Flexible device and method for manufacturing same, and flexible spintronic device

Abstract

The present application discloses a flexible device and a method for manufacturing same, and a spintronic device. The flexible device comprises a flexible substrate, and a two-dimensional van der waals ferromagnetic material layer provided on a surface of the flexible substrate, wherein the two-dimensional van der waals ferromagnetic material layer is provided with a skyrmion lattice. By integrating the two-dimensional van der waals ferromagnetic material layer provided with the skyrmion lattice onto the flexible substrate, the present application realizes the compatibility between the magnetic material and the flexible substrate. The flexible device of the present application not only has good magnetic properties, but also has excellent mechanical flexibility.

Description

Flexible device, method of making the same, and flexible spintronic device TECHNICAL FIELD

[0001] The present application belongs to the field of flexible spintronic devices. Specifically, the present application relates to a flexible device, a method of making the same, and a flexible spintronic device. BACKGROUND

[0002] Spintronic devices, as an emerging electronic technology, utilize the spin polarization characteristics of electrons rather than traditional charge to achieve information storage and processing. This technology opens up a new path distinct from traditional electronic devices, bringing new possibilities for performance improvement and energy consumption reduction of electronic devices. Spintronic devices can complete data writing under extremely small or zero external magnetic field conditions through spin polarization transport in ferromagnetic / non-ferromagnetic multilayer structures, spin-orbit torque (SOT) or spin-transfer torque (STT), etc. Spintronic devices can also stabilize magnetic skyrmions by Dzyaloshinskii Moriya interaction (DMI) induced by strong spin-orbit coupling (SOC), thereby realizing high-density, low-energy logic and storage operations. Even, spintronic devices can form pure spin current with no charge transport by exciting and propagating spin waves (magnons), which is used for low-energy interconnection and processing of information. The core advantage of spintronic devices is that they can significantly reduce energy consumption while maintaining high performance, which is of great significance in meeting the growing demand for high-performance, low-power devices.

[0003] Despite the significant progress made in the research of spintronic devices, the existing technology still faces some challenges. Most traditional magnetic materials exist in a hard form, which is incompatible with the mechanical flexibility required by flexible devices. Hard magnetic materials are limited in spin transport and magnetic domain wall movement, making it difficult to achieve efficient information storage and processing. In addition, three-dimensional ferromagnetic materials are restricted in their application at the nanoscale due to their volume and lattice structure. These limiting factors seriously hinder the widespread application of spintronic devices in flexible electronic devices, such as wearable devices, flexible displays, and flexible sensors.

[0004] With the rapid development of flexible electronic technology, there is an increasing demand for flexible spintronic devices. Flexible spintronic devices not only need to have excellent magnetic properties, but also need to have good mechanical flexibility and durability to adapt to various complex use environments and mechanical deformations. However, the hard characteristics of most magnetic materials are in significant conflict with the requirements of flexible devices, which makes it a current problem to be solved to develop a flexible device that can both maintain mechanical flexibility and enhance magnetic properties. In addition, existing preparation methods often require the introduction of current or voltage, which not only increases energy consumption, but also can have a negative impact on the long-term stability and reliability of the device.

[0005] Magnetic Skyrmion is a nanoscale magnetic domain structure with a topological vortex-like magnetic moment configuration, with a topological charge Q = ± 1. In the exploration of new magnetic storage and computing media, magnetic Skyrmion is expected to break through the superparamagnetic physical limit of traditional magnetic storage media, reduce the energy consumption of reading and writing, and thus become a new generation of high-density, high-speed and low-energy information storage and computing unit due to its topological protection and nanoscale characteristics that can be driven and controlled by low current density.

[0006] Although magnetic Skyrmion shows revolutionary potential in terms of storage density and energy consumption, it is difficult for traditional three-dimensional ferromagnetic materials to stably generate Skyrmion lattice on a flexible substrate. The main reasons are as follows:

[0007] Lack of mechanical compatibility: the rigidity of bulk ferromagnetic materials (such as CoFeB) does not match the deformation of flexible substrates, leading to the annihilation of Skyrmions under strain;

[0008] Current dependence: existing Skyrmion generation techniques rely on current injection, which generates Joule heat and limits flexible scene applications;

[0009] Poor room temperature stability: the Curie temperature of most Skyrmion materials is lower than 300K, which cannot meet the requirements of room temperature devices.

[0010] Therefore, it is urgent to develop a construction scheme for a Skyrmion flexible device that has flexibility adaptation, current-free driving and room temperature stability.

[0011] SUMMARY

[0012] The purpose of the present application is to provide a flexible Skyrmion device that can operate at room temperature and is free of current driving, and has good magnetic properties and mechanical flexibility, and a preparation method thereof, to solve the problems of mechanical mismatch between three-dimensional ferromagnetic materials and flexible substrates, dependence of traditional Skyrmion generation on high-energy consumption current injection, and insufficient room temperature magnetic stability in the prior art.

