Two-dimensional Van der Waals ferromagnetic quantum material with high Curie temperature as well as preparation method and application of two-dimensional Van der Waals ferromagnetic quantum material

Abstract

The invention discloses a two-dimensional Van der Waals ferromagnetic quantum material with high Curie temperature and a preparation method and application thereof, the quantum material is of a two-dimensional nanosheet crystal structure and belongs to a layered Van der Waals material, and the chemical formula of the quantum material is InFeTe3; the two-dimensional InFeTe3 crystal has a hexagonal structure, and the lattice constant # imgabs0 # # imgabs1 # belongs to a trigonal system and a P3m1 space group; the method comprises the following steps: mixing In, Fe and Te elementary substances, pre-crystallizing to obtain an InFeTe metal block, and sublimating, transferring and crystallizing the metal block under vacuum sealing by adopting a double-temperature-zone tubular furnace to obtain millimeter-level InFeTe3 crystals with silver metal luster; stripping and transferring the InFeTe3 crystal, and then annealing the InFeTe3 crystal in inert gas to obtain a few-layer two-dimensional InFeTe3 crystal; the preparation method disclosed by the invention has the characteristics of simplicity, low energy consumption and high repeatability, and the two-dimensional InFeTe3 crystal prepared by the preparation method disclosed by the invention has the characteristics of high saturation magnetization and high Curie temperature, and can be applied to spin electronic devices and quantum devices.

Description

Technical Field

[0001] The invention belongs to the technical field of nano-magnetic material preparation, and specifically relates to a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature and a preparation method and application thereof. Background Art

[0002] Two-dimensional ferromagnetic materials have attracted extensive scientific attention due to their potential applications in future nanoscale magnetic storage technology, spin electronics, and quantum computing. In low-dimensional systems, even weak magnetic exchange interactions can lead to the emergence of ferromagnetism due to the reduced thermodynamic fluctuations caused by the reduced dimensionality. Therefore, two-dimensional van der Waals materials are an ideal platform for studying room-temperature ferromagnetism. Since the first experimental discovery of the two-dimensional ferromagnet CrI in 2017, 3 and Cr 2 Ge 2 Te 6 Since then, researchers have never stopped their pursuit of finding higher Curie temperatures in two-dimensional materials. A high Curie temperature not only means that these materials can maintain their magnetism over a wider temperature range, but also are better compatible with other electronic or photonic devices. Therefore, the development of two-dimensional ferromagnetic materials with high Curie temperatures, especially materials that can operate above room temperature, has become an important research direction in this field.

[0003] However, most of the two-dimensional ferromagnetic materials discovered so far are still below room temperature, and only a few materials can reach room temperature levels of 300K and above. 3 GaTe 2 with large perpendicular magnetic anisotropy.Nat.Commun.2022) et al. reported a two-dimensional van der Waals material Fe 3 GaTe 2, the material has a Curie temperature of 367K, but its application scenarios in industry or research at higher temperatures are still limited; Ma Xiang (Xiang Ma, Ruimin Li, Bo Zheng, Lizhen Huang, Ying Zhang, Shasha Wang, Changlong Wang, Haige Tan, Yalin Lu, Bin Xiang. Ferromagnetism above Room Temperature in Two Intrinsic van der Waals Magnets with Large Coercivity. NanoLett. 2023) et al. reported a MnSiTe 3 The material has a Curie temperature of 378K, which is also the Curie temperature of room temperature, but it is still subject to insurmountable limitations in applications at higher temperatures. The Russian patent with the announcement number RU2002112306A in 2002 disclosed a high Curie temperature ferromagnetic semiconductor material, but the ferromagnetic semiconductor material was prepared by solid phase synthesis, which takes a long time to prepare and is difficult to accurately control the reaction conditions. The produced crystal products are prone to defects; the ferromagnetic semiconductor material prepared by solid phase synthesis belongs to the cubic crystal system, and its Curie temperature only reaches 773K. There is no mention of its key properties such as saturation magnetization at room temperature, and the ferromagnetic semiconductor material does not have a van der Waals layered structure, which cannot meet the current demand for high-performance room temperature two-dimensional ferromagnetic materials in the development of spin electronics devices and quantum information. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the object of the present invention is to provide a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature and a preparation method and application thereof, wherein high-purity In, Fe, and Te are mixed and pre-crystallized into InFeTe 3 The mixed metal blocks are then mixed with the transport agent I 2 Synthesis of InFeTe by vacuum chemical vapor transport 3 Crystals, after mechanical exfoliation transfer, a few or single layers of two-dimensional InFeTe 3 The crystal has a simple preparation method, low energy consumption in the production process, good product quality and high repeatability; the prepared two-dimensional InFeTe 3 The crystal has a van der Waals structure, can be dissociated into a two-dimensional scale, and has a high saturation magnetization intensity and a high Curie temperature. Compared with the two-dimensional ferromagnetic materials in the prior art, the two-dimensional InFeTe prepared by the present invention is 3 The crystal has the strongest room-temperature saturation magnetization and the highest Curie temperature among current two-dimensional ferromagnetic materials, which has greatly promoted the development and practical production application of two-dimensional ferromagnetic quantum materials and related devices.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, the quantum material is a two-dimensional nanosheet crystal structure, belongs to a layered van der Waals material, and its chemical formula is InFeTe 3 ; The two-dimensional InFeTe 3 The crystal has a hexagonal structure, and the lattice constant It belongs to the trigonal crystal system, P3m1 space group.

