Two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmion and high Curie temperature characteristic as well as preparation method and application of two-dimensional ferromagnetic Co2Si / Co3Si nanosheet
Two-dimensional ferromagnetic Co2Si/Co3Si nanosheets were prepared in a dual-temperature zone tube furnace using chemical vapor deposition, solving the problem of controllable preparation of high-quality nanosheets. This process also achieved the stability and high Curie temperature of magnetic skyrmions at room temperature, expanding their applications in spintronics and magnetic storage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-06
- Publication Date
- 2026-04-14
AI Technical Summary
Existing technologies lack controllable and reproducible preparation methods, making it difficult to obtain high-quality two-dimensional Co2Si nanosheets and Co3Si nanosheets. Furthermore, achieving stable magnetic skyrmion structures and high Curie temperatures at room temperature limits their application in spintronic devices and magnetic storage.
Two-dimensional ferromagnetic Co2Si/Co3Si nanosheets were prepared by using chemical vapor deposition (CVD) in a dual-temperature zone tube furnace with CoCl2 powder as the cobalt source, shredded silicon wafers as the silicon source, and fluorinated mica sheets as the growth substrate, under an inert gas environment and by controlling the reaction temperature and time.
Two-dimensional nanosheets with stable ferromagnetic properties and high Curie temperature were prepared at room temperature. The generation and annihilation of magnetic skyrmions could be achieved by applying an external magnetic field, which is suitable for spintronic devices and magnetic storage.
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Figure CN121849970A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of magnetic materials technology, specifically to a two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics, as well as its preparation method and application. Background Technology
[0002] With the rapid development of information technology and microelectronics, spintronic devices based on electron spin degrees of freedom have shown significant application prospects in non-volatile memory, low-power logic devices, and novel information processing fields. Among them, magnetic skyrmions, as a spin structure with topological protection properties, possess advantages such as small size, high stability, and the ability to be driven at low current densities, and are considered potential information carriers for next-generation high-density magnetic memory and spin logic devices. However, existing magnetic skyrmion material systems mostly rely on multilayer thin film structures or heavy metal / ferromagnetic heterojunction interfaces, which involve complex fabrication processes, high requirements for interface quality, and significant challenges in achieving stable magnetic skyrmions at room temperature.
[0003] Transition metal silicides possess potential applications in microelectronics and spintronics due to their excellent thermal stability, electrical properties, and good compatibility with silicon-based processes. Among them, cobalt silicides such as Co₂Si and Co₃Si have been studied to some extent in bulk or thin-film form, but related research mainly focuses on their structure and electrical properties. Systematic research on their magnetic behavior at the two-dimensional nanoscale, especially ferromagnetism, Curie temperature, and magnetic skyrmion properties, remains limited. Furthermore, existing technologies lack a controllable and reproducible preparation method to obtain high-quality two-dimensional Co₂Si and Co₃Si nanosheets, achieving stable magnetic skyrmion structures and high Curie temperatures at room temperature, thus limiting their further applications in spintronic devices and magnetic storage.
[0004] Therefore, this invention provides two-dimensional ferromagnetic Co2Si nanosheets and Co3Si nanosheets with room temperature magnetic skyrmions and high Curie temperature characteristics, as well as their preparation methods and applications. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention focuses on the controllable preparation and magnetic property regulation of two-dimensional cobalt silicide magnetic materials, providing a two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics, along with its preparation method and applications. This invention achieves selective growth of two-dimensional cobalt silicide nanosheets on fluorinated mica sheets through chemical vapor deposition in a dual-temperature zone tube furnace. The two-dimensional cobalt silicide nanosheets exhibit stable ferromagnetic properties at room temperature, enabling the appearance and annihilation of magnetic skyrmions under an applied magnetic field. Simultaneously, they possess a high Curie temperature, allowing for further applications in spintronic devices and magnetic storage.
