Rare earth intermetallic compound with magnetization step and method of making and using same

Abstract

This invention discloses a rare-earth intermetallic compound with magnetization steps, its preparation method, and its applications, belonging to the field of functional materials technology. The rare-earth intermetallic compound is a dysprosium-gold-tin single-crystal material composed of Dy, Au, and Sn elements, with an atomic ratio of 1:1:1. This material exhibits magnetization step behavior, and the magnetization behavior shows a significant magnetic field orientation dependence. The magnetoresistance of this material continuously increases with increasing magnetic field without a significant saturation trend, and it shows a strong correlation coupling with the low-temperature magnetization step behavior, endowing the material with identifiable and controllable magnetic field response behavior. The rare-earth intermetallic compound provided by this invention achieves the synergistic appearance of large magnetoresistance and magnetization steps while maintaining the metal conductive channels, giving it unique advantages in applications such as low-temperature high-sensitivity magnetic sensing, and also providing a reliable material system for constructing novel functional devices.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to a rare earth intermetallic compound with magnetization steps, its preparation method, and its application. Background Technology

[0002] Rare-earth magnetic materials refer to a class of high-performance functional materials formed by combining rare-earth elements with transition metals and other elements as the core components. Their unique physical basis stems from the unfilled 4f electron shell of rare-earth elements. This electronic configuration endows the materials with rich magnetic ordering properties, such as ferromagnetism, antiferromagnetism, and ferrimagnetism, and can exhibit various electrical transport behaviors, including metallic and semiconductor types. Simultaneously, these materials typically possess excellent magnetocrystalline anisotropy, significant magnetocaloric effects, and good physicochemical stability. Due to these properties, rare-earth magnetic materials have become core foundational materials in strategic fields such as modern spintronics, aerospace, precision instruments, and quantum computing, possessing irreplaceable application value in high-density magnetic storage, high-sensitivity magnetic sensors, and low-temperature quantum devices. Their performance directly determines the miniaturization, high precision, and high reliability of related devices.

[0003] In recent years, antiferromagnetic materials, as an important branch of the rare-earth magnetic materials family, have seen a continuous rise in research interest in the field of spintronics due to their unique advantages in spin transport manipulation and quantum state stability, becoming a research frontier in this field. With in-depth research, antiferromagnetic systems with complex magnetic structures and behaviors, exhibiting unique magnetic response characteristics, have shown great application potential in the development of novel ultra-high-density storage and quantum devices, gradually becoming a research focus in the field of materials science.

[0004] To deeply explore the intrinsic physical mechanisms of these materials and promote their device applications, obtaining high-quality single-crystal samples is crucial. However, current rare-earth single crystal research mainly focuses on systems with relatively simple magnetic structures, with insufficient exploration of material systems exhibiting complex magnetic behaviors. The realization of complex magnetic behaviors (such as multi-step magnetization and magnetization steps) depends on the precise control of magnetic coupling and electronic interactions within the crystal. Existing fabrication techniques offer poor controllability over such complex magnetic structures during growth, resulting in a scarcity of reports on single-crystal materials with specific magnetic behaviors and a relatively weak foundation in related research. Therefore, existing material systems cannot meet the stringent requirements of high-end quantum devices regarding magnetic response characteristics and degrees of freedom in control. There is an urgent need to develop novel antiferromagnetic rare-earth single-crystal materials to further enrich and improve the research system in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a rare-earth intermetallic compound with magnetization steps, its preparation method, and its applications. This invention successfully prepared a DyAuSn single-crystal material with magnetization step behavior via a flux method. This magnetization behavior exhibits a significant magnetic field orientation dependence, and the anisotropy of the magnetic behavior can be controlled by external field orientation. The magnetoresistance of this material continuously increases with increasing magnetic field without saturation, and the magnetic transport behavior exhibits a strong correlation coupling with the magnetization steps.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention is to provide a rare earth intermetallic compound having a magnetization step, wherein the rare earth intermetallic compound is a dysprosium-gold-tin single crystal material composed of three elements Dy, Au and Sn, and the atomic ratio of Dy, Au and Sn is 1:1:1.