[0013] The inventors of the present application have found through extensive literature research and experimental research that:

[0014] When the material layer is subjected to 0.4%-1.2% strain on the flexible substrate, the increased Dzyaloshinskii-Moriya interaction reduces the energy barrier of skyrmion nucleation without the need for current injection.

[0015] Meanwhile, the application of a lower (e.g. 300-500 Oe) vertical magnetic field can significantly reduce the skyrmion nucleation energy barrier, promote the nucleation and ordered arrangement of skyrmions, and thus complete the application.

[0016] Based on the above findings, the first aspect of the application provides a flexible device comprising a flexible substrate and a two-dimensional van der Waals ferromagnetic material layer disposed on the surface of the flexible substrate, the two-dimensional van der Waals ferromagnetic material layer having a skyrmion lattice.

[0017] The application achieves the compatibility of magnetic materials with flexible substrates by integrating a two-dimensional van der Waals ferromagnetic material layer having a skyrmion lattice on a flexible substrate. The flexible device of the application not only has good magnetic properties, but also has excellent mechanical flexibility.

[0018] In some embodiments, the two-dimensional van der Waals ferromagnetic material layer has a skyrmion lattice with |Ψ6| greater than 0.65. The greater the bond orientation parameter |Ψ6|, the more the skyrmion lattice tends to be a perfect hexagonal ordered arrangement, the fewer the defects, and the stronger the overall stability. This highly ordered arrangement directly translates into higher signal-to-noise ratio, lower bit error rate, and longer data retention time, thereby improving storage density, logic operation reliability, and device lifetime.

[0019] In some embodiments, the material of the two-dimensional van der Waals ferromagnetic material layer satisfies the chemical formula Fe a Ga b Te2, where a is 3-4 and b is 0.8-1.2. The Fe a Ga b Te2 (a is 3-4 and b is 0.8-1.2) crystal has a two-dimensional van der Waals structure, and its Curie temperature (330K-367K) is higher than room temperature, i.e. the ferromagnetic material crystal exhibits magnetism at room temperature. At the same time, the ferromagnetic material is stacked by van der Waals force, has good mechanical properties and flexibility, and can be compatible with flexible substrates.

[0020] In some embodiments, the flexible substrate is composed of at least one selected from polyethylene terephthalate, polyethylene naphthalate, and polyimide. In the application, the selection of the appropriate material of the flexible substrate can increase the flexibility and durability of the flexible device.

[0021] In some embodiments, the flexible substrate has a thickness of 10 pm to 500 pm. In the present application, the thickness of the flexible substrate is selected to provide mechanical flexibility and lightness.

[0022] In some embodiments, the two-dimensional van der Waals ferromagnetic material layer has a thickness of 100 nm to 500 nm. In the present application, the thickness of the two-dimensional van der Waals ferromagnetic material layer is selected to improve the magnetic properties and response speed of the two-dimensional van der Waals ferromagnetic material, and to improve the storage density and reduce the heat effect.

[0023] In the second aspect of the present application, a method for preparing a flexible device is provided, which comprises the following steps: annealing a two-dimensional van der Waals ferromagnetic material layer to obtain an annealed two-dimensional van der Waals ferromagnetic material layer; the annealing temperature is 40°C to 60°C, and the annealing time is 5 min to 20 min; transferring the annealed two-dimensional van der Waals ferromagnetic material layer to the surface of a flexible substrate; applying stress to the flexible substrate to deform the annealed two-dimensional van der Waals ferromagnetic material layer to make the two-dimensional van der Waals ferromagnetic material layer have a skyrmion lattice, thereby obtaining the flexible device. In the present application, the annealing temperature and time are selected to optimize the crystal structure of the ferromagnetic material and provide conditions for the formation of skyrmions. The method for preparing the flexible device of the present application is efficient, does not require the introduction of current or voltage, and has low energy consumption.

[0024] In some embodiments, the method of the present application further comprises applying a magnetic field to the annealed two-dimensional van der Waals ferromagnetic material layer. In the present application, a magnetic field is applied to the two-dimensional van der Waals ferromagnetic material layer during the formation of skyrmions, which can promote the nucleation and ordered arrangement of skyrmions.

[0025] In some embodiments, the magnetic field has a magnetic field strength of 0 to 1000 Oe, preferably 100 to 800 Oe, and more preferably 100 to 400 Oe. If the magnetic field strength is too large, it can cause the skyrmion lattice to be unstable. In some embodiments, the stress includes at least one of tensile stress, bending stress, and torsional stress. In the present application, various stress application methods are provided to provide different deformation paths for the formation of skyrmion lattices.

[0026] In some embodiments, the two-dimensional van der Waals ferromagnetic material layer has a strain of 0.4% to 1.2%. In the present application, when the two-dimensional van der Waals ferromagnetic material layer has a strain of 0.4% to 1.2%, the two-dimensional van der Waals ferromagnetic material layer has a skyrmion lattice.