[0006] To achieve the above objectives, the specific technical solution of this invention is as follows:
[0007] In a first aspect, the present invention provides a two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics. This nanosheet is obtained by placing a cobalt source in a low-temperature region, a silicon source in a high-temperature region, and a fluorinated mica sheet above the silicon source in the high-temperature region, followed by chemical vapor deposition in a dual-temperature tube furnace under an inert gas environment. The room-temperature magnetic skyrmions and high Curie temperature characteristics of the two-dimensional ferromagnetic Co2Si / Co3Si nanosheet can achieve the generation and annihilation of magnetic skyrmions at room temperature (300 K) through the control of an external magnetic field.
[0008] Furthermore, the two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics exhibit typical two-dimensional structural features, with a hexagonal sheet-like morphology, a lateral dimension of 5-50 μm, and a thickness of 20-300 nm.
[0009] Furthermore, the mass ratio of the cobalt source to the silicon source is 1:0.5-1.
[0010] Furthermore, the cobalt source is anhydrous cobalt chloride (CoCl2) powder; the silicon source is shredded silicon wafers, the planar dimensions of which are 1-2 mm and the thickness is 0.7-1 mm.
[0011] Furthermore, the inert gas is argon (Ar), and the argon flow rate during the chemical vapor deposition reaction is 80-100 sccm, preferably 100 sccm; before heating for the chemical vapor deposition reaction, 800 sccm of argon is introduced to clean the tube furnace to remove impurities inside the furnace.
[0012] A second aspect of the present invention provides a method for preparing two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics, comprising the following steps: placing a cobalt source in a low-temperature region, placing a silicon source in a high-temperature region, and placing a fluorine-crystal mica sheet above the silicon source in the high-temperature region; performing a chemical vapor deposition reaction in an inert gas environment using a dual-temperature zone tube furnace to complete the selective growth of the two-dimensional nanosheets, thereby obtaining two-dimensional ferromagnetic Co2Si nanosheets or Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics.
[0013] This invention uses CoCl2 powder as the sole cobalt source, shredded silicon wafers as the sole silicon source, and fluorinated mica sheets as the growth substrate for two-dimensional cobalt silicide nanosheets. The fluorinated mica sheets possess a high operating temperature, good stability, and vacuum tightness, meeting the requirements for substrate flatness and stability during the growth of two-dimensional nanosheets. In chemical vapor deposition (CVD), the substrate actively participates in the growth process of two-dimensional nanosheets and significantly influences their structure and properties. Using fluorinated mica sheets as the growth substrate in this invention further promotes the acquisition of high-quality two-dimensional cobalt silicide nanosheets with stable specific properties. Furthermore, during the growth of two-dimensional cobalt silicide nanosheets, reaction temperature and time significantly affect the formation and quality of the target product. Too short a reaction time makes it difficult for two-dimensional cobalt silicide nanosheets to form, while an appropriate reaction time is beneficial for improving the yield and crystal quality of the target nanosheets.
[0014] In the specific implementation process, the reaction temperature and reaction time in the dual-temperature zone are adjusted to control the different cobalt silicide phases. When the target product is a two-dimensional ferromagnetic Co2Si nanosheet, the reaction temperature in the low-temperature zone is controlled at 700-730℃, the reaction temperature in the high-temperature zone is controlled at 850-900℃, and the reaction time is controlled at 10-20 min, preferably 15 min. When the target product is a two-dimensional ferromagnetic Co3Si nanosheet, the reaction temperature in the low-temperature zone is also controlled at 700-730℃, the reaction temperature in the high-temperature zone is controlled at 800-850℃, and the reaction time is controlled at 5-10 min, preferably 10 min.
[0015] A third aspect of this invention provides the application of the two-dimensional ferromagnetic Co2Si nanosheets or Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics in the fields of magnetic storage or spintronics. This invention verifies, through tests using magnetic force microscopy, a physical property measurement system, and magneto-optical Kerr microscopy, that the two-dimensional ferromagnetic Co2Si nanosheets and Co3Si nanosheets possess stable room-temperature ferromagnetism and a high Curie temperature. Furthermore, under the control of an applied magnetic field, they can achieve the generation and annihilation of room-temperature magnetic skyrmions, demonstrating broad application prospects in spintronics, low-power information storage, and other fields.