[0007] The two-dimensional InFeTe 3 The crystals are millimeter-scale flake blocks, and after dissociation they become two-dimensional few-layer structures, with the thinnest being 4.2nm, or 6-10 monoatomic layers.

[0008] The two-dimensional InFeTe 3 The crystal has room temperature ferromagnetism, with a saturation magnetization of 42-44emu / g at room temperature, a phase transition temperature of about 832-856K, and a Curie temperature greater than 1000K.

[0009] A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature comprises the following steps:

[0010] The uniformly mixed powdered metal elements In, Fe and Te are sealed in a quartz reaction tube under negative pressure, and the mixed raw materials are heat-treated in a single-temperature zone tube furnace to pre-crystallize them into small gray-black metal blocks; the metal blocks are mixed with a transport agent I 2 The raw materials are vacuum sealed in a dual-zone tube furnace. The temperature of the dual-zone is controlled by a program to sublimate the raw materials in the raw material zone and quickly cool down to room temperature after the growth process. After the cooling, millimeter-sized InFeTe with a silvery white metallic luster can be collected in the growth zone. 3 Crystal; InFeTe 3 The crystal was peeled off and transferred, and annealed in an inert atmosphere to obtain a few-layer two-dimensional InFeTe 3 Crystals, that is, two-dimensional van der Waals ferromagnetic quantum materials with high Curie temperature.

[0011] In molar ratio, In powder:Fe powder:Te powder = 1:(1-3):(1-3), transport agent I 2 The mass of the crystal is 4%-6% of the total mass of the raw materials; the In powder, Fe powder, Te powder and I 2 The purity of the crystals is greater than or equal to 99.9%.

[0012] The heat treatment process is:

[0013] Place the vacuum-sealed quartz tube in a single-temperature zone tubular furnace. The temperature control program is as follows: heat from room temperature to 900°C / h at 30-50°C / h, and keep warm for 10-30 hours to allow the raw materials to fully undergo solid reaction. After the insulation is completed, cool to room temperature within 72 hours.

[0014] The growth control process is:

[0015] The heat-treated metal block and the transport agent I 2 The vacuum sealed quartz tube is placed in a double temperature zone tubular furnace, and the temperature control program of the double temperature zones is started at the same time. The temperature control program is as follows: the raw material zone is heated from room temperature to 740-840℃ at 30-50℃ / h, kept warm for 20-60h, and then naturally cooled to room temperature; the growth zone is heated from room temperature to 640-740℃ at 30-50℃ / h, kept warm for 20-60h; after the program is completed, it is cooled to room temperature within 1h.

[0016] The annealing temperature is 140-160° C., and the annealing time is 2-3 hours; the inert gas is nitrogen or argon.

[0017] The present invention also provides the above-mentioned two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, or a two-dimensional InFeTe prepared according to the above-mentioned method for preparing the two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature. 3 Application of crystals in spin-orbit torque devices or spin resistors.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention greatly enhances the metal gas phase stability during chemical vapor transport by pre-crystallizing high-purity In, Fe, and Te single substances, ensures uniform crystal growth, can form crystals with long-range ordered structures and long-range magnetic order, and improves the crystallization quality of the crystals.

[0020] 2. Two-dimensional InFeTe prepared by the present invention 3 Lattice constant of a crystal It belongs to the trigonal system and P3m1 space group. Due to the special electronic structure and atomic arrangement of the crystal, the orbitals have a higher overlap, which leads to enhanced ferromagnetic exchange. 3 The crystal itself is a van der Waals two-dimensional material. The reduction in dimensionality increases the localization of the electronic state, resulting in enhanced interactions between electrons and reduced effects of lattice vibrations. These factors together enhance the performance of InFeTe 3 The ferromagnetic exchange in the crystal allows the electron spins to remain stably aligned in parallel at temperatures far above room temperature, so the two-dimensional InFeTe 3 The crystals exhibit strong saturation magnetization and Curie temperature.

[0021] 3. Two-dimensional InFeTe prepared by the present invention 3 The crystal has the characteristics of high saturation magnetization and high Curie temperature, which is suitable for micro-nano processing technologies such as electron beam lithography and ion beam etching, and has greatly promoted the development and application of spin electronic devices and quantum devices under high temperature conditions.

[0022] In summary, compared with the solid phase synthesis method in the prior art, the present invention mixes high-purity In, Fe, and Te elements and pre-crystallizes them into InFeTe 3 The mixed metal blocks are then mixed with the transport agent I 2 Millimeter-sized InFeTe with silvery white metallic luster was synthesized by vacuum chemical vapor transport under vacuum sealing conditions. 3 Crystals can be obtained by mechanical exfoliation and transfer to obtain a few or single layers of two-dimensional InFeTe 3 The preparation method of the present invention has the characteristics of simple method, low energy consumption in the production process, good product quality and high repeatability. The prepared two-dimensional InFeTe 3 The crystal is characterized by high saturation magnetization and high Curie temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The two-dimensional InFeTe prepared in Example 2 3 Schematic diagram of the c-plane structure of the crystal.

[0024] Figure 2 InFeTe prepared in Example 2 before stripping 3 Optical image of the crystal.

[0025] Figure 3 The two-dimensional InFeTe prepared in Example 2 3 AFM image of the crystal.

[0026] Figure 4 The two-dimensional InFeTe prepared in Example 2 3 MFM phase shift plot of the crystal.

[0027] Figure 5 The two-dimensional InFeTe prepared in Example 2 3 XRD spectrum of the crystals.

[0028] Figure 6 The two-dimensional InFeTe prepared in Example 2 3 XPS spectrum of the crystals.

