Broadband-gap ferromagnetic insulator material and preparation method thereof

Abstract

The invention provides a wide-band-gap ferromagnetic insulator material. The chemical formula of the wide-band-gap ferromagnetic insulator material is Cd2CrSbO6. The invention also provides a method for preparing the wide-band-gap ferromagnetic insulator material, which comprises the following steps: (1) sufficiently grinding and mixing CdO, Cr2O3 and Sb2O5 in a protective gas atmosphere to obtain a mixture; (2) sealing and wrapping the mixture, and then carrying out heating and pressurizing treatment; and (3) cooling and depressurizing the treated product obtained in the step (2). The ferromagnetic insulator material Cd2CrSbO6 disclosed by the invention has a potential application value in spintronics devices.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material science and spintronics. Specifically, the present application relates to a wide band gap ferromagnetic insulator material and a preparation method thereof. BACKGROUND

[0002] Ferromagnetic insulator has both ferromagnetic and insulating properties. Ferromagnetic refers to the characteristic of spontaneous magnetization, that is, it will show magnetism without the action of external magnetic field; insulator is a material that does not conduct electricity, limited by its atomic structure, electron conduction is hindered and cannot move freely, showing large resistivity and non-conductivity. Based on this, ferromagnetic insulator has the characteristics of non-volatility of storing information and not introducing charge transfer information, which is conducive to achieving the goal of low power consumption. Ferromagnetic insulator, which transmits only spin momentum and not charge, has been widely concerned due to its potential application in spintronic devices, for example: ferromagnetic insulator can be used as an important component of spin transfer torque in spintronics, and the transmission and storage of spin information can be realized by regulating its magnetization and magnetic moment arrangement.

[0003] However, studies have shown that the ferromagnetism of materials is mostly derived from double exchange mechanism or Ruderman-Kittel-Kasuya-Yosida interaction, which often leads to metallicity. Therefore, in single-phase materials, ferromagnetism and insulating properties are usually intrinsically incompatible. Therefore, the number of intrinsic ferromagnetic insulators is very limited. So far, the reported intrinsic ferromagnetic insulators mainly include sulfur europium (EuO, EuS), two-dimensional van der Waals materials of chromium trihalide (CrI3, CrBr3) and ternary materials of chromium trihalide (Cr2Si2Te6, Cr2Ge2Te6), perovskite materials (BiMnO3, La2NiMnO6, Ba2NaOsO6, CaCu3Mn2Te2O 12 ) and Y3Fe5O 12 In addition, two-dimensional van der Waals ferromagnetic insulators are usually unstable under environmental conditions. For ferromagnetic insulators, a wide band gap (greater than 1.0 eV) can effectively prevent charge carriers from being thermally excited, thereby having application value.

[0004] Double perovskite has a chemical formula of A2BB'O6, and its rich element combination and multiple order make it exhibit rich physical properties and excellent material performance, such as high-temperature semimetal Sr2FeB'O6 (B' is Mo or Re), and high dielectric coefficient ferroelectric materials Ca(La)2TiB'O6 (B' is Cr or Cu) and La2MnB'O6 (B' is Mg, Co or Ni).

[0005] In similar double perovskites with the A2BB’O6chemical formula, ferromagnetic insulating behavior is extremely rare due to the presence of magnetic B atoms (e.g. Cr) that form a tetrahedral lattice with geometric frustration that suppresses the onset of ferromagnetism. For example, Sr2CrSbO6(A = Ca, Sr) double perovskites: a neutron diffraction study, J. Mater. Chem., 2007, 17, 3555) proposed by the prior art (M. Retuerto et al.) is antiferromagnetic; A2LnSbO6(where A is Sr and Ba, and Ln is a lanthanide atom) proposed by the prior art (H. Karunadasa et al., Ba2LnSbO6and Sr2LnSbO6(Ln = Dy, Ho, Gd) double perovskites: Lanthanides in the geometrically frustrating fcc lattice, PNAS, 2003, 100, 8097) is paramagnetic; Sr2MnSbO6proposed by the prior art (S. A. Ivanov et al., Temperature evolution of structure and magnetic properties in the perovskite Sr2MnSbO6, Mater. Res. Bull., 2009, 44, 822) is spin glass; and Sr2CuTeO6proposed by the prior art (O. Mustonen et al., Spin-liquid-like state in a spin-1 / 2 square-lattice antiferromagnet perovskite induced by d 10 -d 0 cation mixing, Nat. Commun., 2018, 9, 1085) is a spin liquid.

