Face-centered cubic antiferromagnetic gamma-CoMn alloy single crystal film and preparation method thereof
By growing an ultrathin Cu seed layer on a single-crystal Si(111) substrate and optimizing the epitaxial growth conditions of γ-CoMn, a high-quality face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film was successfully prepared, solving the problem of thin film preparation at room temperature and promoting the development of antiferromagnetic spintronics.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies make it difficult to stably prepare high-quality antiferromagnetic γ-CoMn alloy single-crystal thin films at room temperature, which limits their application in spintronic devices.
An ultrathin Cu seed layer was grown on the surface of a single-crystal Si(111) substrate, and the epitaxial growth conditions of γ-CoMn were optimized. High-quality face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin films were prepared by molecular beam epitaxy.
A single-crystal γ-CoMn alloy film with atomic-level surface flatness and good single-crystal epitaxial orientation was obtained, which is suitable for antiferromagnetic devices and provides a development scheme for high-performance spintronic devices.
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Figure CN121826601A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film and its preparation method, belonging to the field of condensed matter physics materials technology. Background Technology
[0002] In magnetic materials, adjacent magnetic moments in ferromagnetic materials are aligned in parallel, while those in antiferromagnetic materials are aligned in antiparallel. Currently, spintronic devices based on ferromagnetic materials have achieved large-scale applications and play a crucial role in information storage and processing. In contrast, the existence of antiferromagnetic materials was only confirmed by neutron diffraction in the mid-20th century. However, due to their zero net magnetic moment, their application in information technology was long limited, serving only as pinning layers for magnetic moments. Nevertheless, with the rapid development of information technology, antiferromagnetic materials, with their superior resistance to magnetic field interference and ultrafast dynamics, have provided a new direction for constructing high-density, high-speed spintronic devices. Today, antiferromagnetic materials show broad application prospects in cutting-edge fields such as next-generation magnetic random access memories and spin logic devices, further promoting the rapid development of antiferromagnetic spintronics as an emerging research direction.
[0003] In recent years, researchers have been exploring novel antiferromagnetic materials and their underlying physical mechanisms to broaden their applications in spintronics. However, among numerous antiferromagnetic systems, collinear antiferromagnets, due to their strictly antiparallel spin structures, have zero net covariant magnetic moment, making it difficult to directly respond to external fields, thus posing significant challenges to their research and control. Antiferromagnetic materials with non-coplanar spin structures have attracted considerable attention due to their unique magnetic scattering effects, Berry phases, and topological electronic states. Examples include Eu₂Ir₂O₇ thin films with an all-in-all-out (AIAO) magnetic structure and Fe₂ with a two-dimensional helical magnetic structure. 1.3 Antiferromagnetic materials such as Sb can induce the topological Hall effect at low temperatures, exhibiting abundant topological electronic states. However, the topological phenomena of these materials are usually only manifested at low temperatures, which greatly limits their practical application in spintronic devices. Therefore, finding an antiferromagnetic material that is stable at room temperature is crucial for advancing the development of antiferromagnetic spintronics.
[0004] When the Mn content exceeds 43%, γ-CoMn alloys exhibit a non-coplanar antiferromagnetic order similar to γ-FeMn, while avoiding dependence on heavy metals, making them valuable for research in topological magnetic materials. However, their thin film preparation is challenging, and current research on CoMn materials largely focuses on the ferromagnetic α-phase CoMn. γ-CoMn, as a room-temperature stable antiferromagnetic material, offers new possibilities for the design and application of future spintronic devices. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film and its preparation method. This invention optimizes the epitaxial growth conditions of γ-CoMn by growing an ultrathin Cu seed layer on the surface of a single-crystal Si(111) substrate, thereby obtaining a high-quality single-crystal γ-CoMn thin film. Furthermore, this invention effectively improves the crystallinity quality of the film, laying the foundation for the potential applications of γ-CoMn in topological electronics and spintronics, and providing a new process solution for the development of future high-performance antiferromagnetic spintronic devices.
[0006] The technical solution of the present invention is as follows:
[0007] A face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film includes a substrate, a buffer layer, and a γ-CoMn alloy single crystal thin film arranged sequentially from bottom to top; the chemical composition of the γ-CoMn alloy single crystal thin film is γ-Co. 1-x Mn x , 50≤x≤70.
