Flexible self-supporting magnetoelectric composite film and preparation method thereof

Abstract

The invention provides a flexible self-supporting magnetoelectric composite film and a preparation method, the film comprises a magnetic layer, an organic ferroelectric layer and a metal layer, the magnetic layer, the organic ferroelectric layer and the metal layer are sequentially arranged from top to bottom to form the flexible self-supporting magnetoelectric composite film, the magnetic layer is used as an upper electrode, and the metal layer is used as a lower electrode. The upper electrode and the lower electrode are connected with wires. The flexible self-supporting magnetoelectric composite film prepared by the method provided by the invention gets rid of the clamping effect of the substrate, and the effect of regulating and controlling the magnetism of the film by an electric field is more obvious.

Description

Technical Field

[0001] The present invention relates to the technical field of self-supporting magnetoelectric composite films, and in particular to a flexible self-supporting magnetoelectric composite film and a preparation method thereof. Background Art

[0002] Multiferroic materials are materials that exhibit two or more ferroic properties. The coexistence and coupling of ferroelectricity and ferromagnetism enable manipulation of magnetism with electric fields and polarization with magnetic fields. Depending on whether the ferromagnetic and ferroelectric phases coexist in the same spatial phase, multiferroic materials can be divided into single-phase multiferroic materials and multiphase composite multiferroic materials. The former have a limited number of materials and weak magnetoelectric coupling, which greatly limits magnetoelectric properties. The latter, composed of composite ferromagnetic and ferroelectric materials, significantly improves magnetoelectric properties compared to single-phase multiferroic materials, enabling the integration of multiple functions. They have broad application prospects in key fields such as magnetoelectric sensors, memory, and microwave communications.

[0003] Currently, most magnetoelectric composite thin films are grown epitaxially. While these films offer high quality, they also come with numerous limitations. For example, epitaxial growth requires a very high degree of lattice compatibility, and the substrate clamping effect can inhibit many of the properties of the epitaxial film. To address this issue, researchers have proposed and fabricated self-supporting magnetoelectric composite thin films, freeing them from substrate constraints and improving their performance. Furthermore, these self-supporting structures possess the properties of both flexibility and elasticity, offering promising applications in flexible electronic devices.

[0004] The ferroelectric materials used in traditional magnetoelectric composites are inorganic materials, such as lead zirconate titanate (PZT) and lead magnesium niobate-titanate (PMN-PT). These materials have a large Young's modulus and poor flexibility. Polyvinylidene fluoride (PVDF) and its copolymers are a common class of organic materials. Due to their inherent flexibility and biocompatibility, they have broad application prospects in flexible electronic devices such as sensors, actuators, and energy harvesters. Furthermore, these organic materials can generate the same or even greater strain as inorganic ferroelectric materials under the influence of an electric field, further enhancing magnetoelectric coupling performance.

[0005] Ferromagnetic materials used in magnetoelectric composites are currently commonly found in magnetic metals, magnetic alloys, and magnetic oxide thin films. Magnetic oxide thin films, however, have garnered extensive attention and research due to their diverse physical properties. Perovskite-type magnetic oxides, with their diverse physical properties and stable chemical properties, are key candidates for next-generation functional materials. Lanthanum strontium manganate (La0.67Sr0.33MnO3, LSMO), a perovskite-type magnetic oxide, exhibits advantages such as a large magnetostriction coefficient and excellent ferromagnetism, making it a hot research topic in recent years. Extensive research has been conducted on the preparation of magnetoelectric composites using LSMO thin films and the study of their magnetoelectric coupling properties. However, the manipulation of the magnetic properties of LSMO thin films is not very effective, failing to meet the industrial demand for high-performance materials and devices. Furthermore, the inability to achieve flexibility in composite materials hinders their application in flexible devices and other applications. Summary of the Invention

[0006] The object of the present invention is to provide a flexible self-supporting magnetoelectric composite film and a preparation method thereof to solve the above problems.

[0007] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a flexible self-supporting magnetoelectric composite film, comprising a magnetic layer, an organic ferroelectric layer and a metal layer. The magnetic layer, the organic ferroelectric layer and the metal layer are arranged in sequence from top to bottom to constitute a flexible self-supporting magnetoelectric composite film, the magnetic layer serves as an upper electrode, the metal layer serves as a lower electrode, and both the upper electrode and the lower electrode are connected to wires.

