A high coercivity soft-hard magnetic composite ferrite thin film material and its preparation method

Abstract

The application relates to a preparation method of a high-coercivity high-remanence-ratio composite ferrite film material, which comprises the following steps: (1) preparing a BaFe9Al3O 19 ferrite target material;(2) depositing an amorphous BaFe9Al3O 19 ferrite film on an Al2O3 (000l) substrate by a pulse laser deposition method;(3) placing the grown amorphous BaFe9Al3O 19 ferrite film in a muffle furnace to perform annealing, so as to form BaFe2O4 and BaFe9Al3O 19 composite ferrite films.The application prepares a hexagonal ferrite target material with good compactness by solid-phase method and Al ion doping, and selects a pulse laser deposition technology to deposit a film; BaFe2O4 and BaFe9Al3O 19 composite films are formed by controlling the growth conditions of the film, the characteristics of soft and hard magnetic composite are fully exerted, the magnetic performance of the ferrite film is improved, and finally, the composite ferrite film material with the c-axis out-of-plane orientation and the high-coercivity characteristic is prepared.The application has the characteristics that the coercivity is greater than 1.83T, the remanence ratio reaches 93%, and the application has a good application prospect in the fields of self-biased microwave devices and magnetic recording.

Description

Technical Field

[0001] This technology belongs to the field of ferrite material preparation technology, and specifically relates to a high coercivity soft and hard magnetic composite ferrite thin film material and its preparation method. Background Technology

[0002] Microwave ferrite devices are essential fundamental components in microwave / millimeter-wave electronic equipment and systems, mainly including circulators, isolators, and phase shifters. These devices have important applications in military radar, missiles, military communication equipment, electronic countermeasures, aviation, and aerospace systems, and also have wide applications in many fields such as civilian communications and medical and health care.

[0003] With the development of radar electronics and wireless technology, the next generation of magnetic microwave devices, including circulators, phase shifters, and filters, will be planar, self-biased, and low-loss. To meet the demands of miniaturization, self-biasing, and millimeter-wave application frequencies for circulators, research has begun on M-type ferrites with permanent magnet properties (providing self-biasing) for circulator fabrication. Hexagonal barium ferrite (BaFe) is one such material. 12 O 19 BaM thin films possess advantages such as high saturation magnetization and coercivity, large uniaxial magnetic anisotropy field, and suitable ferromagnetic resonance linewidth (FMR), making them considered an ideal material for self-biased microwave devices. It consists of a four-layer structure, including two spinel structures, two oxygen layers, two hexagonal structures, and three oxygen layers. The unit cell of BaM contains 38O 2- 2Ba 2+ 24Fe 3+ Fe 3+ Ions are distributed at octahedral, tetrahedral, and triangular bipyramidal sites. After orientation treatment, it also exhibits a high remanence ratio, making it an important material for fabricating millimeter-wave circulators. For magnetic recording, appropriately increased coercivity leads to more stable and enhanced information storage, while a larger rectangularity ratio can improve writing efficiency and reduce self-demagnetization, giving BaM (BaMe) potential for application in magnetic recording. To achieve miniaturization and thin-film fabrication of circulators, replacing bulk materials with thin-film barium ferrite materials and designing and fabricating thin-film integrated circulators has become a hot topic in circulator research both domestically and internationally in recent years. However, the maximum coercivity of a single hexagonal ferrite is only 0.5T, which is insufficient to meet the requirements of applications and magnetic recording. Therefore, the development of M-type barium ferrite thin films with high coercivity and high remanence ratio has become an urgent need. Summary of the Invention

[0004] This invention primarily addresses the technical challenge of low remanence ratio in hexagonal ferrite materials used in self-biased circulators, providing a high-coercivity, high-remanence composite ferrite thin film material and its preparation method. Based on the aforementioned background and needs, this invention provides a c-axis out-of-plane oriented BaFe2O4 composite BaFe9Al3O4 with high coercivity and high remanence ratio. 19 A method for preparing ferrite thin films. The composition of the target material is controlled by appropriate main formulation and additive formulation, and then ferrite thin films are deposited on Al2O3(000l) substrates using pulsed laser deposition (PLD) process. By optimizing the growth process, soft and hard magnetic phases are combined to leverage the advantages of dual-phase coupling.