[0007] A second aspect of the present invention is to provide a method for preparing rare earth intermetallic compounds as described in the first aspect, comprising the following steps: Dy, Au and Sn were mixed in a molar ratio of 1:1:1 and then smelted to obtain DyAuSn polycrystalline material; The DyAuSn polycrystalline material is mixed with a flux to obtain a mixture. The mixture is then heated to a first temperature in a vacuum-sealed environment to melt it. After holding the mixture at this temperature for 6-12 hours, it is cooled to a second temperature at a rate of 0.5-4℃ / h. The solid product and flux are then separated by centrifugation to obtain the dysprosium gold tin single crystal material. The first temperature is not lower than 900℃; the second temperature is lower than the melting point of the dysprosium-gold-tin single crystal material but higher than the melting point of the flux. At this temperature, the flux is still liquid, which facilitates its separation from the single crystal material by centrifugation. Preferably, the first temperature is 900℃ and the second temperature is 500℃±50℃. During the cooling process from the first temperature to the second temperature, the dysprosium-gold-tin single crystal nucleates and gradually grows from the saturated solution; that is, this temperature range is the growth temperature of the single crystal.

[0008] As a preferred technical solution, Dy, Au, and Sn are mixed in a molar ratio and placed in a copper mold. The system is then evacuated, a protective gas is introduced, and then arc melting is performed for 5-10 minutes to obtain DyAuSn polycrystalline material. More preferably, the protective gas is an inert gas such as high-purity argon.

[0009] As a preferred technical solution, the molar ratio of the DyAuSn polycrystalline material to the flux is 1:(10-15). The flux is Sn.

[0010] A third aspect of the invention is to provide the use of rare earth intermetallic compounds as described in the first aspect in magnetic sensors or spintronic devices.

[0011] The present invention has the following beneficial effects: This invention uses a ternary system of Dy, Au, and Sn to synthesize the target product. This is based on the fact that Dy, as a heavy rare earth element, possesses a strong local magnetic moment and a significant spin-orbit coupling effect, which can serve as a core magnetic source and provide a basis for the anomalous Hall effect. Au combines good chemical stability, suitable spin-orbit coupling strength, and efficient electron transport capability, which can stabilize the crystal structure and form effective hybridization with the 4f electrons of Dy. Sn is a main group element without an intrinsic magnetic moment, which can control the lattice structure, reduce the difficulty of single crystal growth, and suppress impurity phases without interfering with the magnetic order of the system. The three elements achieve a balance between structural stability and magnetic moment activity through appropriate metal-ion hybridization bonding, and synergistically construct a stable intermetallic compound with efficient coupling of magnetic order and electron transport.

[0012] The DyAuSn single-crystal material prepared in this invention exhibits clear magnetization step behavior, with a significant magnetic field orientation dependence. The anisotropy of the magnetic behavior can be tuned by external field orientation. Compared to existing materials, the material prepared in this invention exhibits clear and orientation-dependent step behavior at lower temperatures, combining the isotropic magnetic phase transition temperature with tunable anisotropic magnetization behavior, demonstrating more unique magnetic structure characteristics and application potential. The magnetoresistance of the DyAuSn single-crystal material continuously increases with increasing magnetic field without a significant saturation trend, and shows a strong correlation coupling with the low-temperature magnetization step behavior. This precise correspondence between the magnetic transport characteristics and the spin step rearrangement process endows the material with identifiable and controllable magnetic field response behavior. While maintaining the metallic conductive channels, the synergistic appearance of large magnetoresistance and magnetization steps is achieved, giving it unique advantages over traditional magnetic materials in applications such as low-temperature high-sensitivity magnetic sensing and spin valve devices. It also provides a reliable material system for constructing novel functional devices with strong spin-charge coupling.

