A method for enhancing the Curie temperature of ultra-thin nickel cobalt oxide films

Abstract

This invention discloses a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide thin films, relating to the field of novel functional material processing technology. The method includes the following steps: S1, preparing NiCo2O4 and Co3O4 targets using a ceramic sintering process; S2, depositing NiCo2O4 / Co3O4 thin films on a MgAl2O4(001) single-crystal substrate using magnetron sputtering; S3, measuring the anomalous Hall effect of the grown NiCo2O4 / Co3O4 thin film. The key technical point is that it overcomes the limitations of traditional oxide hard magnetic materials by employing a radio frequency magnetron sputtering process with NiCo2O4 and Co3O4 targets to prepare NiCo2O4 / Co3O4 thin films. The resulting films have a Curie temperature of 380K and excellent conductivity, showing promising application prospects.

Description

Technical Field

[0001] This invention relates to the field of novel functional material processing technology, specifically a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films. Background Technology

[0002] Spinel oxides are a typical representative of transition metal oxide materials. Their crystal structure contains two oxygen coordination structures and two linkage modes, which is beneficial for studying the oxygen coordination mechanism. Spinel oxides are chemically stable and possess advantages such as high hardness, high melting point, wear and corrosion resistance, and excellent thermal conductivity. They have significant research value in fields such as superhard materials, magnetic materials, catalysts, and conductive materials.

[0003] NiCo₂O₄ (NCO), an anti-spinel ferromagnet, is an emerging material due to its unique physical properties, such as perpendicular magnetic anisotropy, excellent metallic conductivity, high spin polarization, and high transition temperature. Furthermore, the physical properties of NCO thin films can be easily tuned by changing growth conditions due to the complex interactions between charge, spin, orbitals, and lattice degrees of freedom. However, when the thickness of NCO films is reduced to a few atomic layers, their room-temperature magnetic and electrical properties decrease, limiting their practical applications. Therefore, there is an urgent need to find a method to increase the Curie temperature (Tc) of nano / sub-nanometer NCO thin films.

[0004] While various methods have been proposed to improve the performance of nickel cobalt oxide thin films, such as adjusting synthesis conditions, doping with other metal ions, and employing different preparation methods, some challenges remain. Existing techniques often struggle to maintain or improve conductivity while simultaneously increasing the Curie temperature.

[0005] Therefore, the existing solutions are not widely applicable and do not meet people's usage requirements. To address this, we have developed a method to enhance the Curie temperature of ultrathin nickel cobalt oxide films. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films. This method overcomes the limitations of traditional oxide hard magnetic materials. By employing a radio frequency magnetron sputtering process with NiCo2O4 and Co3O4 targets, NiCo2O4 / Co3O4 films are prepared. The resulting films have a Curie temperature of 380K and excellent conductivity, showing promising application prospects.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films includes the following steps:

[0011] S1. NiCo2O4 and Co3O4 targets were prepared by ceramic sintering process;

[0012] S2. NiCo2O4 / Co3O4 thin films are deposited on MgAl2O4(001) single crystal substrates by magnetron sputtering, and the thickness of the film is controlled by sputtering time.

[0013] S3. Measure the anomalous Hall effect of the grown NiCo2O4 / Co3O4 thin film using a comprehensive physical property measurement system.

[0014] Preferably, the preparation methods of the NiCo2O4 target and Co3O4 target are as follows:

[0015] S11. Raw material mixing: Weigh the raw materials according to the stoichiometric ratio according to the requirements of the chemical reaction, and then put the raw materials into the ball mill jar and ball mill them together with the zirconium dioxide balls in the ball mill.

[0016] When preparing NiCo2O4 target material, accurately weigh cobalt oxide and nickel oxide according to the stoichiometric ratio of cobalt and nickel. When preparing Co3O4 target material, weigh 15-30 grams of Co3O4.

