A non-collinear antiferromagnetic Mn3Sn single crystal film and its molecular beam epitaxial preparation method

Abstract

The present invention relates to a non-collinear antiferromagnetic Mn3Sn single crystal thin film and a molecular beam epitaxial preparation method thereof, belonging to the technical field of spintronics materials and devices. The thin film comprises a substrate and a Mn3Sn thin film arranged sequentially from bottom to top. When the crystal orientation of the Mn3Sn thin film is (0001), #imgabs0# or #imgabs1# is (0001), the Mn3Sn thin film has six degrees of symmetry. The present invention prepares D0 19 The nonlinear antiferromagnetic Mn3Sn film with a hexagonal crystal structure has excellent crystal order and spin order, and well reflects the novel physical properties and topological electron transport properties in bulk materials. It is suitable for subsequent scientific research and is an excellent material for use in antiferromagnetic spintronics devices.

Description

Technical Field

[0001] The invention relates to a non-collinear antiferromagnetic Mn3Sn single crystal film and a molecular beam epitaxial preparation method thereof, belonging to the technical field of spin electronics materials and devices. Background Art

[0002] With the advent of the information age characterized by big data, the Internet of Things, and cloud computing, people have put forward higher requirements for data storage and processing. Spin electronics, which realizes information storage and logical operations by manipulating the spin degree of freedom, has become one of the main development directions of current and future information technology. Compared with ferromagnetic materials, antiferromagnetic materials have ultrafast magnetodynamic processes (THz), no stray magnetic fields and zero magnetization intensity, and a critical current density two orders of magnitude lower than that of ferromagnetic materials (~10 6 A / cm 2 ) and other characteristics, can meet the high frequency, high stability and low energy consumption requirements of spin memory devices, and has become a hot topic in current condensed matter physics research. However, the bottleneck of antiferromagnetic spin electronics lies in the difficulty of reading and writing. The readout signal of the order parameter of antiferromagnetic materials is very weak, and writing or controlling the order parameter is also very difficult.

[0003] Mn3Sn material is a non-collinear antiferromagnetic Weyl semimetal and one of the most representative members of the Mn3X (X = Ga, Sn, Ge, Ir, Rh and Pt) family. The antiferromagnetic Neel temperature of Mn3Sn is 420K, and it transforms into a spin glass state when the temperature is below 50K. The crystal structure is a Ni3Sn-type hexagonal crystal structure with a space group of P63 / mmc. The magnetic moments of the Mn atoms of Mn3Sn are all located on the ab basal plane, i.e., the (0001) plane, forming a typical coplanar nonlinear Kagome lattice. The spin structure of Mn3Sn is determined by polarized neutron diffraction, where the magnetic moment of each Mn atom is about 3μ B Due to the DMI interaction (Dzyaloshinski-Moriya interaction), the magnetic moments of Mn atoms form a triangular chiral spin structure (spin charity texture) with a magnetic moment compensation at an angle of 1200 in the ab basal plane. The adjacent ab basal plane forms an inverted triangular chiral spin structure. In bulk single crystals, since the Mn magnetic moment has only a very small deviation from the ab basal plane, it exhibits a very weak remanent magnetization intensity, with an average magnetic moment of about 0.002μ B / Mn.