[0027] In some embodiments, the two-dimensional van der Waals ferromagnetic material layer is obtained by mechanical exfoliation. In this invention, the two-dimensional ferromagnetic material layer can be obtained from a bulk ferromagnetic material crystal by mechanical exfoliation, while maintaining the uniformity and integrity of the two-dimensional ferromagnetic material layer.

[0028] In a third aspect, this application provides a flexible spintronic device, which includes the flexible device of this invention, or a flexible device prepared by the method of this invention. The flexible spintronic device of this invention combines the characteristics of flexible devices with the applications of spintronics, providing new possibilities for applications in fields such as storage, logic operations, and quantum computing.

[0029] The present invention has the following beneficial effects:

[0030] 1. High storage density

[0031] Advantages of skyrmion lattices: Skyrmions are topologically stable magnetic structures with small dimensions, enabling the storage of more information in a smaller area. Therefore, the formation of skyrmion lattices in two-dimensional van der Waals ferromagnetic material layers can realize high-density data storage in flexible devices.

[0032] Specifically, compared to traditional magnetic storage technologies, skyrmion lattices can operate at higher storage densities, significantly improving data storage efficiency.

[0033] 2. Low energy consumption

[0034] No current or voltage required: The fabrication method of this invention does not require the introduction of current or voltage to form a skyrmion lattice, significantly reducing energy consumption. Traditional skyrmion manipulation methods typically require the application of spin polarization current, which leads to Joule heating, increasing energy consumption and potentially negatively impacting the long-term stability of the device.

[0035] Magnetic field-assisted nucleation: By applying a magnetic field, the nucleation energy barrier of skyrmions can be further reduced, making skyrmion formation more efficient and further reducing energy consumption.

[0036] 3. High stability

[0037] Non-volatile characteristics: Skymint lattices are non-volatile, maintaining their magnetic structure even after power loss, thus improving the long-term stability and security of data.

[0038] Mechanical stability: By strain-induced formation of a skyrmion lattice, skyrmions maintain a good magnetic structure under different mechanical deformations (such as tension, bending, and torsion) and external conditions. Experiments show that after multiple tension, bending, and torsion tests, the skyrmion lattice state remains unchanged, demonstrating good mechanical stability.

[0039] 4. Good mechanical flexibility

[0040] Flexible substrate material: The material selection of the flexible substrate (such as polyethylene terephthalate, polyethylene naphthalate, polyimide, etc.) has good toughness and strength, can withstand certain mechanical deformation without damage, and at the same time maintains dimensional stability.

[0041] Two-dimensional van der Waals ferromagnetic material layer: The two-dimensional van der Waals ferromagnetic material layer is stacked by van der Waals force, has good mechanical properties and flexibility, and is compatible with the flexible substrate, further enhancing the overall flexibility of the flexible device.

[0042] 5. Efficient preparation method

[0043] Annealing treatment: Through low-temperature annealing treatment, the crystal structure of the ferromagnetic material is optimized to provide conditions for the formation of skyrmions. This treatment method is simple and efficient, and does not require complex equipment.

[0044] Stress induction: By applying stress (tensile stress, bending stress, torsional stress, etc.), the generation and manipulation of skyrmions are realized without introducing current, further improving the preparation efficiency and device performance.

[0045] 6. Wide application prospect

[0046] Spintronic device: The flexible device of the present application combines the mechanical flexibility of the flexible substrate and the excellent magnetic properties of the two-dimensional van der Waals ferromagnetic material layer, providing new possibilities for the application of spintronic devices in storage, logic operation, and quantum computing, etc.

[0047] Flexible electronic equipment: The flexible device is suitable for various flexible electronic equipment, such as wearable devices, flexible display screens, and flexible sensors, etc., which can significantly improve the performance and functionality of these devices.

[0048] In summary, the present application integrates a two-dimensional van der Waals ferromagnetic material layer with a skyrmion lattice on a flexible substrate, realizing the compatibility of magnetic materials with flexible substrates, with significant advantages such as high storage density, low energy consumption, high stability, and good mechanical flexibility. Its efficient preparation method and wide application prospect provide important technical support for the development and application of flexible spintronic devices.

[0049] Brief description of the accompanying drawings

[0050] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings in which:

[0051] Figure 1 is a graph showing the relationship between the 2D peak position of single-layer graphene and the strain of Fe3GaTe2 in one specific embodiment of the present application.