[0017] S12. Pre-calcination: Transfer the ball-milled raw material to an alumina crucible, then place it in a muffle furnace for sintering, and then cool it down;

[0018] S13. Ball milling: Ball milling is performed on the sintered material that has been cooled to obtain powder.

[0019] S14. Granulation: Add 5% polyvinyl alcohol aqueous solution to the powder and then grind it into fine particles;

[0020] This grinding step can be done manually.

[0021] S15. Pressing and sintering: Use a tablet press to press the fine particles into a blank, then sinter it in an alumina crucible and cool it down.

[0022] Preferably, the ball milling time in step S11 is 1 to 5 hours, and the sintering temperature in the muffle furnace in step S12 is 600°C to 900°C, and the sintering time is 10 to 15 hours.

[0023] Preferably, the particle size after ball milling in step S13 is 10-100 μm, and the particle size range of fine particles ground in step S14 is 20 mesh-80 mesh.

[0024] Preferably, in step S15, the sintering temperature in the alumina crucible is 600℃~900℃, and the sintering time is 10~15 hours.

[0025] Preferably, the step of depositing a NiCo2O4 / Co3O4 thin film on a MgAl2O4(001) single crystal substrate by magnetron sputtering is as follows:

[0026] S21. Substrate cleaning: The substrate is cleaned and dried in sequence to remove oil and dirt from the surface of the substrate.

[0027] S22, Vacuum treatment: The substrate is placed on the stage of the deposition chamber of the magnetron sputtering system and a vacuum is drawn to ensure the purity and performance of the deposited film;

[0028] S23. Heat treatment: Heat the substrate to remove moisture from the substrate surface and improve the adhesion between the film and the substrate;

[0029] S24. Pressure adjustment: Adjust the pressure of the magnetron sputtering system to 0.5-2 Pa in order to meet the gas pressure conditions for glow discharge;

[0030] S25. Pre-sputtering: Pre-sputter the target material for 3-10 minutes to remove these impurities or surface oxide film from the target material surface;

[0031] S26. Sputtering: Magnetron sputtering is performed on the target material. Ar+ is formed after argon gas is ionized under high pressure. Under the action of mutually perpendicular magnetic and electric fields, the Ar+ moves rapidly and impacts the target material, thereby obtaining target material particles, which are eventually deposited to form a thin film.

[0032] Preferably, in step S21, the substrate is immersed in a mixed liquid of acetone, ethanol, and deionized water for ultrasonic cleaning, and the vacuum pressure in step S22 is 2 × 10⁻⁶. -4 Pa or higher, and the heating temperature in step S23 is 300-500℃.

[0033] Preferably, in step S26, the magnetron sputtering power is 40W and the sputtering rate is 14nm / hour. After magnetron sputtering, the sputtering is kept at 420℃ for 30 minutes, and then cooled.

[0034] Preferably, the steps for measuring the anomalous Hall effect of the grown NiCo2O4 / Co3O4 thin film are as follows:

[0035] S31. Sample Preparation: First, select a suitable sample, ensuring it meets experimental requirements such as shape, size, and weight. The measurement chamber of the PPMS equipment typically has specific dimensional requirements for the sample. Next, process the sample; depending on experimental needs, annealing, cooling, or surface treatment may be required. Finally, calibrate the sample. Before measurement, the equipment can be calibrated using standard samples to ensure the accuracy of the measurement results.

[0036] S32. Equipment Preheating and Calibration: First, turn on the equipment, start the PPMS device and perform a self-test to ensure the system is running normally. Check hardware connections, sensor status, etc. Then preheat the system. If low-temperature measurement is required, start the liquid helium system and preheat to the required experimental temperature. Finally, calibrate the sensors, including temperature, magnetic field, current, and magnetic force sensors, to ensure measurement accuracy.

[0037] S33. Sample Installation: First, secure the sample by carefully placing it into the measurement sample chamber. Select a suitable sample clamping device according to the different measurement methods (e.g., magnetic measurement, conductivity measurement) to ensure the sample is secure and free from external interference. Then connect the electrodes: If measuring electrical properties (e.g., conductivity), the electrodes need to be in contact with the sample to ensure good electrical contact.