[0008] Furthermore, the magnetic layer is lanthanum strontium manganese oxide La 0.67 S 0.33 MnO3 film.

[0009] Furthermore, the thickness of the magnetic layer is 20-40 nm.

[0010] Furthermore, the organic ferroelectric layer is polyvinylidene fluoride-trifluoroethylene copolymer P (VDF-TrFE).

[0011] In a second aspect, the present invention provides a method for preparing a flexible self-supporting magnetoelectric composite film, comprising the following steps: epitaxially growing a sacrificial layer and a magnetic layer on an initial substrate using a pulsed laser deposition growth method to obtain an initial substrate / sacrificial layer / magnetic layer structure; Spin coating an organic ferroelectric layer on the obtained initial substrate / sacrificial layer / magnetic layer to obtain an initial substrate / sacrificial layer / magnetic layer / organic ferroelectric layer structure; spin coating an organic ferroelectric layer on a target substrate to obtain a target substrate / organic ferroelectric layer structure; Laminating the surfaces of the two organic ferroelectric layers and clamping them with a clamp; placing the film to be transferred and the target substrate clamped by the clamp in a solution that dissolves the sacrificial layer until the sacrificial layer is completely dissolved, thereby obtaining a target substrate / organic ferroelectric layer / magnetic layer self-supporting structure; The organic ferroelectric layer / magnetic layer composite film is peeled off from the target substrate, and a metal layer is sputtered on the other side of the organic ferroelectric layer to obtain a flexible self-supporting magnetoelectric composite film.

[0012] Furthermore, the initial substrate is any one of strontium titanate SrTiO3, lanthanum aluminate LaAlO3, and lanthanum strontium aluminum tantalum (La, Sr)(Al, Ta) O3.

[0013] Furthermore, the sacrificial layer is a strontium aluminate Sr3Al2O6 sacrificial layer, and the thickness of the sacrificial layer is 30-60 nm.

[0014] Furthermore, the thickness of P(VDF-TrFE) on the initial substrate is 500-700 nm, and the thickness of P(VDF-TrFE) on the target substrate is 5-10 μm.

[0015] Furthermore, the target substrate is a silicon substrate with a gold-plated surface, and the gold thickness is 5-10 nm.

[0016] Furthermore, after obtaining a flexible self-supporting magnetoelectric composite film, the upper and lower electrodes were led out, and an electric field was applied to regulate the magnetic properties of the film: the electric field was applied to the upper and lower surfaces of P(VDF-TrFE) to test the magnetic changes of LSMO; and electron paramagnetic resonance was used to test the magnetic changes of the LSMO film.

[0017] Compared with the prior art, the present invention has the following technical effects: The flexible self-supporting magnetoelectric composite film prepared by the method proposed in the present invention gets rid of the clamping effect of the substrate, and the effect of electric field regulating the magnetic properties of the film is more significant. The EPR test results show that the maximum offset of the out-of-plane resonance field of the LSMO film is 106.66 Oe, and the maximum offset of the in-plane resonance field is 50.21 Oe.

[0018] The method proposed in this paper can improve the performance of magnetoelectric composite films, enabling significant electric field control of the film's magnetic properties. The control method is simple and easy to operate, providing technical support for the control of magnetoelectric composite films. Furthermore, a flexible magnetoelectric composite film is obtained, further promoting its application in flexible devices and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the method for preparing the flexible self-supporting magnetoelectric composite film of the present invention; Figure 2 Schematic diagram of the structure of the flexible self-supporting P(VDF-TrFE) / LSMO magnetoelectric composite film of the present invention; Figure 3 The polarization curve of the flexible self-supporting P(VDF-TrFE) / LSMO magnetoelectric composite film of the present invention changes with the electric field; Figure 4 The strain curve of the flexible self-supporting P(VDF-TrFE) / LSMO magnetoelectric composite film of the present invention changes with the electric field; Figure 5 The X-ray diffraction (XRD) test results of the LSMO film before and after transfer of the present invention; Figure 6 The results of the electron paramagnetic resonance (EPR) test of the flexible self-supporting P(VDF-TrFE) / LSMO magnetoelectric composite film of the present invention under an external electric field are shown; Figure 7 These are the EPR test results of the in-plane electric field applied to the flexible self-supporting P(VDF-TrFE) / LSMO magnetoelectric composite film of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and specific examples. The present invention is described in detail below with reference to specific exemplary embodiments. However, it should be understood that various modifications and variations may be made without departing from the scope of the present invention as defined by the appended claims. The detailed description and drawings are to be considered merely illustrative and not restrictive, and any such modifications and variations, if any, are intended to fall within the scope of the present invention as described herein.

