Magnetic Weel semimetal single crystal with novel quantum oscillation as well as preparation method and application of magnetic Weel semimetal single crystal
High-quality PrAlSi single crystals were prepared by adjusting the Al/Si occupancy ratio, solving the problem of preparing stable and high-quality magnetic Weyl half-metal materials. This enabled the study of the coupling between magnetism and topological states and quantum oscillation phenomena, and has promising applications in spintronic devices and sensors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YUNNAN NORMAL UNIV
- Filing Date
- 2026-01-29
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies make it difficult to prepare stable and high-quality magnetic Weyl half-metal materials, and there are limited means to study their novel properties and control methods for magnetic coupling with topological states.
Using elemental Al as a flux, and by controlling the pressure of Ar in the quartz tube to regulate the Al/Si occupancy ratio in the single crystal, PrAlSi single crystals that simultaneously break T-symmetry and P-symmetry were prepared. High-purity magnetic Weyl half-metal single crystals were obtained using a high-temperature muffle furnace and centrifugation technology.
Stable Weyl state observations were achieved, facilitating the study of the interaction between magnetic states and Weyl electrons. Temperature-dependent resistivity oscillations were demonstrated, showing potential applications in spintronic devices and sensors.
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Figure CN122039221A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of magnetic topological materials and crystal growth technology, specifically relating to a novel magnetic Weyl semimetal single crystal with quantum oscillations, its preparation method, and its application. Background Technology
[0002] Topological quantum materials possess electronic states with unique degeneracy and chirality, exhibiting not only peculiar physical properties but also immense application potential in information storage and quantum computing. Weyl half-metals are a crucial family of topological quantum materials. Their Weyl fermions can be understood as the degeneracy of quadruple-degenerate Dirac fermions into doubly degenerate fermions. This degeneracy requires the breaking of spatial inversion (P) symmetry or time inversion (T) symmetry, corresponding to non-magnetic and magnetic Weyl half-metals, respectively. Compared to non-magnetic Weyl half-metals, the combination of magnetic and topological states in magnetic Weyl half-metals can generate a wider variety of materials. The most significant characteristic of these materials is that non-trivial Weyl fermions can induce extremely strong Berry curvature, the origin of many novel properties and effects. Furthermore, the coupling of magnetism and topology makes it possible to manipulate and modulate topological states through magnetic fields, temperature, and pressure, providing an excellent platform for studying the coupling between magnetism and non-trivial topology.
[0003] Current research on magnetic Weyl half-metal materials largely focuses on intrinsic T-symmetry-broken material systems. Significant progress has been made in theoretical research, experimental verification, the manipulation of magnetic states and topological properties by external magnetic fields, and magnetic field-induced topological quantum phase transitions. However, due to the complex magnetic structure and the presence of magnetic domain walls, theoretical simulations and experimental characterization of Weyl states and topological phase transitions remain challenging. Therefore, the number of materials that have been verified and systematically studied is limited, and the main focus is on the influence of magnetic structure on topological band structure and corresponding states and effects, while the study of the interaction between magnetism and Weyl fermions requires further investigation. Therefore, experimentally preparing high-quality novel intrinsic magnetic Weyl half-metal materials with stable Weyl states, and further studying the novel properties generated by the coupling of magnetic and topological states, as well as corresponding manipulation techniques, will have significant scientific and application value. Summary of the Invention
[0004] The purpose of this invention is to provide a novel magnetic Weyl half-metal single crystal with stable Weyl states and quantum oscillations, and its preparation method. By optimizing the preparation process, novel quantum transport behavior can be further explored, providing an experimental basis for the potential application of this material in topological quantum devices. The PrAlSi single crystal prepared by this invention is a novel magnetic Weyl half-metal material that simultaneously breaks P-symmetry and T-symmetry. This magnetic Weyl half-metal material has the following three major characteristics: (1) Weyl fermions, which are highly stable and have a temperature range that extends above the magnetic order temperature; (2) By replacing Pr with other rare earth elements, the system composition has rich and varied magnetic states and various types of Weyl fermions, providing convenient conditions for studying the interaction between magnetic structure and topological Weyl electrons; (3) Theory has predicted that Weyl half-metals that simultaneously break P-symmetry and T-symmetry have quantum spin current, but without the generation of charge current. Therefore, the study of PrAlSi has potential application value in energy-free spin quantum devices.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: a novel magnetic Weyl semimetal single crystal with quantum oscillations. The chemical formula of the magnetic Weyl semimetal single crystal is PrAlSi. The single crystal structure belongs to the LaPtSi-type tetragonal crystal system. The space group is asymmetric I41md (No. 109). The lattice parameters are a=b=4.204(7)Å and c=14.524(7)Å. The single crystal belongs to a novel magnetic Weyl semimetal system with simultaneous breaking of T symmetry and P symmetry. Moreover, the single crystal exhibits temperature-dependent resistivity oscillations.