[0038] S34. Set measurement parameters: Temperature setting: Set the target temperature according to experimental needs; you can set a constant temperature or scanning temperature range. Magnetic field setting: If performing magnetic testing, set the strength and variation mode of the magnetic field (e.g., scanning magnetic field, constant magnetic field, etc.). Measurement mode selection: Select the appropriate measurement mode, such as temperature scan, magnetic field scan, or current scan, etc.

[0039] S35. Start Measurement: Start the measurement program and experimental software. After setting the data acquisition parameters, begin the measurement. During the measurement process, ensure real-time data monitoring and check the stability of temperature, magnetic field, etc. Data Acquisition and Analysis: Based on the set measurement conditions, the PPMS system will automatically acquire and store data. You can view the experimental curves in real time and adjust the experimental parameters as needed.

[0040] S36. End Measurement and Save Data: Measurement complete. Once the measurement is finished, data acquisition stops. The system will automatically generate measurement data and charts. Data can be saved to the computer or exported in DAT format for later analysis.

[0041] S37. Sample Removal and Cleaning: Remove the sample carefully from the measuring chamber to avoid damage. Clean the equipment as needed, especially the sample chamber and electrode sections, to ensure accuracy for the next measurement.

[0042] S38. Result Analysis: Data Processing: Use the software included with PPMS or other professional data processing software to analyze the experimental data and obtain the required physical parameters (such as conductivity, magnetization, etc.). Result Verification: Verify the reliability of the measurement results by comparing with standard data or repeating the experiment.

[0043] (III) Beneficial Effects

[0044] This invention provides a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films, which has the following beneficial effects:

[0045] 1. This invention provides a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films, which can overcome the limitations of traditional oxide hard magnetic materials. By using a radio frequency magnetron sputtering process and NiCo2O4 and Co3O4 targets, NiCo2O4 / Co3O4 films are prepared. The resulting films have a Curie temperature of 380K and excellent conductivity, showing good application prospects.

[0046] 2. This invention describes a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films. The preparation method of this invention is of great significance for promoting the application of magnetic oxide films in spintronics and can provide new possibilities for the research and development of high-density, high-speed and low-power magnetic storage devices. At the same time, this method has the advantage of low material cost, which is conducive to large-scale preparation and industrial production. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of a NiCo2O4 / Co3O4 film provided at the Curie temperature to enhance the ultrathin nickel cobalt oxide film according to the present invention;

[0048] Figure 2 X-ray reflectance and related fitting data of NiCo2O4 / Co3O4 film in a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide film according to the present invention;

[0049] Figure 3 This is a magnetization curve of the NiCo2O4 / Co3O4 film in the method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films according to the present invention.

[0050] Figure 4 This is an anomalous Hall curve of NiCo2O4 / Co3O4 film as a function of temperature in a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films according to the present invention.

[0051] Figure 5 The RT curves of NiCo2O4 / Co3O4 thin films and monolayer NiCo2O4 are compared in the method for enhancing the Curie temperature of ultrathin nickel cobalt oxide thin films according to the present invention. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0053] A method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films includes the following steps:

[0054] Step 1: Prepare NiCo2O4 target material using standard ceramic sintering process. NiO powder and Co3O4 powder are wet-milled in a ball mill jar with alcohol as a grinding aid at 400 rpm for 40 minutes, according to stoichiometric ratio. The mixture is then sintered for the first time in a muffle furnace at 750°C for 12 hours with a heating rate of 5°C per minute. The pre-sintered powder is then dry-milled again in a ball mill jar at 200 rpm for 20 minutes, followed by the addition of a binder. The mixture is then pressed into shape using a tablet press at 20 MPa for 15 minutes. Finally, a second sintering is performed in a muffle furnace at 750°C for 12 hours with a heating rate of 5°C per minute to obtain the desired ceramic target material.

