magnetism, and electron movement of metallic materials.

[0053] Oxides are typically nonmagnetic, and their crystal structure differs from that of the original metallic material. Oxide layers The presence of this element causes additional scattering of electrons as they cross the interface. This scattering typically causes the electron's spin to scatter in random directions, losing its original spin polarization direction.

[0054] The conductivity of the oxide layer is generally low, so the speed of electron flow is affected. This difference in conductivity can make the interaction between electrons in the oxide layer and the metal layer more complex, further exacerbating the loss of spin current.

[0055] The formation of the oxide layer changes the electronic structure of the interface. Due to the shift of the electronic band produced by the oxide layer, the injection and propagation process of electrons is disturbed, resulting in the loss of spin.

[0056] The oxide layer not only causes scattering of electrons, but also can reduce the spin injection efficiency of the metal / heavy metal interface. Oxidation makes the interface more complex, leading to attenuation of the spin current.

[0057] Lattice mismatch causes strong scattering of electrons during the spin current injection process, causing the spin current to lose polarization during injection. The scattering mechanism (especially elastic and inelastic scattering) increases the randomization of electrons, destroying the directionality of the spin current, thus exacerbating spin loss. Interface oxidation reduces the spin current injection efficiency by changing the propagation and scattering mechanisms of electrons, especially between the oxide layer and the metal / heavy metal interface. The above factors work together to cause strong loss of spin current at the metal / heavy metal interface, resulting in poor spin transport efficiency from the spin orbit coupling layer to the magnetic free layer.

[0058] Figure 2 A high spin transport efficiency SOT-MRAM device is provided for an embodiment of the present application. Referring to Figure 2 , comprising: a spin orbit coupling layer 11, an insertion layer 15, and a magnetic tunnel junction 12 stacked in sequence; Wherein, the insertion layer 15 is a two-dimensional material layer.

[0059] In one example, the spin orbit coupling layer 11 includes a heavy metal material layer.

[0060] In one example, the heavy metal material layer includes any one of a Pt layer, a Ta layer.

[0061] In one example, the magnetic tunnel junction 12 includes a magnetic free layer 121, a barrier layer 122, and a magnetic fixed layer 123 stacked in sequence on the insertion layer 15.

[0062] In one example, the magnetic free layer 121 is a magnetic material layer, which can be a ferromagnetic alloy, a ferrimagnetic material, etc.

[0063] As an example, the ferromagnetic alloy includes but is not limited to CoFeB (cobalt iron boron), Co / Pt or Co / Pd multilayer film, FePt (iron platinum alloy), etc.

[0064] As an example, ferrimagnetic materials include, but are not limited to, (Tb / Co)n multilayer films or TbCo alloys.

[0065] As an example, the ferromagnetic material layer may include, but is not limited to, .

[0066] For example, magnetic free layer 121 is .

[0067] As an example, the thickness of the magnetic free layer 121 is 20 nm to 80 nm.

[0068] For example, the thickness of the magnetic free layer 121 is 40 nm.

[0069] It should be noted that the thickness of the magnetic free layer 121 varies depending on the magnetic material used. Those skilled in the art can set the thickness of the magnetic free layer according to the material of the magnetic free layer as needed.

[0070] In one example, the barrier layer 122 can be an MgO layer.

[0071] As an example, the thickness of barrier layer 122 is 0.5 nm to 3 nm.

[0072] In one example, the magnetically fixed layer 123 is a layer of magnetic material. The magnetically fixed layer 123 needs to maintain a fixed magnetization direction, typically achieved through a "pinning" technique. The material needs to be matched with the magnetically free layer 121 to optimize tunnel magnetoresistance (TMR).

[0073] It should be noted that the working principle of the SOT-MRAM device provided in this application is as follows: When the write current ( When electrons flow through the spin-orbit coupling layer (SOC layer) 11, a spin Hall effect occurs, causing the electron spin to deflect in the vertical direction and generating a transverse spin current. Spin current () A spin-orbit torque (SOT) is generated by injecting a magnetization into the adjacent free magnetic layer 121, driving the magnetization to flip. The free magnetic layer 121 is used to store data, and its magnetization direction (parallel or antiparallel to the magnetically fixed layer 123) determines its storage state ("0" or "1"). The barrier layer 122 is used to form a magnetic tunnel junction to enable data reading. The magnetically fixed layer 123 provides a reference magnetization direction (its magnetization direction is fixed) and is used to compare the magnetic moments with the free magnetic layer 121 for resistance detection.

