Method for regulating and controlling magnetic anisotropy of Cr-based MXene material through charges

Abstract

The invention discloses a method for regulating and controlling magnetic anisotropy of a Cr-based MXene material through charges. The method comprises the following steps: synthesizing an MAX precursor; the MAX precursor is subjected to etching and stripping, and a single-layer Cr-based MXene nanosheet is obtained; on the basis of a single-layer Cr-based MXene nanosheet, a substrate, an electrode and ionic liquid are used for synthesizing and regulating a Cr-based MXene material charge-doped ionic liquid gate structure. The method has the remarkable effects that the magnetic anisotropy (MAE) of the Cr2TiC2O2 material is improved through charge doping, the magnetic easy axis direction is regulated and controlled, the magnetism and the magnetic phase change can be accurately regulated, the magnetic order temperature of the material is remarkably improved, and the application potential of the material in a high-temperature environment is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of two-dimensional magnetic material regulation, and specifically relates to a method for regulating the magnetic anisotropy of charge-regulated Cr-based MXene materials. Background Art

[0002] In recent years, due to their unique magnetic properties, two-dimensional magnetic materials have shown broad application prospects in the fields of spintronics, magnetic storage, and sensors. Among them, charge doping has been proven to be an effective means of regulating magnetism, which can adjust properties including magnetic arrangement, critical temperature, etc. [Science, 351, 587, 2016], [Nature, 595, 521, 2021], [Acta Phys. Sin., 70, 2021]. Research has shown that by introducing organic cations, changing the electron doping concentration can induce a transition of two-dimensional magnetic materials from the antiferromagnetic state to the ferromagnetic state [Adv. Funct. Mater., 32, 2112750, 2022]. In the Cr2Ge2Te6 material, charge doping can significantly increase the Curie temperature of two-dimensional magnetic materials [Molecules, 28, 2023].

[0003] Cr-based MXene (such as Cr2TiC2O2) is a new type of high-spin-polarized two-dimensional magnetic material [Matter, 1, 1304, 2019]. Due to its special structure, its magnetism is easily regulated by external factors. Previous studies on the magnetism of these materials have achieved some meaningful results [ACS Nano, 13, 2831, 2019], [Nanoscale, 11, 356, 2019]. However, there are still few studies on the regulation of magnetic anisotropy at present, mainly relying on external magnetic fields, interface coupling, or strain, etc. [ACS Nano, 13, 2831, 2019].

[0004] In the prior art, the magnetic regulation of magnetic two-dimensional MXene and other materials mainly relies on external magnetic fields, electric fields, interface coupling, and chemical doping, etc. However, there are still some problems at present: one is that the magnetic anisotropy energy (MAE) is relatively low, which limits its application in high-temperature environments or spintronic devices; the second is the lack of a systematic magnetic anisotropy regulation strategy, and the main research focuses on the intrinsic magnetism of materials, while there is less discussion on the methods for regulating magnetic anisotropy; the third is that as a more direct, controllable, and non-destructive regulation method, the influence of charge doping on the magnetic anisotropy of Cr2TiC2O2 has not been fully studied.

[0005] Therefore, how to regulate the magnetic anisotropy of Cr2TiC2O2 by charge doping and optimize magnetic regulation is still a problem to be solved at present. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for charge regulating the magnetic anisotropy of Cr-based MXene materials. This method can enhance the magnetic anisotropy energy (MAE) of Cr2TiC2O2 and regulate the direction of the magnetic easy axis through charge doping, enabling lossless charge regulation, effectively avoiding lattice distortion and defect states, improving the stability and service life of devices, and providing new technical support for the design of spintronics, magnetic storage, and high-temperature magnetic materials.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for charge regulating the magnetic anisotropy of Cr-based MXene materials, which is characterized in that it includes the following steps:

[0009] Step 1: Synthesize the MAX precursor;

[0010] Step 2: Etch and exfoliate the MAX precursor to obtain single-layer Cr-based MXene nanosheets;

[0011] Step 3: Based on the single-layer Cr-based MXene nanosheets, use a substrate, an electrode, and an ionic liquid to synthesize an ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material.