[0004] The topological characteristics of the Weyl semimetal of Mn3Sn (Mn3Sn) possess unique electronic behavior and a rich array of physical effects, such as the giant anomalous Hall effect (AHE) and spin Hall effect (SHE) at room temperature, the anomalous Nernst effect, the giant magneto-optical Kerr effect (MOKE) at room temperature, and detectable antiferromagnetic chiral spin domain walls. Further research into the physical effects of noncollinear antiferromagnetic materials is expected to drive the rapid development of spintronics. The development of a current-driven antiferromagnetic read-write mechanism based on Mn3Sn thin films without an external magnetic field will provide a new path for the development of a new generation of high-speed, high-stability, and low-energy spin memories. To date, one of the greatest challenges in realizing the spintronic applications of noncollinear antiferromagnetic materials, such as Mn3Sn, has been the acquisition of highly crystalline and spin-ordered thin films. First, only highly ordered noncollinear antiferromagnetic films can exhibit ordered chiral spin structures and topological electronic structures, and the corresponding large anomalous Hall effect. Second, noncollinear antiferromagnetic Mn3Sn exhibits strong anisotropy, and the read and write mechanisms of antiferromagnetic order are crystal-orientation-specific. However, current experimental results have primarily been reported for polycrystalline or quasi-epitaxial films. Therefore, the present invention was proposed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a non-collinear antiferromagnetic Mn3Sn single crystal film and a molecular beam epitaxial preparation method thereof, and prepares D0 19 The nonlinear antiferromagnetic Mn3Sn film with a hexagonal crystal structure has excellent crystal order and spin order, and well reflects the novel physical properties and topological electron transport properties in bulk materials. It is suitable for subsequent scientific research and is an excellent material for use in antiferromagnetic spintronics devices.

[0006] The technical solutions of the present invention are as follows:

[0007] A non-collinear antiferromagnetic Mn3Sn single crystal film comprises a substrate and a Mn3Sn film arranged in sequence from bottom to top, wherein the crystal orientation of the Mn3Sn film is (0001), or

[0008] Preferably, when the crystal orientation of the Mn3Sn film is (0001), the epitaxial relationship of the Mn3Sn film is MgO(111)

[110] / / The crystal orientation is When the epitaxial relationship of Mn3Sn film is MgO(110)

[001] / /

[0009] Preferably, the crystal orientation of the Mn3Sn film is or When the substrate is heated, a low-temperature buffer layer is provided between the substrate and the Mn3Sn film.

[0010] A method for preparing a non-collinear antiferromagnetic Mn3Sn single crystal thin film by molecular beam epitaxy, wherein the steps for preparing a (0001) oriented Mn3Sn single crystal thin film are as follows:

[0011] (1) The MgO (111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, substrate annealing temperature is 700℃, annealing time is 20 minutes;

[0012] (2) The bottom of the metal Mn dual-temperature evaporation source was heated to 927°C, the source port was heated to 932°C, and the Sn high-temperature evaporation source was heated to 1120°C. The vacuum in the growth chamber was lower than 1.7×10 -9 mbar;

[0013] The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.45:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:1.

[0014] (3) During growth, the substrate temperature is stabilized between 480-520°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time;

[0015] (4) The average film growth rate was controlled at 1.5 nm / min, and epitaxial growth was performed for 100 minutes to obtain a Mn3Sn film with a thickness of 150 nm.

[0016] Preferably, in step (2), the purity of metal Mn is 99.95%, the purity of Sn is 99.999%, and in step (3), the substrate temperature is 500° C., and the growth effect is optimal.

[0017] A molecular beam epitaxial method for preparing non-collinear antiferromagnetic Mn3Sn single crystal thin films. When preparing crystal-oriented Mn3Sn single crystal thin films, the steps are as follows:

[0018] ① The MgO (111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, substrate annealing temperature is 700℃, annealing time is 20 minutes;

[0019] ② The bottom of the metal Mn dual-temperature evaporation source was heated to 922°C, the source port was heated to 934°C, and the Sn high-temperature evaporation source was heated to 1131°C. The vacuum in the growth chamber was lower than 3.1×10 -9 mbar;

[0020] The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.43:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:1.

[0021] ③ The substrate temperature is 420°C. The Mn source baffle and the Sn source baffle are opened to grow a 1.3nm low-temperature buffer layer to release the stress between the substrate and the film. After the buffer layer growth is completed, the Mn source and Sn source baffles are closed, the substrate temperature is raised to 600°C, and annealed for 3 minutes. This can greatly improve the lattice quality and surface flatness of the low-temperature buffer layer.

[0022] ④ During growth, the substrate temperature is stabilized between 450-470°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time;

[0023] ⑤ The average growth rate of the film is controlled at 1.6 nm / min, and the epitaxial growth is carried out for 100 minutes to obtain a Mn3Sn film with a thickness of approximately 160 nm.

[0024] Preferably, in step ④, the substrate temperature is 460° C., which achieves the best growth effect.