[0016] Compared with the prior art, the advantages of the present invention are:
[0017] 1. This invention utilizes a chemical vapor deposition process, employing CoCl2 powder as the sole cobalt source, fragmented silicon wafers as the sole silicon source, and fluorinated mica sheets as the growth substrate for two-dimensional cobalt silicide nanosheets. Under controllable reaction and growth parameters, two-dimensional ferromagnetic Co2Si nanosheets and Co3Si nanosheets are prepared. The preparation method has a clear process flow, strong parameter controllability, and good repeatability, making it suitable for the preparation and research of two-dimensional cobalt silicide magnetic materials.
[0018] 2. The two-dimensional ferromagnetic Co2Si nanosheets and Co3Si nanosheets prepared according to the method of the present invention exhibit stable ferromagnetic properties at room temperature and have a high Curie temperature. Moreover, the two-dimensional ferromagnetic Co2Si nanosheets and Co3Si nanosheets can achieve the generation and annihilation of magnetic skyrmions by external magnetic field control at room temperature, showing potential application value in the fields of magnetic storage and spintronics. Attached Figure Description
[0019] Figure 1 This is a schematic diagram illustrating the principle of preparing two-dimensional ferromagnetic Co2Si / Co3Si nanosheets using chemical vapor deposition in this invention.
[0020] Figure 2 Atomic force microscopy (A) and thickness characterization results (B) of the two-dimensional ferromagnetic Co2Si nanosheets in Example 1 of this invention are shown.
[0021] Figure 3 This is the elemental distribution diagram of the energy dispersive X-ray spectrum of the two-dimensional ferromagnetic Co2Si nanosheets in Example 1 of the present invention;
[0022] Figure 4 These are high-resolution transmission electron microscope images of the two-dimensional ferromagnetic Co2Si nanosheets in Example 1 of the present invention; wherein, image a is a high-resolution transmission electron microscope image; and image b is a selected area electron diffraction pattern.
[0023] Figure 5 This is the elemental distribution diagram of the energy dispersive X-ray spectrum of the two-dimensional ferromagnetic Co3Si nanosheets in Example 2 of the present invention;
[0024] Figure 6 This is a high-resolution transmission electron microscope image of the two-dimensional ferromagnetic Co3Si nanosheets in Example 2 of the present invention;
[0025] Figure 7 The magnetization of the two-dimensional ferromagnetic Co2Si nanosheets in Experiment Example 1 of this invention is shown as the field-cooled and zero-field-cooled curves of temperature variation.
[0026] Figure 8The magnetization of the two-dimensional ferromagnetic Co3Si nanosheets in Experiment Example 1 of this invention is shown as the field-cooled and zero-field-cooled curves of temperature variation.
[0027] Figure 9 The images show the magneto-optical Kerr effect imaging and hysteresis loop of the two-dimensional ferromagnetic Co2Si nanosheets in Experimental Example 1 of this invention; wherein, Figure a shows the magneto-optical Kerr effect imaging of the two-dimensional ferromagnetic Co2Si nanosheets at 1000 Oe, Figure b shows the magneto-optical Kerr effect imaging of the two-dimensional ferromagnetic Co2Si nanosheets at -1000 Oe, and Figure c shows the magneto-optical Kerr effect hysteresis loop of the two-dimensional ferromagnetic Co2Si nanosheets.
[0028] Figure 10 The generation and annihilation process of magnetic skyrmions were obtained by magnetic force microscopy under different external magnetic field conditions in Experiment 2 of this invention for two-dimensional ferromagnetic Co2Si nanosheets; wherein, the external magnetic field in Figure a is 0 Oe, the external magnetic field in Figure b is 500 Oe, the external magnetic field in Figure c is 1100 Oe, and the external magnetic field in Figure d is 4000 Oe.