[0052] Figure 2 is a dynamic process diagram of the magnetic domain structure of the Fe3GaTe2 layer in Example 1 of the present application as a function of the strain amount;

[0053] Figure 3 is a transport property curve diagram of Fe3GaTe2 in Example 1 of the present application;

[0054] Figure 4 is a tensile test diagram of the flexible device in Example 1 of the present application;

[0055] Figure 5 is a state diagram of the skyrmion lattice after 1000 and 2000 times of stretching, respectively, of the flexible device in Example 1 of the present application;

[0056] Figure 6 is a bending test diagram of the flexible device in Example 1 of the present application;

[0057] Figure 7 is a state diagram of the skyrmion lattice after 1000 and 2000 times of bending, respectively, of the flexible device in Example 1 of the present application;

[0058] Figure 8 is a torsion test diagram of the flexible device in Example 1 of the present application;

[0059] Figure 9 is a state diagram of the skyrmion lattice after 1000 and 2000 times of torsion, respectively, of the flexible device in Example 1 of the present application;

[0060] Figure 10 is a dynamic process diagram of the magnetic domain structure of the Fe3GaTe2 layer in Example 2 of the present application as a function of the strain amount;

[0061] Figure 11 is a dynamic process diagram of the magnetic domain structure of the Fe3GaTe2 layer in Example 3 of the present application as a function of the strain amount;

[0062] Figure 12 is a dynamic process diagram of the magnetic domain structure of the Fe3GaTe2 layer in Comparative Example 1 of the present application as a function of the strain amount;

[0063] Figure 13 is a dynamic process diagram of the magnetic domain structure of the Fe3GaTe2 layer in Comparative Example 2 of the present application as a function of the strain amount.

[0064] Best Mode for Carrying Out the Invention

[0065] Hereinafter, specific embodiments of the flexible device of the present application, a method of manufacturing the same, and a flexible spintronic device will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed descriptions are omitted. For example, there will be cases where detailed descriptions of matters that are well known, repetitive descriptions of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0066] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0067] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0068] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0069] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise stated, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0070] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0071] In the research of flexible spintronic devices, magnetic materials play a core role. It not only plays a role in realizing non-volatile storage of information, but also involves advanced applications such as logic operation and quantum computing. However, most of the current magnetic materials exist in a hard form, which is incompatible with the mechanical flexibility characteristics required by flexible devices, limiting the application of flexible devices in flexible spintronic devices. Therefore, developing a flexible device that can not only maintain mechanical flexibility but also enhance magnetic performance has become a problem to be solved.

[0072] In the first aspect of the present application, the present application provides a flexible device, which comprises a flexible substrate, and a two-dimensional van der Waals ferromagnetic material layer arranged on the surface of the flexible substrate, and the two-dimensional van der Waals ferromagnetic material layer has a skyrmion lattice.

[0073] Due to the limitations of volume and lattice structure, three-dimensional ferromagnetic materials are subject to many limitations in spin transport and domain wall movement. In contrast, two-dimensional van der Waals ferromagnetic materials construct a layered or thin film structure at the nanoscale, making the electronic spin degree of freedom more easily controllable and the magnetic domain wall movement more efficient, thereby realizing the improvement of magnetic and electronic transport performance. In addition, two-dimensional van der Waals materials exhibit good mechanical performance and flexibility due to their atomic-level thickness and the characteristics of interlayer stacking through van der Waals forces, which enhances the compatibility of two-dimensional van der Waals ferromagnetic materials with flexible substrates.

[0074] Skyrmions are a kind of topologically stable magnetic structure that can exist and remain stable at room temperature. The skyrmion lattice in the two-dimensional van der Waals ferromagnetic material layer can store more information in a smaller area due to the small size of the skyrmions, thereby realizing high-density data storage of the flexible device. Compared with traditional magnetic storage technology, skyrmions can be manipulated by a smaller current or local magnetic field, so their manipulation requires only low energy consumption. At the same time, the non-volatile feature of the skyrmion lattice allows it to maintain its state after power failure, significantly improving the long-term stability and security of the data. Therefore, the two-dimensional van der Waals ferromagnetic material layer with a skyrmion lattice can replace traditional storage units to manufacture non-volatile magnetic memories with high storage density, low power consumption and high stability.

[0075] In summary, the present application integrates a two-dimensional van der Waals ferromagnetic material layer with a skyrmion lattice on a flexible substrate, realizing the compatibility of magnetic materials with flexible substrates. The flexible device of the present application not only has good magnetic performance, but also has excellent mechanical flexibility.

[0076] In some embodiments, the material of the two-dimensional van der Waals ferromagnetic material layer satisfies the chemical formula Fe a Ga b Te2, wherein a is 3-4, b is 0.8-1.2. The Fe aGa b Te2(a is 3-4, b is 0.8-1.2) crystal has a two-dimensional van der Waals structure, and its Curie temperature (330K-367K) is higher than room temperature, that is, the ferromagnetic material crystal exhibits magnetism at room temperature. At the same time, the ferromagnetic material is stacked by van der Waals force, has good mechanical properties and flexibility, and can be compatible with flexible substrates.

[0077] Taking Fe3GaTe2 as an example, its Curie temperature is about 336K, so Fe3GaTe2 can maintain its ferromagnetic properties at room temperature.

[0078] In some embodiments, the flexible substrate is composed of at least one selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and polyimide (PI). PET, PEN and PI have good toughness and strength, so that the flexible substrate can withstand certain mechanical deformation without breaking; at the same time, these materials have good dimensional stability. Therefore, selecting a suitable flexible substrate material can increase the flexibility and durability of the flexible device.