[0005] The prepared composite ferrite film is a composite of a hexagonal ferrite material with hard magnetic characteristics and a spinel structure with soft magnetic characteristics. Based on the coupling effect between the hard and soft magnets, it achieves anisotropy in structure and performance with high coercivity and remanence ratio, and out-of-plane c-axis orientation.

[0006] The technical solution adopted by this invention to solve the aforementioned technical problem is a method for preparing composite ferrite thin films with high coercivity and remanence, comprising the following steps:

[0007] S1 manufactures target materials:

[0008] Using BaCO3, Fe2O3, and Al2O3 as raw materials, according to the molecular formula BaFe9Al3O 19 The molar ratio of Ba, Fe, and Al in the raw material is used to calculate the mass percentage of BaCO3, Fe2O3, and Al2O3.

[0009] Based on the total mass of raw materials, zirconium balls in the ball mill, and alcohol, the raw materials and alcohol are mixed in a mass percentage ratio of 25% raw materials, 45% zirconium balls in the ball mill, and 30% alcohol. The raw materials and alcohol are placed in a ball mill jar for the first ball milling to obtain slurry one.

[0010] The slurry is dried and ground to obtain powder.

[0011] The powder was placed in a muffle furnace for pre-firing at a heating rate of 4°C / min for 3 hours at 1000°C.

[0012] After grinding the pre-calcined product, it is mixed with 25% raw material, 45% zirconium balls from the ball mill and 30% alcohol by mass percentage. The raw material and alcohol are placed in a ball mill jar for a second ball milling to obtain slurry two.

[0013] After drying and grinding the second slurry, powder two is obtained;

[0014] A polyvinyl alcohol solution with a mass concentration of 8% was added to powder two as a binder. The mass of the binder added was 5-10% of the mass of powder two. The mixture was then thoroughly mixed in a mortar to obtain powder three.

[0015] Place the powder into a mold and press to obtain a green body;

[0016] The green blank is placed in a muffle furnace for debinding to obtain a debinded green blank;

[0017] The debinding green body was placed in a muffle furnace and heated to 1300–1350°C. After holding at 1300–1350°C for 3 hours, the temperature was lowered to 800°C at a rate of 4°C / min, and then allowed to cool naturally to room temperature to obtain BaFe9Al3O. 19 Target material;

[0018] S2 cleaning substrate:

[0019] The Al2O3(000l) substrate was ultrasonically cleaned using acetone solution, anhydrous ethanol, and deionized water, respectively, to obtain the substrate.

[0020] Where (000l) represents the Miller index of the crystallographic unit cell;

[0021] S3 deposited thin film:

[0022] The distance between the target material obtained in step S1 and the substrate obtained in step S2 is set to 45 mm, and the gas pressure in the sputtering cavity is pumped down to below 1 × 10⁻⁶ mm. -4 Pa, then heat the substrate to 400-600°C, set the laser frequency to 5Hz and the laser intensity to 350mJ, and maintain the gas pressure in the sputtering chamber at 1×10 -3 Pa ~ 5 × 10 -3 At Pa, an amorphous BaFe9Al3O layer with a thickness of 500–1000 nm was deposited. 19 film;

[0023] S4 annealing and crystallization treatment:

[0024] Amorphous BaFe9Al3O was grown. 19 The substrate of the thin film was placed in a muffle furnace and heated from room temperature to 900–1000°C at a rate of 4°C / min. It was then held at 900–1000°C in air for 3 hours, followed by a cooling rate of 4°C / min to 800°C, and finally allowed to cool naturally to room temperature to obtain c-axis out-of-plane oriented BaFe9Al3O. 19 BaFe2O4 thin films with hard magnetic thin film composite soft magnetic properties.

[0025] Preferably, the conditions for the first and second ball milling are: ball mill speed of 225 r / min and ball milling time of 12 hours.