[0013] The present invention discloses a flux-based method for preparing DyAuSn single crystals. This method involves mixing DyAuSn polycrystalline material with a flux. Under the action of a low-melting-point flux, the raw materials dissolve at a temperature far below their own melting point to form a homogeneous melt. Subsequently, the melt is slowly cooled to achieve supersaturation, thereby spontaneously nucleating and growing high-quality single crystals. Compared to other growth techniques such as the Czochralski method and the floating zone method, the flux-based method offers significant advantages, including lower growth temperature, simpler process, and controllable cost. It effectively avoids high-temperature phase transformations and component volatilization, resulting in ideal single crystals with good crystal integrity and low defect density. This provides a solid structural guarantee for characterizing and utilizing the intrinsic physical properties of the material. Attached Figure Description

[0014] Figure 1 Here is a photograph of the DyAuSn single crystal material prepared in the example; Figure 2 This is a schematic diagram of the crystal structure of a DyAuSn single crystal, with space group P63mc. Figure 3 X-ray diffraction patterns of DyAuSn single crystals and powders; Figure 4 The SEM morphology of DyAuSn single crystal is shown. Figure 5 This is a surface distribution diagram of elements in a DyAuSn single crystal; Figure 6 The graph shows the magnetization intensity of the magnetic field of DyAuSn single crystal along different directions as a function of temperature and magnetic field. Figure 7 The curve showing the longitudinal resistivity of DyAuSn single crystal as a function of temperature. Figure 8 The curves showing the magnetoresistance of DyAuSn single crystal as a function of magnetic field. Detailed Implementation

[0015] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention. In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail. The raw materials used in the present invention are all commercially available products.

[0016] Example A method for preparing a rare earth intermetallic compound includes the following steps: Polycrystalline synthesis: 99.9% pure Dy blocks, 99.99% pure Au flakes, and 99.99% pure Sn particles are mixed in a molar ratio of 1:1:1 and placed into a copper mold. The electric arc melting furnace door is closed and a vacuum is drawn to 2 × 10⁻⁶. -3 After the pressure drops below 0.05 MPa, high-purity argon gas is introduced as a protective gas until the pressure reaches 0.05 MPa. Arc melting then begins, with the following process parameters: voltage stabilized at 20V, current slowly increased to 180±10A, and melting continued for 10 minutes to allow the raw materials to dissolve, diffuse, and react, ultimately yielding DyAuSn polycrystalline material.

[0017] Weighing and Packaging of Single Crystal Growth Raw Materials: In a glove box protected by high-purity argon (water content < 0.1 ppm, oxygen content < 0.1 ppm), the DyAuSn polycrystalline material obtained by arc melting and the Sn flux particles were weighed at a molar ratio of approximately 1:15 and placed into an alumina crucible. The crucible was then placed into a quartz tube, and the quartz tube was evacuated to 10°C using a vacuum pump. -3 Pa, and then a vacuum seal is completed using an oxyhydrogen flame.

[0018] Single crystal growth: The sealed quartz tube is placed in a high-temperature box furnace and heat-treated according to the following procedure: the temperature is raised to 900 ℃ at a rate of 100 ℃ / h and held for 10 h. During this process, the raw materials are fully melted, diffused, and mixed evenly. Then the temperature is slowly lowered to 500 ℃ at a rate of 2 ℃ / h. The growth temperature of the single crystal is 900~500 ℃. During this process, the crystal nucleates from the saturated melt and gradually grows.

[0019] Crystal separation: Single crystal growth ends at 500℃, and the flux Sn is still liquid at this temperature. Therefore, centrifugation can be used to separate the flux from the single crystal at this temperature. The quartz tube is quickly removed from the high-temperature box furnace at 500℃, inverted, and placed in a centrifuge. It is then centrifuged at 1500 r / min for 10 min to separate the crystal from the flux, ultimately obtaining DyAuSn single crystal material. Figure 1 The image shows a physical picture of the DyAuSn single crystal material prepared in the example, which can be seen to exhibit a metallic luster.

[0020] The structure and properties of the DyAuSn single crystals prepared in the examples were characterized. The structure was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic and electrical transport were measured by superconducting quantum interference device (MPMS) and comprehensive physical property measurement system (PPMS).

[0021] Figure 2 This is a schematic diagram of the crystal structure of a DyAuSn single crystal, with space group P63mc.

[0022] Figure 3 The figure shows the X-ray diffraction patterns of DyAuSn single crystals and powder. The upper part of the figure is the pattern of DyAuSn single crystals, and the lower part is the pattern of powder. It can be seen that the surface of naturally grown DyAuSn single crystals is the (002) crystal plane. The refined X-ray diffraction pattern of DyAuSn powder yields the following unit cell parameters: a=b=4.632Å, c=7.359Å, α=β=90°, γ=120°. In the figure, "Experiment" represents the experimental data of DyAuSn powder XRD, "Calculation" represents the theoretically calculated value, and "Experiment-Calculation" corresponds to the difference between the two data.