[0029] Figure 11 The generation and annihilation processes of magnetic skyrmions were obtained by Lorentz transmission electron microscopy of two-dimensional ferromagnetic Co2Si nanosheets under different applied magnetic fields in Experimental Example 2 of this invention; wherein, the applied magnetic field in Figure a is 0 T, the applied magnetic field in Figure b is 340 mT, the applied magnetic field in Figure c is 430 mT, and the applied magnetic field in Figure d is 628 mT. Detailed Implementation
[0030] To enable those skilled in the art to clearly and completely understand the technical solution of the present invention, the present invention will be further described in detail below with reference to embodiments. Obviously, the embodiments described herein are only for explaining the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0031] This invention provides a two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics. It is obtained by placing a cobalt source in a low-temperature region, a silicon source in a high-temperature region, and a fluorine-crystal mica sheet above the silicon source in the high-temperature region, and performing a chemical vapor deposition reaction in an inert gas environment using a dual-temperature zone tube furnace. The two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics can achieve the generation and annihilation of magnetic skyrmions at room temperature (300 K) by controlling the external magnetic field.
[0032] The method for preparing two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics, such as... Figure 1As shown, a dual-temperature zone tube furnace is used for chemical vapor deposition. CoCl2 powder is placed in the low-temperature zone as a cobalt source, and shredded silicon wafers (with a planar size of 1-2 mm and a thickness of 0.7-1 mm) are placed in the high-temperature zone as a silicon source. Fluorocrystalline mica sheets are placed above the silicon source in the high-temperature zone. Selective growth of two-dimensional nanosheets is completed in an inert gas environment to obtain two-dimensional ferromagnetic Co2Si nanosheets or Co3Si nanosheets with room temperature magnetic skyrmions and high Curie temperature characteristics.
[0033] By controlling the growth conditions such as reaction temperature and reaction time, two-dimensional Co2Si nanosheets and Co3Si nanosheets with different stoichiometric ratios and crystal structures can be selectively obtained. In some examples, the reaction temperature in the low-temperature region is controlled at 700-730 ℃, the reaction temperature in the high-temperature region is controlled at 850-900 ℃, and the reaction time is controlled at 10-20 min, thus obtaining two-dimensional ferromagnetic Co2Si nanosheets; similarly, the reaction temperature in the low-temperature region is controlled at 700-730 ℃, the reaction temperature in the high-temperature region is controlled at 800-850 ℃, and the reaction time is controlled at 5-10 min, thus obtaining two-dimensional ferromagnetic Co3Si nanosheets.
[0034] The preparation methods of two-dimensional ferromagnetic Co2Si nanosheets and Co3Si nanosheets are described in detail below through Examples 1 and 2; and their room temperature ferromagnetic behavior and magnetic skyrmion properties are illustrated in conjunction with Experiments 1 and 2.
[0035] Example 1
[0036] This embodiment provides a two-dimensional ferromagnetic Co2Si nanosheet, the specific preparation steps of which are as follows:
[0037] (1) Place anhydrous CoCl2 powder in the low-temperature zone of a dual-temperature zone tube furnace, place shredded silicon wafers in the high-temperature zone of the dual-temperature zone tube furnace, and use fluorinated mica sheets as growth substrates, placing them directly above the shredded silicon wafers in the high-temperature zone; wherein the mass ratio of anhydrous CoCl2 powder to shredded silicon wafers is 1:0.8.
[0038] (2) After cleaning the quartz tube with argon gas at a flow rate of 800 sccm for 10 min, the temperature of the low-temperature zone is raised to 730 ℃ and the temperature of the high-temperature zone is raised to 870 ℃.
[0039] (3) Argon gas with a flow rate of 100 sccm is continuously introduced during the reaction process to transport the cobalt source vapor generated in the low temperature zone to the high temperature zone and react with the silicon source to grow on the surface of the fluorine crystal mica sheet.
[0040] (4) After the reaction continued for 15 min, the heating was stopped and then the mixture was allowed to cool naturally to room temperature to obtain two-dimensional ferromagnetic Co2Si nanosheets grown on fluorine crystal mica sheets.
[0041] Figure 2 The atomic force microscopy (AFM) image (a) and thickness characterization results (b) of the two-dimensional ferromagnetic Co2Si nanosheets prepared in this embodiment show that the two-dimensional ferromagnetic Co2Si nanosheets have a hexagonal morphology and a relatively uniform thickness.