[0025] A molecular beam epitaxial method for preparing non-collinear antiferromagnetic Mn3Sn single crystal thin films. When preparing crystal-oriented Mn3Sn single crystal thin films, the steps are as follows:

[0026] Ⅰ The MgO(111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, two-step substrate annealing process: first, substrate annealing temperature is 700℃, annealing for 8 minutes; second, substrate annealing temperature is 800℃, annealing for 12 minutes;

[0027] II. The bottom of the Mn dual-temperature evaporation source was heated to 922°C, the source port was heated to 934°C, and the Sn high-temperature evaporation source was heated to 1131°C. The vacuum in the growth chamber was lower than 3.1×10 -9 mbar;

[0028] The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.43:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:1.

[0029] III. The substrate temperature is 420°C. The Mn and Sn source shutters are opened to grow a 1.5nm low-temperature buffer layer to relieve stress between the substrate and the film. After the buffer layer growth is completed, the Mn and Sn source shutters are closed, the substrate temperature is raised to 550°C, and annealed for 2.5 minutes.

[0030] During the IV growth, the substrate temperature is stabilized between 450-470°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time;

[0031] The average growth rate of the V film was controlled at 1.6 nm / min, and the epitaxial growth was carried out for 100 minutes to obtain a Mn3Sn film with a thickness of approximately 160 nm.

[0032] Preferably, in step IV, the substrate temperature is 460° C., which achieves the best growth effect.

[0033] The beneficial effects of the present invention are:

[0034] The present invention provides a non-collinear antiferromagnetic Mn3Sn single crystal film and a molecular beam epitaxial preparation method thereof, and prepares D0 19 The nonlinear antiferromagnetic Mn3Sn film with a hexagonal crystal structure has excellent crystal order and spin order, and well reflects the novel physical properties and topological electron transport properties in bulk materials. It is suitable for subsequent scientific research and is an excellent material for use in antiferromagnetic spintronics devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a high-energy electron diffraction pattern of the Mn3Sn single crystal thin film of Example 1 of the present invention;

[0036] Figure 2 (a) Mn3Sn single crystal thin film of Example 1 of the present invention High-resolution transmission electron microscopy image of the cross section;

[0037] Figure 2 (b) is a selected area electron diffraction image of the Mn3Sn single crystal thin film of Example 1 of the present invention;

[0038] Figure 3 (a) is an X-ray θ-2θ scanning diagram of the Mn3Sn single crystal thin film of Example 1 of the present invention;

[0039] Figure 3 (b) is the X-ray φ scan pole figure of the Mn3Sn single crystal thin film of Example 1 of the present invention;

[0040] Figure 4 (a) and 4(b) are reciprocal space scanning images of the Mn3Sn single crystal thin film of Example 1 of the present invention;

[0041] Figure 5 1. Magnetic hysteresis loops in the plane and perpendicular directions of the Mn3Sn single crystal thin film of Example 1 of the present invention and a zero-field cold-field cold magnetization intensity diagram varying with temperature;

[0042] Figure 6The anomalous Hall resistivity, anomalous Hall conductivity and hysteresis loop of the Mn3Sn single crystal film according to Example 1 of the present invention vary with temperature;

[0043] Figure 7 (a) is a graph showing the dependence of longitudinal magnetoresistance on θ of the Mn3Sn single crystal thin film of Example 1 of the present invention under different magnetic fields;

[0044] Figure 7 (b) is a graph showing the dependence of the plane Hall resistivity on θ for the Mn3Sn single crystal thin film of Example 1 of the present invention under different magnetic fields;

[0045] Figure 7 (c) is a schematic diagram of the measurement space of the Mn3Sn single crystal thin film experiment in Example 1 of the present invention;

[0046] Figure 7 (d) is Δρ of Example 1 of the present invention chiral A square dependence graph with magnetic field;

[0047] Figure 8 This is a high-energy electron diffraction pattern of the Mn3Sn single crystal thin film of Example 2 of the present invention;

[0048] Figure 9 (a) is an X-ray θ-2θ scanning diagram of the Mn3Sn single crystal thin film of Example 2 of the present invention;