[0008] According to a preferred embodiment of the present invention, the substrate is a single-crystal Si(111) substrate.
[0009] According to a preferred embodiment of the present invention, the buffer layer is a single-crystal Cu(111) buffer layer.
[0010] According to a preferred embodiment of the present invention, the chemical composition of the γ-CoMn alloy single crystal thin film is γ-Co. 40 Mn 60 .
[0011] According to a preferred embodiment of the present invention, the structure of the γ-CoMn alloy single crystal thin film is a face-centered cubic phase, and the epitaxial relationship between the γ-CoMn alloy single crystal thin film and the substrate is CoMn(111)[ 10]||Si(111)[11 ] and CoMn(111)[1 0]||Si(111)[11 Coexisting twin growth.
[0012] The preparation method of the above-mentioned face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film includes the following steps:
[0013] (1) The substrate was ultrasonically cleaned in sequence with chloroform, acetone and anhydrous ethanol, and then treated with hydrofluoric acid.
[0014] (2) Place the cleaned substrate into a molecular beam epitaxy apparatus and heat treat it for 8 to 12 minutes at 700 to 800°C in a high vacuum environment;
[0015] (3) Heat the Cu metal thermal evaporation source to 900~950℃, and in a vacuum below 5×10 -10 A single-crystal Cu(111) buffer layer was grown on the heat-treated substrate under the condition that the substrate was at room temperature after heat treatment (mbar).
[0016] (4) The temperature of the Co metal thermal evaporation source is raised to 1250~1350℃, the temperature of the bottom of the Mn metal dual thermal evaporation source is raised to 700~750℃, and the temperature of the source outlet is raised to 750~800℃; in a vacuum below 1×10 -9 mbar, under the condition that the substrate containing the single crystal Cu(111) buffer layer obtained in step (3) is at room temperature, γ-CoMn alloy single crystal thin film is grown on the single crystal Cu(111) buffer layer to obtain face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film.
[0017] According to a preferred embodiment of the present invention, in step (1), the treatment times for chloroform, acetone, anhydrous ethanol and hydrofluoric acid are 15 min, 5 min and 5 min, respectively; the mass concentration of hydrofluoric acid is 5% and the treatment time is 30 s.
[0018] According to a preferred embodiment of the present invention, in step (2), the specific conditions for the heat treatment are: at 700°C and 10... -8 Heat treatment for 10 minutes at mbar.
[0019] According to a preferred embodiment of the present invention, in step (3), the growth rate of the single-crystal Cu(111) buffer layer is 0.05~0.08 nm / min, the growth time is 25~35 min, and the thickness is 1.8~2.2 nm.
[0020] More preferably, the growth rate of the single-crystal Cu(111) buffer layer at 926℃ is 0.0067nm / min, the growth time is 30min, and the thickness is 2nm.
[0021] According to a preferred embodiment of the present invention, in step (3), the growth rate of the single-crystal Cu(111) buffer layer is 0.05~0.08 nm / min, the growth time is 25~35 min, and the thickness is 1.8~2.2 nm.
[0022] According to a preferred embodiment of the present invention, in step (4), the growth rate of the γ-CoMn alloy single crystal thin film is 0.08~0.1 nm / min, the growth time is 180~220 min, and the thickness is 18~22 nm.
[0023] More preferably, the growth rate of the γ-CoMn alloy single crystal thin film is 0.092 nm / min, the growth time is 217 min, and the thickness is 20 nm.
[0024] The beneficial effects of this invention are as follows:
[0025] 1. The antiferromagnetic γ-CoMn alloy single crystal thin film provided by this invention is a face-centered cubic phase, and the epitaxial relationship between the γ-CoMn alloy single crystal thin film and the substrate is CoMn(111)[ 10]||Si(111)[11 ] and CoMn(111)[1 0]||Si(111)[11 The coexisting twin growth exhibits atomic-level surface smoothness, good single-crystal epitaxial orientation, and antiferromagnetism, making it suitable for subsequent scientific research and an excellent material for antiferromagnetic electronic devices.
[0026] 2. The method for preparing face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin films provided by this invention successfully obtains high-quality γ-CoMn single-crystal epitaxial thin films by first epitaxially growing an ultrathin Cu seed layer on a single-crystal Si(111) substrate, effectively solving the problem of difficult γ-CoMn single-crystal growth. Furthermore, this invention is the first to successfully grow γ-CoMn single-crystal epitaxial thin films on a single-crystal Si(111) substrate, providing a new process solution for the development of future high-performance antiferromagnetic spintronic devices.