[0012] Furthermore, the synthesis of the MAX precursor in Step 1 includes the following steps:

[0013] Step 1.1: Ball-mill and mix Cr powder, Ti powder, Al powder, and graphite powder in proportion;

[0014] Step 1.2: Cold-press the mixed powder into a block and sinter it under inert gas protection to form a dense MAX precursor.

[0015] Furthermore, in Step 1.1, the molar ratio of Cr powder, Ti powder, Al powder, and graphite powder is 2:1:1:2, and the ball-milling and mixing are carried out under inert gas protection.

[0016] Furthermore, in Step 1.2, the temperature for sintering the block is 1450 °C, and the sintering duration is 4 hours.

[0017] Furthermore, the etching and exfoliation of the MAX precursor in Step 2 includes the following steps:

[0018] Step 2.1: HF etching: Immerse the MAX precursor in an HF solution and perform ultrasonic treatment at 40 °C for 18 - 24 hours;

[0019] Step 2.2: Centrifugal washing: Centrifugally wash the etched MAX precursor several times with deionized water and then dry it in vacuum;

[0020] Step 2.3, Surface functionalization: Place the dried MAX precursor in a tetramethylammonium hydroxide solution for intercalation reaction to obtain monolayer Cr-based MXene nanosheets.

[0021] Furthermore, the concentration of the HF solution in Step 2.1 is 30%; the rotation speed during centrifugal washing in Step 2.2 is 10,000 rpm, the temperature during vacuum drying is 60 °C, and the duration is 12 hours; the concentration of the tetramethylammonium hydroxide solution in Step 2.3 is 0.5 mol / L, and the duration of the intercalation reaction is 1 hour.

[0022] Furthermore, the ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material in Step 3 includes a substrate layer, a platinum electrode layer, a nanomaterial layer, an ionic liquid layer, and a glass cover slip. The platinum electrode layer is formed on the upper surface of the substrate layer, the Cr-based MXene nanosheets are compounded on the upper surface of the platinum electrode layer to form a nanomaterial layer, an ionic liquid is drop-coated on the nanomaterial layer to form an ionic liquid layer, and a glass cover slip is covered on the ionic liquid layer.

[0023] Furthermore, the synthesis of the ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material in Step 3 includes the following steps:

[0024] Step 3.1, Select high-resistance silicon as the substrate and clean it for standby;

[0025] Step 3.2, Use the substrate as the substrate layer, and select platinum metal as the electrode material to electro-deposit on the substrate layer to form a platinum electrode layer;

[0026] Step 3.3, Compound the Cr-based MXene nanosheets on the platinum electrode layer to form a nanomaterial layer;

[0027] Step 3.4, Select EMIM-BF4 as the ionic liquid, and drop-coat the ionic liquid on the upper surface of the Cr-based MXene nanosheets in a glove box to form the ionic liquid layer;

[0028] Step 3.5, Seal and encapsulate the layered structure with the ionic liquid layer formed, and then cover the glass cover slip with ultraviolet curing glue. After ultraviolet curing, the ionic liquid gate structure for synthesizing and regulating the charge doping of the Cr-based MXene material is obtained.

[0029] Furthermore, the thickness of the substrate in Step 3.1 is 300 nm; during cleaning, acetone and deionized water are used and ultrasonic cleaning is carried out for 15 min, and after cleaning, it is dried with nitrogen.

[0030] Further, before drop-coating the ionic liquid in Step 3.4, the layered structure formed by the base layer, the platinum electrode layer, and the nanomaterial layer is pre-dried in a vacuum environment for 12 hours at a drying temperature of 60°C; in Step 3.5 during UV curing, the wavelength of the UV light is 365 nm and the curing duration is 10 min.

[0031] The remarkable effects of the present invention are as follows:

[0032] 1. Due to its unique layered structure and rich surface effects, the Cr-based MXene material exhibits great research value in multiple aspects such as magnetism, electronic structure, and surface chemistry. By charge doping, the present invention enhances the magnetic anisotropy energy (MAE) of the Cr2TiC2O2 material and regulates the direction of the magnetic easy axis, enabling precise adjustment of magnetism and magnetic phase transition, significantly increasing the magnetic ordering temperature of the material, and broadening its application potential in high-temperature environments.