[0006] The prior art (see M. Retuerto et al., Synthesis, structure and magnetic properties of the new double perovskite Ca2CrSbO6, Solid State Commun., 2006, 139, 19) discloses a double perovskite material Ca2CrSbO6 which, although exhibiting ferromagnetism and insulating property, has a low Curie temperature of 13 K, i.e. exhibits ferromagnetism only below 13 K. Moreover, in this material, there are about 8% anti-site defects of Cr and Sb. As is well known, anti-site defects can significantly weaken the insulating property of the material, making it prone to problems such as leakage and breakdown in applications.

[0007] Therefore, there is an urgent need for a new wide-bandgap ferromagnetic insulator material which can expand new functional materials in the field of materials science and provide novel material basis for the field of spintronics. SUMMARY

[0008] In view of this, the purpose of the present application is to provide a new wide-bandgap ferromagnetic insulator material and a preparation method thereof. The ferromagnetic insulator material of the present application can expand new functional materials in the field of materials science and provide novel material basis for the field of spintronics.

[0009] The purpose of the present application is achieved by the following technical solutions.

[0010] In one aspect, the present application provides a wide-bandgap ferromagnetic insulator material with a chemical formula of Cd2CrSbO6.

[0011] As is well known in the art, in a double perovskite with a chemical formula of A2BB'O6, changing the chemical element at a certain position can bring unexpected changes to the performance. The inventors of the present application unexpectedly found that the Cd2CrSbO6 material can simultaneously have ferromagnetism and insulating property.

[0012] Preferably, in the wide-bandgap ferromagnetic insulator material according to the present application, the space group of the ferromagnetic insulator material is P21 / n, and the lattice constants are a = 5. 16 A, b = 5. 16 A, c = 12. 62 A, β = 90. 16°. β = 90. 16°.

[0013] Preferably, in the wide-bandgap ferromagnetic insulator material according to the present application, the Curie temperature of the ferromagnetic insulator material is 25 K.

[0014] Preferably, in the wide-bandgap ferromagnetic insulator material according to the present application, the band gap of the ferromagnetic insulator material is 1. 6 eV.

[0015] Preferably, in the wide-gap ferromagnetic insulator material of the present invention, the saturation magnetization of the ferromagnetic insulator material at a temperature of 2K is 2.1 μm. B / fu.

[0016] Preferably, in the wide-bandgap ferromagnetic insulator material of the present invention, X-ray diffraction with a wavelength of 0.065 nm is used, and the X-ray powder diffraction pattern expressed in 2θ angle has diffraction peaks at 8.40°, 8.51°, 10.92°, 13.70°, 13.80°, 13.96°, 16.15°, 16.30°, 19.53°, 19.61°, 22.33°, 23.92°, 24.19°, 27.79°, 26.34°, 27.79°, 31.10°, 37.21°, 42.15°, 44.65°, and 47.32°, with a 2θ angle measurement error of ±0.001°.

[0017] On the other hand, the present invention provides a method for preparing the wide-bandgap ferromagnetic insulator material described herein, which includes the following steps:

[0018] (1) CdO, Cr2O3 and Sb2O5 are thoroughly ground and mixed in a protective gas atmosphere to obtain a mixture;

[0019] (2) After sealing and wrapping the mixture, heat and pressurize it.

[0020] (3) Cool and depressurize the processed product obtained in step (2).

[0021] The high-pressure synthesis method of this invention can effectively shorten the interatomic spacing, cause electron cloud deformation, enhance overlap, and broaden the band structure, thereby changing the electronic structure and the interactions between atoms, and consequently altering bond lengths, symmetry, and other properties. This invention produces a wide-bandgap ferromagnetic insulator material through high-pressure synthesis.

[0022] Preferably, in the method described in this invention, the molar ratio of CdO, Cr2O3, and Sb2O5 in step (1) is CdO:Cr2O3:Sb2O5 = 4:1:1.

[0023] Preferably, in the method described in this invention, the protective gas is selected from one or more of nitrogen, helium, and argon.

[0024] Preferably, in the method of the present invention, the particle size of the mixture after grinding in step (1) is 100–1000 mesh, more preferably 200–600 mesh. According to the method provided by the present invention, the grinding in step (1) includes grinding in an agate mortar for 30 minutes to 5 hours, preferably 1–3 hours.