[0079] In some embodiments, the thickness of the flexible substrate is 10-500μm. Selecting a suitable thickness of the flexible substrate can make the flexible substrate have mechanical flexibility and lightness. For example, the thickness of the flexible substrate can be 10μm, 20μm, 50μm, 100μm, 200μm, 300μm, 400μm or 500μm.

[0080] In some embodiments, the thickness of the two-dimensional van der Waals ferromagnetic material layer is 100-500nm. Selecting a suitable thickness of the two-dimensional van der Waals ferromagnetic material layer can improve the magnetic properties and response speed of the two-dimensional van der Waals ferromagnetic material, as well as improve its storage density and reduce its thermal effect. For example, the thickness of the two-dimensional van der Waals ferromagnetic material layer can be 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm.

[0081] As a carrier of information storage and processing, the core advantage of skyrmion lies in its unique topological stability and nanoscale size. In order to effectively manipulate skyrmions, precise external stimuli are needed to induce the generation or disappearance of skyrmions. At present, skyrmions are mainly regulated by applying spin-polarized current, but the application of current inevitably causes Joule heat in the material, which not only leads to a large amount of energy dissipation, but also may have a negative impact on the long-term stability and reliability of flexible devices.

[0082] Therefore, the second aspect of the present application provides a method for preparing a flexible device, comprising the following steps: annealing a two-dimensional van der Waals ferromagnetic material layer to obtain an annealed two-dimensional van der Waals ferromagnetic material layer; the annealing temperature is 40-60°C, and the annealing time is 5-20 min; transferring the annealed two-dimensional van der Waals ferromagnetic material layer to the surface of a flexible substrate; and applying stress to the flexible substrate to make the annealed two-dimensional van der Waals ferromagnetic material layer deform so that the two-dimensional van der Waals ferromagnetic material layer has a skyrmion lattice, thereby obtaining the flexible device.

[0083] First, the two-dimensional van der Waals ferromagnetic material layer is subjected to low-temperature annealing. Low-temperature annealing can cause the surface structure of the two-dimensional van der Waals ferromagnetic material to deform, locally break the inversion symmetry of the material system, and regulate the local magnetic anisotropy and DMI, thereby providing conditions for the formation of skyrmions. Second, stress is applied to the flexible substrate, and the flexible substrate deforms, and the deformation is transmitted to the annealed two-dimensional van der Waals ferromagnetic material layer, so that the two-dimensional van der Waals ferromagnetic material layer deforms. The deformation of the two-dimensional van der Waals ferromagnetic material layer induces the appearance of a skyrmion lattice. Through the application of stress, the two-dimensional van der Waals ferromagnetic material layer realizes the generation and manipulation of skyrmions without applying an electric current. This method alleviates energy dissipation caused by Joule heat and reduces the operating power consumption of the flexible device. In addition, the strain-induced skyrmion lattice exhibits stability and uniformity, improving its storage density and read-write speed.

[0084] The method for preparing the flexible device of the present application is efficient and does not require the introduction of an electric current or voltage, resulting in less energy loss.

[0085] As an example, the annealing temperature can be 40°C, 45°C, 50°C, 55°C, or 60°C.

[0086] As an example, the annealing time can be 5 min, 7 min, 9 min, 11 min, 13 min, 15 min, 17 min, or 20 min.

[0087] In some embodiments, the method of the present application further comprises applying a magnetic field to the annealed two-dimensional van der Waals ferromagnetic material layer. The application of a magnetic field during the formation of skyrmions can promote the nucleation and ordered arrangement of skyrmions.

[0088] In some embodiments, the magnetic field strength is 0-1000 Oe, preferably 100-800 Oe, and more preferably 100-400 Oe. The energy barrier of the deformed two-dimensional van der Waals ferromagnetic material layer is reduced, and a magnetic field strength of 300 Oe is sufficient to make it evolve from the initial strip-shaped magnetic domain to a skyrmion lattice and remain stable.

[0089] As an example, the magnetic field strength is 200 Oe, 300 Oe, 400 Oe, 500 Oe, 600 Oe, 700 Oe, 800 Oe, 900 Oe, 1000 Oe.

[0090] In some embodiments, the stress includes at least one of tensile stress, bending stress, torsional stress. The diversified stress application provides different deformation paths to form the skyrmion lattice.

[0091] In some embodiments, the strain of the two-dimensional van der Waals ferromagnetic material layer is 0.4%-1.2%. When the strain of the two-dimensional van der Waals ferromagnetic material layer reaches 0.4%-1.2%, it has a desired skyrmion lattice. For example, the strain can be 0.4%, 0.6%, 0.8%, 1.0% or 1.2%.

[0092] In some embodiments, the formation of the skyrmion lattice is observed using a magnetic force microscope or a magneto-optical Kerr microscope.