[0033] 2. By enhancing the perpendicular magnetic anisotropy energy (MAE), the present invention improves the magnetic storage stability and the ability to resist thermal perturbation, increasing the MAE value from 487 μeV to 833 μeV. This can effectively suppress the spontaneous reversal of the magnetic moment caused by thermal fluctuations, ensuring the stability of magnetic storage units (such as MRAM) in high-temperature (100–150°C) or high-frequency (>1 GHz) environments; in addition, the enhancement of perpendicular MAE helps to optimize the perpendicular magnetic tunnel junction; at the same time, the change of the easy magnetization axis from the perpendicular direction to the horizontal direction brings the flexibility of multi-dimensional magnetic regulation. By adjusting the gate voltage polarity (positive / negative voltage), the magnetic anisotropy can be dynamically and reversibly switched, which is suitable for reconfigurable magnetic logic devices. Moreover, the horizontal easy magnetization axis (such as

[100] ) is more suitable for the design of planar magnetic tunnel junctions (MTJs), reducing the device manufacturing complexity (such as eliminating the need for vertical magnetization layer stacking process). In addition, during the ferromagnetic-antiferromagnetic phase transition process, accompanied by the switching of the easy magnetization axis, the magnetoresistance effect (such as GMR / TMR) is significantly enhanced, which can be used for high-sensitivity magnetic sensing or storage units, further expanding the application value of the present invention in the fields of spintronics, magnetic storage, and magnetic sensing. Description of the Drawings

[0034] Figure 1 is a schematic structural diagram of the Cr2TiC2O2 structure;

[0035] Figure 2 is a schematic diagram of 4 magnetic structures existing in the Cr2TiC2O2 structure;

[0036] Figure 3 is a schematic diagram of the change of the energy of 4 magnetic structures and magnetic phase transition of Cr2TiC2O2 during charge doping;

[0037] Figure 4 is a schematic diagram of the change of the MAE value and the change of the direction of the easy magnetization axis of Cr2TiC2O2 during charge doping;

[0038] Figure 5 It is a schematic diagram of the exchange interaction energy and a schematic diagram of the change in the exchange interaction energy of charge doping.

[0039] Figure 6 It is the temperature resistance simulation curve and the temperature resistance bar chart during charge doping.

[0040] Figure 7 It is a schematic diagram of the ionic liquid gate structure for regulating the charge doping of Cr2TiC2O2. Detailed implementation manners

[0041] The following further elaborates in detail on the specific implementation manners and working principles of the present invention in conjunction with the accompanying drawings.

[0042] The present invention provides a method for regulating the magnetic anisotropy of a Cr-based MXene material by charge, and the specific steps are as follows:

[0043] Step 1: Synthesize the MAX precursor.

[0044] Step 2: Etch and exfoliate the MAX precursor to obtain single-layer Cr-based MXene nanosheets.

[0045] Step 3: Based on the single-layer Cr-based MXene nanosheets, use a substrate, an electrode, and an ionic liquid to synthesize an ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material.

[0046] In specific implementation, the synthesis of the MAX precursor in Step 1 includes the following steps:

[0047] Step 1.1: Mix Cr powder, Ti powder, Al powder, and graphite powder in a molar ratio of 2:1:1:2, and perform ball milling under the protection of an inert gas.

[0048] Step 1.2: Cold press the mixed powder into a block, and sinter it under the protection of an inert gas to form a dense MAX precursor. The sintering temperature is 1450 °C, and the sintering duration is 4 hours.

[0049] Specifically, the etching and exfoliation of the MAX precursor in Step 2 includes the following steps:

[0050] Step 2.1: HF etching: Immerse the MAX precursor in a 30% HF solution and perform ultrasonic treatment at 40 °C for 18 - 24 hours.

[0051] Step 2.2: Centrifugal washing: Centrifuge and wash the etched MAX precursor several times with deionized water and then vacuum dry it. The rotation speed during centrifugal washing is 10000 rpm, and the temperature during vacuum drying is 60 °C, and the duration is 12 hours.