[0029] Figure 7 The two-dimensional InFeTe prepared in Example 2 3 Low-resolution TEM image of the crystal, where Figure 7 a is a TEM image, Figure 7 b is the distribution diagram of In element, Figure 7 c is the distribution diagram of Fe element, Figure 7 d is the Te element distribution diagram.

[0030] Figure 8 The two-dimensional InFeTe prepared in Example 2 3 High-resolution TEM image of the crystal.

[0031] Fig. 9 The two-dimensional InFeTe prepared in Example 2 3 Deflected SHG image of the crystal.

[0032] Fig.10 The two-dimensional InFeTe prepared in Example 2 and Example 5 3 The MT curve of the crystal, where Fig.10 a is Example 2, Fig.10 b is Example 5.

[0033] Fig.11 The two-dimensional InFeTe prepared in Example 2 and Example 5 3 MH curves of crystals at different temperatures, where: Fig.11 a is Example 2, Fig.11 b is Example 5.

[0034] Fig.12 This is an optical picture of the silver-white alloy with irregular morphology prepared in Comparative Example 1.

[0035] Fig.13 This is an optical picture of the black and colorful block alloy with irregular morphology prepared in Comparative Example 2. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only embodiments of a part of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0037] like Figure 1 As shown, a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature is a two-dimensional nanosheet crystal structure with a few layers or a single layer, which belongs to a layered van der Waals material and has a chemical formula of InFeTe 3 , 2D InFeTe 3 The crystal has a hexagonal structure, and the lattice constant Belongs to the trigonal system, P3m1 space group; the two-dimensional InFeTe 3 The thickness of the crystal is at least 4.2nm, which is 6-10 monoatomic layers.

[0038] A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, using In, Fe, and Te as raw materials, and synthesizing InFeTe by vacuum chemical vapor transport method 3 The block is obtained after mechanical peeling and transfer; the specific steps include:

[0039] Step 1: Weigh powder raw materials In, Fe, and Te to form a mixed powder; in terms of molar ratio, In powder:Fe powder:Te powder=1:(1-3):(1-3); the purity of the In powder, Fe powder, and Te powder is greater than or equal to 99.9%;

[0040] Step 2: Load the mixed powder formed in step 1 into a quartz reaction tube, and vacuum seal the mixed powder in the quartz reaction tube under the protection of liquid nitrogen;

[0041] Step 3: Place the sealed quartz reaction tube in a single-temperature zone tube furnace for heat treatment. The temperature of the single temperature zone is controlled by a program to allow the various components in the mixed powder to react fully to obtain small gray-black metal blocks.

[0042] The heat treatment process is:

[0043] Place the vacuum-sealed quartz tube in a single temperature zone, and the temperature control program is as follows: heat from room temperature to 900°C / h at 30-50°C / h, and keep warm for 10-30h to allow the raw materials to fully react in a solid state. After the end of the heat preservation, cool to room temperature within 72h. Rapid cooling can inhibit the growth of impurities and improve the quality of crystals.

[0044] Step 4: Weigh 4%-6% of the total mass of the raw materials 2 The crystals are mixed with the gray-black small metal blocks obtained in step 3, placed in a quartz reaction tube, and vacuum-sealed in the quartz reaction tube under the protection of liquid nitrogen; the I 2 The purity of the powder is greater than or equal to 99.9%;

[0045] Step 5: Place the sealed quartz reaction tube in a dual-temperature zone tube furnace for thermal growth. The temperature of the dual-temperature zone is controlled by a program to allow the components in the mixed powder to react fully and grow InFeTe with a silvery white metallic luster. 3 Crystals;

[0046] The growth control process is:

[0047] The transport agent I 2The vacuum sealed quartz tube is placed in a dual temperature zone tube furnace, and the temperature control program is as follows: the raw material zone is heated from room temperature to 740-840℃ at 30-50℃ / h, kept warm for 20-60h, so that the raw material sublimates, and then naturally cools to room temperature; the growth zone is heated from room temperature to 640-740℃ at 30-50℃ / h, kept warm for 20-60h, so that the gaseous molecules sublimated in the raw material zone are deposited, crystallized and grown in the growth zone; the window temperature interval between the raw material zone and the growth zone is 100℃, which can ensure that the crystal is fully crystallized and grown; the dual temperature zones start the temperature control program at the same time, so that the raw material sublimates and grows in the transport medium I 2 With the assistance of 3 After the program is completed, the air flow on the surface of the quartz tube is enhanced by a blower or other mechanical equipment to cool it to room temperature within 1 hour. Setting the growth zone temperature to 740-840℃ can effectively avoid the formation of by-products such as indium telluride and iron telluride.

[0048] Step 6: Use peeling tape to remove the InFeTe obtained in step 5 3 The crystals are peeled off into few-layer or single-layer two-dimensional nanosheets and transferred to a rigid substrate. The organic residues are removed by annealing under the protection of nitrogen or argon to obtain clean few-layer or single-layer two-dimensional InFeTe 3 Crystal, that is, a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature; the annealing temperature is 140-160° C., and the annealing time is 2-3 hours;

[0049] The stripping process is:

[0050] Use peeling tape to 3 The crystal is covered on both sides, and uniform pressure is applied to the area covering the sample, and then the tape is quickly torn off; the peeled sample is covered again with new tape, and the peeling process is repeated to obtain a few-layer or single-layer two-dimensional InFeTe 3 Crystal, repeated at least 4 times; a few layers or a single layer of two-dimensional InFeTe 3 The crystal is attached to a rigid substrate, uniformly pressed, and then the tape is uniformly torn off to obtain a few or single layers of two-dimensional InFeTe 3 Crystal.