[0049] Figure 9 (b) and 9(c) are reciprocal space scanning diagrams of Example 2 of the present invention;

[0050] Figure 10 (a) and (b) are the hysteresis loops in the vertical direction of the Mn3Sn single crystal film of Example 2 of the present invention and the zero-field cold-field cold magnetization intensity diagrams that vary with temperature;

[0051] Figure 11 (a) is a θ-2θ scanning diagram of the Mn3Sn single crystal thin film of Example 3 of the present invention;

[0052] Figure 11 (b) is a reciprocal space scanning diagram of Example 3 of the present invention;

[0053] Figure 11 (c) is a φ scan image of the Mn3Sn single crystal thin film of Example 3 of the present invention;

[0054] Figure 12 (a) and (b) are respectively the vertical hysteresis loop and the zero-field cold-field cold magnetization intensity diagram of the Mn3Sn single crystal film of Example 3 of the present invention as a function of temperature;

[0055] Figure 13(a) and (b) are graphs showing the relationship between the anomalous Hall resistivity and anomalous Hall conductivity of the Mn3Sn single crystal film of Example 3 of the present invention at room temperature and the magnetic field;

[0056] Figure 13 (c) and (d) are the temperature-dependent anomalous Hall resistivity and anomalous Hall conductivity diagrams of the Mn3Sn single crystal film of Example 3 of the present invention;

[0057] Figure 13 (e) and (f) are diagrams showing the variation of the anomalous Hall resistivity and conductivity of the Mn3Sn single crystal film with temperature in Example 3 of the present invention. DETAILED DESCRIPTION

[0058] The present invention will be further described below with reference to embodiments and accompanying drawings, but is not limited thereto.

[0059] Example 1:

[0060] A non-collinear antiferromagnetic Mn3Sn single crystal film with a crystal orientation of (0001), or When the crystal orientation is (0001), the Mn3Sn single crystal film has six degrees of symmetry.

[0061] When the crystal orientation is (0001), the epitaxial relationship of the film is MgO(111)

[110] / / The crystal orientation is When the epitaxial relationship of the film is MgO(110)

[001] / /

[0062] A method for preparing a non-collinear antiferromagnetic Mn3Sn single crystal thin film by molecular beam epitaxy, wherein the steps for preparing a (0001) oriented Mn3Sn single crystal thin film are as follows:

[0063] (1) The MgO (111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, substrate annealing temperature is 700℃, annealing time is 20 minutes;

[0064] (2) The bottom of the metal Mn dual-temperature evaporation source was heated to 927°C, the source port was heated to 932°C, and the Sn high-temperature evaporation source was heated to 1120°C. The vacuum in the growth chamber was lower than 1.7×10 -9 mbar;

[0065] The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.45:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:1.

[0066] (3) During growth, the substrate temperature is stabilized between 480-520°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time;

[0067] (4) The average film growth rate was controlled at 1.5 nm / min, and epitaxial growth was performed for 100 minutes to obtain a Mn3Sn film with a thickness of 150 nm.

[0068] In step (2), the purity of metal Mn is 99.95%, the purity of Sn is 99.999%, and in step (3), the substrate temperature is 500° C., and the growth effect is optimal.

[0069] Characterization of the crystal structure and properties of the Mn3Sn film of this embodiment. Figure 1 (a) and 1(b) are the high energy electron diffraction (RHEED) patterns of Mn3Sn(0001) thin films (150nm). The incident directions of the electron beam are and RHEED showed that the film exhibited an atomically flat layered growth pattern. Figure 2 (a) and 2(b) are the high-resolution image and diffraction pattern of transmission electron microscopy, respectively. The selected area aperture of the selected area electron diffraction pattern is 100 nm. Figure 3 (a) Measurements show that the film has only one crystal orientation (0001). Figure 3 (b) X-ray pole figure measurement, when the X-ray inclination angle is 28.1°, corresponding to the 6-degree symmetry crystal plane; when the inclination angle is 35.7°, it corresponds to the MgO (200) crystal plane, indicating that Mn3Sn has very good six-degree symmetry on the (0001) plane.