[0052] Step 2.3. Surface functionalization: Place the dried MAX precursor in a 0.5 mol / L tetramethylammonium hydroxide solution for an intercalation reaction for 1 hour to obtain monolayer Cr-based MXene nanosheets.

[0053] In the present invention, the steps for synthesizing and regulating the ionic liquid gate structure for charge doping of the Cr-based MXene material in Step 3 are as follows:

[0054] Step 3.1. Select a high-resistance silicon with a thickness of 300 nm as the substrate, clean it and set it aside. When cleaning, use acetone and deionized water and ultrasonically clean for 15 min, and then blow dry with nitrogen after cleaning;

[0055] Step 3.2. Use the substrate as the base layer, and select platinum metal as the electrode material to electro-deposit a platinum electrode layer on the base layer;

[0056] Step 3.3. Composite the Cr-based MXene nanosheets on the platinum electrode layer to form a nanomaterial layer;

[0057] Step 3.4. Pre-dry the layered structure formed by the base layer, the platinum electrode layer and the nanomaterial layer in a vacuum environment for 12 hours, and the drying temperature is 60 °C;

[0058] EMIM-BF4 is used as the ionic liquid. Drop the ionic liquid on the upper surface of the Cr-based MXene nanosheets in a glove box to form the ionic liquid layer;

[0059] Step 3.5. Seal and encapsulate the layered structure with the ionic liquid layer, then cover it with a glass cover slip using ultraviolet curing glue, and obtain the ionic liquid gate structure for synthesizing and regulating the charge doping of the Cr-based MXene material after ultraviolet curing for 10 min. The wavelength of the ultraviolet light used for ultraviolet curing is 365 nm.

[0060] In the specific implementation process, the method of the present invention can achieve the magnetic anisotropy of Cr-based MXene materials such as Cr2TiC2O2, Cr2TiC2F2, Cr2CO2, etc. In order to further illustrate the principle of the present invention, taking the precise adjustment of the magnetic anisotropy of Cr2TiC2O2 by charge regulation as an example, the specific implementation process is as follows:

[0061] Step 1: Synthesize the MAX precursor Cr2TiAlC2. Specifically:

[0062] Step 1.1. Ball-mill and mix 2 mol of Cr powder, 1 mol of Ti powder, 1 mol of Al powder, and 2 mol of graphite powder. When ball-milling and mixing, use high-purity argon for protection, the ball-milling speed is 400 rpm, and the ball-milling and mixing duration is 8 h;

[0063] Step 1.2: Cold press the mixed powder into a block and sinter it under the protection of inert gas to form a dense MAX precursor, i.e., Cr2TiAlC2 block (the structure is as shown in Figure 1 , and the schematic diagram of the magnetic structure is as shown in Figure 2 ). The temperature during sintering is 1450 °C and the sintering duration is 4 hours.

[0064] Step 2: Etch and exfoliate the MAX precursor, i.e., Cr2TiAlC2 block, to obtain single-layer Cr2TiC2O2 nanosheets. Specifically:

[0065] Step 2.1: HF etching: Immerse the MAX precursor in a 30% HF solution and ultrasonically treat it at 40 °C for 20 hours to completely remove the Al layer;

[0066] Step 2.2: Centrifugal washing: Centrifugally wash the etched Cr2TiAlC2 block 5 times with deionized water and then vacuum dry it. The rotation speed during centrifugal washing is 10,000 rpm and pH > 6; the temperature during vacuum drying is 60 °C and the duration is 12 hours;

[0067] Step 2.3: Surface functionalization: Place the dried Cr2TiAlC2 block in a tetramethylammonium hydroxide solution for an intercalation reaction for 1 hour. The concentration of the tetramethylammonium hydroxide solution is 0.5 mol / L to form stable -O terminals and obtain single-layer Cr2TiC2O2 nanosheets.