[0027] 3. Compared with ferromagnetic α-CoMn, the antiferromagnetic γ-CoMn alloy single crystal thin film provided by this invention can easily form special magnetic structures (such as 3Q magnetic structures), which have good detectability and manipulation, and have significant scientific and technological significance for next-generation spintronics applications. Attached Figure Description
[0028] Figure 1 This is a 7×7 reconstructed high-energy electron diffraction pattern of the heat-treated single-crystal Si(111) substrate prepared in step (2) of Embodiment 1 of the present invention.
[0029] Figure 2 This is the reflection high-energy electron diffraction pattern of the single-crystal Cu(111) buffer layer prepared in step (3) of Embodiment 1 of the present invention.
[0030] Figure 3 This is a high-energy electron diffraction pattern of the γ-CoMn alloy single crystal thin film prepared in step (4) of Example 1 of the present invention.
[0031] Figure 4 This is the symmetry plane X-ray diffraction pattern of the face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film prepared in Example 1 of this invention; where the vertical axis is the measured diffraction intensity, and the horizontal axis 2θ is the scanning range, which is 10. o -110 o .
[0032] Figure 5 This is the φ scan result of the single-crystal Si(111) substrate and the γ-CoMn alloy single-crystal thin film in the face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film prepared in Example 1 of this invention; where the vertical axis is the measured diffraction intensity and the horizontal axis is the φ scan range, which is -180. o Up to 180 o .
[0033] Figure 6 The out-of-plane hysteresis loop is measured at a temperature of 300K for the face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film prepared in Example 1 of this invention; wherein, the vertical axis is the measured magnetic moment and the horizontal axis is the applied magnetic field, with the maximum magnetic field being 70 kilo-Oerst.
[0034] Figure 7 The anomalous Hall resistivity of the face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film prepared in Example 1 of this invention is measured by applying an out-of-plane magnetic field at a temperature of 300K. The vertical axis represents the measured anomalous Hall resistivity, and the horizontal axis represents the applied magnetic field. The maximum applied magnetic field is 90 kOerst. Detailed Implementation
[0035] The present invention will be further described below through specific embodiments, but is not limited thereto.
[0036] All raw materials and equipment used in the examples are conventional and can be purchased commercially. The room temperature is 20~30℃.
[0037] Example 1
[0038] A face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film comprises, from bottom to top, a single-crystal Si(111) substrate, a single-crystal Cu(111) buffer layer, and a γ-Co alloy. 40 Mn 60 Alloy single-crystal thin films.
[0039] The preparation method of the above-mentioned face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film includes the following steps;
[0040] (1) In a fume hood, the single crystal Si(111) substrate was ultrasonically cleaned with chloroform, acetone and anhydrous ethanol for 15 min, 5 min and 5 min respectively, and finally treated with 5% hydrofluoric acid for 30 s.
[0041] (2) After the cleaning process is completed, the single-crystal Si(111) substrate is placed into the sample inlet chamber of the molecular beam epitaxy equipment, and the sample inlet chamber is evacuated to 10°C. -8After mbar, the single crystal Si(111) substrate is transferred into the growth chamber and heated to 700℃ in the growth chamber for 10 min to obtain the heat-treated single crystal Si(111) substrate.
[0042] (3) Cool the heat-treated single-crystal Si(111) substrate to room temperature, and evacuate the growth chamber to 2×10⁻⁶. -10 mbar, and then the metal Cu thermal evaporation source is heated to 926℃; under this condition, a single crystal Cu(111) buffer layer is grown on the heat-treated substrate to obtain a substrate containing a single crystal Cu(111) buffer layer.
[0043] The growth rate of the single-crystal Cu(111) buffer layer is 0.067 nm / min, the growth time is 30 min, and the thickness of the single-crystal Cu(111) buffer layer is 2 nm.