[0051] Example 1

[0052] A two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, wherein the quantum material is a two-dimensional nanosheet crystal structure and belongs to a layered van der Waals material. 3 The crystal has a hexagonal structure, and the lattice constant Belongs to the trigonal system, P3m1 space group; the two-dimensional InFeTe 3The crystal is a few-layer structure with a minimum thickness of 4.2 nm. 3 The crystal has room temperature ferromagnetism, with a saturation magnetization of 42.5emu / g at room temperature, a phase transition temperature of 850K, and a Curie temperature greater than 1000K.

[0053] A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature comprises the following steps:

[0054] Step 1: 89.9 mg of In powder, 131.25 mg of Fe powder, and 300 mg of Te powder were mixed in a molar ratio of 1:3:3 to form a mixed powder;

[0055] Step 2: Place the mixed powder into a quartz reaction tube and use a high vacuum pump to pump the pressure inside the reaction tube to 10 -4 Pa or less, and then immerse the end of the reaction tube in liquid nitrogen for protection, and use a flame gun to vacuum seal the mixed powder in the quartz reaction tube;

[0056] Step 3: Place the sealed quartz reaction tube in a single-temperature zone tubular furnace for heat treatment. Set the temperature control program of the single temperature zone as follows: heat up from room temperature at 30°C / h to 900°C / h, and keep warm for 10 hours to allow the raw materials to fully undergo solid reaction. After the end of the heat preservation, cool to room temperature for 70 hours to obtain small gray-black metal blocks.

[0057] Step 4: Add 20.85 mg of I 2 The crystals were mixed with small gray-black metal pieces and placed in a quartz reaction tube. A high vacuum pump was used to evacuate the pressure inside the reaction tube to 10 -4 Pa, then the end of the reaction tube was immersed in liquid nitrogen for protection, and a flame gun was used to 2 The crystal and the small gray-black metal block are vacuum-sealed in a quartz reaction tube;

[0058] Step 5: Place the sealed quartz tube in a dual-temperature zone tube furnace, heat the raw material zone from room temperature to 740°C at 30°C / h, keep it warm for 24 hours, sublime the raw material, and then cool it naturally to room temperature; heat the growth zone from room temperature to 640°C at 30°C / h, keep it warm for 24 hours, so that the gaseous molecules sublimated in the raw material zone are deposited, crystallized and grown in the growth zone; start the temperature control program in the dual temperature zones at the same time, so that the raw material is sublimated and placed in the transport medium I 2 With the assistance of 3 After the procedure, the quartz tube was cooled to room temperature within 1 hour by a blower to obtain millimeter-sized InFeTe with a silvery white metallic luster. 3 Crystals;

[0059] Step 6: Use the peeling tape to 3The crystal is covered on both sides, and uniform pressure is applied to the area covering the sample, followed by rapid removal of the tape. 3 The crystal was peeled into two parts, one of which was covered with new tape again, and the peeling process was repeated; after repeating 6 times, the crystal with a few layers of InFeTe 3 The crystal tape is attached to a rigid substrate, uniformly pressed, and then the tape is uniformly torn off to obtain a few layers of two-dimensional InFeTe on the substrate. 3 crystal; then a few layers of two-dimensional InFeTe 3 The rigid substrate of the crystal was transferred to a tube furnace filled with argon, heated to 150 °C, and kept warm for 2 h for annealing. After annealing, it was naturally cooled to room temperature to obtain a clean few-layer two-dimensional InFeTe 3 Crystals, that is, two-dimensional van der Waals ferromagnetic quantum materials with high Curie temperature.

[0060] Example 2

[0061] A two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, wherein the quantum material is a two-dimensional nanosheet crystal structure and belongs to a layered van der Waals material. 3 The crystal has a hexagonal structure, and the lattice constant Belongs to the trigonal system, P3m1 space group; the two-dimensional InFeTe 3 The crystal is a few-layer structure with the thinnest thickness of 9.4nm. 3 The crystal has room temperature ferromagnetism, with a saturation magnetization of 43.5emu / g at room temperature, a phase transition temperature of 856K, and a Curie temperature greater than 1000K.

[0062] A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature comprises the following steps:

[0063] Step 1: 89.9 mg of In powder, 131.25 mg of Fe powder, and 200 mg of Te powder were mixed in a molar ratio of 1:3:2 to form a mixed powder;

[0064] Step 2: The mixed powder formed in step 1 is placed in a quartz reaction tube, and the pressure inside the reaction tube is pumped down to 10 -4 Pa or less, and then immerse the end of the reaction tube in liquid nitrogen for protection, and use a flame gun to vacuum seal the mixed powder in the quartz reaction tube;

[0065] Step 3: Place the sealed quartz reaction tube in a single-temperature zone tubular furnace for heat treatment. Set the temperature control program of the single temperature zone as follows: heat up from room temperature at 35°C / h to 900°C / h, and keep warm for 18h to allow the raw materials to fully undergo solid reaction. After the end of the heat preservation, cool to room temperature for 40h to obtain small gray-black metal blocks.