[0055] Co3O4 targets were prepared using a standard ceramic sintering process. 20 grams of Co3O4 powder were accurately weighed and placed in a ball mill jar with alcohol as a grinding aid. The mixture was wet-milled at 400 rpm for 40 minutes until homogeneous. The mixture was then subjected to a first sintering in a muffle furnace at 750°C for 12 hours with a heating rate of 5°C per minute. The pre-sintered powder was then dry-milled again at 200 rpm for 20 minutes, followed by the addition of a binder. The mixture was then pressed into shape using a tablet press at 20 MPa for 15 minutes. Finally, a second sintering was performed in a muffle furnace at 750°C for 12 hours with a heating rate of 5°C per minute to obtain the desired ceramic target.

[0056] Step 2: Immerse the MgAl2O4 substrate in alcohol and clean it with an ultrasonic cleaner for 5 minutes. After cleaning, dry the MgAl2O4 substrate with nitrogen and immediately place it into the deposition chamber of the magnetron sputtering system.

[0057] Step 3: Close the magnetron sputtering system deposition chamber, start the mechanical pump, open the valve connecting the mechanical pump and the chamber to evacuate, and start the resistance gauge to measure the internal pressure of the chamber. Once the pressure drops below 1×10 Pa, close the connecting valve, open the molecular pump isolation valve, start the molecular pump, and fully open the molecular pump gate valve to connect the molecular pump and the chamber. When the pressure drops to 1×10 Pa... -1 At a pressure of Pa, open the ionization gauge. When the vacuum reaches 1 × 10⁻⁶ Pa, [the ionization gauge is activated]. -4After Pa, a 1:1 argon / oxygen (Ar / O2) mixture is introduced, and the opening of the gate valve is adjusted to maintain the gas pressure at 1 Pa. Then, the substrate is heated to 420°C.

[0058] Step 4: First, deposit a thin film on a MgAl2O4(001) single crystal substrate using a Co3O4 target via magnetron sputtering. Then, deposit a thin film on the Co3O4 film using a NiCo2O4 target (e.g., ...). Figure 1 As shown, first adjust the power supply, start the RF power supply, and keep the baffle closed for pre-sputtering for 5 minutes. After pre-sputtering, open the baffle to start sputtering, and control the film thickness by adjusting the sputtering time; specifically, the magnetron sputtering power is 40W and the rate is 14nm / hour.

[0059] During magnetron sputtering, the compositional uniformity and crystal quality of the thin film can be optimized by adjusting the sputtering energy, the appropriate temperature of the target, and the angle of the substrate.

[0060] Step 5: After the film deposition is complete, keep it at 420℃ for 30 minutes to make its composition more uniform, and then cool it down to room temperature.

[0061] The obtained samples were subjected to XRD tests (using a SmartLab SE XRD diffractometer manufactured by Rigaku Corporation, Japan), magnetic measurements of MPMS3, and electrical transport measurements of PPMS (MPMS3 and PPMS were from QuantumDesign, USA).

[0062] Atomic-scale interface engineering has become an important method for tuning the physical properties of thin films. This is achieved by introducing interfacial coupling effects, such as epitaxial strain, symmetry breaking, charge transfer, and orbital reconstruction. These findings provide an important pathway for manipulating the magnetic and transport properties of NCO thin films by adjusting cation valence states and site occupancy through interface engineering. Figure 1 As shown, we propose a NiCo2O4 / Co3O4 (NCO / CO) bilayer system, which can significantly improve the resistivity (Tc) above room temperature through interface engineering. This helps to address the miniaturization requirements and further promotes the application of NCO thin films as spintronic materials. Our study found that the film resistivity decreases sharply with increasing Co3O4 thickness. This observed phenomenon may be due to the interface coupling of Ni... 3+ The increased occupancy of ions at octahedral sites leads to an inherent linear relationship between resistivity and Curie temperature.