[0070] Figure 4 (a) is the symmetric reciprocal space scan (RSM) of the Mn3Sn(0001) film. There are only Mn3Sn(0001) diffraction spots, and no diffraction spots of other crystal directions. In addition, the Mn3Sn(0001) diffraction peak and the substrate peak are not on the same axis, which indicates that there is an orientation difference between the film and the substrate. Figure 4 (b) Asymmetric RSM of Mn3Sn(0001) thin film. Figure 4 (a) and 4(b) can further confirm that the epitaxial film is of single crystal orientation and the existence of other objects can be excluded. The in-plane and out-of-plane lattice constants of the Mn3Sn(0001) film are The Mn3Sn(0001) film is subjected to tensile stress in the plane and compressive stress out of the plane, with strains of 0.5973% and 2.065% respectively.

[0071] Magnetic properties of the Mn3Sn film in this example. Figure 5(a) and (b) show the in-plane and perpendicular directions hysteresis loops and the temperature-dependent zero-field cold-field cold magnetization (with substrate background removed). The film exhibits excellent soft magnetic properties, and the average magnetic moment at room temperature is very small, approximately 5 mμB / Mn in the film plane and approximately 20 mμB / Mn perpendicular to the film. This is due to epitaxial stress in the film. The average magnetic moment in the perpendicular direction shows a jump at around 270 K, corresponding to the phase transition point of the magnetic structure.

[0072] Magnetoretic transport properties of the Mn3Sn thin film of this example. Figure 6 (a) and (b) are the anomalous Hall resistivity, anomalous Hall conductivity and hysteresis loop of Mn3Sn(0001) thin film at room temperature. At room temperature, the anomalous Hall resistivity is as high as 0.38μΩcm and the anomalous Hall conductivity is as high as 57Ω -1 cm -1 ; The coercive field of AHE is about 2T while the coercive field of hysteresis loop is close to zero. Figure 6 (c) Anomalous Hall resistivity at variable temperatures (5-300K), with a maximum anomalous Hall resistivity of about 1μΩcm at 250K. Figure 6 (d) Anomalous Hall conductivity at variable temperatures (5-300K), with a maximum anomalous Hall conductivity of about 210Ω at 250K -1 cm -1 .

[0073] Planar Hall effect of Mn3Sn(0001) thin film at 300K. Figure 7 (a) Dependence of longitudinal magnetoresistance on θ under different magnetic fields, Figure 7 (b) Dependence of the planar Hall resistivity on θ under different magnetic fields, Figure 7 (c) is a schematic diagram of the experimental measurement space, where the magnetic field rotates within the Mn3Sn(0001) plane, and the angle between the magnetic field and the current is θ. represents the in-plane Hall resistivity, Δρ chiral =ρ ⊥ -ρ || (ρ ⊥ and ρ || represents the resistivity when the magnetic field is perpendicular and parallel to the current direction, respectively), and represents the anisotropic resistivity caused by chiral anomaly, Δρ xx =ρ-ρ || It represents the angle dependence of the longitudinal resistivity when the magnetic field direction is rotated in the plane of the sample. Figure 7 (d) is Δρ chiral It has a square dependence on the magnetic field. According to theoretical calculations, the planar Hall effect is entirely derived from the chiral anomalous properties of Weyl fermions in Mn3Sn.

[0074] In this embodiment, the Mn3Sn film with (0001) crystal orientation also has a huge anomalous Hall effect at room temperature, while in bulk materials, this crystal orientation has no anomalous Hall effect.

[0075] Example 2:

[0076] A molecular beam epitaxial method for preparing non-collinear antiferromagnetic Mn3Sn single crystal thin films. When preparing crystal-oriented Mn3Sn single crystal thin films, the steps are as follows:

[0077] ① The MgO (111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, substrate annealing temperature is 700℃, annealing time is 20 minutes;

[0078] ② The bottom of the metal Mn dual-temperature evaporation source was heated to 922°C, the source port was heated to 934°C, and the Sn high-temperature evaporation source was heated to 1131°C. The vacuum in the growth chamber was lower than 3.1×10 -9 mbar;

[0079] The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.43:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:1.