[0025] Preferably, in the method of the present invention, the treatment in step (2) is carried out under the following conditions: temperature of 800–1200°C and pressure of 5–20 GPa.

[0026] Preferably, in the method described in this invention, the processing in step (2) is carried out for more than 10 minutes, preferably 20–120 minutes, and more preferably 20–60 minutes.

[0027] Preferably, the sealing and wrapping in step (2) is done using a gold capsule or a platinum capsule.

[0028] Preferably, in the method described in this invention, the thickness of the gold capsule or platinum capsule is 0.05–1.00 mm.

[0029] Preferably, in the method described in this invention, the processing in step (2) is carried out in a six-sided anvil press or a two-stage push press of type DIA, Walker, or Kawai.

[0030] Preferably, in the method of the present invention, the cooling in step (3) is carried out by reducing the product to room temperature within 10 hours, more preferably within 20 seconds or 2–10 hours.

[0031] Preferably, in the method of the present invention, the depressurization in step (3) is carried out by reducing the product to ambient pressure over 30 minutes to 20 hours.

[0032] The present invention has the following beneficial effects:

[0033] (1) This invention utilizes a unique high-pressure, high-temperature synthesis method to prepare a stable wide-bandgap ferromagnetic insulator material, Cd₂CrSbO₆. This invention provides a new approach and new ideas for the exploration and discovery of ferromagnetic insulator materials.

[0034] (2) The wide-bandgap ferromagnetic insulator Cd2CrSbO6 of the present invention is a rare material with long-range ferromagnetism among similar structural fault-blocking systems, and has significant research and application value.

[0035] (3) Ferromagnetic and insulating properties are often physically mutually exclusive, and materials that possess both intrinsic ferromagnetism and intrinsic insulation are relatively rare. The wide-bandgap ferromagnetic insulator Cd2CrSbO6 of the present invention provides a novel ferromagnetic insulating material and its preparation method.

[0036] (4) The wide-gap ferromagnetic insulator Cd2CrSbO6 of the present invention has a very small coercivity, which is less than 0.001T, indicating that its magnetization direction is very easy to control and has low energy consumption characteristics in application.

[0037] (5) The wide-bandgap ferromagnetic insulator Cd2CrSbO6 of the present invention has a large magnetization intensity, which reaches 2.1 μ. B / fu.

[0038] (6) The wide bandgap ferromagnetic insulator Cd2CrSbO6 of the present invention has a large bandgap, which reaches 1.6eV, and has good insulation properties.

[0039] (7) The wide-bandgap ferromagnetic insulator Cd2CrSbO6 of the present invention has potential application value in the field of spintronics as a ferromagnetic insulator. Attached Figure Description

[0040] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0041] Figure 1 The X-ray diffraction pattern of the wide-bandgap ferromagnetic insulator Cd2CrSbO6 in Example 1 of the present invention is shown below.

[0042] Figure 2 The curve showing the change in magnetic susceptibility of the wide-gap ferromagnetic insulator Cd2CrSbO6 with temperature in Embodiment 1 of the present invention is shown.

[0043] Figure 3 The curves showing the variation of magnetization intensity with magnetic field strength of the wide-bandgap ferromagnetic insulator Cd2CrSbO6 in Embodiment 1 of the present invention at different temperatures.

[0044] Figure 4 The resistivity curve of the wide-bandgap ferromagnetic insulator Cd₂CrSbO₆ as a function of temperature in Embodiment 1 of the present invention is shown; and

[0045] Figure 5 This is the band structure of the wide bandgap ferromagnetic insulator Cd2CrSbO6 in Embodiment 1 of the present invention. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0047] In the following detailed description of the invention, certain specific details are described in detail. However, those skilled in the art will fully understand the invention even without these details. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail. Unless the context clearly requires it, the terms "comprising," "including," and similar words throughout the specification and claims should be interpreted as encompassing rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0048] Example 1

[0049] CdO, Cr2O3, and Sb2O5 with a purity higher than 99.9% were mixed in a molar ratio of CdO:Cr2O3:Sb2O5 = 4:1:1, resulting in a total powder mass of 0.5 g. The mixture was ground in an argon-filled glove box for 1 hour to obtain a mixture with a particle size of 200 mesh. The mixture was then filled and sealed in gold capsules with a wall thickness of 0.1 mm. The gold capsules were placed in a six-sided anvil press and reacted with the raw materials inside the gold capsules for 30 minutes at a pressure of 8 GPa and a temperature of 900 °C to obtain the reaction product. The heating power was then directly cut off, and the temperature dropped to room temperature within 10 seconds. Subsequently, the pressure was reduced back to atmospheric pressure over 8 hours, and the reaction product was removed from the gold capsules to obtain Cd2CrSbO6.