[0042] Figure 3 The image shows the elemental distribution of the two-dimensional ferromagnetic Co2Si nanosheets prepared in this embodiment using energy dispersive X-ray spectroscopy (EDS). As can be seen from the image, Co and Si elements are uniformly distributed in the two-dimensional ferromagnetic Co2Si nanosheets.
[0043] Figure 4 The images shown are high-resolution transmission electron microscope (HRTEM) images of the two-dimensional ferromagnetic Co2Si nanosheets prepared in this embodiment. Image a is a HRTEM image, and image b is a selected area electron diffraction (SAED) image. Clear lattice fringes can be observed in image a, with a hexagonal atomic structure and interplanar spacing consistent with Co2Si, indicating that the two-dimensional ferromagnetic Co2Si nanosheets have good crystallinity. In image b, the (101) crystal plane of Co2Si is marked with a red circle, and its interplanar spacing, after measurement, also conforms to the interplanar spacing parameters of Co2Si.
[0044] Example 2
[0045] This embodiment provides a two-dimensional ferromagnetic Co3Si nanosheet, the specific preparation steps of which are as follows:
[0046] (1) Place anhydrous CoCl2 powder in the low-temperature zone of a dual-temperature zone tube furnace, place shredded silicon wafers in the high-temperature zone of the dual-temperature zone tube furnace, and use fluorinated mica sheets as growth substrates, placing them directly above the shredded silicon wafers in the high-temperature zone; wherein the mass ratio of anhydrous CoCl2 powder to shredded silicon wafers is 1:0.5.
[0047] (2) After cleaning the quartz tube with argon gas at a flow rate of 800 sccm for 10 min, the temperature of the low temperature zone is raised to 730 ℃ and the temperature of the high temperature zone is raised to 830 ℃.
[0048] (3) Argon gas with a flow rate of 100 sccm is continuously introduced during the reaction process to transport the cobalt source vapor generated in the low temperature zone to the high temperature zone and react with the silicon source to grow on the surface of the fluorine crystal mica sheet.
[0049] (4) After the reaction continued for 10 min, the heating was stopped and then the mixture was allowed to cool naturally to room temperature to obtain two-dimensional ferromagnetic Co3Si nanosheets grown on fluorine crystal mica sheets.
[0050] Figure 5The figure shows the EDS elemental distribution of the two-dimensional ferromagnetic Co3Si nanosheets prepared in this embodiment. As can be seen from the figure, Co and Si elements are uniformly distributed in the two-dimensional ferromagnetic Co3Si nanosheets.
[0051] Figure 6 The image shows an HRTEM image of the two-dimensional ferromagnetic Co3Si nanosheets prepared in this embodiment. The image shows that the two-dimensional ferromagnetic Co3Si nanosheets have good crystallization characteristics and the interplanar spacing matches that of Co3Si.
[0052] Experimental Example 1
[0053] This experiment uses the two-dimensional ferromagnetic Co2Si nanosheets prepared in Example 1 and the two-dimensional ferromagnetic Co3Si nanosheets prepared in Example 2 as research objects to test their magnetic properties.
[0054] The magnetization of two-dimensional ferromagnetic Co2Si nanosheets as a function of temperature was measured using a physical property measurement system (PPMS). An out-of-plane magnetic field of 1000 Oe was used, with a temperature range of 2-390 K, and measurements were taken at intervals of 2 K. Furthermore, the hysteresis loop of the two-dimensional ferromagnetic Co2Si nanosheets prepared in Example 1 was measured using a magneto-optical Kerr microscope (MOKE). The out-of-plane magnetic field range was -1000 to 1000 Oe, with measurements taken at intervals of 8.5 Oe.
[0055] Figure 7 The figures show the magnetization of two-dimensional ferromagnetic Co2Si nanosheets as a function of temperature under field-cooled (FC) and zero field-cooled (ZFC) conditions. As can be seen from the figures, the two-dimensional ferromagnetic Co2Si nanosheets exhibit stable ferromagnetic behavior at room temperature and even at 390 K, indicating that the Curie temperature of the two-dimensional ferromagnetic Co2Si nanosheets is higher than 390 K.