[0021] The present invention provides a method for preparing a flexible self-supporting magnetoelectric composite film. The method comprises the following steps: spin-coating an organic film on the surface of an initial substrate / sacrificial layer / magnetic layer and the surface of a target substrate, tightly laminating the two organic film layers by hot pressing, heating them in a vacuum environment at 160°C for 1 hour, and then immersing them in deionized water at room temperature for 24-36 hours until the SAO sacrificial layer is completely dissolved. The composite film is removed and dried using a nitrogen flow to obtain a magnetoelectric composite film tightly laminating to the target substrate. The magnetoelectric composite film is peeled off from the target substrate, and a metal layer is sputtered on the other side of the organic film to obtain a flexible self-supporting magnetoelectric composite film. The lead is then subjected to an electric field EPR test to verify the effect of electric field on the magnetic properties of the flexible self-supporting magnetoelectric composite film.

[0022] Example 1. The present invention provides a flexible self-supporting magnetoelectric composite film, including a magnetic layer, an organic ferroelectric layer and a metal layer. The magnetic layer, the organic ferroelectric layer and the metal layer are arranged in sequence from top to bottom to constitute a flexible self-supporting magnetoelectric composite film, the magnetic layer serves as an upper electrode, and the metal layer serves as a lower electrode, and both the upper electrode and the lower electrode are connected to wires.

[0023] The method provided by the present invention breaks away from the constraints of the initial substrate, has a better control effect on the magnetic properties of the thin film, and overcomes the difficulties of small control amount and high control cost of the thin film magnetic properties in traditional control methods.

[0024] Example 2: The present invention provides a method for preparing a flexible self-supporting magnetoelectric composite film.

[0025] In order to overcome the problems of substrate clamping effect, insignificant magnetic control, and poor flexibility in magnetoelectric composite films, the present invention provides a method for preparing a flexible self-supporting magnetoelectric composite film, which gets rid of the clamping of the substrate and can achieve significant control of the magnetic properties of the film while obtaining a flexible self-supporting magnetoelectric composite film.

[0026] The present invention adopts the following technical solutions: In one aspect, the present invention discloses a method for preparing a flexible self-supporting magnetoelectric composite film, comprising the following steps: Step S1: epitaxially growing a sacrificial layer and a magnetic layer on an initial substrate in sequence using a pulsed laser deposition (PLD) method, with the magnetic layer serving as the film to be transferred; Step S2: Spin-coating a layer of organic thin film on the surface of the thin film to be transferred and the surface of the target substrate obtained in step S1; Step S3: Laminating the surface of the film to be transferred / organic film obtained in step S2 with the surface of the organic film / target substrate, fixing them with a glass sheet, and clamping them with a clamp to achieve full lamination of the film to be transferred and the target substrate; Step S4: placing the film to be transferred and the target substrate clamped by the clamp into an oven for hot pressing; Step S5: placing the film to be transferred and the target substrate after the hot pressing in step S4 in deionized water until the sacrificial film is completely dissolved; Step S6: taking out the film to be transferred and the target substrate from which the sacrificial layer is dissolved in step S5 and drying them to obtain a magnetoelectric composite film transferred to the target substrate; Step S7: peeling the magnetoelectric composite film from the target substrate, sputtering a metal layer on the other side of the organic film, and finally obtaining a flexible self-supporting magnetoelectric composite film; The organic solution is prepared by mixing N,N-dimethylformamide (DMF) and polyvinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)) in a mass ratio of 9:1 to obtain a 10% wt P(VDF-TrFE) organic solution.

[0027] The fixture is resistant to high temperatures and is made of a material that does not react with deionized water; The clamp is a stainless steel clamp.

[0028] The hot pressing temperature is not less than 150° C., the hot pressing time is not less than 30 min, and the hot pressing environment is vacuum.

[0029] The hot pressing temperature is 160° C., and the hot pressing time is 30 min.

[0030] In step S5, the immersion temperature in deionized water is room temperature and the immersion time is not less than 20 hours to ensure that the sacrificial layer can be completely dissolved.