[0068] Step 3: Based on the single-layer Cr2TiC2O2 nanosheets, use a substrate, electrodes, and ionic liquid to synthesize an ionic liquid gate structure for regulating the charge doping of Cr2TiC2O2 materials. Specifically:

[0069] Step 3.1: Select a high-resistance silicon with a thickness of 300 nm as the substrate, clean it and set it aside. During cleaning, use acetone and deionized water and ultrasonically clean it for 15 min, and then blow it dry with nitrogen after cleaning;

[0070] Step 3.2: Use the substrate as the base layer and select platinum metal as the electrode material to electro-deposit a platinum electrode layer on the base layer;

[0071] Step 3.3: Composite the Cr2TiC2O2 nanosheets on the platinum electrode layer to form a nanomaterial layer;

[0072] Step 3.4: Pre-dry the layered structure formed by the base layer, platinum electrode layer, and nanomaterial layer in a vacuum environment for 12 hours, and the drying temperature is 60 °C;

[0073] Use EMIM-BF4 as the ionic liquid, and drop the ionic liquid on the upper surface of the Cr2TiC2O2 nanosheets in the glove box to form the ionic liquid layer;

[0074] Step 3.5: After hermetically encapsulating the layered structure forming the ionic liquid layer, cover the glass cover slip with an ultraviolet curable adhesive, and after ultraviolet curing for 10 min, obtain the ionic liquid gate structure for regulating the charge doping of the Cr2TiC2O2 material. The wavelength of the ultraviolet light used for ultraviolet curing is 365 nm.

[0075] The structure of the ionic liquid gate structure for regulating the charge doping of the Cr2TiC2O2 material is as Figure 7 shown, and it includes a base layer 1, a platinum electrode layer 2, a nanomaterial layer 3, an ionic liquid layer 4, and a glass cover slip 5. The platinum electrode layer 2 is formed on the upper surface of the base layer 1, the Cr2TiC2O2 nanosheets are compounded on the upper surface of the platinum electrode layer 2 to form the nanomaterial layer 3, the ionic liquid is drop-coated on the nanomaterial layer 3 to form the ionic liquid layer 4, and the glass cover slip 5 is covered on the ionic liquid layer 4.

[0076] Perform an effect test on the synthesized ionic liquid gate structure for regulating the charge doping of the Cr2TiC2O2 material. The test process is as follows: Apply a gate voltage Vg from +1 V to +3 V (step size 0.5 V, stable for 5 min at each step). Additionally, perform negative voltage application (electron doping) and positive voltage application (hole doping) as control groups. When Vg = +2.5 V is applied, a ferromagnetic-antiferromagnetic phase transition occurs, and the easy magnetization axis changes from

[001] to

[100] . When Vg = -3 V needs to be applied, the MAE can be increased from 487 μeV to 833 μeV.

[0077] The test results are as Figures 3 - 6 shown, where Figure 3 shows the changes in the energies of 4 magnetic structures and the magnetic phase changes of the Cr2TiC2O2 material during charge doping; Figure 4 shows the changes in the MAE value and the changes in the direction of the easy magnetization axis of the Cr2TiC2O2 material during charge doping; Figure 5 shows the schematic diagram of the exchange interaction energy of the Cr2TiC2O2 material and the changes in the exchange interaction energy during charge doping; Figure 6 shows the temperature resistance simulation curve and the temperature resistance bar chart of the Cr2TiC2O2 material during charge doping. From Figures 3 - 6It can be seen that when the charge doping concentration reaches 1 e / unit cell, the MAE of Cr2TiC2O2 can be increased from 487 μeV to 833 μeV, and the easy magnetization axis direction is

[001] , significantly enhancing the magnetic stability. When the further hole doping concentration reaches 0.8 e / unit cell, it can induce the transformation of the magnetic easy axis direction from

[001] to

[100] , endowing the material with more excellent magnetic regulation ability. At the same time, charge doping can also enhance the exchange interaction inside the material, causing a ferromagnetic-antiferromagnetic phase transition when the hole concentration is greater than 0.8 e / unit cell, and increasing the magnetic order temperature (Curie temperature / Néel temperature), broadening the application range of Cr-based MXene materials in high-temperature magnetic devices, and enabling it to have better performance under different working conditions.