[0050] Example 2

[0051] CdO, Cr2O3, and Sb2O5 with a purity higher than 99.9% were mixed in a molar ratio of CdO:Cr2O3:Sb2O5 = 4:1:1, resulting in a total powder mass of 1 g. The mixture was then ground for 120 minutes in an argon-filled glove box to obtain a mixture with a particle size of 600 mesh. The mixture was then filled and sealed in platinum capsules with a wall thickness of 0.1 mm. The platinum capsules were placed in a six-sided anvil press and the raw materials inside were reacted for 30 minutes at a pressure of 8 GPa and a temperature of 1000 °C to obtain the reaction product. The temperature was uniformly reduced to room temperature over 2 hours, and then the pressure was reduced back to atmospheric pressure over 8 hours. The reaction product was then removed from the platinum capsules to obtain Cd2CrSbO6.

[0052] Example 3

[0053] CdO, Cr2O3, and Sb2O5 with a purity higher than 99.9% were mixed in a molar ratio of CdO:Cr2O3:Sb2O5 = 4:1:1, resulting in a total powder mass of 1 g. The mixture was then ground for 120 minutes in an argon-filled glove box to obtain a mixture with a particle size of 600 mesh. The mixture was then filled and sealed in gold capsules with a wall thickness of 0.1 mm. The gold capsules were placed in a DIA-type two-stage press and reacted for 20 minutes at a pressure of 10 GPa and a temperature of 1000 °C to obtain the reaction product. The heating power was then directly cut off, and the temperature dropped to room temperature within 10 seconds. Subsequently, the pressure was reduced back to atmospheric pressure over 12 hours, and the reaction product was removed from the platinum capsule to obtain Cd2CrSbO6.

[0054] Example 4

[0055] CdO, Cr2O3, and Sb2O5 with a purity higher than 99.9% were mixed in a molar ratio of CdO:Cr2O3:Sb2O5 = 4:1:1 and ground for 30 minutes in an argon-filled glove box to obtain a mixture with a particle size of 200 mesh. The mixture was then filled and sealed in platinum capsules with a wall thickness of 0.1 mm. The platinum capsules were placed in a Walker-type two-stage press and reacted for 30 minutes at a pressure of 20 GPa and a temperature of 1100 °C to obtain the reaction product. The heating power was then directly cut off, and the temperature dropped to room temperature within 10 seconds. Subsequently, the pressure was reduced back to atmospheric pressure over 15 hours, and the reaction product was removed from the platinum capsules to obtain Cd2CrSbO6.

[0056] Example 5

[0057] CdO, Cr2O3, and Sb2O5 with a purity higher than 99.9% were mixed in a molar ratio of CdO:Cr2O3:Sb2O5 = 4:1:1 and ground for 30 minutes in an argon-filled glove box to obtain a mixture with a particle size of 200 mesh. The mixture was then filled and sealed in platinum capsules with a wall thickness of 0.1 mm. The platinum capsules were placed in a Kawai-type two-stage press and reacted with the raw materials inside the capsules at a pressure of 20 GPa and a temperature of 1100 °C for 1 hour to obtain the reaction product. The temperature was uniformly reduced to room temperature over 2 hours, and then the pressure was reduced back to atmospheric pressure over 20 hours. The reaction product was then removed from the platinum capsules to obtain Cd2CrSbO6.

[0058] Performance measurements

[0059] 1. X-ray diffraction measurement

[0060] The crystal structure was characterized using synchrotron X-rays generated by the BL02B2 beamline of the Spring-8 synchrotron radiation source in Japan. The wavelength was 0.065 nm, and the measurements were performed under ambient temperature and pressure conditions, with a diffraction angle 2θ ranging from 5 to 50°.

[0061] Figure 1 The X-ray diffraction pattern of Cd2CrSbO6 prepared in Example 1 is shown. Figure 1The X-ray powder diffraction pattern of the Cd₂CrSbO₆ material prepared in Example 1, expressed in 2θ angles, is shown using X-ray diffraction at a wavelength of 0.065 nm. The diffraction peaks are observed at 8.40°, 8.51°, 10.92°, 13.70°, 13.80°, 13.96°, 16.15°, 16.30°, 19.53°, 19.61°, 22.33°, 23.92°, 24.19°, 27.79°, 26.34°, 27.79°, 31.10°, 37.21°, 42.15°, 44.65°, and 47.32°. The 2θ angle measurement error is ±0.001°.