[0031] The sample was immersed in deionized water at room temperature for 24-36 hours.

[0032] In step S6, nitrogen flow is used for drying until there is no water stain on the surface of the target substrate and the film to be transferred.

[0033] The sacrificial layer is a Sr3Al2O6 (SAO) sacrificial layer.

[0034] The film to be transferred is an LSMO single crystal magnetic oxide film.

[0035] The initial substrate is any one of strontium titanate (SrTiO3, STO), lanthanum aluminate (LaAlO3), and lanthanum strontium aluminum tantalum ((La, Sr)(Al, Ta)O3).

[0036] In the present invention, there is no requirement on the thickness and type of the target substrate, but the target substrate should be hard and have a flat surface.

[0037] The target substrate is a single crystal silicon (Si) substrate with a flat surface and hard texture, and the surface is covered with a layer of gold (Au) electrode with a thickness of 5 nm.

[0038] Preferably, the thickness of the organic film spin-coated on the surface of the film to be transferred is 600 nm.

[0039] Preferably, the thickness of the organic film spin-coated on the target substrate surface is 6 μm.

[0040] The above method is used to prepare a flexible self-supporting magnetoelectric composite film. In the preparation process of the flexible self-supporting magnetoelectric composite film, the initial substrate is an STO substrate, the film to be transferred is an LSMO film with a thickness of 30 nm, and the target substrate is a single crystal silicon substrate with a layer of Au electrode on the surface. A layer of organic film is spin-coated on the surface of the film to be transferred and the target substrate, and then hot-pressed and immersed in deionized water. After the sacrificial layer is dissolved, taken out and dried, it is peeled off to obtain a flexible self-supporting magnetoelectric composite film.

[0041] Using Au electrode as the lower electrode and LSMO magnetic film as the upper electrode, the above method was applied to prepare a flexible self-supporting magnetoelectric composite film. KE6517B and electron paramagnetic resonance system (EPR) were used to realize electric field control of ferromagnetism of the flexible self-supporting magnetoelectric composite film, and the control effect of the magnetic properties of the LSMO film was significant.