[0078] It can be seen from this that by charge doping to enhance the magnetic anisotropy (MAE) of Cr2TiC2O2 material and regulate the magnetic easy axis direction, the invention can precisely adjust magnetism and magnetic phase transition, significantly increase the magnetic order temperature of the material, and broaden its application potential in high-temperature environments. By enhancing the magnetic anisotropy energy (MAE) in the vertical direction, the magnetic storage stability and the ability to resist thermal disturbance are improved. The MAE value is increased from 487 μeV to 833 μeV, which can effectively suppress the spontaneous flipping of the magnetic moment caused by thermal fluctuations, ensuring the stability of magnetic storage units (such as MRAM) in high-temperature (100–150 °C) or high-frequency (>1 GHz) environments. In addition, the enhancement of the vertical MAE helps to optimize the vertical magnetic tunnel junction. At the same time, the transformation of the easy magnetization axis from the vertical direction to the horizontal direction brings the flexibility of multi-dimensional magnetic regulation. The magnetic anisotropy can be dynamically and reversibly switched by adjusting the gate voltage polarity (positive / negative voltage), which is suitable for reconfigurable magnetic logic devices. Moreover, the easy magnetization axis in the horizontal direction (such as

[100] ) is more suitable for the design of planar magnetic tunnel junctions (MTJ), reducing the device manufacturing complexity (such as eliminating the need for vertical magnetization layer stacking process). In addition, during the ferromagnetic-antiferromagnetic phase transition, accompanied by the switching of the easy magnetization axis, the magnetoresistance effect (such as GMR / TMR) is significantly enhanced, which can be used for highly sensitive magnetic sensing or storage units, further expanding the application value of the invention in the fields of spintronics, magnetic storage, and magnetic sensing.

[0079] In summary, the invention precisely adjusts the magnetic anisotropy of Cr2TiC2O2 through charge regulation, breaking through the limitations of traditional two-dimensional magnetic material regulation methods, and realizing a more efficient and controllable magnetic regulation method. The main innovation points include:

[0080] The key technical points of the present invention compared with the prior art are to precisely adjust the magnetic anisotropy (MAE) and the direction of the magnetic easy axis of the Cr2TiC2O2 material through the methods of charge doping and charge regulation, and to be able to effectively control the magnetic phase transition. At the same time, by enhancing the magnetic anisotropy energy (MAE) in the vertical direction, the magnetic storage stability and the ability to resist thermal disturbance are improved, and the spontaneous reversal of the magnetic moment caused by thermal fluctuations can be effectively suppressed, ensuring that the magnetic storage unit (such as MRAM) remains stable in a high-temperature (100–150 °C) or high-frequency (>1 GHz) environment. In addition, the enhancement of the vertical MAE helps to optimize the vertical magnetic tunnel junction. At the same time, the change of the easy magnetization axis from the vertical direction to the horizontal direction brings the flexibility of multi-dimensional magnetic regulation. By adjusting the gate voltage polarity (positive / negative voltage), the magnetic anisotropy can be dynamically and reversibly switched, which is applicable to reconfigurable magnetic logic devices. Moreover, the easy magnetization axis in the horizontal direction (such as

[100] ) is more suitable for the design of planar magnetic tunnel junctions (MTJ), reducing the device manufacturing complexity (such as no need for vertical magnetization layer stacking process).

[0081] This method utilizes the charge regulation ability of the ionic liquid gate (ILG) or the double-gate electric field to precisely adjust the electron concentration in the unit cell, which can not only significantly increase the magnetic ordering temperature of the material, but also avoid the lattice distortion and defect states that may be caused by traditional chemical doping, thereby improving the stability and service life of the device.

[0082] Compared with the prior art, the technical solution of the present invention is not a simple replacement or an easily conceivable alternative method. The existing magnetic regulation means mainly rely on chemical doping or external magnetic fields, and these methods may lead to the instability or difficulty in control of the material structure. The present invention provides a brand-new means through a non-destructive charge regulation method, realizing efficient and controllable magnetic regulation and avoiding the disadvantages of traditional methods. Its innovation lies in the flexibility and efficiency of the charge regulation method, which can precisely adjust the magnetism of the material and provide new technical support for the applications in the fields of spintronics, magnetic storage, etc.