[0080] ③ The substrate temperature is 420°C. The Mn source baffle and the Sn source baffle are opened to grow a 1.3nm low-temperature buffer layer to release the stress between the substrate and the film. After the buffer layer growth is completed, the Mn source and Sn source baffles are closed, the substrate temperature is raised to 600°C, and annealed for 3 minutes. This can greatly improve the lattice quality and surface flatness of the low-temperature buffer layer.

[0081] ④ During growth, the substrate temperature is stabilized between 450-470°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time;

[0082] ⑤ The average growth rate of the film was controlled at 1.6 nm / min, and the epitaxial growth was carried out for 100 minutes to obtain a Mn3Sn film with a thickness of approximately 160 nm.

[0083] In step ④, the substrate temperature is 460°C, and the growth effect is optimal.

[0084] This embodiment Crystal structure performance characterization of thin films: Figure 8 (a) and (b) are the high energy electron diffraction (RHEED) patterns of the thin film. The incident directions of the electron beam are and

[0001] . Figure 9 (a) is the θ-2θ scan of X-rays, and the measurement shows that the film has only A crystal orientation. Figure 9 (b) and 9(c) further confirm that the epitaxial film is a single crystal phase and the existence of other objects can be excluded.

[0085] In this embodiment Magnetic properties of thin films: Figure 10 Figures 10(a) and 10(b) show the perpendicular magnetic hysteresis loop and the temperature-dependent zero-field cold-field cold magnetization (with substrate background removed). The film exhibits excellent soft magnetic properties, and the average magnetic moment at room temperature is very small, approximately 10 mμB / Mn perpendicular to the film. The average magnetic moment shows a jump at around 270 K, corresponding to the phase transition point of the antiferromagnetic structure.

[0086] In this embodiment Magnetoretic transport properties of the film: Compared with the bulk material, the anomalous Hall resistivity of the film is 2 orders of magnitude smaller, which proves that sufficiently large epitaxial stress can break the Weyl topological properties of the film.

[0087] In this embodiment, The crystal-oriented Mn3Sn thin film exhibits only a weak anomalous Hall effect, unlike the bulk material. This sample demonstrates that when the film is subjected to sufficiently large stress, the Weyl topological properties of the Mn3Sn film can be destroyed, thus demonstrating the possibility of stress regulation in Mn3Sn thin films.

[0088] Example 3:

[0089] A molecular beam epitaxial method for preparing non-collinear antiferromagnetic Mn3Sn single crystal thin films. When preparing crystal-oriented Mn3Sn single crystal thin films, the steps are as follows:

[0090] Ⅰ The MgO(111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, two-step substrate annealing process: first, substrate annealing temperature is 700℃, annealing for 8 minutes; second, substrate annealing temperature is 800℃, annealing for 12 minutes;

[0091] II. The bottom of the Mn dual-temperature evaporation source was heated to 922°C, the source port was heated to 934°C, and the Sn high-temperature evaporation source was heated to 1131°C. The vacuum in the growth chamber was lower than 3.1×10 -9 mbar;

[0092] The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.43:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:1.

[0093] III. The substrate temperature is 420°C. The Mn and Sn source shutters are opened to grow a 1.5nm low-temperature buffer layer to relieve stress between the substrate and the film. After the buffer layer growth is completed, the Mn and Sn source shutters are closed, the substrate temperature is raised to 550°C, and annealed for 2.5 minutes.

[0094] During IV growth, the substrate temperature is stabilized between 450-470°C, with 460° being the optimal temperature. The growth method is co-evaporation of Mn and Sn sources, with both the Mn source baffle and the Sn source baffle open.

[0095] The average growth rate of the V film was controlled at 1.6 nm / min, and the epitaxial growth was carried out for 100 minutes to obtain a Mn3Sn film with a thickness of approximately 160 nm.