[0042] Example 3 This embodiment provides a method for preparing a flexible self-supporting magnetoelectric composite film, the specific process is as follows: 1) Select a (001) oriented single crystal STO substrate with a size of 5 mm × 5 mm × 0.5 mm as the initial substrate. Use alcohol, acetone, and alcohol ultrasonic cleaning for 5 min in sequence. Use nitrogen to blow dry the residual liquid on the STO surface to obtain a cleaned STO substrate. 2) Using PLD technology, a SAO sacrificial layer was grown on the STO substrate according to the following process parameters: chamber oxygen pressure 20 Pa, deposition temperature 800 ° C, laser power 1 W / cm 2 , laser frequency 3 Hz, growth time 20 min; then the LSMO magnetic layer was grown on the SAO surface according to the following process parameters: chamber oxygen pressure 30 Pa, deposition temperature 800 ° C, laser power 1.4 W / cm 2 , laser frequency 2 Hz, growth time 20 min; STO / SAO / LSMO heterojunction film was obtained; 3) A (001)-oriented single-crystal Si was selected as the target substrate. A layer of Au electrode was sputtered onto the Si surface. A layer of P(VDF-TrFE) organic film was spin-coated onto the Si / Au and STO / SAO / LSMO surfaces. The spin-coating conditions for the organic film on the Si / Au surface were: first, spin-coating at a rate of 1000 r / min for 6 s, then at a rate of 2000 r / min for 20 s, with a thickness of 6 μm. The spin-coating conditions for the organic film on the STO / SAO / LSMO surface were: first, spin-coating at a rate of 1000 r / min for 6 s, then at a rate of 4000 r / min for 20 s, with a thickness of 600 nm. After spin-coating, the substrate was placed in an oven, evacuated, set to 100°C, and heated for 30 minutes to cure the P(VDF-TrFE) organic film. 4) A 10 mm × 10 mm × 0.02 mm polydimethylsiloxane (PDMS) film was attached to the surface of STO / SAO / LSMO / P(VDF-TrFE). The STO / SAO / LSMO / P(VDF-TrFE) heterojunction film was cut into 2.5 mm × 2.5 mm × 0.5 mm pieces. PDMS was used to remove dust and residue from the surface of STO / SAO / LSMO. 5) Place Si / Au / P(VDF-TrFE) on a glass slide, place the STO / SAO / LSMO / P(VDF-TrFE) surface upside down on the Si / Au / P(VDF-TrFE) surface, cover the STO / SAO / LSMO / P(VDF-TrFE) with a glass slide, and fix the two glass slides with stainless steel clamps. Place the slides in an oven, evacuate the air, set the oven temperature to 160°C, heat for 1 hour, and perform hot pressing. 6) After hot pressing, remove the fixture and soak the Si / Au / P(VDF-TrFE) / LSMO / SAO / STO in deionized water for 24-36 hours until the SAO sacrificial layer is completely dissolved. Remove the Si / Au / P(VDF-TrFE) / LSMO and dry it with nitrogen flow to obtain a Si / Au / P(VDF-TrFE) / LSMO composite structure. 7) Peeling the P(VDF-TrFE) / LSMO magnetoelectric composite film from the Si / Au substrate, and sputtering an Au layer on the other side of the P(VDF-TrFE) to obtain an Au / P(VDF-TrFE) / LSMO flexible self-supporting magnetoelectric composite film; 8) Use copper wires with polished ends to lead out the upper and lower electrodes and secure them with thermal tape. Use KE6517B to apply a DC electric field and perform an electric field EPR test to verify the effect of electric field on the magnetic properties of the flexible self-supporting magnetoelectric composite film. In this embodiment, the thickness of the LSMO magnetic layer is 30 nm, the thickness of the P(VDF-TrFE) organic film is 6.6 μm, and the thickness of the Au electrode is 5 nm. The Au electrode is used as the lower electrode, and the LSMO magnetic layer is used as the upper electrode. Copper wires are used to successfully lead out the upper and lower electrodes. The structural diagram is shown in the attached figure. Figure 2 The polarization and strain curves of P(VDF-TrFE) / LSMO flexible self-supporting magnetoelectric composite films are shown in the attached figure. Figure 3 and 4 , P(VDF-TrFE) has good ferroelectricity and can produce 4‰ strain under 140 MV / m electric field. Figure 5 The XRD results before and after LSMO transfer show that LSMO still has good single crystal properties and good film quality after transfer. Figure 6-7The results show that under a 60 MV / m positive electric field, the out-of-plane resonance field of the LSMO film increases from an initial 7512.52 Oe to 7619.18 Oe, with a resonance field shift of 106.66 Oe. Upon removing the electric field, the resonance field returns to normal. The in-plane resonance field of the LMSO film increases from an initial 2092.97 Oe to 2143.18 Oe, with a resonance field shift of 50.21 Oe. Upon removing the electric field, the resonance field returns to normal. This demonstrates that the electric field can significantly modulate the magnetic properties of the LSMO film in the Au / P(VDF-TrFE) / LSMO flexible free-standing magnetoelectric composite film.

[0043] Example 4 The basic content of this example is the same as that of Example 1, except that in this example, the P(VDF-TrFE) / LSMO magnetoelectric composite film is not peeled off from the target Si / Au substrate. Au serves as the lower electrode, and LSMO serves as the upper electrode. The magnetoelectric composite film was prepared using the same method as in Example 1, and the effect of electric field manipulation of the film's magnetic properties was studied. The results showed that the out-of-plane and in-plane resonance field offset directions of the LSMO film were the same as in Example 1, and the resonance field offset was essentially the same as in Example 1, but slightly smaller. When the electric field was removed, both the out-of-plane and in-plane resonance fields returned to normal, demonstrating that the Au / P(VDF-TrFE) / LSMO flexible, self-supporting magnetoelectric composite film has similar control principles to the Si / Au / P(VDF-TrFE) / LSMO composite structure, but with better control effects.

[0044] Example 5 The basic content of this example is the same as that of Example 1, except that the thickness of the organic film spin-coated on the target Si / Au substrate in this example is 10 μm, and the spin-coating conditions are first 1000 r / min for 6 seconds and then 1500 r / min for 20 seconds. A flexible self-supporting magnetoelectric composite film was prepared using the same method as in Example 1, and the effect of electric field on the magnetic properties of the film was studied. The results showed that the out-of-plane and in-plane resonance field offset directions of the LSMO film were the same as in Example 1, and the resonance field offset was essentially the same as in Example 1. When the electric field was removed, both the out-of-plane and in-plane resonance fields returned to normal, demonstrating that the electric field can significantly regulate the magnetic properties of the LSMO film in P(VDF-TrFE) / LSMO flexible self-supporting magnetoelectric composite films of different thicknesses.