[0074] In one example, the SOT-MRAM device also includes: The bottom electrode 13 is used for writing (i.e., providing write current), and the top electrode 14 is used for reading (i.e., measuring the resistance of the magnetic tunnel junction).

[0075] It should be noted that the bottom electrode 13 is responsible for converting current into spin current, and the material thereof needs to meet three requirements of high spin Hall angle (θSH)

[0076] In an example, the bottom electrode 13 can be a heavy metal single-layer structure or a laminated metal composite structure.

[0077] It should be noted that the heavy metal single-layer structure refers to that the bottom electrode includes a single-layer heavy metal layer.

[0078] As an example, the material of the single-layer heavy metal layer adopted by the bottom electrode can be tungsten (W), tantalum (Ta) and the like.

[0079] It should be noted that the laminated metal composite structure refers to that the bottom electrode can be formed by stacking multiple metal layers.

[0080] As an example, the laminated metal composite structure adopted by the bottom electrode can be Ta / W / Ta or Ta / W / Ta / W. .

[0081] indicates a multilayer structure of tungsten (W) and tantalum (Ta) periodically stacked, indicates a stacking period of tungsten (W) and tantalum (Ta), which is generally an odd number of layers, for example, 3 layers, 5 layers, etc.

[0082] It should be noted that the top electrode 14 needs to provide low contact resistance, oxidation resistance and magnetic shielding protection functions, and the material selection is mainly inert metal.

[0083] In an example, the top electrode 14 can be a Ta / Ru double-layer structure or a composite top electrode.

[0084] As an example, the composite top electrode can be a Ta / Ru / Ta composite structure.

[0085] In an example, the insertion layer 15 can include a single-layer two-dimensional material layer or a laminated multilayer two-dimensional material layer. When the insertion layer 15 includes a multilayer two-dimensional material layer, any two two-dimensional material layers in the multilayer two-dimensional material layer can be the same or different two-dimensional materials.

[0086] In an example, when the insertion layer 15 includes a single-layer two-dimensional material layer, the thickness of the insertion layer is 0.3 nm to 0.7 nm.

[0087] For example, when the insertion layer 15 includes a single-layer two-dimensional material layer, the thickness of the insertion layer is 0.4 nm.

[0088] ​In another example, the thickness of the insertion layer 15 is 1 nm to 5 nm when the insertion layer 15 includes a plurality of layers of two-dimensional material.

[0089] For example, the thickness of the insertion layer 15 is 3 nm when the insertion layer 15 includes a plurality of layers of two-dimensional material.

[0090] In one example, the two-dimensional material employed by the two-dimensional material layer includes any one of: graphene, transition metal dichalcogenide, black phosphorus, MXenes, reduced graphene oxide (RGO), tungsten diselenide (WS2), ), sulfur dioxide (SO2), ), two-dimensional boron nitride (h-BN), ), indium sulfide (InS), ), two-dimensional molybdenum diselenide (MoSe2), ), two-dimensional titanium nitride (TiN), ).

[0091] For example, the material employed by the two-dimensional material layer is graphene.

[0092] It should be noted that transition metal dichalcogenide (TMD) is a kind of two-dimensional material with layered structure, and the chemical general formula can be represented as . Among them, represents a transition metal, represents a chalcogen element.

[0093] As an example, the transition metal may include but is not limited to metals such as Mo, W, etc.

[0094] For example, the transition metal may represent Mo.

[0095] As an example, the chalcogen element may include but is not limited to elements such as S, Se, Te, etc.

[0096] For example, the chalcogen element may represent S. Then the transition metal dichalcogenide (TMD) can be represented as .

[0097] It should be noted that MXenes represent two-dimensional transition metal carbide, nitride or carbonitride. The chemical general formula of MXenes can be represented as . Among them, represents a transition metal, represents carbon (C) or nitrogen (N), represents a surface functional group.

[0098] As an example, the transition metal It can include, but is not limited to, metals such as Mo and W.

[0099] For example, transition metals It can represent Mo.

[0100] As an example, The surface functional groups represented may include, but are not limited to, -OH, -O, -F, and -Cl.

[0101] Figure 3 This is a flowchart illustrating the fabrication method of an SOT-MRAM device according to an embodiment of this application. See also... Figure 3 ,include: S101, Prepare the spin-orbit coupling layer.

[0102] In one example, step S101 includes: The first step is to provide a substrate.

[0103] As an example, the substrate is a silicon substrate with 300nm silicon oxide deposited on its surface (that is, a Si substrate with SiO2 deposited on its surface), and the size of the substrate is 5mm*5mm (the area of ​​the growth surface).

[0104] The second step is to form a spin-orbit coupling layer on the substrate surface.