[0026] Preferably, in step S1, the pressure applied during the pressing process is 12 MPa, and the green blank is pressed into a diameter of 3 cm.

[0027] Preferably, in step S1, the depolymerization process includes the following steps: heating to 650°C, calcining for 3 hours, and depolymerizing polyvinyl alcohol.

[0028] Preferably, the S2 cleaning of the substrate specifically includes the following steps: ultrasonically cleaning the Al2O3(000l) substrate with acetone solution for 10 minutes, then ultrasonically cleaning the substrate with anhydrous ethanol for 10 minutes, finally ultrasonically cleaning with deionized water for 10 minutes, and then drying with nitrogen to obtain the substrate.

[0029] This invention also provides a high coercivity soft-hard magnetic composite ferrite thin film material, comprising an Al2O3(000l) substrate and BaFe9Al3O3 deposited on the Al2O3(000l) substrate. 19 Thin film layer, BaFe9Al3O 19 The thickness of the thin film layer is 500–1000 nm;

[0030] The BaFe9Al3O 19 The thin film layer comprises c-axis out-of-plane oriented hexagonal ferrite BaFe9Al3O 19 The BaFe2O4 phase with a spinel structure;

[0031] The coercivity of the high coercivity soft-hard magnetic composite ferrite thin film material is 18300 Oe, and the remanence ratio is 93%.

[0032] This invention prepares a dense hexagonal ferrite target material by solid-state doping with Al ions, and deposits a thin film using pulsed laser deposition technology. By controlling the growth conditions of the film, the full potential of BaFe2O4 and BaFe9Al3O4 is realized. 19 The advantages of soft and hard magnetic phase coupling are utilized to improve the magnetic properties of hexagonal ferrite thin films, ultimately leading to the fabrication of hexagonal ferrite thin film materials with high coercivity. These materials are characterized by a coercivity of 18300 Oe and a remanence ratio of 93%, showing promising application prospects in self-biased microwave devices and magnetic recording. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Some specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings indicate the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0034] Figure 1 BaFe9Al3O prepared in Example 1 19 XRD pattern of ferrite target material.

[0035] Figure 2 BaFe2O4 / BaFe9Al3O4 prepared in Example 1 19 XRD pattern of composite ferrite thin film.

[0036] Figure 3 BaFe2O4 / BaFe9Al3O4 prepared in Example 1 19 Magnetic hysteresis loop of composite ferrite thin films,

[0037] Figure 4 BaFe prepared in Example 2 9.5 Al 2.5 O 19 XRD pattern of ferrite target material.

[0038] Figure 5 BaFe2O4 / BaFe prepared in Example 2 9.5 Al 2.5 O 19 XRD pattern of composite ferrite thin film.

[0039] Figure 6 BaFe2O4 / BaFe prepared in Example 2 9.5 Al 2.5 O 19 Magnetic hysteresis loop of composite ferrite thin films,

[0040] Figure 7 BaFe2O4 / BaFe prepared in Example 3 9.5 Al 2.5 O 19 XRD pattern of composite ferrite thin film.

[0041] Figure 8 BaFe2O4 / BaFe prepared in Example 3 9.5 Al 2.5 O 19 Hysteresis loop of composite ferrite thin film.

[0042] Figure 9 BaFe2O4 / BaFe9Al3O4 prepared in Example 4 19 XRD pattern of composite ferrite thin film.

[0043] Figure 10 BaFe2O4 / BaFe9Al3O4 prepared in Example 4 19 Hysteresis loop of composite ferrite thin film. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. In this invention, unless otherwise specified, the raw materials and equipment used are commercially available or commonly used in the art. The methods in the embodiments, unless otherwise specified, are conventional methods in the art.