[0096] This embodiment Characterization of the crystal structure and properties of thin films: Figure 11 (a) is the θ-2θ scan of the film, the main diffraction peaks are There is also a relatively weak diffraction peak Figure 11 (b) is the symmetric RSM diagram of the film, except The diffraction spots on the crystal surface are bright and sharp, and there are relatively weak Diffraction spots on a crystal plane. Figure 11 (c) φ scan of Mn3Sn film.

[0097] This embodiment Magnetic properties of thin films: Figure 12 Figures (a) and (b) show the perpendicular magnetic hysteresis loop and the temperature-dependent zero-field cold-field cold magnetization (with substrate background removed), respectively. The film exhibits excellent soft magnetic properties, with a very low average magnetic moment at room temperature, approximately 46 mμB / Mn perpendicular to the film. The average magnetic moment experiences a jump at around 270 K, corresponding to the phase transition point of the magnetic structure, from the noncollinear inverted triangular antiferromagnetic term at the high-temperature end to the helical antiferromagnetic phase at the low-temperature end.

[0098] This embodiment Magnetotransport properties of thin films. Figure 12 (a) The MH curve of the film's hysteresis loop (with diamagnetic background subtracted). The film has a low coercive force, exhibits excellent soft magnetic properties, and has only a weak residual magnetization intensity, with an in-plane magnetic moment of less than 47mμ. B / Mn. Figure 12 (b) The MT curves of the film under zero-field cooling and field cooling (1000Oe) show a large jump in magnetization intensity at around 270K, corresponding to the phase transition between the antiferromagnetic magnetic structure and the helical antiferromagnetic structure. Figure 13(a) and (b) show the relationship between the anomalous Hall resistivity and anomalous Hall conductivity of Mn3Sn film and magnetic field at room temperature, where I / /

[0001] , The anomalous Hall resistivity is as high as 2.4 μΩcm, which is the highest value among the films reported so far. Figure 13 (c) and (d) are the anomalous Hall resistivity and anomalous Hall conductivity at variable temperatures (30-370K). Figure 13 (e) and (f) show the temperature-dependent changes in the anomalous Hall resistivity and conductivity of the film. At 270K, the inverted triangle Weyl topological state at the high temperature transitions to the helical antiferromagnetic structure at the low temperature.

[0099] In this embodiment, Crystalline oriented Mn3Sn films exhibit a huge anomalous Hall effect at room temperature, with an anomalous Hall resistivity of up to 2.4μΩ·cm and an anomalous Hall conductivity of up to 27Ω. -1 cm -1 The anomalous Hall effect of this sample at room temperature is comparable to that of bulk materials.

Claims

1. A non-collinear antiferromagnetic Mn3Sn single crystal thin film, characterized in that: It includes a substrate and a Mn3Sn film arranged in sequence from bottom to top. The crystal orientation of the Mn3Sn film is (0001). The Mn3Sn film has six degrees of symmetry. The epitaxial relationship of the Mn3Sn film is 2. A non-collinear antiferromagnetic Mn3Sn single crystal thin film, characterized in that: It includes a substrate and a Mn3Sn film arranged in sequence from bottom to top, and the crystal orientation of the Mn3Sn film is The epitaxial relationship of Mn3Sn film is 3. The non-collinear antiferromagnetic Mn3Sn single crystal thin film according to claim 2, characterized in that A low-temperature buffer layer is provided between the substrate and the Mn3Sn film.

4. A method for preparing non-collinear antiferromagnetic Mn3Sn single crystal thin films by molecular beam epitaxy, characterized in that: Prepare (0001) crystal oriented Mn3Sn single crystal film, the Mn3Sn single crystal film includes a substrate and a Mn3Sn film arranged in sequence from bottom to top, the Mn3Sn film has six degrees of symmetry, and the epitaxial relationship of the Mn3Sn film is The preparation steps are as follows: (1) The MgO (111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, substrate annealing temperature is 700℃, annealing time is 20 minutes; (2) The bottom of the metal Mn dual-temperature evaporation source was heated to 927°C, the source port was heated to 932°C, and the Sn high-temperature evaporation source was heated to 1120°C. The vacuum in the growth chamber was lower than 1.7×10 -9 mbar; The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.45:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:

1. (3) During growth, the substrate temperature is stabilized between 480-520°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time; (4) The average film growth rate was controlled at 1.5 nm / min, and epitaxial growth was performed for 100 minutes to obtain a Mn3Sn film with a thickness of 150 nm.