[0006] The present invention describes a method for preparing a novel magnetic Weyl semimetal single crystal with quantum oscillations. Al, one of the elements in the target single crystal PrAlSi, is used as a flux. In a glove box filled with Ar, excess Al is weighed and initially mixed with appropriate amounts of Pr and Si. This mixture is then placed in an alumina crucible and then into a quartz tube. The quartz tube is evacuated, and Ar at different pressures is injected for encapsulation. By changing the pressure of Ar in the sealed quartz tube, the elemental occupancy ratio in the single crystal can be finely adjusted, thereby controlling the distance between the Fermi surface and the Weyl point. The encapsulated quartz tube is placed in a high-temperature muffle furnace and heated to 1100-1200°C to ensure thorough and uniform fusion of the elements. The temperature is then slowly lowered to a temperature higher than the melting point of Al. The quartz tube is quickly removed and centrifuged to separate the target single crystal and the Al flux. The remaining Al flux is removed by soaking in an alkaline aqueous solution to obtain the magnetic Weyl semimetal single crystal PrAlSi.
[0007] The preparation method of the novel magnetic Weyl half-metal single crystal with quantum oscillation described in this invention comprises the following specific preparation steps:
[0008] Step S1: In a glove box filled with Ar, weigh out Pr, Al and Si with a molar ratio of 1:8 to 12:1 and a purity of 99.99% and place them into an alumina crucible.
[0009] Step S2: Place the alumina crucible into the quartz tube, evacuate the quartz tube and inject Ar into it for sealing. Control the Al / Si occupancy ratio by controlling the pressure intensity of the injected Ar, thereby adjusting the distance between the Fermi surface and the Weyl point.
[0010] Step S3: Place the packaged quartz tube in a high-temperature furnace, heat it to 1100~1200℃ at a heating rate of 50~100℃ / h and hold it for 6~10h to make the metal elements uniformly mixed. Then cool it down to 750~780℃ at a cooling rate of 2℃ / h and quickly centrifuge to separate the single crystal and Al elemental flux.
[0011] Step S4: The residual Al flux on the single crystal surface is removed by soaking in sodium hydroxide solution to obtain a shiny, large-scale single crystal PrAlSi with a size of 3mm*4mm.
[0012] Furthermore, the molar ratio of the Pr, Al, and Si elements is 1:10:1.
[0013] Furthermore, the magnetic Weyl semimetal single crystal belongs to a novel magnetic Weyl semimetal system with simultaneous breaking of T-symmetry and P-symmetry. This characteristic enables the magnetic Weyl semimetal single crystal to have stable Weyl states, which facilitates experimental observation and confirmation of Weyl states and is beneficial for studying the correlation between magnetic states and Weyl electrons.
[0014] Furthermore, the magnetic Weyl semimetal single crystal exhibits temperature-dependent resistivity oscillations, which is a novel quantum oscillation phenomenon. Quantum oscillations are an important means of studying the Fermi surface and electronic structure information of materials, making the magnetic Weyl semimetal single crystal show unique application potential in the field of preparing ultra-high sensitivity nanomagnetic sensor devices and imaging equipment.
[0015] Furthermore, the magnetic Weyl semimetal single crystal is a magnetic quantum material that combines topological states and magnetism, and can be used to prepare spintronic devices and sensors.
[0016] Furthermore, the spintronic devices and sensors mainly include magnetic storage devices, logic gates, and quantum-limited magnetic sensors.