[0045] Example 1:

[0046] (1) Target material preparation: Using BaCO3, Fe2O3, and Al2O3 as raw materials, according to the molecular formula (BaFe9Al3O3... 19 Calculate the mass percentage of each raw material. Based on the total mass of the raw materials, zirconium balls in the ball mill, and alcohol, mix 25% raw materials, 45% zirconium balls, and 30% alcohol. Place the raw materials and alcohol in a ball mill jar for the first ball milling at 225 r / min for 12 hours. Dry and grind the slurry to obtain powder, then pre-calcine it in a muffle furnace at 1000℃ for 3 hours at a heating rate of 4℃ / min. Grind the pre-calcineed product and mix it again with the raw materials in a ball mill jar for a second ball milling at 225 r / min for 12 hours. After drying and grinding the slurry, an 8% (w / w) polyvinyl alcohol solution is added as a binder to the powder. The binder content is 5-10% of the barium ferrite powder mass. The mixture is thoroughly mixed in a mortar. The resulting barium ferrite powder is then placed in a mold and pressed into a green body with a diameter of 3 cm under a pressure of 12 MPa. The green body is placed in a muffle furnace and heated to 650°C for 3 hours to remove PVA. The removed green body is then placed in a muffle furnace and heated to 1300-1350°C for 3 hours. The temperature is then reduced to 800°C at a rate of 4°C / min, and finally allowed to cool naturally to room temperature to obtain BaFe9Al3O. 19 Ferrite target material.

[0047] (2) Cleaning the substrate: First, use acetone solution to ultrasonically clean the Al2O3(000l) substrate for 10 minutes, then use anhydrous ethanol to ultrasonically clean the substrate for 10 minutes, and finally use deionized water to ultrasonically clean the substrate for 10 minutes and dry it with nitrogen.

[0048] (3) Thin film deposition: Before depositing the thin film, the distance between the target and the substrate is first adjusted to 45 mm, and the gas pressure in the sputtering cavity is evacuated to below 1 × 10⁻⁶ mm. -4 Pa, then the substrate is heated to 400–600°C, the laser frequency is set to 5 Hz, and the laser intensity is set to 350 mJ. The chamber pressure is 1 × 10⁻⁶. -3 Pa ~ 5 × 10 -3 At Pa, an amorphous BaFe9Al3O layer with a thickness of 500–1000 nm was deposited. 19 film.

[0049] (4) Annealing and crystallization treatment: The amorphous BaFe9Al3O3 grown on the substrate is then subjected to annealing and crystallization treatment. 19 The substrate of the thin film was placed in a tube furnace and heated from room temperature to 900–1000°C at a rate of 4°C / min. It was then held at 900–1000°C in air for 3 hours, followed by a cooling rate of 4°C / min to 800°C, and finally allowed to cool naturally to room temperature to obtain c-axis out-of-plane oriented BaFe9Al3O. 19 BaFe2O4 thin films with hard magnetic thin film composite soft magnetic properties.

[0050] Figure 1 BaFe9Al3O prepared in Example 1 19 XRD patterns of the target material, from Figure 1 The XRD pattern shows that the product is BaFe9Al3O. 19 Furthermore, the peaks are sharp, indicating good crystal growth. Figure 2 The BaFe2O4 / BaFe9Al3O4 prepared in Example 1 19 The XRD pattern of the composite ferrite film shows that, apart from BaFe9Al3O 19 The formation of the BaFe2O4 phase, as well as the BaFe2O4 phase. Figure 3 The BaFe2O4 / BaFe9Al3O4 prepared in Example 1 19 The hysteresis loop of composite ferrite thin films, from Figure 3 It can be seen that the coercivity of the thin film is 18300 Oe and the remanence ratio is 93%.

[0051] Example 2:

[0052] (1) Target material preparation: Using BaCO3, Fe2O3, and Al2O3 as raw materials, according to the molecular formula (BaFe... 9.5 Al 2.5 O19 Calculate the mass percentage of each raw material. Based on the total mass of the raw materials, zirconium balls in the ball mill, and alcohol, mix 25% raw materials, 45% zirconium balls, and 30% alcohol. Place the raw materials and alcohol in a ball mill jar for the first ball milling at 225 r / min for 12 hours. Dry and grind the slurry to obtain powder, then pre-calcine it in a muffle furnace at 1000℃ for 3 hours at a heating rate of 4℃ / min. Grind the pre-calcineed product and mix it again with the raw materials in a ball mill jar for a second ball milling at 225 r / min for 12 hours. After drying and grinding the slurry, an 8% (w / w) polyvinyl alcohol solution is added as a binder to the powder. The binder content is 5-10% of the barium ferrite powder mass. The mixture is thoroughly mixed in a mortar. The resulting barium ferrite powder is then placed in a mold and pressed into a green body with a diameter of 3 cm under a pressure of 12 MPa. The green body is placed in a muffle furnace and heated to 650°C for 3 hours to remove PVA. The removed green body is then placed in a muffle furnace and heated to 1300-1350°C for 3 hours. The temperature is then reduced to 800°C at a rate of 4°C / min, and finally allowed to cool naturally to room temperature to obtain BaFe. 9.5 Al 2.5 O 19 Ferrite target material.

[0053] (2) Cleaning the substrate: First, use acetone solution to ultrasonically clean the Al2O3(000l) substrate for 10 minutes, then use anhydrous ethanol to ultrasonically clean the substrate for 10 minutes, and finally use deionized water to ultrasonically clean the substrate for 10 minutes and dry it with nitrogen.

[0054] (3) Thin film deposition: Before depositing the thin film, the distance between the target and the substrate is first adjusted to 45 mm, and the gas pressure in the sputtering cavity is evacuated to below 1 × 10⁻⁶ mm. -4 Pa, then the substrate is heated to 400–600°C, the laser frequency is set to 5 Hz, and the laser intensity is set to 350 mJ. The chamber pressure is 1 × 10⁻⁶. -3 ~5×10 -3 Under Pa, an amorphous BaFe layer with a thickness of 500–1000 nm was deposited. 9.5 Al 2.5 O 19 film.

[0055] (4) Annealing and crystallization treatment: The amorphous BaFe grown on the substrate is then subjected to annealing and crystallization treatment. 9.5 Al 2.5 O 19The substrate of the thin film was placed in a tube furnace and heated from room temperature to 900–1000°C at a heating rate of 4°C / min. It was then held at 900–1000°C in air for 3 hours, followed by a cooling rate of 4°C / min to 800°C, and finally allowed to cool naturally to room temperature, yielding c-axis out-of-plane oriented BaFe. 9.5 Al 2.5 O 19 BaFe2O4 thin films with hard magnetic thin film composite soft magnetic properties.

[0056] Figure 4 BaFe prepared in Example 2 9.5 Al 2.5 O 19 XRD patterns of the target material, from Figure 4 The XRD pattern shows that the product is BaFe. 9.5 Al 2.5 O 19 It is a ferrite with sharp peaks and good crystal growth. Figure 5 The BaFe2O4 / BaFe prepared in Example 2 9.5 Al 2.5 O 19 The XRD patterns of the composite ferrite thin film show that, apart from BaFe... 9.5 Al 2.5 O 19 The composite film also exhibits the formation of the BaFe2O4 phase, but the intensity of the diffraction peaks of BaFe2O4 in Example 1 shows a significant decrease, which will be detrimental to the coupling effect between soft and hard magnetic materials. This indicates that the concentration of Al ions in the ferrite film affects the performance of the composite film. Figure 6 The BaFe2O4 / BaFe prepared in Example 2 9.5 Al 2.5 O 19 The hysteresis loop of composite ferrite thin films, from Figure 6 It can be seen that the coercivity of the thin film is 11270 Oe and the remanence ratio is 83%.

[0057] Example 3:

[0058] The target material used was the same as that used in Example 2, except that during the film deposition process, when the substrate was heated to 400–600°C, the chamber was filled with high-purity oxygen (99.999%) and the oxygen pressure was adjusted to 0.08 Pa. All other experimental conditions were the same as in Example 2.