[0083] The above has introduced the technical solution provided by the present invention in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for regulating the magnetic anisotropy of a charge-regulated Cr-based MXene material, characterized in that, It includes the following steps: Step 1: Synthesize the MAX precursor; Step 2: Etch and exfoliate the MAX precursor to obtain single-layer Cr-based MXene nanosheets; Step 3: Based on the single-layer Cr-based MXene nanosheets, use a substrate, electrodes, and ionic liquid to synthesize an ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material.

2. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 1, wherein The synthesis of the MAX precursor in Step 1 includes the following steps: Step 1.1: Ball-mill and mix Cr powder, Ti powder, Al powder, and graphite powder in proportion; Step 1.2: Cold-press the mixed powder into a block and sinter it under inert gas protection to form a dense MAX precursor.

3. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 2, wherein In Step 1.1, the molar ratio of Cr powder, Ti powder, Al powder, and graphite powder is 2∶1∶1∶2, and ball-milling and mixing are carried out under inert gas protection.

4. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 2, characterized in that In Step 1.2, the temperature for sintering the block is 1450 °C, and the sintering duration is 4 hours.

5. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 1, wherein The etching and exfoliation of the MAX precursor in Step 2 includes the following steps: Step 2.1: HF etching: Immerse the MAX precursor in an HF solution and perform ultrasonic treatment at 40 °C for 18 - 24 hours; Step 2.2: Centrifugal washing: Centrifugally wash the etched MAX precursor several times with deionized water and then vacuum dry it; Step 2.3: Surface functionalization: Place the dried MAX precursor in a tetramethylammonium hydroxide solution for intercalation reaction to obtain single-layer Cr-based MXene nanosheets.

6. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 5, wherein In Step 2.1, the concentration of the HF solution is 30%; in Step 2.2, the rotation speed during centrifugal washing is 10000 rpm, the temperature during vacuum drying is 60 °C, and the duration is 12 hours; in Step 2.3, the concentration of the tetramethylammonium hydroxide solution is 0.5 mol / L, and the duration of the intercalation reaction is 1 hour.

7. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 1, characterized in that, The synthesis of the ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material in Step 3 includes a substrate layer, a platinum electrode layer, a nanomaterial layer, an ionic liquid layer, and a glass cover slip. The platinum electrode layer is formed on the upper surface of the substrate layer, the Cr-based MXene nanosheets are compounded on the upper surface of the platinum electrode layer to form the nanomaterial layer, an ionic liquid is drop-coated on the nanomaterial layer to form the ionic liquid layer, and a glass cover slip is covered on the ionic liquid layer.

8. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 7, wherein, The synthesis of the ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material in Step 3 includes the following steps: Step 3.1: Select high-resistance silicon as the substrate and clean it for standby; Step 3.2: Use the substrate as the substrate layer and select platinum metal as the electrode material to electro-deposit a platinum electrode layer on the substrate layer; Step 3.3: Compound the Cr-based MXene nanosheets on the platinum electrode layer to form the nanomaterial layer; Step 3.4: Select EMIM-BF4 as the ionic liquid and drop-coat the ionic liquid on the upper surface of the Cr-based MXene nanosheets in a glove box to form the ionic liquid layer; Step 3.5: Seal and package the layered structure with the ionic liquid layer formed, and then cover the glass cover slip with ultraviolet curing glue. After ultraviolet curing, the ionic liquid gate structure for regulating the charge doping of the Cr-based MXene material is obtained.

9. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 7, characterized in that, The thickness of the substrate described in Step 3.1 is 300 nm; during cleaning, acetone and deionized water are used and ultrasonic cleaning is carried out for 15 min, and after cleaning, it is dried with nitrogen.

10. The method for regulating the magnetic anisotropy of the charge-regulated Cr-based MXene material according to claim 7, wherein, Before drop-coating the ionic liquid in Step 3.4, the layered structure formed by the base layer, the platinum electrode layer and the nanomaterial layer is pre-dried in a vacuum environment for 12 hours, and the drying temperature is 60 °C; during ultraviolet curing in Step 3.5, the wavelength of the ultraviolet light is 365 nm, and the curing duration is 10 min.

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