[0062] Furthermore, the X-ray spectra were further refined using GSAS software, revealing that the Cd₂CrSbO₆ prepared in Example 1 has a monoclinic phase double perovskite structure, belonging to space group P21 / n, with a lattice constant of [missing value]. β = 90.16°. Notably, Cr and Sb form a fully ordered rock salt structure, without any anti-occupation defects. The fitting parameters for structural refinement are R... wp =4.35%, R p =3.21%, indicating that the refinement results are highly reliable.

[0063] The X-ray diffraction patterns of Cd₂CrSbO₆ prepared in Examples 2–5 were essentially the same as those of the sample in Example 1. The results showed that the Cd₂CrSbO₆ prepared in Examples 2–5 exhibited a monoclinic double perovskite structure, with Cr and Sb forming a rock-salt-type ordered structure belonging to space group P21 / n, and a lattice constant of [missing value]. β = 90.16°.

[0064] 2. Magnetic susceptibility measurement

[0065] The magnetic property measurement system (MPMS) from Quantum Design, Inc. (USA) was used to measure the change in magnetic susceptibility with temperature. Zero field cooling (ZFC) was used without an external magnetic field, and the measurement was performed as the temperature decreased from 320K to 2K. Field cooling (FC) was used with an external magnetic field of 0.1T, and the measurement was performed as the temperature increased from 2K to 320K. The temperature rise and fall rates were 2K per minute.

[0066] Figure 2 The graphs showing the change in magnetic susceptibility as a function of temperature for Cd₂CrSbO₆ prepared in Example 1, measured in ZFC and FC modes, are displayed. Figure 2As shown, the Cd2CrSbO6 prepared in Example 1 underwent a typical paramagnetic-ferromagnetic transition when the temperature dropped to 25K.

[0067] The magnetic susceptibility curves of Cd2CrSbO6 prepared in Examples 2–5 as a function of temperature are basically the same as those of the sample in Example 1. A typical paramagnetic-ferromagnetic transition occurred when the temperature dropped to 25K.

[0068] 3. Magnetization Measurement

[0069] Magnetization was measured at 200K, 50K, and 2K using a Magnetic Property Measurement System (MPMS) from Quantum Design, Inc. At each temperature, the applied magnetic field was decreased from 7T to -7T and then increased back to 7T. The rate of change of the applied magnetic field was 0.01T per second.

[0070] Figure 3 The graph shows the magnetization of Cd₂CrSbO₆ prepared in Example 1 as a function of magnetic field strength. From top to bottom on the left side of the graph, the measurement temperatures for each curve are 200 K, 50 K, and 2 K, respectively. The results show that at temperatures of 50 K and 200 K, above their Curie temperature, the magnetization of the sample is very small and increases linearly with increasing applied magnetic field, exhibiting paramagnetism. At 2 K, below its Curie temperature, the magnetization of the sample increases rapidly with increasing applied magnetic field and reaches saturation, exhibiting typical ferromagnetic characteristics. The saturation magnetization of the Cd₂CrSbO₆ material prepared in Example 1 is approximately 2.1 μm. B / fu indicates the ferromagnetic characteristics of Cd2CrSbO6 and its large saturation magnetization.

[0071] Figure 3 The enlarged illustration shows the magnetization intensity of Cd₂CrSbO₆ prepared in Example 1 as a function of magnetic field strength at 2K. It can be seen that the intercept of the magnetization intensity on the horizontal axis is less than 0.001T, indicating that the coercivity of Cd₂CrSbO₆ prepared in Example 1 is less than 0.001T, suggesting that its magnetization direction is easily reversed and can be easily controlled in applications, exhibiting excellent low-energy consumption characteristics.

[0072] The magnetization of Cd₂CrSbO₆ prepared in Examples 2–5 as a function of magnetic field strength is basically the same as that in Example 1. The results show that at temperatures of 50 K and 200 K, i.e., above its Curie temperature, the magnetization of the sample is very small and increases linearly with increasing applied magnetic field, exhibiting paramagnetism. At a temperature of 2 K, i.e., below its Curie temperature, the magnetization of the sample increases rapidly with increasing applied magnetic field and reaches saturation, exhibiting typical ferromagnetic characteristics. The saturation magnetization of the material is approximately 2.1 μm. B / fu, further demonstrating the ferromagnetic characteristics of Cd2CrSbO6 and its large saturation magnetization.