[0066] Step 4: 21.05 mg of I 2 The crystals were mixed with small gray-black metal pieces and placed in a quartz reaction tube. A high vacuum pump was used to evacuate the pressure inside the reaction tube to 10 -4 Pa, then the end of the reaction tube was immersed in liquid nitrogen for protection, and a flame gun was used to 2 The crystal and the small gray-black metal block are vacuum-sealed in a quartz reaction tube;

[0067] Step 5: Place the quartz tube in a dual-temperature zone tube furnace, heat the raw material zone from room temperature to 780°C at 35°C / h, keep it warm for 30 hours, sublime the raw material, and then naturally cool it to room temperature; heat the growth zone from room temperature to 680°C at 35°C / h, keep it warm for 30 hours, so that the gaseous molecules sublimated in the raw material zone are deposited, crystallized and grown in the growth zone; start the temperature control program in the dual temperature zones at the same time, so that the raw material is sublimated and placed in the transport agent I 2 With the assistance of 3 After the procedure, the quartz tube was cooled to room temperature within 1 hour by a blower to obtain millimeter-sized InFeTe with a silvery white metallic luster. 3 Crystals;

[0068] Step 6: Use the peeling tape to 3 The crystal is covered on both sides, and uniform pressure is applied to the area covering the sample, followed by rapid removal of the tape. 3 The crystal was peeled into two parts, one of which was covered with new tape again, and the peeling process was repeated; after repeating 7 times, the crystal with a few layers of InFeTe 3 The crystal tape is attached to a rigid substrate, uniformly pressed, and then the tape is uniformly torn off to obtain a few layers of two-dimensional InFeTe on the substrate. 3 crystal; then a few layers of two-dimensional InFeTe 3 The rigid substrate of the crystal was transferred to a tube furnace filled with argon, heated to 140 °C, and kept warm for 3 h for annealing. After annealing, it was naturally cooled to room temperature to obtain a clean few-layer two-dimensional InFeTe 3 Crystals, that is, two-dimensional van der Waals ferromagnetic quantum materials with high Curie temperature.

[0069] Example 3

[0070] A two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, wherein the quantum material is a two-dimensional nanosheet crystal structure and belongs to a layered van der Waals material. 3 The crystal has a hexagonal structure, and the lattice constant Belongs to the trigonal system, P3m1 space group; the two-dimensional InFeTe 3The crystal is a few-layer structure with the thinnest thickness of 14.7nm. 3 The crystal has room temperature ferromagnetism, with a saturation magnetization of 43.1emu / g at room temperature, a phase transition temperature of 838K, and a Curie temperature greater than 1000K.

[0071] A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature comprises the following steps:

[0072] Step 1: 89.9 mg of In powder, 87.5 mg of Fe powder, and 200 mg of Te powder were mixed in a molar ratio of 1:2:2 to form a mixed powder;

[0073] Step 2: Place the mixed powder into a quartz reaction tube and use a high vacuum pump to pump the pressure inside the reaction tube to 10 -4 Pa or less, and then immerse the end of the reaction tube in liquid nitrogen for protection, and use a flame gun to vacuum seal the mixed powder in the quartz reaction tube;

[0074] Step 3: Place the sealed quartz reaction tube in a single-temperature zone tubular furnace for heat treatment. Set the temperature control program of the single temperature zone as follows: heat up from room temperature at 40°C / h to 900°C / h, and keep warm for 24 hours to allow the raw materials to fully undergo solid reaction. After the end of the heat preservation, cool to room temperature for 72 hours to obtain small gray-black metal blocks.

[0075] Step 4: 22.64 mg of I 2 The crystals were mixed with small gray-black metal pieces and placed in a quartz reaction tube. A high vacuum pump was used to evacuate the pressure inside the reaction tube to 10 -4 Pa, then the end of the reaction tube was immersed in liquid nitrogen for protection, and a flame gun was used to 2 The crystal and the small gray-black metal block are vacuum-sealed in a quartz reaction tube;

[0076] Step 5: Place the quartz tube in a dual-temperature zone tube furnace, heat the raw material zone from room temperature to 800°C at 40°C / h, keep it warm for 40 hours, sublime the raw material, and then cool it naturally to room temperature; heat the growth zone from room temperature to 700°C at 40°C / h, keep it warm for 40 hours, so that the gaseous molecules sublimated in the raw material zone are deposited, crystallized and grown in the growth zone; start the temperature control program in the dual temperature zones at the same time, so that the raw material sublimates and is transported in the transport medium I. 2 With the assistance of 3 After the procedure, the quartz tube was cooled to room temperature within 1 hour by a blower to obtain millimeter-sized InFeTe with a silvery white metallic luster. 3 Crystals;

[0077] Step 6: Use the peeling tape to 3The crystal is covered on both sides, and uniform pressure is applied to the area covering the sample, followed by rapid removal of the tape. 3 The crystal was peeled into two parts, one of which was covered with new tape again, and the peeling process was repeated; after repeating 5 times, the crystal with a few layers of InFeTe 3 The crystal tape is attached to a rigid substrate, uniformly pressed, and then the tape is uniformly torn off to obtain a few layers of two-dimensional InFeTe on the substrate. 3 crystal; then a few layers of two-dimensional InFeTe 3 The rigid substrate of the crystal was transferred to a tube furnace filled with nitrogen, heated to 150°C, and kept warm for 3 hours for annealing. After annealing, it was naturally cooled to room temperature to obtain a clean few-layer two-dimensional InFeTe 3 Crystals, that is, two-dimensional van der Waals ferromagnetic quantum materials with high Curie temperature.