[0045] This invention can significantly control the magnetic properties of thin films using electric fields. The control method is simple and the operation process is easy. It can provide technical support for the control of magnetoelectric composite films. At the same time, a flexible magnetoelectric composite film is obtained, further promoting the application of magnetoelectric composite films in flexible devices and other fields.

[0046] The above description is only a preferred embodiment of the present invention; however, the protection scope of the present invention is not limited thereto.

[0047] Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solutions and improved concepts of the present invention within the technical scope disclosed by the present invention, and these changes should be covered by the protection scope of the present invention.

Claims

1. A flexible self-supporting magnetoelectric composite film, characterized in that: It includes a magnetic layer, an organic ferroelectric layer and a metal layer, which are arranged in sequence from top to bottom to form a flexible self-supporting magnetoelectric composite film. The magnetic layer serves as the upper electrode and the metal layer serves as the lower electrode. Both the upper electrode and the lower electrode are connected with wires.

2. The flexible self-supporting magnetoelectric composite film according to claim 1, characterized in that: The magnetic layer is lanthanum strontium manganese oxide La 0.67 S 0.33 MnO3 film.

3. The flexible self-supporting magnetoelectric composite film according to claim 1, characterized in that: The thickness of the magnetic layer is 20~40 nm.

4. The flexible self-supporting magnetoelectric composite film according to claim 1, characterized in that: The organic ferroelectric layer is polyvinylidene fluoride-trifluoroethylene copolymer P (VDF-TrFE).

5. The method for preparing a flexible self-supporting magnetoelectric composite film according to any one of claims 1 to 4, characterized in that: The following steps are involved: epitaxially growing a sacrificial layer and a magnetic layer on an initial substrate using a pulsed laser deposition growth method to obtain an initial substrate / sacrificial layer / magnetic layer structure; Spin coating an organic ferroelectric layer on the obtained initial substrate / sacrificial layer / magnetic layer to obtain an initial substrate / sacrificial layer / magnetic layer / organic ferroelectric layer structure; spin coating an organic ferroelectric layer on a target substrate to obtain a target substrate / organic ferroelectric layer structure; Laminating the surfaces of the two organic ferroelectric layers and clamping them with a clamp; placing the film to be transferred and the target substrate clamped by the clamp in a solution that dissolves the sacrificial layer until the sacrificial layer is completely dissolved, thereby obtaining a target substrate / organic ferroelectric layer / magnetic layer self-supporting structure; The organic ferroelectric layer / magnetic layer composite film is peeled off from the target substrate, and a metal layer is sputtered on the other side of the organic ferroelectric layer to obtain a flexible self-supporting magnetoelectric composite film.

6. The method for preparing a flexible self-supporting magnetoelectric composite film according to claim 5, characterized in that: The initial substrate is any one of strontium titanate SrTiO3, lanthanum aluminate LaAlO3, and lanthanum strontium aluminum tantalum (La, Sr)(Al, Ta) O3.

7. The method for preparing a flexible self-supporting magnetoelectric composite film according to claim 5, wherein: The sacrificial layer is a strontium aluminate Sr3Al2O6 sacrificial layer, and the thickness of the sacrificial layer is 30-60 nm.

8. The method for preparing a flexible self-supporting magnetoelectric composite film according to claim 5, characterized in that: The thickness of P(VDF-TrFE) on the initial substrate is 500~700nm, and the thickness of P(VDF-TrFE) on the target substrate is 5~10μm.

9. The method for preparing a flexible self-supporting magnetoelectric composite film according to claim 5, wherein: The target substrate is a silicon substrate with a gold-plated surface, and the gold thickness is 5-10 nm.

10. The method for preparing a flexible self-supporting magnetoelectric composite film according to claim 5, characterized in that: After obtaining a flexible self-supporting magnetoelectric composite film, the upper and lower electrodes are drawn out, and an electric field is applied to regulate the magnetic properties of the film: the electric field is applied to the upper and lower surfaces of P(VDF-TrFE) to test the magnetic changes of LSMO; and electron paramagnetic resonance is used to test the magnetic changes of the LSMO film.

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