[0063] The test results are shown in the attached figure:

[0064] Figure 1 The image shows a structural diagram of the NCO / CO thin film sample we grew;

[0065] Figure 2 The X-ray reflectance (XRR) of NCO, CO, and NCO / CO films is shown, exhibiting a good correlation between time and thickness. The extracted thicknesses of the NCO, CO, and NCO / CO films are 3.1 nm, 4.6 nm, and 3.1 nm / 4.6 nm, respectively. The well-defined periodic oscillations observed in the XRR patterns indicate that the films all possess ordered periodic structures and clear interfaces.

[0066] Figure 3 The temperature-dependent in-plane (IP) and out-of-plane (OOP) magnetization of the NCO (3.1 nm) / CO (4.6 nm) film after 2T field cooling is shown. In the out-of-plane direction, the magnetization is 0.18 μB / fu at around 380 K, close to 0, indicating that Tc reaches approximately 380 K, much higher than room temperature. This suggests that the insertion of the CO buffer layer leads to an increase in Tc of the NCO / CO film due to charge transfer and interfacial coupling effects at the CO-NCO interface.

[0067] Figure 4 An anomalous Hall effect was observed in NCO / CO thin films. The typical anomalous Hall resistance of a 3.1 nm thick NCO thin film and 3.1 nm / 4.6 nm thick NCO / CO thin films changes with temperature as follows: Figure 4 As shown. In Figure 4 As can be seen from a, a weak anomalous Hall effect can be observed at a temperature of 340K, which proves that the Tc of the 3.1nm monolayer NCO film is 340K. Figure 4 As can be seen in b, a weak anomalous Hall effect can also be observed at a temperature of 380K, which further proves that the Tc of the 3.1nm / 4.6nm NCO / CO thin film has reached 380K, which is much higher than room temperature.

[0068] Figure 5 As shown, at room temperature, the sheet resistance of a 1.1 nm NCO film with a CO buffer layer is reduced by two orders of magnitude compared to a monolayer NCO film, while the sheet resistance of a 3.1 nm NCO film is reduced by a factor of two. This indicates that the insertion of the CO buffer layer leads to a decrease in resistivity and an increase in conductivity in the NCO / CO film, due to charge transfer and interfacial coupling effects at the CO-NCO interface.

[0069] In summary, this invention provides a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films, resulting in the growth of high-quality NCO / CO heterostructures on MgAl2O4(001) substrates. Results show that the Curie temperature (Tc) of the NCO / CO heterostructure (with a CO buffer layer) is significantly enhanced compared to monolayer NCO films. Furthermore, compared to monolayer NCO films, a significant reduction in film resistance and enhanced conductivity were observed. The NCO / CO heterostructure also exhibits a clear anomalous Hall effect. These findings demonstrate that interfacial coupling is an effective strategy for modulating the physical properties of oxides, opening new opportunities for the application of NiCo2O4 materials in micro-spintronic devices and holding significant importance for promoting the application of magnetic oxide films in spintronics.

[0070] This invention provides a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films, which can overcome the limitations of traditional oxide hard magnetic materials. By using a radio frequency magnetron sputtering process with NiCo2O4 and Co3O4 targets, NiCo2O4 / Co3O4 films are prepared. The resulting films have a Curie temperature of 380K and excellent conductivity, showing good application prospects.

[0071] This invention discloses a method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films. The preparation method of this invention is of great significance for promoting the application of magnetic oxide films in spintronics and can provide new possibilities for the development of high-density, high-speed and low-power magnetic storage devices. At the same time, this method has the advantage of low material cost, which is conducive to large-scale preparation and industrial production.