[0023] Figure 4 The image shows the SEM morphology of a DyAuSn single crystal, revealing some cracks on the crystal surface.

[0024] Figure 5 To measure the surface distribution of elements on the sample using an EDS instrument, the EDS results showed that Dy, Au, and Sn were uniformly distributed in the single crystal.

[0025] Magnetic measurements of DyAuSn single crystal materials were performed using a superconducting quantum interference device (MPMS-5T, 1.9 K ≤ T ≤ 400 K, 0 ≤ H ≤ 5 T). The magnetization curves of the DyAuSn single crystals were measured using MPMS. The results are as follows: Figure 6 As shown.

[0026] Figure 6 Figure (a) shows the magnetization intensity as a function of temperature when the magnetic field is perpendicular (⊥) and parallel (∥) to the (002) crystal plane, respectively. The curve shows a significant peak at 8 K, corresponding to the Nell temperature T. N =8 K. Where, T N The Nell temperature is the characteristic temperature at which the material undergoes a paramagnetic-antiferromagnetic phase transition. The two curves have overlapping peaks and similar line shapes, indicating that the material exhibits consistent magnetic phase transition characteristics under different magnetic field orientations, and that the phase transition temperature has good isotropy.

[0027] Figure 6 Figure (b) shows the magnetization-magnetic field curves at 2 K. The sample exhibits clear magnetization step behavior, and the step features are more pronounced when the magnetic field is perpendicular (⊥) to the (002) crystal plane, indicating that its magnetization behavior has a significant magnetic field orientation dependence, and the anisotropy of magnetic behavior can be controlled by external field orientation. Compared with existing magnetic materials with magnetization steps, the material of this invention exhibits clear and orientation-dependent step behavior at a lower temperature, combining the isotropic magnetic phase transition temperature with tunable anisotropic magnetization behavior, demonstrating more unique magnetic structure characteristics and application potential.

[0028] Electrical properties were measured using a low-temperature property measurement system (PPMS-9T, 1.8 K ≤ T ≤ 400 K, 0 ≤ H ≤ 9 T). Electrode leads were fabricated using the four-lead method, and the electrical transport of the DyAuSn single crystal was measured to obtain the relationship between its longitudinal resistivity and temperature and magnetic field. The results are as follows: Figure 7 and 8 As shown.

[0029] Figure 7 The curves showing the longitudinal resistivity of DyAuSn single crystal as a function of temperature reveal that the longitudinal resistivity of DyAuSn single crystal gradually decreases with decreasing temperature, exhibiting metallic behavior. The transition at 8K corresponds to a magnetic phase transition. Figure 8The curves show the magnetoresistance of DyAuSn single crystal as a function of magnetic field. It can be seen that the magnetoresistance of DyAuSn single crystal is positive, and generally increases with increasing magnetic field. The DyAuSn single crystal prepared in this invention not only exhibits typical metallic conductivity but also achieves a positive magnetoresistance of up to 612% at 2.2 K and 8.5 T, far exceeding the level of most similar compounds. Furthermore, the magnetoresistance continuously increases with increasing magnetic field without a significant saturation trend, and shows a strong correlation with the low-temperature magnetization step behavior (the transition points correspond to...). Figure 6 (At the step of the magnetization curve in Figure (b)). This precise correspondence between the magnetic transport characteristics and the spin step rearrangement process endows the material's magnetic field response behavior with identifiability and controllability; while maintaining the metal conductive channel, it achieves the synergistic appearance of large magnetoresistance and magnetization steps, giving it unique advantages over traditional magnetic materials in applications such as low-temperature high-sensitivity magnetic sensing and spin valve devices, and also providing a reliable material system for constructing novel functional devices with strong spin-charge coupling.