[0093] In some embodiments, the strain of the two-dimensional van der Waals ferromagnetic material is calibrated by the shift of the single-layer graphene 2D peak. The magnetic force microscope can directly observe the formation of skyrmions in the ferromagnetic material, providing direct evidence for confirming the existence and distribution of skyrmions. However, the magnetic force microscope does not provide quantitative information about the strain required to generate skyrmions. Given that the formation and stability of skyrmions are closely related to the strain, and there is a known linear relationship between the 2D Raman peak shift of single-layer graphene and the strain it bears, the strain size applied to the material can be quantitatively analyzed by monitoring the 2D peak shift of single-layer graphene. This method not only provides a key parameter for regulating the formation of skyrmions, but also regulates the stability of skyrmions.

[0094] Specifically, taking the ferromagnetic material Fe3GaTe2 as an example, although graphene and Fe3GaTe2 are two different materials with different physical and chemical properties, graphene can closely adhere to the surface of Fe3GaTe2 due to its good conformability. When Fe3GaTe2 deforms, the strain is transmitted to graphene, causing it to also deform, thereby changing the lattice parameters of graphene. The change in the lattice of graphene can be monitored by Raman spectroscopy, thereby obtaining the relationship between the 2D peak position of graphene and the applied strain. Since the strain experienced by graphene is consistent with the strain of Fe3GaTe2, the degree of deformation of Fe3GaTe2 can be indirectly determined by measuring the shift of the 2D peak of graphene. As shown in FIG. 1, the 2D peak position of single-layer graphene has a linear relationship with the strain of Fe3GaTe2. Therefore, the shift of the single-layer graphene 2D peak can be used as an indirect means to monitor and calibrate the deformation of Fe3GaTe2.

[0095] In some embodiments, the two-dimensional van der Waals ferromagnetic material layer is obtained by a mechanical exfoliation method. The two-dimensional ferromagnetic material layer can be obtained from a bulk ferromagnetic material crystal by a mechanical exfoliation method, maintaining the uniformity and integrity of the two-dimensional ferromagnetic material layer.

[0096] Taking the ferromagnetic material Fe3GaTe2 as an example, the steps of the mechanical exfoliation method are as follows: selecting Fe3GaTe2 crystal as the starting material; attaching a tape or a polydimethylsiloxane (PDMS) film on the surface of the Fe3GaTe2 crystal, and using the adhesion of the tape or the viscoelasticity of the PDMS film to exfoliate the two-dimensional material layer.

[0097] The third aspect of the present application provides a flexible spintronic device, which comprises the flexible device of the present application, or comprises the flexible device prepared by the preparation method of the present application. The flexible spintronic device combines the characteristics of the flexible device and the application of spintronics, providing new possibilities for the application in the fields of storage, logic operation and quantum computing.

[0098] The scheme of the present application is described below through specific examples. It should be noted that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. If the specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0099] The algorithm is used to identify the skyrmions in the observed phase MFM image, the Voronoi diagram enables the skyrmions sharing the edge of the Voronoi unit to be defined as adjacent skyrmions, and the local orientation order parameter-bond orientational parameter (|Ψ6|) of each skyrmion is calculated according to the following formula to further quantify the phase state. When the numerical value is closer to 1, it represents the solid phase (order); when it is close to 0, it represents the liquid phase (disorder).

[0100] Where N is the number of adjacent skyrmions, θ j represents the included angle formed by the center of the central skyrmion and the center of its jth adjacent skyrmion, and the summation operation covers all adjacent particles.

[0101] By averaging the |Ψ6| values of all skyrmions in the image, a quasi-global measure of the order of the skyrmion lattice is obtained.

[0102] Example 1

[0103] A flexible device comprises a flexible substrate polyethylene terephthalate (PET), and a two-dimensional van der Waals ferromagnetic material Fe3GaTe2 layer disposed on the surface of the PET, the Fe3GaTe2 layer having a skyrmion lattice; wherein the thickness of the Fe3GaTe2 layer is 280 nm, and the thickness of the flexible substrate is 300 μm.

[0104] The specific preparation process is as follows:

[0105] (1) The Fe3GaTe2 single crystal is subjected to peeling treatment using a blue adhesive tape dedicated to mechanical peeling, to obtain a Fe3GaTe2 layer; the Fe3GaTe2 layer is adhered to the surface of a polydimethylsiloxane (PDMS) adhesive film;

[0106] (2) The other side of the PDMS adhesive film is adhered to a glass sheet, and the glass sheet with the Fe3GaTe2 layer and the PDMS adhesive film is placed on a heating table and heated at 50°C for 10 min; after heating, the glass sheet is naturally cooled to room temperature;

[0107] (3) The Fe3GaTe2 layer is transferred to the surface of a PET flexible substrate;

[0108] (4) The PET flexible substrate is fixed on a stress table; a tensile stress is applied to the PET flexible substrate, so that the PET flexible substrate is deformed; the deformation of the PET flexible substrate is transmitted to the Fe3GaTe2 layer, so that the Fe3GaTe2 layer is deformed;

[0109] (5) The Fe3GaTe2 layer is scanned multiple times using a 300 Oe magnetic field strength probe of a magnetic force microscope (MFM); when the magnetic force microscope scanning observes that the Fe3GaTe2 generates a skyrmion lattice, the application of the tensile stress is stopped, and at this time the deformation amount of the Fe3GaTe2 layer is 0.80% (Fig. 2k).