[0017] The present invention has the following advantages and beneficial effects: (1) The present invention uses the self-fluxing method with Al element flux to prepare magnetic Weyl semimetal single crystal PrAlSi, which effectively avoids the introduction of foreign elements and ensures a clean analytical environment for the single crystal. By changing the pressure of Ar in the closed quartz tube, the Al / Si element occupancy ratio in the single crystal can be finely adjusted, thereby controlling the distance between the Fermi surface and the Weyl point. (2) The PrAlSi single crystal prepared by the present invention simultaneously breaks T symmetry and P symmetry. This feature makes the single crystal system have stable Weyl states, which is convenient for experimental observation and confirmation of Weyl states and conducive to studying the correlation between magnetic states and Weyl electrons. This makes the single crystal material system have attractive application prospects in spintronic devices and sensors. (3) The PrAlSi single crystal prepared by the present invention exhibits temperature-dependent resistivity oscillation, which is a new type of quantum oscillation phenomenon. Quantum oscillation is an important means of studying the Fermi surface and electronic structure information of materials, which makes PrAlSi single crystal show unique application potential in the field of preparing ultra-high sensitivity nanomagnetic sensor devices and imaging equipment. (4) The equipment used in the preparation process involved in this invention is conventional equipment such as glove box, molecular pump unit, muffle furnace, centrifuge, etc. No other additional equipment is required. The preparation process is simple and easy to implement, has good repeatability, and is convenient for mass production. Furthermore, the prepared PrAlSi single crystal has stable chemical properties and is very environmentally friendly. The preparation of the corresponding devices can be completed in air and it remains highly stable to air, alcohol, water and other environments. Attached Figure Description
[0018] Figure 1 The following are the refined powder XRD patterns of the PrAlSi single crystal synthesized in the examples (a); single crystal XRD pattern (b); inset: optical image of the crystal; EDX spectrum of the crystal (c); crystal structure (d).
[0019] Figure 2 The curves show the specific heat, magnetic susceptibility, and zero-field resistivity of the PrAlSi single crystal synthesized in the examples.
[0020] Figure 3 The resistivity-temperature (ρ-T) curves of the PrAlSi single crystal synthesized in the example are shown from 0 to 16T.
[0021] Figure 4 The magnetoresistance (MR) curves of the PrAlSi single crystal synthesized in the example are shown at 2-34K.
[0022] Figure 5 The following is an analysis of the SdH oscillation of the PrAlSi single crystal synthesized in the example: (a) the dependence of the amplitude on the inverse of the magnetic field; (b) the fast Fourier transform spectrum of the corresponding oscillation.
[0023] Figure 6The magnetoresistance (MR) curves of the PrAlSi single crystal synthesized in the example are shown at 2-44K.
[0024] Figure 7 This is a comparative analysis between the direct ρ-T measured at 6-9T of the PrAlSi single crystal synthesized in the examples and the ρ-T (MR) extracted from the magnetoresistance curve. Detailed Implementation
[0025] The present invention will be further described in detail below with reference to embodiments and accompanying drawings. However, it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.
[0026] The specific preparation method of the magnetic Weyl half-metal PrAlSi crystal provided in this embodiment is as follows:
[0027] Al, one of the target single-crystal elements, was used as a flux because it has a low melting point, is easy to clean, effectively avoids the introduction of foreign impurity elements, and facilitates centrifugation. In a glove box filled with Ar, a total of 6g of high-purity (99.99%) Pr, Al, and Si in a molar ratio of 1:10:1 was weighed and placed in an alumina crucible, which was then placed inside a quartz tube. The quartz tube was then evacuated (below 10°C). -4 The target single crystal is then encapsulated with Ar at different pressures (0.05-0.25 MPa). By adjusting the Ar pressure, the occupancy ratio of Al / Si atoms in the crystal lattice is precisely controlled, thereby affecting the distance between the Fermi surface and the Weyl point, as well as the coupling between the 4f electrons and the Weyl point. The encapsulated quartz tube is vertically placed in a high-temperature muffle furnace, and the programmed heating rate is set to 100℃ / h. After 11h, the temperature is increased to 1150℃ and held for 10h. Then, the temperature is decreased to 750℃ (200h) at a cooling rate of 2℃ / h. The quartz tube is quickly removed, inverted, and placed in a centrifuge cup to quickly separate the target single crystal and the Al flux. The residual Al flux is removed by soaking in sodium hydroxide aqueous solution, finally yielding a shiny, sheet-like bulk single crystal PrAlSi.