[0030] This invention successfully prepared DyAuSn single crystals, and systematically characterized their crystal structure, composition, and physical properties using X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, MPMS, and PPMS. Test results show that the preferred orientation of the single crystal growth is the (002) crystal plane, with uniform elemental distribution and good crystal purity. The DyAuSn single crystal of this invention is antiferromagnetically ordered, with a Nell temperature of 8 K. It exhibits clear magnetization step behavior at low temperatures, while also possessing typical metallic conductivity and a high positive magnetoresistance effect of up to 612% at 2.2 K and 8.5 T. The magnetoresistance continuously increases with increasing magnetic field without saturation, and the magnetic transport behavior exhibits a strong correlation coupling characteristic with the magnetization steps.

[0031] This invention, using DyAuSn single crystal, integrates antiferromagnetic phase transition, magnetization steps, metallic conductivity, and ultra-high positive magnetoresistance, breaking through the performance boundaries of existing rare-earth magnetic materials. Leveraging the synergistic response characteristics of the magnetization steps and ultra-high magnetoresistance, it enables the development of highly sensitive, high-resolution ultra-low temperature magnetic field detection devices, achieving precise identification of weak magnetic field signals and adapting to high-end applications such as precision measurement in low-temperature physics and magnetic sensing for quantum devices. Its unique spin step rearrangement and strong magnetoelectric coupling mechanism provide a novel experimental platform for studying cutting-edge physics issues such as spin-carrier coupling and ordered magnetic moment control in antiferromagnetic systems. It also provides new material support for novel device design and fundamental physics research in spintronics and low-temperature functional devices, demonstrating significant research value and innovative applications.

[0032] It should be noted that in other embodiments, the objective of this invention can be achieved when the experimental process meets the following conditions: The preferred molar ratio of DyAuSn polycrystalline material to flux Sn is 1:(10-15), specifically 1:10, 1:12, or 1:15, etc. The main purpose of the cooling rate from 900℃ to 500℃ is to control the cooling to be slow. The cooling rate is preferably set to 0.5-4℃ / h, specifically 0.5℃ / h, 1℃ / h, 2℃ / h or 4℃ / h, etc.

[0033] Those skilled in the art can make appropriate selections of the above process parameters according to actual needs, and all of them can achieve the purpose of this invention.

[0034] Obviously, the described embodiments are only some, not all, of the embodiments 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.

Claims

1. A rare-earth intermetallic compound with magnetization steps, characterized in that, The rare earth intermetallic compound is a dysprosium-gold-tin single crystal material, composed of three elements: Dy, Au, and Sn, with the atomic ratio of Dy, Au, and Sn being 1:1:

1.

2. The method for preparing rare earth intermetallic compounds as described in claim 1, characterized in that, Includes the following steps: Dy, Au and Sn were mixed in a molar ratio of 1:1:1 and then smelted to obtain DyAuSn polycrystalline material; The DyAuSn polycrystalline material is mixed with a flux to obtain a mixture. The mixture is then heated to a first temperature in a vacuum-sealed environment to melt it. After heat preservation, the mixture is cooled to a second temperature at a rate of 0.5-4℃ / h. At the second temperature, the solid product and the flux are separated to obtain the dysprosium gold tin single crystal material. The first temperature is not lower than 900°C; the second temperature is higher than the melting point of the flux.

3. The preparation method according to claim 2, characterized in that, The heat preservation treatment time is 6-12 hours.

4. The preparation method according to claim 2, characterized in that, The method for separating the solid product from the flux is centrifugal separation.

5. The preparation method according to claim 2, characterized in that, The melting process is an electric arc melting process. The specific method is as follows: Dy, Au, and Sn are mixed in molar ratio and placed in a copper mold. The system is evacuated and a protective gas is introduced. Then, electric arc melting is carried out for 5-10 minutes to obtain DyAuSn polycrystalline material.

6. The preparation method according to claim 5, characterized in that, The protective gas is an inert gas.

7. The preparation method according to claim 2, characterized in that, The molar ratio of the DyAuSn polycrystalline material to the flux is 1:(10-15).

8. The preparation method according to any one of claims 2 to 7, characterized in that, The flux is Sn.

9. The preparation method according to claim 8, characterized in that, The first temperature is 900 ℃; the second temperature is 500℃±50℃.

10. The application of the rare earth intermetallic compound as described in claim 1 in magnetic sensors or spintronic devices.

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