[0056] Figure 8 The figures show the magnetization of two-dimensional ferromagnetic Co3Si nanosheets as a function of temperature under field-cooled (FC) and zero field-cooled (ZFC) conditions. This also shows that the two-dimensional ferromagnetic Co3Si nanosheets maintain obvious magnetic order characteristics at room temperature and even at 390 K, and the Curie temperature is higher than 390 K.
[0057] Figure 9The images show magneto-optical Kerr effect (MOKE) imaging and hysteresis loops of two-dimensional ferromagnetic Co2Si nanosheets during bidirectional magnetic field scanning. Figure a shows the MOKE imaging of the two-dimensional ferromagnetic Co2Si nanosheets at 1000 Oe, figure b shows the MOKE imaging of the two-dimensional ferromagnetic Co2Si nanosheets at -1000 Oe, and figure c shows the hysteresis loop of the MOKE of the two-dimensional ferromagnetic Co2Si nanosheets. Figure a shows that the overall magnetization remains essentially constant before the magnetic field exceeds the critical value (coercive field). After exceeding this critical value, the contrast completely reverses, indicating that the magnetization has flipped to saturation. Subsequent reverse scanning exhibits similar behavior, suggesting that even after merging, the two-dimensional ferromagnetic Co2Si nanosheets retain their single-domain magnetic structure. Figure b shows that the two-dimensional ferromagnetic Co2Si nanosheets possess clear hysteresis characteristics at room temperature.
[0058] Experimental Example 2
[0059] This experiment selected two-dimensional ferromagnetic Co2Si nanosheets prepared in Example 1 and studied the generation and annihilation behavior of magnetic skyrmions under an applied magnetic field at room temperature.
[0060] Figure 10 The generation and annihilation processes of magnetic skyrmions in two-dimensional ferromagnetic Co₂Si nanosheets were observed using magnetic force microscopy under different applied magnetic fields. As shown in the figures, under zero applied magnetic field, the two-dimensional ferromagnetic Co₂Si nanosheets exhibit clear striped domains (Figure a). By increasing the applied perpendicular magnetic field to 500 Oe, the originally stable striped magnetic domains undergo compression and breakage, with some striped domains transitioning to skyrmion states (Figure b). Discrete bright spots formed by the breakage of striped magnetic domains can be observed at the dashed circle position in Figure b; these isolated magnetic domains with stable topological structures are the magnetic skyrmions. When the applied perpendicular magnetic field is further increased, the magnetic skyrmions gradually shrink in size and eventually annihilate, as shown in Figures c and d, where the magnetic contrast is significantly weakened or even almost disappears. These results demonstrate that the evolution and annihilation processes of striped magnetic domains to magnetic skyrmions can be achieved in two-dimensional ferromagnetic Co₂Si nanosheets under room temperature conditions and with the control of an applied magnetic field. This further demonstrates the tunability of the topological magnetic structure in this material, laying an experimental foundation for its application in low-power spintronic devices.
[0061] Figure 11The figures illustrate the generation and annihilation processes of magnetic skyrmions in two-dimensional ferromagnetic Co₂Si nanosheets obtained by Lorentz transmission electron microscopy under different applied magnetic fields. As shown in the figures, without an applied magnetic field, periodically arranged striped magnetic domain structures form inside the two-dimensional ferromagnetic Co₂Si nanosheets. Under Lorentz under-focus imaging, these striped domains exhibit alternating bright and dark stripes distributed along a specific direction, corresponding to electron beam deflection caused by the magnetic induction intensity at the domain walls (Figure a). With increasing applied magnetic field, the width of the original striped domains gradually decreases, the stripe spacing changes, and local breakage occurs, transforming continuous stripes into irregular curved or short striped domains. Simultaneously, magnetic skyrmions with closed magnetization structures form in some areas, marked with red circles in Figures b and c. With further strengthening of the applied magnetic field, magnetic skyrmions annihilate, and the domain contrast in the sample gradually weakens. However, within this magnetic field range, the sample has not yet fully entered a single-domain saturation state, and residual domain signals can still be observed in some areas (Figure d). The above results show that two-dimensional ferromagnetic Co2Si nanosheets can realize the evolution and annihilation process of striped magnetic domains to magnetic skyrmions under the control of an external magnetic field at room temperature. Moreover, this process occurs in the magnetic field range where the magnetic field is not fully magnetically saturated, which reflects the stability of the topological magnetic structure and good magnetic field controllability of the material.