[0110] Performance test:

[0111] a. Skyrmion stability test

[0112] The dynamic process diagram of the magnetic domain structure of the Fe3GaTe2 layer in this embodiment changes with the strain is shown in Fig. 2. Specifically as follows:

[0113] As shown in Fig. 2a, when the Fe3GaTe2 layer is not stretched, its magnetic domain structure is in a strip shape.

[0114] As shown in Fig. 2b, the magnetic probe scanning of the Fe3GaTe2 layer is started, and its magnetic domain structure starts to change.

[0115] As shown in FIG. 2(c-k), as the strain amount of the Fe3GaTe2 layer increases, the disordered magnetic domain structure gradually transforms into a uniform and regular lattice state. When the strain amount reaches 0.80% (FIG. 2k), the Fe3GaTe2 layer forms a uniform and regular skyrmion lattice state. At this time, the Fe3GaTe2 layer has a skyrmion lattice with a bond orientation parameter |Ψ6| = 0.80.

[0116] As shown in FIG. 2(l-m), after the strain on the Fe3GaTe2 layer is released, the strain amount is re-applied to 0.80%, and the Fe3GaTe2 layer remains in the skyrmion lattice state.

[0117] As shown in FIG. 2(n-o), after the Fe3GaTe2 layer is subjected to erasing treatment in a magnetic field of 4000 Oe while maintaining the strain amount of 0.80%, the magnetic domain structure of the Fe3GaTe2 layer returns to the stripe state, but after being scanned by a magnetic probe, the magnetic domain structure of the Fe3GaTe2 layer returns to the skyrmion lattice state again.

[0118] Therefore, as shown in FIG. 2, the Fe3GaTe2 layer processed by the present application can form a skyrmion lattice, and once the skyrmion is induced by strain, the skyrmion will stably exist.

[0119] b. Transport properties of Fe3GaTe2

[0120] The transport properties of the flexible device of Example 1 are plotted, and the transport property curve of the Fe3GaTe2 layer is shown in FIG. 3. FIG. 3 shows the topological Hall resistivity R T xy With the increase or decrease of the applied magnetic field, there is a significant difference peak in the low field region, which indicates the existence of a significant topological Hall effect component, and also proves the existence of the topological spin configuration skyrmion in the Fe3GaTe2 layer.

[0121] Example 2

[0122] Example 2 differs from Example 1 in that the annealing temperature is different, and the annealing temperature is 40°C. The dynamic process diagram of the magnetic domain structure of the Fe3GaTe2 layer in this embodiment with the change of the strain amount is shown in FIG. 10. Specifically as follows:

[0123] As shown in FIG. 10a, the magnetic domain structure of the Fe3GaTe2 layer is in a strip shape when the Fe3GaTe2 layer is not stretched.

[0124] As shown in FIG. 10(b-i), as the strain amount of the Fe3GaTe2layer increases, the disordered magnetic domain structure of the Fe3GaTe2layer gradually transforms into an ordered lattice state. When the strain amount reaches 1.00% (FIG. 10i), the Fe3GaTe2layer forms a skyrmion lattice state. At this time, the Fe3GaTe2layer has a skyrmion lattice with a bond orientation parameter |Ψ6| = 0.70.

[0125] As shown in FIG. 10(j-l), after the strain of the Fe3GaTe2layer is released, the strain amount is re-applied to 1.00% (FIG. 10k), the Fe3GaTe2layer remains in the skyrmion lattice state, and the strain amount continues to increase to 1.50% (FIG. 10l), the Fe3GaTe2layer continues to remain in the skyrmion lattice state.

[0126] Therefore, as shown in FIG. 10, the Fe3GaTe2layer processed by the method of the present application can form a skyrmion lattice, and once the skyrmion is induced by the strain, the skyrmion will stably exist.

[0127] The comparison between FIG. 10 and FIG. 2 shows that the higher the annealing temperature applied to the Fe3GaTe2layer, the more likely it is to successfully form a skyrmion under a lower deformation condition.

[0128] Example 3

[0129] The difference between Example 3 and Example 1 is the annealing temperature and the thickness of the Fe3GaTe2layer. In Example 3, the annealing temperature is set to 60°C, and the thickness of the Fe3GaTe2layer is 130 nm. The dynamic process of the magnetic domain structure of the Fe3GaTe2layer in this embodiment changes with the strain amount, as shown in FIG. 11, and is as follows:

[0130] As shown in FIG. 11a, when the Fe3GaTe2layer is not stretched, its magnetic domain structure presents a skyrmion lattice state with a bond orientation parameter |Ψ6| = 0.41. Compared with Example 1, the Fe3GaTe2layer in Example 3 is thinner and the annealing temperature is higher. Therefore, during the preparation of a flexible device, even a small strain is enough to change the magnetic domain structure of the Fe3GaTe2layer.