[0105] The spin-orbit coupling layer was deposited using a magnetron sputtering system. In a high vacuum environment of Pa, Pt target material was bombarded with Ar ions, and the substrate was sputtered at a pressure of 2 mtorr. Furthermore, after the spin-orbit coupling layer was sputtered, it was etched using photolithography and reactive ion etching to form the bottom electrode.

[0106] The material used in the spin-orbit coupling layer has been described in the preceding introduction and will not be repeated here.

[0107] In one example, the spin-orbit coupling layer can be fabricated using magnetron sputtering.

[0108] In addition, after the spin-orbit coupling layer is sputtered, the spin-orbit coupling layer is etched by photolithography and reactive ion etching to form the bottom electrode.

[0109] S102. An insertion layer is formed on the spin-orbit coupling layer; wherein the insertion layer is a two-dimensional material layer.

[0110] In one example, step S102 includes: The first step is to provide two-dimensional materials.

[0111] In one example, the two-dimensional material can be a purchased finished two-dimensional material.

[0112] It should be noted that the two-dimensional material can also be prepared, and the preparation process of the two-dimensional material can be a chemical vapor deposition (CVD) process.

[0113] Secondly, the two-dimensional material layer is transferred to the surface of the spin-orbit coupling layer by a dry transfer process through a two-dimensional transfer platform, as an insertion layer.

[0114] The specific operation method is as follows: First, polydimethylsiloxane (PDMS) is pasted to a glass slide, then a small piece of two-dimensional material is taken out and placed on the tape, and repeatedly folded several times until there is no obvious granular; then the PDMS on the glass slide is aligned with the two-dimensional material on the tape, and is gently pasted, and the tape is quickly torn, and the PDMS with the two-dimensional material is obtained; then the PDMS with the two-dimensional material is aligned to the spin-orbit coupling layer through the two-dimensional transfer platform, the height is adjusted until the PDMS is pressed onto the surface of the spin-orbit coupling layer, then the heating table is opened, and is heated at 90° for 5 minutes; at this time, the PDMS loses adhesion after heating, the two-dimensional material falls off from the PDMS, and is stuck to the surface of the spin-orbit coupling layer; finally, the glass slide is gently lifted to separate the PDMS and the glass slide, and the insertion layer is formed on the surface of the spin-orbit coupling layer. (This process is carried out in a glove box environment, and different two-dimensional materials have slightly different heating temperatures and times due to their own characteristics) S103, forming a magnetic tunnel junction on the insertion layer.

[0115] In one example, step S103 includes: First, a magnetic free layer is made on the surface of the insertion layer.

[0116] As an example, the magnetic free layer is formed by sputtering using a magnetron sputtering process.

[0117] The preparation process and material of the magnetic free layer belong to the prior art. Herein, the present application will not be described.

[0118] Secondly, a barrier layer is made on the surface of the magnetic free layer.

[0119] As an example, the magnetic fixed layer is formed by sputtering using a magnetron sputtering process.

[0120] The preparation process and material of the barrier layer belong to the prior art. Herein, the present application will not be described.

[0121] Thirdly, a magnetic fixed layer is made on the surface of the barrier layer to obtain a magnetic tunnel junction.

[0122] As an example, the magnetic fixed layer is formed by sputtering using a magnetron sputtering process.

[0123] The preparation process and material of the magnetic fixed layer belong to the prior art. Herein, the present application will not be described.

[0124] Fourthly, a top electrode is made on the magnetic tunnel junction.

[0125] The top electrode can be obtained by etching the magnetic fixed layer.

[0126] To further explore the performance of the insertion layer in improving spin Hall efficiency, the following verification experiment is performed on a heavy metal layer / two-dimensional material layer (insertion layer) / magnetic material layer (magnetic free layer) structure: Step 1: Provide a comparative structure.

[0127] The comparative structure provided in the experiment is a heavy metal layer / two-dimensional material layer (insertion layer) / magnetic material layer (magnetic free layer) structure and a heavy metal layer / magnetic material layer (magnetic free layer) structure.

[0128] The heavy metal layer / two-dimensional material layer (insertion layer) / magnetic material layer (magnetic free layer) structure is a stack of (Note: indicates graphene (two-dimensional material)) The heavy metal layer / magnetic material layer (magnetic free layer) structure is structure.

[0129] Step 2: Test the performance of the comparative structure.

[0130] To verify the superior performance of the structure constructed by the present application in terms of spin-orbit torque effect and spin current injection efficiency, a turn angle second harmonic Hall measurement method is used to systematically test the structure. This test injects a low-frequency sinusoidal alternating current into the structure, and uses a lock-in amplifier to accurately extract the second harmonic component in the Hall voltage, thereby realizing the separation and quantitative analysis of the damping-like and field-like spin-orbit torques.