[0044] (4) The temperature of the Co metal thermal evaporation source is raised to 1300℃, the temperature of the bottom of the Mn metal dual thermal evaporation source is raised to 718℃, the temperature of the source port is raised to 768℃, and the growth chamber is evacuated to 5×10⁻⁶℃. -10 mbar; Under these conditions, a γ-CoMn alloy single crystal film is grown on the single crystal Cu(111) buffer layer of the substrate obtained in step (3) to obtain a face-centered cubic antiferromagnetic γ-CoMn alloy single crystal film.
[0045] The growth rate of the γ-CoMn alloy single crystal thin film is 0.092 nm / min, the growth time is 217 min, and the thickness is 20 nm.
[0046] The 7×7 reconstructed high-energy electron diffraction pattern of the heat-treated single-crystal Si(111) substrate obtained in step (2) of this embodiment is as follows: Figure 1 As shown, the reflection high-energy electron diffraction pattern of the single-crystal Cu(111) buffer layer prepared in step (3) is as follows: Figure 2 As shown.
[0047] Depend on Figures 1-2 It can be seen that the heat treatment yielded a clear 7×7 reconstruction of the Si substrate, providing the necessary foundation for the subsequent epitaxial growth of Cu. Furthermore, the Cu epitaxially grown on Si exhibits clear and sharp striations, indicating high-quality growth of the fcc-Cu thin film.
[0048] The high-energy electron diffraction pattern of the γ-CoMn alloy single crystal thin film prepared in step (4) of this embodiment is as follows: Figure 3 As shown.
[0049] Depend on Figure 3 As can be seen, the clear diffraction fringes show the atomic-level surface smoothness of the γ-CoMn single-crystal thin film and its excellent single-crystal epitaxial orientation.
[0050] The symmetry plane X-ray diffraction pattern of the face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film prepared in this embodiment is as follows: Figure 4 As shown.
[0051] Depend on Figure 4 It can be seen that the sharp γ-CoMn(111) peak and the absence of obvious impurity peaks indicate that the γ-CoMn thin film prepared in this embodiment has excellent single crystal properties.
[0052] The φ-scan results of the face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film prepared in this embodiment are as follows: Figure 5 As shown.
[0053] Depend on Figure 5 It can be seen that γ-CoMn is epitaxially grown, which confirms that... Extensional relationship.
[0054] The out-of-plane hysteresis loop of the face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film prepared in this embodiment, measured at a temperature of 300K, is as follows: Figure 6 As shown.
[0055] Depend on Figure 6 It can be seen that even with an applied field of 70 kilo-Oersted, the saturation magnetization is only 24 emu / cm. 3 This fully demonstrates the antiferromagnetism of γ-CoMn single crystal thin films.
[0056] In this embodiment, the face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film was prepared with an out-of-plane magnetic field applied at a temperature of 300 K. The anomalous Hall resistivity measured was as follows: Figure 7 As shown.
[0057] Depend on Figure 7 It can be seen that the maximum out-of-plane anomalous Hall resistivity is approximately 0.053 μΩ·cm.
[0058] Example 2
[0059] A method for preparing a face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film includes the following steps;
[0060] (1) In a fume hood, the single crystal Si(111) substrate was ultrasonically cleaned with chloroform, acetone and anhydrous ethanol for 15 min, 5 min and 5 min respectively, and finally treated with 5% hydrofluoric acid for 30 s.
[0061] (2) After the cleaning process is completed, the single-crystal Si(111) substrate is placed into the sample inlet chamber of the molecular beam epitaxy equipment, and the sample inlet chamber is evacuated to 10°C. -8After mbar, the single crystal Si(111) substrate is transferred into the growth chamber and heated to 800℃ in the growth chamber for 8 min to obtain the heat-treated single crystal Si(111) substrate.
[0062] (3) Cool the heat-treated single-crystal Si(111) substrate to room temperature, and evacuate the growth chamber to 2.5 × 10⁻⁶. -10 mbar, and then the metal Cu thermal evaporation source is heated to 926℃; under this condition, a single crystal Cu(111) buffer layer is grown on the heat-treated substrate to obtain a substrate containing a single crystal Cu(111) buffer layer.
[0063] The growth rate of the single-crystal Cu(111) buffer layer is 0.067 nm / min, the growth time is 22.5 min, and the thickness of the single-crystal Cu(111) buffer layer is 1.5 nm.