5. The method for preparing a non-collinear antiferromagnetic Mn3Sn single crystal thin film by molecular beam epitaxy according to claim 4, characterized in that: In step (2), the purity of metal Mn is 99.95%, the purity of Sn is 99.999%, and in step (3), the substrate temperature is 500°C.

6. A method for preparing non-collinear antiferromagnetic Mn3Sn single crystal thin films by molecular beam epitaxy, characterized in that: preparation A crystal-oriented Mn3Sn single crystal film includes a substrate and a Mn3Sn film arranged sequentially from bottom to top, with a low-temperature buffer layer provided between the substrate and the Mn3Sn film. The preparation steps are as follows: ① The MgO (111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, substrate annealing temperature is 700℃, annealing time is 20 minutes; ② The bottom of the metal Mn dual-temperature evaporation source was heated to 922°C, the source port was heated to 934°C, and the Sn high-temperature evaporation source was heated to 1131°C. The vacuum in the growth chamber was lower than 3.1×10 -9 mbar; The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.43:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:

1. ③ The substrate temperature is 420°C. The Mn source baffle and the Sn source baffle are opened to grow a 1.3nm low-temperature buffer layer. After the buffer layer growth is completed, the Mn source and Sn source baffles are closed, and the substrate temperature is raised to 600°C and annealed for 3 minutes. ④ During growth, the substrate temperature is stabilized between 450-470°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time; ⑤ The average growth rate of the film was controlled at 1.6 nm / min, and the epitaxial growth was carried out for 100 minutes to obtain a Mn3Sn film with a thickness of 160 nm.

7. The method for preparing a non-collinear antiferromagnetic Mn3Sn single crystal thin film by molecular beam epitaxy according to claim 6, characterized in that: In step ④, the substrate temperature is 460°C.

8. A method for preparing non-collinear antiferromagnetic Mn3Sn single crystal thin films by molecular beam epitaxy, characterized in that: preparation Crystal orientation of Mn3Sn single crystal film, Mn3Sn single crystal film includes a substrate and Mn3Sn film arranged in sequence from bottom to top, the epitaxial relationship of the Mn3Sn film is A low-temperature buffer layer is provided between the substrate and the Mn3Sn film. The preparation steps are as follows: Ⅰ The MgO(111) single crystal substrate was introduced into the growth chamber, and the background vacuum was 6×10 -10 mbar, two-step substrate annealing process: first, substrate annealing temperature is 700℃, annealing for 8 minutes; second, substrate annealing temperature is 800℃, annealing for 12 minutes; II. The bottom of the Mn dual-temperature evaporation source was heated to 922°C, the source port was heated to 934°C, and the Sn high-temperature evaporation source was heated to 1131°C. The vacuum in the growth chamber was lower than 3.1×10 -9 mbar; The growth rate was measured using an in-situ quartz crystal oscillator. The mass ratio of Mn to Sn deposition per unit time was 1.43:1, and the atomic number rate ratio of Mn to Sn was 3 to 3.1:

1. III. The substrate temperature is 420°C. The Mn source shutter and the Sn source shutter are opened to grow a 1.5 nm low-temperature buffer layer. After the buffer layer growth is completed, the Mn source and Sn source shutters are closed, and the substrate temperature is raised to 550°C and annealed for 2.5 minutes. During the IV growth, the substrate temperature is stabilized between 450-470°C, the growth mode is the co-evaporation of Mn and Sn sources, and the Mn source baffle and Sn source baffle are opened at the same time; The average growth rate of the V film was controlled at 1.6 nm / min, and the epitaxial growth was carried out for 100 minutes to obtain a Mn3Sn film with a thickness of 160 nm.

9. The method for preparing a non-collinear antiferromagnetic Mn3Sn single crystal thin film by molecular beam epitaxy according to claim 8, characterized in that: In step IV, the substrate temperature is 460°C.

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