[0062] In summary, this invention places a cobalt source in a low-temperature region, a silicon source in a high-temperature region, and a fluorine-crystal mica sheet above the silicon source in the high-temperature region, and performs a chemical vapor deposition reaction in an inert gas environment to obtain two-dimensional ferromagnetic Co2Si nanosheets or Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics. The two-dimensional ferromagnetic Co2Si nanosheets and Co3Si nanosheets have stable room-temperature ferromagnetism and high Curie temperature, and can achieve the generation and annihilation of room-temperature magnetic skyrmions by external magnetic field control, which has broad application prospects in the fields of spintronics and low-power information storage.
[0063] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
Claims
1. A two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics, characterized in that, The two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room temperature magnetic skyrmions and high Curie temperature characteristics are obtained by placing a cobalt source in a low-temperature zone, a silicon source in a high-temperature zone, and a fluorine crystal mica sheet above the silicon source in the high-temperature zone, and by performing a chemical vapor deposition reaction in an inert gas environment using a dual-temperature zone tube furnace. The generation and annihilation of room temperature magnetic skyrmions can be achieved by controlling the external magnetic field.
2. The two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics according to claim 1, characterized in that, The two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics exhibit typical two-dimensional structural features, with a hexagonal sheet-like morphology, a lateral dimension of 5-50 μm, and a thickness of 20-300 nm.
3. The two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics according to claim 1, characterized in that, The mass ratio of the cobalt source to the silicon source is 1:0.5-1.
4. The two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics according to claim 3, characterized in that, The cobalt source is anhydrous cobalt chloride powder, and the silicon source is shredded silicon wafers.
5. The two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics according to claim 1, characterized in that, The inert gas is argon, and the argon flow rate is 80-100 sccm during the chemical vapor deposition reaction.
6. The two-dimensional ferromagnetic Co2Si / Co3Si nanosheet with room-temperature magnetic skyrmions and high Curie temperature characteristics according to claim 5, characterized in that, Before the chemical vapor deposition reaction, the tubular furnace was pre-cleaned with 800 sccm of argon gas to remove impurities.
7. The method for preparing two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics according to any one of claims 1-6, characterized in that, The cobalt source is placed in the low-temperature zone, the silicon source is placed in the high-temperature zone, and the fluorine crystal mica sheet is placed above the silicon source in the high-temperature zone. A chemical vapor deposition reaction is carried out in an inert gas environment using a dual-temperature zone tube furnace to complete the selective growth of two-dimensional nanosheets and obtain two-dimensional ferromagnetic Co2Si nanosheets or Co3Si nanosheets with room temperature magnetic skyrmions and high Curie temperature characteristics.
8. The method for preparing two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics according to claim 7, characterized in that, The reaction temperature in the low-temperature region was controlled at 700-730 ℃, the reaction temperature in the high-temperature region was controlled at 850-900 ℃, and the reaction time was controlled at 10-20 min, to obtain two-dimensional ferromagnetic Co2Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics.
9. The method for preparing two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics according to claim 7, characterized in that, The reaction temperature in the low-temperature region was controlled at 700-730 ℃, the reaction temperature in the high-temperature region was controlled at 800-850 ℃, and the reaction time was controlled at 5-10 min, to obtain two-dimensional ferromagnetic Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics.
10. The application of the two-dimensional ferromagnetic Co2Si / Co3Si nanosheets with room-temperature magnetic skyrmions and high Curie temperature characteristics as described in any one of claims 1-6 in the fields of magnetic storage or spintronics.