[0131] As shown in FIG. 11(b-c), as the strain amount of the Fe3GaTe2layer increases, its magnetic domain structure gradually transforms into a skyrmion lattice state with uniform size and regular arrangement, at which time the bond orientation parameter |Ψ6| reaches 0.75.

[0132] The comparison between FIG. 11 and FIG. 2 shows that the higher the annealing temperature applied to the Fe3GaTe2layer and the thinner the Fe3GaTe2layer, the more likely it is to successfully form a skyrmion under a lower deformation condition.

[0133] Example 4

[0134] Flexibility device stability test

[0135] The flexibility device of Example 1 was subjected to a stability test, and multiple stretching, bending, and twisting tests were performed using a tensile and torsion test system.

[0136] The stability test procedure was as follows:

[0137] 1. A long strip-shaped flexibility device was selected;

[0138] 2. The flexibility device was mounted on a dedicated test fixture to ensure stable installation of the flexibility device; and the flexibility device was subjected to multiple stretching forces using a tensile testing machine;

[0139] 3. A new flexibility device was mounted on a dedicated test fixture to ensure stable installation of the flexibility device; and the flexibility device was subjected to repeated bending;

[0140] 4. A new flexibility device was mounted on a dedicated test fixture to ensure stable installation of the flexibility device; and the flexibility device was subjected to repeated twisting.

[0141] The stability test results of Example 1 are shown in FIGS. 4 to 9. After 1000 and 2000 times of stretching, 1000 and 2000 times of bending, and 1000 and 2000 times of twisting tests, the Sagnac lattice state of the Fe3GaTe2 layer did not change, which indicates that the Sagnac lattice of the Fe3GaTe2 layer in Example 1 has good stability.

[0142] Comparative Example 1

[0143] Comparative Example 1 differs from Example 1 in that the annealing temperature is 30°C. When the annealing temperature is 30°C, the strain of the Fe3GaTe2 layer increases from 0 to 1.2%, and no Sagnac lattice is detected in the Fe3GaTe2 layer. As the strain of the Fe3GaTe2 layer continues to increase, no Sagnac lattice is detected in the Fe3GaTe2 layer.

[0144] Comparative Example 2

[0145] Comparative Example 2 differs from Example 1 in that the annealing temperature is 70°C. When the annealing temperature is 70°C, the strain of the Fe3GaTe2 layer increases from 0 to 1.2%, and no Sagnac lattice is detected in the Fe3GaTe2 layer. As the strain of the Fe3GaTe2 layer continues to increase, no Sagnac lattice is detected in the Fe3GaTe2 layer.

[0146] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art, without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A flexible device, characterized in that, The flexible device comprises a flexible substrate, and a two-dimensional van der Waals ferromagnetic material layer disposed on a surface of the flexible substrate, wherein the two-dimensional van der Waals ferromagnetic material layer has a skyrmion lattice.

2. The flexible device of claim 1, wherein, The material of the two-dimensional van der Waals ferromagnetic material layer satisfies the chemical formula Fe a Ga b Te2, wherein a is 3-4, and b is 0.8-1.2; Preferably, the two-dimensional van der Waals ferromagnetic material layer has a skyrmion lattice with a bond orientation parameter |Ψ6| greater than 0.

65.

3. The flexible device according to claim 1 or 2, wherein, The flexible substrate is composed of at least one selected from polyethylene terephthalate, polyethylene naphthalate and polyimide.

4. The flexible device of claim 1 or 2, wherein, The thickness of the flexible substrate is 10 μm-500 μm; and / or, The thickness of the two-dimensional van der Waals ferromagnetic material layer is 100 nm-500 nm.

5. A method for preparing the flexible device of any one of claims 1-4, comprising the following steps: annealing the two-dimensional van der Waals ferromagnetic material layer to obtain an annealed two-dimensional van der Waals ferromagnetic material layer; the annealing temperature is 40-60°C, and the annealing time is 5-20 min; transferring the annealed two-dimensional van der Waals ferromagnetic material layer to a surface of a flexible substrate; applying stress to the flexible substrate to deform the annealed two-dimensional van der Waals ferromagnetic material layer so that the two-dimensional van der Waals ferromagnetic material layer has a skyrmion lattice, to obtain the flexible device.

6. The method of claim 5, further comprising applying a magnetic field to the annealed two-dimensional van der Waals ferromagnetic material layer. Preferably, the magnetic field strength of the magnetic field is 0-1000 Oe.

7. The method of claim 5 or 6, wherein, The stress comprises at least one of tensile stress, bending stress and torsional stress.

8. The method of claim 5 or 6, wherein, The strain of the two-dimensional van der Waals ferromagnetic material layer is 0.4%-1.2%.

9. The method of claim 5 or 6, wherein, The two-dimensional van der Waals ferromagnetic material layer is obtained by a mechanical exfoliation method.

10. A flexible spintronic device comprising the flexible device of any one of claims 1-4, or comprising a flexible device prepared by the method of any one of claims 5-9.

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