[0064] (4) The temperature of the Co metal thermal evaporation source is raised to 1300℃, the temperature of the bottom of the Mn metal dual thermal evaporation source is raised to 718℃, the temperature of the source port is raised to 768℃, and the growth chamber is evacuated to 5×10⁻⁶℃. -10 mbar; Under these conditions, a γ-CoMn alloy single crystal film is grown on the single crystal Cu(111) buffer layer of the substrate obtained in step (3) to obtain a face-centered cubic antiferromagnetic γ-CoMn alloy single crystal film.
[0065] The growth rate of the γ-CoMn alloy single crystal thin film is 0.092 nm / min, the growth time is 196 min, and the thickness is 18 nm.
[0066] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film, characterized in that, The structure comprises, from bottom to top, a substrate, a buffer layer, and a γ-CoMn alloy single-crystal thin film; the chemical composition of the γ-CoMn alloy single-crystal thin film is γ-Co. 1- x Mn x , 50≤x≤70.
2. The face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film as described in claim 1, characterized in that, The substrate is a single-crystal Si(111) substrate; the buffer layer is a single-crystal Cu(111) buffer layer.
3. The face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film as described in claim 1, characterized in that, The chemical composition of the γ-CoMn alloy single crystal thin film is γ-Co 40 Mn 60 .
4. The face-centered cubic antiferromagnetic γ-CoMn alloy single-crystal thin film as described in claim 1, characterized in that, The structure of the γ-CoMn alloy single crystal thin film is face-centered cubic, and the epitaxial relationship between the γ-CoMn alloy single crystal thin film and the substrate is CoMn(111)[ 10]||Si(111)[11 ] and CoMn(111)[1 0]||Si(111)[11 Coexisting twin growth.
5. The method for preparing a face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film according to any one of claims 1 to 4, characterized in that, The steps include the following: (1) The substrate was ultrasonically cleaned in sequence with chloroform, acetone and anhydrous ethanol, and then treated with hydrofluoric acid. (2) Place the cleaned substrate into a molecular beam epitaxy apparatus and heat treat it for 8 to 12 minutes at 700 to 800°C in a high vacuum environment; (3) Heat the Cu metal thermal evaporation source to 900~950℃, and in a vacuum below 5×10 -10 A single-crystal Cu(111) buffer layer was grown on the heat-treated substrate under the condition that the substrate was at room temperature after heat treatment (mbar). (4) The temperature of the Co metal thermal evaporation source is raised to 1250~1350℃, the temperature of the bottom of the Mn metal dual thermal evaporation source is raised to 700~750℃, and the temperature of the source outlet is raised to 750~800℃; in a vacuum below 1×10 -9 mbar, under the condition that the substrate containing the single crystal Cu(111) buffer layer obtained in step (3) is at room temperature, γ-CoMn alloy single crystal thin film is grown on the single crystal Cu(111) buffer layer to obtain face-centered cubic antiferromagnetic γ-CoMn alloy single crystal thin film.
6. The preparation method according to claim 5, characterized in that, In step (1), the treatment times for chloroform, acetone, anhydrous ethanol and hydrofluoric acid are 15 min, 5 min and 5 min, respectively; the mass concentration of hydrofluoric acid is 5% and the treatment time is 30 s.
7. The preparation method according to claim 5, characterized in that, In step (2), the specific conditions for the heat treatment are: at 700℃ and 10 -8 Heat treatment for 10 minutes at mbar.
8. The preparation method according to claim 5, characterized in that, In step (3), the growth rate of the single-crystal Cu(111) buffer layer is 0.05~0.08 nm / min, the growth time is 25~35 min, and the thickness is 1.8~2.2 nm; More preferably, the growth rate of the single-crystal Cu(111) buffer layer at 926℃ is 0.0067nm / min, the growth time is 30min, and the thickness is 2nm.
9. The preparation method according to claim 5, characterized in that, In step (3), the growth rate of the single-crystal Cu(111) buffer layer is 0.05~0.08 nm / min, the growth time is 25~35 min, and the thickness is 1.8~2.2 nm.
10. The preparation method according to claim 5, characterized in that, In step (4), the growth rate of the γ-CoMn alloy single crystal thin film is 0.08~0.1 nm / min, the growth time is 180~220 min, and the thickness is 18~22 nm; More preferably, the growth rate of the γ-CoMn alloy single crystal thin film is 0.092 nm / min, the growth time is 217 min, and the thickness is 20 nm.