[0072] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0073] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0074] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for enhancing the Curie temperature of ultrathin nickel cobalt oxide films, characterized in that, Includes the following steps: S1. NiCo2O4 and Co3O4 targets were prepared by ceramic sintering process; S2. NiCo2O4 / Co3O4 thin films are deposited on MgAl2O4(001) single crystal substrates by magnetron sputtering. Specifically, a thin film is first deposited on a MgAl2O4(001) single crystal substrate using a Co3O4 target, and then a thin film is deposited on the Co3O4 thin film using a NiCo2O4 target to obtain NiCo2O4 / Co3O4 thin films. S3. Measure the anomalous Hall effect of the grown NiCo2O4 / Co3O4 thin film.

2. The method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 1, characterized in that: The preparation methods of the NiCo2O4 target and Co3O4 target are as follows: S11. Raw material mixing: Weigh the raw materials according to the stoichiometric ratio, and then put the raw materials into the ball mill jar and ball mill them together with the zirconium dioxide balls in the ball mill. S12. Pre-calcination: Transfer the ball-milled raw material to an alumina crucible, then place it in a muffle furnace for sintering, and then cool it down; S13. Ball milling: Ball milling is performed on the sintered material that has been cooled to obtain powder. S14. Granulation: Add 5% polyvinyl alcohol aqueous solution to the powder and then grind it into fine particles; S15. Pressing and sintering: Use a tablet press to press the fine particles into a blank, then sinter it in an alumina crucible and cool it down.

3. The method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 2, characterized in that: In step S11, the ball milling time is 1 to 5 hours, and in step S12, the sintering temperature in the muffle furnace is 600℃ to 900℃, and the sintering time is 10 to 15 hours.

4. The method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 3, characterized in that: The particle size after ball milling in step S13 is 10-100 μm, and the particle size range of fine particles ground in step S14 is 20 mesh-80 mesh.

5. The method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 4, characterized in that: In step S15, the sintering temperature in the alumina crucible is 600℃~900℃, and the sintering time is 10~15 hours.

6. The method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 5, characterized in that: The steps for depositing NiCo2O4 / Co3O4 thin films on a MgAl2O4(001) single crystal substrate by magnetron sputtering are as follows: S21. Substrate cleaning: Clean and dry the substrate sequentially; S22, Vacuum treatment: Place the substrate on the stage of the magnetron sputtering system deposition chamber and evacuate it; S23. Heat treatment: Heat the substrate to remove moisture from the substrate surface; S24. Pressure adjustment: Adjust the pressure of the magnetron sputtering system to 0.5-2 Pa; S25. Pre-sputtering: Pre-sputter the target material for 3-10 minutes to remove these impurities or surface oxide film from the target material surface; S26. Sputtering: Magnetron sputtering of the target material.

7. The method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 6, characterized in that: In step S21, the substrate is immersed in a mixture of acetone, ethanol, and deionized water for ultrasonic cleaning. In step S22, the vacuum pressure is 2 × 10⁻⁶. -4 Pa or higher, and the heating temperature in step S23 is 300-500℃.

8. The method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 7, characterized in that: In step S26, the magnetron sputtering power is 40W and the sputtering rate is 14nm / hour. After magnetron sputtering, the temperature is maintained at 420℃ for 30 minutes, and then cooled.

9. A method for enhancing the Curie temperature of an ultrathin nickel cobalt oxide film according to claim 8, characterized in that: The steps for measuring the anomalous Hall effect of the grown NiCo2O4 / Co3O4 thin film are as follows: S31. Sample preparation: Cut the sample to the standard experimental size; S32. Equipment preheating and calibration: Start the equipment to perform a self-test, check the hardware connections and sensor status, and then preheat the system. S33. Sample installation: Fix the cut sample in the measurement sample chamber; S34. Set measurement parameters: Set the parameters required for sample testing; S35. Start Measurement: Measure, collect, and store the data during sample measurement; S36. End Measurement and Save Data: The measurement is completed. Once the measurement is finished, data acquisition stops, and measurement data and charts are generated. S37. Sample removal and cleaning: Remove the sample and clean the equipment; S38. Results Analysis: Data processing. Use the software included with PPMS or other professional data processing software to analyze the experimental data and obtain the required physical parameters.

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