[0078] Example 4

[0079] A two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, wherein the quantum material is a two-dimensional nanosheet crystal structure and belongs to a layered van der Waals material. 3 The crystal has a hexagonal structure, and the lattice constant Belongs to the trigonal system, P3m1 space group; the two-dimensional InFeTe 3 The crystal is a few-layer structure with a minimum thickness of 5.6 nm. 3 The crystal has room temperature ferromagnetism, with a saturation magnetization of 42.9emu / g at room temperature, a phase transition temperature of 847K, and a Curie temperature greater than 1000K.

[0080] A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature comprises the following steps:

[0081] Step 1: 89.9 mg of In powder, 43.75 mg of Fe powder, and 300 mg of Te powder were mixed in a molar ratio of 1:1:3 to form a mixed powder;

[0082] Step 2: Place the mixed powder formed in step 1 into a quartz reaction tube and use a high vacuum pump to pump the pressure inside the reaction tube to 10 -4 Pa or less, and then immerse the end of the reaction tube in liquid nitrogen for protection, and use a flame gun to vacuum seal the mixed powder in the quartz reaction tube;

[0083] Step 3: Place the sealed quartz reaction tube in a single-temperature zone tubular furnace for heat treatment. Set the temperature control program of the single temperature zone as follows: heat up from room temperature at 45°C / h to 900°C / h, and keep warm for 28h to allow the raw materials to fully undergo solid reaction. After the end of the heat preservation, cool to room temperature for 72h to obtain small gray-black metal blocks.

[0084] Step 4: Add 20 mg of I 2 The crystals were mixed with small gray-black metal pieces and placed in a quartz reaction tube. A high vacuum pump was used to evacuate the pressure inside the reaction tube to 10 -4 Pa, then the end of the reaction tube was immersed in liquid nitrogen for protection, and a flame gun was used to 2 The crystal and the small gray-black metal block are vacuum-sealed in a quartz reaction tube;

[0085] Step 5: Place the quartz tube in a dual-temperature zone tubular furnace, heat the raw material zone from room temperature to 820°C at 45°C / h, keep it warm for 50 hours, sublime the raw material, and then naturally cool it to room temperature; heat the growth zone from room temperature to 720°C at 45°C / h, keep it warm for 50 hours, so that the gaseous molecules sublimated in the raw material zone are deposited, crystallized and grown in the growth zone; start the temperature control program in the dual temperature zones at the same time, so that the raw material is sublimated and placed in the transport medium I 2 With the assistance of 3 After the procedure, the quartz tube was cooled to room temperature within 1 hour by a blower to obtain millimeter-sized InFeTe with a silvery white metallic luster. 3 Crystals;

[0086] Step 6: Use the peeling tape to 3 The crystal is covered on both sides, and uniform pressure is applied to the area covering the sample, followed by rapid removal of the tape. 3 The crystal was peeled into two parts, one of which was covered with new tape again, and the peeling process was repeated; after repeating 5 times, the crystal with a few layers of InFeTe 3 The crystal tape is attached to a rigid substrate, uniformly pressed, and then the tape is uniformly torn off to obtain a few layers of two-dimensional InFeTe on the substrate. 3 crystal; then a few layers of two-dimensional InFeTe 3 The rigid substrate of the crystal was transferred to a tube furnace filled with nitrogen, heated to 160°C, and kept warm for 2 hours for annealing. After annealing, it was naturally cooled to room temperature to obtain a clean few-layer two-dimensional InFeTe 3 Crystals, that is, two-dimensional van der Waals ferromagnetic quantum materials with high Curie temperature.

[0087] Example 5

[0088] A two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, wherein the quantum material is a two-dimensional nanosheet crystal structure and belongs to a layered van der Waals material. 3 The crystal has a hexagonal structure, and the lattice constant Belongs to the trigonal system, P3m1 space group; the two-dimensional InFeTe 3The crystal is a few-layer structure with a thickness of 12.4 nm at its thinnest. 3 The crystal has room temperature ferromagnetism, with a saturation magnetization of 42.3emu / g at room temperature, a phase transition temperature of 832K, and a Curie temperature greater than 1000K.

[0089] A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature comprises the following steps:

[0090] Step 1: 89.9 mg of In powder, 43.75 mg of Fe powder, and 100 mg of Te powder were mixed at a molar ratio of 1:1:1 to form a mixed powder;

[0091] Step 2: Place the mixed powder into a quartz reaction tube and use a high vacuum pump to pump the pressure inside the reaction tube to 10 -4 Pa or less, and then immerse the end of the reaction tube in liquid nitrogen for protection, and use a flame gun to vacuum seal the mixed powder in the quartz reaction tube;

[0092] Step 3: Place the sealed quartz reaction tube in a single-temperature zone tubular furnace for heat treatment. Set the temperature control program of the single temperature zone as follows: heat up from room temperature at 50°C / h to 900°C / h, and keep warm for 30 hours to allow the raw materials to fully undergo solid reaction. After the end of the heat preservation, cool to room temperature for 72 hours to obtain small gray-black metal blocks.