[0059] Figure 7 The BaFe2O4 / BaFe prepared in Example 3 9.5 Al 2.5 O 19 XRD patterns of composite ferrite films, from Figure 7The XRD pattern shows that the product is a highly c-axis oriented BaFe. 9.5 Al 2.5 O 19 Furthermore, the peaks are sharp, indicating good crystal growth. Most importantly, BaFe2O4 is absent, making it difficult to achieve coupling between soft and hard magnetic materials. This suggests that gas pressure during film growth affects the structure of the composite film. Figure 8 The BaFe2O4 / BaFe prepared in Example 3 9.5 Al 2.5 O 19 The hysteresis loop of composite ferrite thin films, from Figure 8 It can be seen that the coercivity of the thin film is 2750 Oe and the remanence ratio is 83.3%.

[0060] Example 4:

[0061] The target material was the same as that in Example 1, except that during the film deposition process, when the substrate was heated to 400-600°C, the chamber was filled with high-purity oxygen with a purity of 99.999%, and the oxygen pressure was adjusted to 0.08 Pa. All other experimental conditions were the same as in Example 1.

[0062] Figure 9 The BaFe2O4 / BaFe9Al3O4 prepared in Example 4 19 The XRD pattern of the composite ferrite thin film shows that BaFe9Al3O has a distinct c-axis orientation. 19 No BaFe2O4 diffraction peaks were observed. Figure 10 The BaFe2O4 / BaFe9Al3O4 prepared in Example 4 19 The hysteresis loop of composite ferrite thin films, from Figure 10 It can be seen that the coercivity of this thin film is only 4230 Oe and the remanence ratio is 95%.

[0063] In recent years, Kranov [doi:10.1063 / 1.2800890] and Hu Bolin [doi:10.1063 / 1.4864043] et al. have also prepared out-of-plane oriented BaM films using liquid phase epitaxy. Although the saturation magnetization and other properties have reached the values ​​required for circulator fabrication, the coercivity (tens of Oersted) of the BaM films prepared by this method is too low, resulting in a very low remanence ratio that cannot achieve self-biasing of the circulator. Soog [doi:10.1063 / 1.1608475] et al. prepared BaM films with perpendicular film orientation on Al2O3 substrates using pulsed laser deposition (PLD). Although the remanence and other properties of the films have been improved, the remanence ratio is still less than 0.3. Li et al. [doi:10.1063 / 1.3272811] studied the effect of a buffer layer on vertically oriented BaM thin films using magnetron sputtering. The buffer layer further improved the remanence ratio of the film, reaching 0.87. However, due to limitations of the magnetron sputtering equipment, BaM thin films could only be deposited and grown at relatively low substrate temperatures.

[0064] in conclusion:

[0065] By doping the target material with Al ions at an appropriate ratio (Al / (Al+Fe)) = 3, barium ferrite thin films were deposited using PLD technology. During the film deposition process, the growth conditions were controlled to maintain the chamber pressure at 1 × 10⁻⁶. -3 ~5×10 -3 Using a laser with a substrate temperature of 400–600 °C, a laser frequency of 5 Hz, and a laser intensity of 350 mJ, the thin film was grown in an amorphous or semi-crystalline state. After annealing at 900–1000 °C, a BaFe9Al3O3 film with c-axis out-of-plane orientation, high coercivity, and high remanence was obtained. 19 The hard magnetic thin film combined with soft magnetic properties of BaFe2O4 film has a coercivity of 18300 Oe and a remanence of 93%. However, changing the pressure of the chamber during film deposition by filling it with oxygen and adjusting the oxygen pressure to 0.08 Pa improved the orientation of the film to some extent. At the same time, the coercivity of the film also decreased significantly due to the disappearance of the BaFe2O4 phase.