[0073] 4. Resistivity Measurement

[0074] Resistance measurements were performed using a Physical Property Measurement System (PPMS) from Quantum Design, Inc., USA. Measurements were taken at temperatures ranging from 350K to 2K, with a temperature rise and fall rate of 2K per minute.

[0075] Figure 4 The resistivity of Cd2CrSbO6 prepared in Example 1 as a function of temperature is shown. Figure 4 The resistivity of the Cd2CrSbO6 material prepared in Example 1 increases exponentially with decreasing temperature, indicating that Cd2CrSbO6 has insulating characteristics.

[0076] Similarly, the resistivity curves of Cd2CrSbO6 prepared in Examples 2–5 as a function of temperature are basically the same as those in Example 1. The exponential increase in resistivity with decreasing temperature indicates that Cd2CrSbO6 prepared in Examples 2–5 also has insulating characteristics.

[0077] 5. Band structure calculation

[0078] The band structure of Cd₂CrSbO₆ was calculated using first-principles calculations; the results are shown in [reference needed]. Figure 5 .like Figure 5 As shown, Cd2CrSbO6 has an insulating band structure with a band gap of approximately 1.6 eV, indicating that Cd2CrSbO6 is a wide-bandgap ferromagnetic insulator material.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wide-bandgap ferromagnetic insulator material with the chemical formula Cd₂CrSbO₆.

2. The wide-bandgap ferromagnetic insulator material according to claim 1, wherein, The space group of the ferromagnetic insulator material is P21 / n, and the lattice constant is . β = 90.16°.

3. The wide-bandgap ferromagnetic insulator material according to claim 1, wherein, The Curie temperature of the ferromagnetic insulator material is 25K.

4. The wide-bandgap ferromagnetic insulator material according to claim 1, wherein, The band gap of the ferromagnetic insulator material is 1.6 eV.

5. The wide-bandgap ferromagnetic insulator material according to claim 1, wherein, The ferromagnetic insulator material has a saturation magnetization of 2.1 μ at 2 K. B / fu.

6. The wide-bandgap ferromagnetic insulator material according to claim 1, wherein, Using X-ray diffraction with a wavelength of 0.065 nm, the X-ray powder diffraction pattern expressed in 2θ angles shows diffraction peaks at 8.40°, 8.51°, 10.92°, 13.70°, 13.80°, 13.96°, 16.15°, 16.30°, 19.53°, 19.61°, 22.33°, 23.92°, 24.19°, 27.79°, 26.34°, 27.79°, 31.10°, 37.21°, 42.15°, 44.65°, and 47.32°. The 2θ angle measurement error is ±0.001°.

7. A method for preparing a wide-bandgap ferromagnetic insulator material according to any one of claims 1 to 6, comprising the following steps: (1) CdO, Cr2O3 and Sb2O5 are thoroughly ground and mixed in a protective gas atmosphere to obtain a mixture; (2) After sealing and wrapping the mixture, heat and pressurize it. (3) Cool and depressurize the processed product obtained in step (2).

8. The method according to claim 7, wherein, The molar ratio of CdO, Cr2O3, and Sb2O5 in step (1) is CdO:Cr2O3:Sb2O5 = 4:1:1; Preferably, the protective gas is selected from one or more of nitrogen, helium, and argon; Preferably, the particle size of the mixture after grinding in step (1) is 100-1000 mesh, more preferably 200-600 mesh.

9. The method according to claim 7, wherein, The treatment in step (2) is carried out under the following conditions: temperature of 800-1200℃ and pressure of 5-20GPa.

10. The method according to claim 7, wherein, The processing in step (2) shall be carried out for more than 10 minutes, preferably 20-120 minutes, and more preferably 20-60 minutes; Preferably, the sealing and wrapping in step (2) is done using a gold capsule or a platinum capsule; More preferably, the thickness of the gold capsule or platinum capsule is 0.05-1.00 mm; Preferably, the processing in step (2) is carried out in a six-sided anvil press or a two-stage push press of type DIA, Walker, or Kawai. Preferably, the cooling in step (3) is carried out by reducing the product to room temperature within 10 hours, more preferably within 20 seconds or 2-10 hours; Preferably, the depressurization in step (3) is carried out by reducing the product to ambient pressure over 30 minutes to 20 hours.

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