[0093] Step 4: Add 14 mg of I 2 The crystals were mixed with small gray-black metal pieces and placed in a quartz reaction tube. A high vacuum pump was used to evacuate the pressure inside the reaction tube to 10 -4 Pa, then the end of the reaction tube was immersed in liquid nitrogen for protection, and a flame gun was used to 2 The crystal and the small gray-black metal block are vacuum-sealed in a quartz reaction tube;

[0094] Step 5: Place the quartz tube in a dual-temperature zone tube furnace, heat the raw material zone from room temperature to 840°C at a rate of 50°C / h, keep it warm for 60 hours, sublime the raw material, and then naturally cool it to room temperature; heat the growth zone from room temperature to 740°C at a rate of 50°C / h, keep it warm for 60 hours, so that the gaseous molecules sublimated in the raw material zone are deposited, crystallized, and grown in the growth zone; start the temperature control program in the dual temperature zones at the same time, so that the raw material is sublimated and placed in the transport medium I 2 With the assistance of 3 After the procedure, the quartz tube was cooled to room temperature within 1 hour by a blower to obtain millimeter-sized InFeTe with a silvery white metallic luster. 3 Crystals;

[0095] Step 6: Use the peeling tape to 3The crystal is covered on both sides, and uniform pressure is applied to the area covering the sample, followed by rapid removal of the tape. 3 The crystal is peeled into two parts, one of which is covered with new tape again, and the peeling process is repeated; after repeating 4 times, the crystal with a few layers of InFeTe 3 The crystal tape is attached to a rigid substrate, uniformly pressed, and then the tape is uniformly torn off to obtain a few layers of two-dimensional InFeTe on the substrate. 3 crystal; then a few layers of two-dimensional InFeTe 3 The rigid substrate of the crystal was transferred to a tube furnace filled with nitrogen, heated to 160°C, and kept warm for 3 hours for annealing. After annealing, it was naturally cooled to room temperature to obtain a clean few-layer two-dimensional InFeTe 3 Crystals, that is, two-dimensional van der Waals ferromagnetic quantum materials with high Curie temperature.

[0096] Comparative Example 1

[0097] The process and parameters of this comparative example 1 are the same as those of Example 2, except that: in step 5, the raw material zone is heated from room temperature to 1000° C. at a rate of 35° C. / h, kept at that temperature for 30 hours, so that the raw material is sublimated, and then naturally cooled to room temperature; the growth zone is heated from room temperature to 900° C. at a rate of 35° C. / h, kept at that temperature for 30 hours, and after the program is completed, the quartz tube is cooled to room temperature within 1 hour by a blower, and an InFeTe alloy with irregular morphology is obtained, which cannot be peeled off; Fig.12 As shown, when the temperature of the crystal growth zone is 900°C, the product is a silver-white alloy with irregular morphology.

[0098] Comparative Example 2

[0099] The process and parameters of Comparative Example 1 are the same as those of Example 2, except that the mixed powder formed by In powder, Fe powder and Te powder is not heat treated, but In powder, Fe powder, Te powder and I powder are directly mixed. 2 The mixed powder formed by the crystal is placed in a double-temperature zone tube furnace and sealed for thermal growth, and an InFeTe alloy with irregular morphology is obtained, which cannot be peeled off; Fig.13 As shown, the product prepared by the raw material-free heat treatment process is a black and colorful block alloy with irregular morphology.

[0100] like Figure 1 As shown in the atomic structure diagram, the two-dimensional InFeTe prepared in Example 2 3 The crystal structure belongs to the trigonal system, P3m1 space group, composed of Figure 1 It can be seen that Te-In-Te-Fe-Te atoms are arranged alternately.

[0101] like Figure 2 As shown in the optical photograph, the InFeTe prepared in Example 2 before peeling 3The crystal appears as a millimeter-scale bulk structure with a silvery-white metallic luster. Due to the smooth and flat surface of the sample, the light is totally reflected and appears black.

[0102] like Figure 3 As shown in the atomic force microscopy morphology, the two-dimensional InFeTe prepared in Example 2 3 The thinnest crystal thickness reaches 4.2nm, which is about 6-10 monoatomic layers, and also has a layered layer structure, indicating that the preparation method of the present invention has successfully prepared a two-dimensional nanosheet crystal with a few-layer layer structure.

[0103] like Figure 4 As shown in the magnetic force microscope phase image, the two-dimensional InFeTe prepared in Example 2 3 The crystal can detect magnetic phase shift signals of different intensities on ultra-thin multilayer two-dimensional nanosheet crystals, indicating that InFeTe 3 The crystal still retains obvious room temperature ferromagnetism, and has a tendency for the magnetic strength to increase with increasing thickness.

[0104] like Figure 5 As shown in the XRD spectrum, the two-dimensional InFeTe prepared in Example 2 3 The crystals have sharp interlayer diffraction peaks at 14.2°, 28.5°, 43.3°, and 58.9°, respectively, indicating that the two-dimensional InFeTe 3 The crystals have highly oriented crystal plane arrangement and good crystal quality.

[0105] like Figure 6 As shown in the XPS spectrum, the two-dimensional InFeTe prepared in Example 2 3 The crystal exhibits Te3d at 572.98eV and 583.28eV 3 / 2 With Te3d 5 / 2 The peaks at 703.28eV and 704.78eV show that Fe2p 1 / 2 With Fe2p 3 / 2 The peaks of 445.28eV and 452.88eV show that In3d 3 / 2 With In3d 5 / 2 The peak of 3 The crystals formed In-Fe-Te chemical bonds and had good crystal quality.

[0106] like Figure 7 As shown in the low-magnification transmission electron microscope image and element distribution map, Figure 7 a is two-dimensional InFeTe 3 The morphology of the crystal after peeling is Figure 7 It can be seen that the two-dimensional InFeTe prepared in Example 23 After the crystal is peeled off, it has a distinct layered structure; Figure 7 b. Figure 7 c and Figure 7 d shows that the two-dimensional InFeTe 3 In, Fe and Te elements are clearly distributed on the crystal, and each element is evenly distributed in the crystal layered structure.