[0028] Detailed analysis of test results:
[0029] Figure 1 This includes crystal structure analysis, crystal optical images, and energy dispersive spectroscopy (EDS) of a magnetic Weyl half-metal PrAlSi single crystal in the examples. Crystal structure analysis results ( Figure 1(a), (b), and (d) show that the PrAlSi single crystal structure belongs to the LaPtSi-type tetragonal crystal system, with the space group being asymmetric I41md (No. 109), and the lattice parameters being a=b=4.204(7)Å and c=14.524(7)Å. EDX energy dispersive spectroscopy analysis shows that the elemental ratio of the crystal is close to 1:1:1. Figure 1 This demonstrates that the simple and easy-to-implement experimental scheme of this invention can be used to prepare high-quality bulk single crystals with broken P-symmetry.
[0030] Figure 2 These are the temperature-dependent specific heat, magnetic susceptibility, and zero-field resistivity curves of the magnetic Weyl half-metal PrAlSi single crystal in the examples. The data results indicate that the PrAlSi single crystal is ferromagnetic, and its magnetic transition temperature (T) is... c The K value is approximately 17.6 K, and there are corresponding responses in specific heat, magnetic data, and electrical transport data. Figure 2 The main point is that PrAlSi single crystals can be prepared using the simple and easy experimental scheme of this invention. PrAlSi is a ferromagnetic Weyl half-metal with broken T symmetry.
[0031] Figure 3 These are the ρ-T curves of the magnetic Weyl half-metal PrAlSi single crystal under different magnetic fields in the examples. As the applied magnetic field increases, the ferromagnetic transition temperature is gradually suppressed. When the applied magnetic field is 4T, a weak quantum oscillation phenomenon appears in the ρ-T curve. When the magnetic field reaches 6T or higher, obvious ρ-T quantum oscillations can be observed. Quantum oscillations (SdH) are a powerful tool for obtaining Fermi surface information and revealing novel physical phenomena. In existing reports, the oscillation period of SdH is generally the reciprocal of the magnetic field (1 / B). However, Wang Jian et al. from Peking University first discovered a novel quantum phenomenon in ZrTe5 exhibiting a logarithmic periodicity with increasing magnetic field, which has attracted widespread attention. To date, no temperature-dependent resistivity quantum oscillations have been reported in ferromagnetic Weyl half-metal materials, indicating that this is a novel quantum oscillation phenomenon.
[0032] Figure 4 These are the MR-H curves of the magnetic Weyl half-metal PrAlSi single crystal at different temperatures in the examples. The data shows that T... c The clear and distinct SdH quantum oscillations below demonstrate that the prepared single crystal is clean and of high quality. Temperatures above T... c Furthermore, SdH quantum oscillations also exist in the paramagnetic region. In typical SdH quantum oscillations, the peak and trough positions remain largely unchanged with increasing temperature, only the amplitude gradually weakens. However, in this invention, the SdH quantum oscillation peaks and troughs exhibit a certain relative displacement, suggesting a change in the Fermi level.
[0033] Figure 5This example illustrates the SdH oscillation analysis of a magnetic Weyl half-metal PrAlSi single crystal. The SdH oscillation amplitude ΔR can be obtained by subtracting the smooth background R0 from the resistance versus magnetic field curve. xx =R xx -R0, such as Figure 5 As shown in (a), the oscillation amplitude gradually decreases with increasing temperature, and in the three temperature ranges (curves 1, 2, and 3), the peaks and troughs completely reverse. The Fast Fourier Transform (FFT) of the corresponding oscillation portion shows only one main peak α with a frequency of F. α =37T (2K), gradually decreasing to 10T (34K). In the SdH oscillation, according to the Onsag relation It is pointed out that the frequency F is proportional to the cross-sectional area of the Fermi surface extremum perpendicular to the magnetic field. This indicates that PrAlSi single crystal has at least one Fermi pocket, and that this pocket changes with temperature.