[0066] The above description is only a part of the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high coercivity soft-hard magnetic composite ferrite thin film material, characterized in that, The method comprises the following steps: S1: preparing a target material: BaCO3, Fe2O3, Al2O3 as raw materials, according to the molecular formula BaFe9Al3O 19 The mass percentage of BaCO3, Fe2O3, Al2O3 in the raw materials is calculated according to the amount-of-substance ratio of Ba, Fe, and Al. According to the mass percentage of 25% raw material, 45% ball mill zirconium ball and 30% alcohol, the raw material and alcohol are placed in a ball mill tank for first ball milling to obtain slurry one; The slurry one is dried and ground to obtain powder one, The powder one is pre-fired in a muffle furnace at a heating rate of 4 ℃ / min for 3 hours at 1000 ℃; After grinding the pre-fired product, the raw material and alcohol are placed in a ball mill tank for second ball milling according to the mass percentage of 25% raw material, 45% ball mill zirconium ball and 30% alcohol to obtain slurry two; The slurry two is dried and ground to obtain powder two; A polyvinyl alcohol solution with a mass concentration of 8% polyvinyl alcohol is added as an adhesive to the powder two, the mass of the adhesive is 5-10% of the mass of the powder two, and the mixture is uniformly mixed in a mortar to obtain powder three; The powder three is placed in a mold and pressed to obtain a green body; The green body is placed in a muffle furnace for degassing to obtain a green body after degassing; The green body after the glue is discharged is placed in a muffle furnace, heated to 1300-1350 °C, kept for 3 h, then cooled to 800 °C at 4 °C / min, and then cooled to room temperature naturally to obtain BaFe9Al3O 19 Target material S2: cleaning the substrate: The Al2O3(000l) substrate is ultrasonically cleaned with acetone solution, anhydrous ethanol and deionized water to obtain a substrate. S3: depositing a thin film: The distance between the target material obtained in step S1 and the substrate obtained in step S2 is set to 45mm, the gas pressure in the sputtering chamber is extracted to be lower than 1x10 -4 Pa, the substrate is heated to 400-600℃, the laser frequency is set to 5Hz, the laser intensity is set to 350mJ, the gas pressure in the sputtering chamber is kept to be 1x10 -3 Pa-5x10 -3 Pa, and a layer of amorphous BaFe9Al3O 19 thin film with a thickness of 500-1000nm is deposited. S4: annealing and crystallization treatment: The substrate with amorphous BaFe9Al3O 19 The substrate with amorphous BaFe9Al3O 19 BaFe2O4 thin film with hard-magnetic thin film composite soft-magnetic characteristics.

2. The method for preparing a high coercivity soft-hard magnetic composite ferrite thin film material as described in claim 1, characterized in that, The conditions of the first ball milling and the second ball milling are as follows: the rotation speed of the ball mill is 225 r / min, and the ball milling time is 12 hours.

3. The method of claim 1, wherein the high-coercivity soft-hard magnetic composite ferrite thin film material is prepared by the steps of: preparing a soft magnetic ferrite thin film material on a substrate; and depositing a hard magnetic thin film material on the soft magnetic ferrite thin film material. In the S1, the pressure applied in the pressing process is 12 MPa, and the green body with a diameter of 3 cm is pressed.

4. The method of claim 1, wherein the high-coercivity soft-hard magnetic composite ferrite thin film material is prepared by the steps of: preparing a soft magnetic ferrite thin film material on a substrate; and depositing a hard magnetic thin film material on the soft magnetic ferrite thin film material. In the S1, the degassing process comprises the following steps: heating to 650 ℃, calcining for 3 h, and discharging polyvinyl alcohol.

5. The method for preparing a high coercivity soft-hard magnetic composite ferrite thin film material as described in claim 1, characterized in that, The S2 cleaning the substrate specifically comprises the following steps: the Al2O3(000l) substrate is ultrasonically cleaned with acetone solution for 10 minutes, then ultrasonically cleaned with anhydrous ethanol for 10 minutes, finally ultrasonically cleaned with deionized water for 10 minutes, and dried with nitrogen to obtain a substrate.

6. A high-coercivity soft-hard magnetic composite ferrite thin film material, which is produced by the production method of the high-coercivity soft-hard magnetic composite ferrite thin film material according to claim 1, characterized by comprising an Al203(0001) substrate and BaFe9Al3O 19 a thin film layer of BaFe9Al3O 19 the thickness of the thin film layer is 500-1000 nm; The BaFe9Al3O 19 The thin film layer comprises c-axis out-of-plane oriented hexagonal ferrite BaFe9Al3O 19 The phase and spinel structure BaFe2O4 phase; the coercivity of the high coercivity soft and hard magnetic composite ferrite thin film material is 18300 Oe, and the remanence ratio is 93%.

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