[0107] like Figure 8 As shown in the high-magnification transmission electron microscopy image, the two-dimensional InFeTe prepared in Example 2 3 The crystal has an ideal lattice structure. Figure 8 shows the two-dimensional InFeTe 3 Atomic image of crystal c-plane, lattice constant The P3m1 space group indicates that the two-dimensional InFeTe 3 The crystals have extremely high crystalline quality and ideal microstructure.

[0108] like Fig. 9 As shown in the deflected SHG spectrum, the two-dimensional InFeTe prepared in Example 2 3 The crystal has a three-fold rotational symmetry, which is consistent with the properties of its P3m1 space group, indicating that the two-dimensional InFeTe 3 The crystal has an ideal crystal structure.

[0109] like Fig.10 Two-dimensional InFeTe prepared in Example 2 and Example 5 under an external magnetic field of 1000 Oe 3 The MT spectrum of the crystal shows that the two-dimensional InFeTe prepared in Example 2 under an external magnetic field of 100Oe 3 The phase transition temperature of the crystal is 856K ( Fig.10 a), 2D InFeTe prepared in Example 5 under 100Oe external magnetic field 3 The phase transition temperature of the crystal is 832K ( Fig.10 b), indicating that the two-dimensional InFeTe prepared by the present invention 3 The crystal has stable ferromagnetism at 400-100K.

[0110] like Fig.11 Two-dimensional InFeTe prepared in Example 2 and Example 5 at room temperature 3 The MH spectrum of the crystal shows that the two-dimensional InFeTe prepared in Example 2 3 The saturation magnetization of the crystal is 43.5emu / g ( Fig.11 a), two-dimensional InFeTe prepared in Example 5 3 The saturation magnetization of the crystal is 42.3emu / g ( Fig.11 b), indicating that the two-dimensional InFeTe prepared by the present invention3 The crystals are strongly ferromagnetic at room temperature.

Claims

1. A two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, characterized in that: The quantum material is a two-dimensional nanosheet crystal structure, belonging to a layered van der Waals material, and its chemical formula is InFeTe3; the two-dimensional InFeTe3 crystal has a hexagonal structure, and the lattice constant It belongs to the trigonal crystal system, P3m1 space group.

2. The high Curie temperature two-dimensional van der Waals ferromagnetic quantum material according to claim 1, characterized in that: The two-dimensional InFeTe3 crystal is a millimeter-scale flake block, which becomes a two-dimensional few-layer structure after dissociation, and its thinnest thickness is 4.2nm, that is, 6-10 monoatomic layers.

3. The high Curie temperature two-dimensional van der Waals ferromagnetic quantum material according to claim 1, characterized in that: The two-dimensional InFeTe3 crystal has room temperature ferromagnetism, a saturation magnetization of 42-44emu / g at room temperature, a phase transition temperature of 832-856K, and a Curie temperature greater than 1000K.

4. A method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature, characterized in that: The following steps are involved: The uniformly mixed powdered metal elements In, Fe and Te are sealed in a quartz reaction tube under negative pressure conditions, and the mixed raw materials are heat treated in a single-temperature zone tubular furnace to pre-crystallize them into a gray-black metal block; the metal block and the transport agent I2 are vacuum-sealed in a double-temperature zone tubular furnace, and the temperature of the double temperature zones is controlled by a program to allow the raw materials to sublime in the raw material zone, and then quickly cooled to room temperature after the growth program is completed; millimeter-scale InFeTe3 crystals with a silvery-white metallic luster can be collected in the growth zone after the cooling is completed; the InFeTe3 crystals are peeled and transferred by a mechanical peeling method, and annealed in an inert atmosphere to obtain a few-layer two-dimensional InFeTe3 crystal, that is, a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature.

5. The method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature according to claim 4, characterized in that: In terms of molar ratio, In powder:Fe powder:Te powder=1:(1-3):(1-3), the mass of the transport agent I2 crystal is 4%-6% of the total mass of the raw materials; the purity of the In powder, Fe powder, Te powder and I2 crystal is greater than or equal to 99.9%.

6. The method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature according to claim 4, characterized in that: The heat treatment process is: Place the vacuum-sealed quartz tube in a single-temperature zone tubular furnace. The temperature control program is as follows: heat from room temperature to 900°C / h at 30-50°C / h, and keep warm for 10-30 hours to allow the raw materials to fully undergo solid reaction. After the insulation is completed, cool to room temperature within 72 hours.

7. The method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature according to claim 4, characterized in that: The growth control process is: A vacuum-sealed quartz tube containing the heat-treated metal block and the transport agent I2 is placed in a double-temperature-zone tubular furnace, and the temperature control program of the double-temperature zones is started simultaneously. The temperature control program is as follows: the raw material zone is heated from room temperature to 740-840°C at 30-50°C / h, kept warm for 20-60h, and then naturally cooled to room temperature; the growth zone is heated from room temperature to 640-740°C at 30-50°C / h, kept warm for 20-60h; after the program is completed, it is cooled to room temperature within 1h.

8. The method for preparing a two-dimensional van der Waals ferromagnetic quantum material with a high Curie temperature according to claim 4, characterized in that: The annealing temperature is 140-160° C., and the annealing time is 2-3 hours; the inert gas is nitrogen or argon.

9. Application of the two-dimensional van der Waals ferromagnetic quantum material with high Curie temperature according to any one of claims 1 to 3, or the two-dimensional InFeTe3 crystal prepared according to the preparation method of the two-dimensional van der Waals ferromagnetic quantum material with high Curie temperature according to any one of claims 4 to 8 in spin-orbit torque devices or spin resistors.

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