[0131] The experimental device includes a current source, a lock-in amplifier, an electromagnet, and a magnetic field control system, which can apply a constant amplitude and direction-adjustable external magnetic field, and realize continuous scanning in the polar or azimuthal angle range through precise rotation. During the test, the magnetic field is parallel to the z-axis direction, parallel to the initial position of the sample, and parallel to the current direction, and the sample rotates around the xy direction in a fixed magnetic field, with an angle from the initial position of 0° to 360°. By measuring the second harmonic Hall voltage response curve at different angles and combining with the angle-dependent signal fitting, the key parameters such as interface spin injection efficiency and spin Hall angle can be accurately obtained.

[0132] Please refer to Figure 4 , Figure 4 describes the second harmonic test results (second harmonic voltage of the structure under a current of 1.2 mA and a magnetic field of 5T~8T (Diagram showing the relationship between angles).

[0133] The electric field-induced spin-orbit torque behavior was studied using the harmonic Hall effect measurement method. In the experiment, the second harmonic Hall voltage was measured. And the following fitting formula was used for analysis:

[0134] By studying different magnetic field angles The data was fitted to extract the coefficients of the damped spin-orbit torque. (damping torque generated in the y-direction), etc. Value using formula By fitting, we can obtain (Effective field value generated by damping torque in the corresponding direction).

[0135] Please see Figure 5 , for the basis Figure 4 The damped spin orbit torque obtained by fitting in the y-direction The value, Then it means The value of .

[0136] Please see Figure 6 , for the basis Figure 5 The schematic diagram obtained by fitting the data in the diagram.

[0137] The spin Hall effect was further calculated using the following formula:

[0138] in, It is the saturation magnetization of the ferromagnetic layer. It is the thickness of the ferromagnetic layer. It is an effective field of equivalent damping generated by current excitation. It is the applied current density.

[0139] Please see Figure 7 The effective field values ​​obtained by fitting calculations under different currents (1.2mA, 1.6mA, 2.0mA) are... .

[0140] Please see Figure 8 , where is the value of the spin Hall efficiency obtained by fitting calculation under different currents (1.2mA, 1.6mA, 2.0mA).

[0141] After substituting the fitting results into the above formula, we obtain... The spin Hall efficiency of the damped spin orbital moment in the structure is approximately 0.09~0.12. The spin Hall efficiency of the damping type spin-orbit torque in the structure is about 0.5-0.6. Therefore, the efficiency achieved by the method proposed in the application is 4-5 times that of the traditional structure. The test fully proves that the spin transport efficiency can be effectively improved by optimizing the heavy metal interface structure through the two-dimensional material as an insertion layer.

[0142] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A SOT-MRAM device with high spin transport efficiency, characterized in that, The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The insertion layer is a two-dimensional material layer. The insertion layer comprises a plurality of two-dimensional material layers.

2. The SOT-MRAM device of claim 1, wherein, When the insertion layer comprises a single two-dimensional material layer, the thickness of the insertion layer is 0.3nm-0.7nm.

3. The SOT-MRAM device of claim 1, wherein, When the insertion layer comprises a plurality of two-dimensional material layers, the thickness of the insertion layer is 1nm-5nm.

4. The SOT-MRAM device of claim 1, wherein, The two-dimensional material used in the two-dimensional material layer comprises any one of the following:

5. The SOT-MRAM device of claim 1, wherein, Graphene, transition metal disulfide, black phosphorus, MXenes, black graphene oxide, tungsten diselenide, sulfur dioxide, two-dimensional boron nitride, indium sulfide, two-dimensional molybdenum diselenide, two-dimensional titanium nitride. The magnetic injection layer comprises a heavy metal material layer.

6. The SOT-MRAM device of any one of claims 1 to 5, wherein, The heavy metal material layer comprises any one of a Pt layer and a Ta layer.

7. The high spin transfer efficiency SOT-MRAM device of claim 6, wherein, The magnetic tunnel junction comprises a magnetic free layer, a barrier layer and a magnetic fixed layer which are sequentially stacked on the insertion layer.

8. The SOT-MRAM device of any one of claims 1 to 5, wherein, The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction.

9. A method for manufacturing a SOT-MRAM device with high spin transport efficiency, characterized in that, The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction.

10. The method of claim 9, wherein the method further comprises: The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application relates to a spin-orbit coupling layer, an insertion layer and a magnetic tunnel junction. The application

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