[0034] Figure 6 These are the MR-H curves of the magnetic Weyl half-metal PrAlSi crystal from 2 to 44 K in the examples. To investigate the origin of the p-T quantum oscillations in this invention, we characterized more detailed MR-H curves, such as... Figure 6 As shown. Based on MR-H data, resistance data points with magnetic fields fixed at 6T, 7T, 8T, and 9T were extracted, and ρ-T(MR) was obtained by plotting against temperature. Figure 7 (As shown by the red line). Directly measured ρ-T curve ( Figure 7 The figure shown by the black line almost perfectly coincides with ρ-T (MR), indicating that the ρ-T quantum oscillation originates from the destructive interference between SdH oscillations of the spin-splittered Fermi surface. In summary, the change in the Fermi surface is mainly due to the strong exchange interaction between Weyl fermions and -4f electrons. The magnetic Weyl half-metal PrAlSi single crystal in this invention is a magnetic Weyl half-metal material with novel quantum oscillations, and it holds promise for applications in magnetic memories, logic gates, quantum-limited magnetic sensors, ultra-high sensitivity nanomagnetic sensing, and imaging.
[0035] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.
Claims
1. A novel magnetic Weyl semimetal single crystal with quantum oscillations, characterized in that: The chemical formula of this magnetic Weyl half-metal single crystal is PrAlSi. The single crystal structure belongs to the LaPtSi-type tetragonal crystal system, and the space group is asymmetric. I 41 md (No. 109), lattice parameters are a = b =4.204(7)Å, c =14.524(7)Å, single crystal belongs to T Symmetry and P A novel magnetic Weyl half-metal system with simultaneously broken symmetry, and single crystals exhibit temperature-dependent resistivity oscillations.
2. A method for preparing a novel quantum oscillation magnetic Weyl half-metal single crystal as described in claim 1, characterized in that: Al, one of the elements in the target single crystal PrAlSi, is used as a flux. In a glove box filled with Ar, excess Al is weighed and preliminarily mixed with Pr and Si. The mixture is then placed in an alumina crucible and then placed in a quartz tube. The quartz tube is evacuated and sealed with Ar at different pressures. By changing the pressure of Ar in the sealed quartz tube, the elemental occupancy ratio in the single crystal can be finely adjusted, thereby controlling the distance between the Fermi surface and the Weyl point. The sealed quartz tube is placed in a high-temperature muffle furnace and heated to 1100~1200℃ to ensure that the elements are fully fused and homogenized. The temperature is then slowly lowered to a temperature higher than the melting point of Al. The quartz tube is then quickly removed and centrifuged to separate the target single crystal and the Al flux. The remaining Al flux is removed by soaking in an alkaline aqueous solution to obtain the magnetic Weyl half-metal single crystal PrAlSi.
3. The method for preparing a novel quantum oscillation magnetic Weyl half-metal single crystal according to claim 2, characterized in that... The specific preparation steps are as follows: Step S1: In a glove box filled with Ar, weigh out Pr, Al and Si with a molar ratio of 1:8 to 12:1 and a purity of 99.99% and place them into an alumina crucible. Step S2: Place the alumina crucible into the quartz tube, evacuate the quartz tube and inject Ar into it for sealing. Control the Al / Si occupancy ratio by controlling the pressure intensity of the injected Ar, thereby adjusting the distance between the Fermi surface and the Weyl point. Step S3: Place the packaged quartz tube in a high-temperature furnace, heat it to 1100~1200℃ at a heating rate of 50~100℃ / h and hold it for 6~10h to make the metal elements uniformly mixed. Then cool it down to 750~780℃ at a cooling rate of 2℃ / h and quickly centrifuge to separate the single crystal and Al elemental flux. Step S4: The residual Al flux on the single crystal surface is removed by soaking in sodium hydroxide solution to obtain a shiny, sheet-like bulk single crystal PrAlSi with a size of 3mm*4mm.
4. The method for preparing a novel quantum oscillation magnetic Weyl half-metal single crystal according to claim 3, characterized in that: The molar ratio of Pr, Al, and Si is 1:10:
1.
5. The application of the magnetic Weyl semimetal single crystal with novel quantum oscillation as described in claim 1 in the preparation of ultra-high sensitivity nanomagnetic sensor devices and imaging equipment, wherein the magnetic Weyl semimetal single crystal exhibits temperature-dependent resistivity oscillation, which is a novel quantum oscillation phenomenon.
6. The application of the magnetic Weyl semimetal single crystal according to claim 1 in the fabrication of spintronic devices and sensors.
7. The application according to claim 6, characterized in that: The spintronic devices and sensors mainly include magnetic storage devices, logic gates, and quantum-limited magnetic sensors.