Artificial spinning ice system based on macroscopic magnet and preparation method and regulation and control method thereof

Abstract

The invention relates to an artificial spinning ice system based on a macroscopic magnet and a preparation method and a regulation and control method thereof. The system comprises an empty trap array and a plurality of macroscopic magnets, the empty trap array comprises a plurality of empty traps, preset different distances are formed between adjacent empty traps, the number of the macroscopic magnets corresponds to the number of the empty traps, and the height of the macroscopic magnets is smaller than the depth of the corresponding empty traps; the macroscopic magnets are arranged in the empty trap according to the same magnetic moment direction, one part of the macroscopic magnets are close to the bottom of the corresponding empty trap, and the other part of the macroscopic magnets are close to the top of the corresponding empty trap. Compared with the prior art, the method has the advantages of avoiding the problem that the nano-magnet is difficult to enter an expected ground state due to instability of the experimental process caused by the influence of heating fluctuation, and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic materials, and in particular to an artificial spin ice system based on a macroscopic magnet and a preparation method and a control method thereof. Background Art

[0002] Frustration refers to the phenomenon that in a system, there is a competitive relationship between the interactions between the various parts, which makes the system unable to meet all energy minimization conditions at the same time, and thus cannot reach the global energy minimization state. The magnetic spins in spin ice materials exhibit ice-like rule behavior, forming a low-energy degenerate state with residual entropy at low temperatures. These materials show constrained disordered behavior similar to the "ice rule" in water ice through the interaction of magnetic spins.

[0003] With the development of nanotechnology, researchers have constructed an artificial spin ice system to simulate the frustration phenomenon in the spin ice system by precisely designing arrays of magnetic nano-islands with specific geometric shapes. Artificial spin ice systems are usually made of ferromagnetic materials (such as cobalt, nickel, iron, etc.), and by designing arrays of nano-islands with different geometric arrangements, each magnetic nano-island can be regarded as a spin, and its direction can be controlled by an external magnetic field. The system has high adjustability and controllability. Researchers can adjust the size, arrangement structure and interaction strength of the nano-islands to conduct in-depth research on the collective behavior, energy minimization process and thermodynamic properties in spin ice. The artificial spin ice system not only provides a platform for studying the frustration phenomenon, but can also be applied to fields such as information storage, computing and quantum information processing.

[0004] However, although artificial spin ices provide an important experimental platform for studying frustrated phenomena at the microscopic and mesoscopic scales, they also face some challenges. At the microscopic scale, nanomagnets are susceptible to thermal fluctuations and have difficulty in stably entering the expected ground state, resulting in large instabilities during the experiment. In addition, the rapidly changing domain walls and particle motions in the microstructure make it difficult to study collective dynamical behavior. At the mesoscopic scale, although the size of the system is large, it is usually difficult to observe stable dynamic processes and complete phase transition phenomena over long time scales due to structural and material limitations. Traditional microscopic theoretical models (such as the Ising model) often fail to take into account factors such as gravity and energy barriers, and the effects of these factors on frustrated phenomena and collective dynamical processes have not yet been fully quantitatively described. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide an artificial spin ice system based on macroscopic magnets and its preparation method and regulation method, which can avoid the limitations of traditional spin ice systems, utilize the more stable magnet interactions on a macroscopic scale, rationally design the arrangement of magnets and their interactions, form an "up and down" state arrangement to analogize the two states of Ising spin, and thereby realize the study of frustration phenomena in arbitrary lattice structures.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to a first aspect of the present invention, there is provided an artificial spin ice system based on a macroscopic magnet, comprising an empty well array and a plurality of macroscopic magnets, wherein the empty well array comprises a plurality of empty wells, adjacent empty wells have preset different spacings, the number of the macroscopic magnets corresponds to the number of the empty wells, and the height of the macroscopic magnets is less than the depth of the corresponding empty wells; the plurality of the macroscopic magnets are placed in the empty wells in the same magnetic moment direction, with a portion of the macroscopic magnets being close to the bottom of the corresponding empty wells and another portion of the macroscopic magnets being close to the top of the corresponding empty wells.

[0008] As a preferred technical solution, the macro magnet includes a cylindrical neodymium iron boron magnet.

[0009] As a preferred technical solution, the empty well array is a triangular structure array, and the spacing includes 0.5mm, 0.9mm, 1mm, 1.5mm, 1.9mm, 3mm, 5mm, 7mm and 9mm.

[0010] As a preferred technical solution, the empty well array is a compressed triangular structure array, and the spacing includes 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 7mm and 9mm.

[0011] As a preferred technical solution, the empty well array is a quasi-crystal structure array, and the spacing includes 0.9 mm, 1 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm and 5 mm.

[0012] As a preferred technical solution, the empty well array is a square structure array, and the spacing includes 0.2mm, 0.5mm, 1mm, 1.2mm, 1.5mm, 1.9mm, 2.2mm, 2.5mm and 3mm.

[0013] As a preferred technical solution, the empty well array has periodic symmetry.

[0014] According to a second aspect of the present invention, a method for preparing an artificial spin ice system is provided, and the method is used to obtain the artificial spin ice system, comprising the following steps: S1, determining an empty well array according to a preset geometric shape, and inserting a circular hole pattern at the vertices of the geometric shape to obtain a geometric array and a corresponding program file, wherein the circular hole pattern is used to determine the position of the empty wells, and there are preset different spacings between adjacent empty wells, and the spacings are used to determine the geometric shape corresponding to the empty well array; S2, importing the program file into a preset laser cutting machine program; S3, cutting the geometric array into a preset acrylic sheet; S4, placing pre-acquired macroscopic magnets vertically and row by row in the corresponding empty well positions in the geometric array according to the same magnetic moment direction, and covering them with acrylic sheets; S5, drilling holes around the current acrylic sheet and fixing it with non-magnetic screws to obtain the artificial spin ice system.

[0015] As a preferred technical solution, in step S3, the acrylic sheet has a thickness of 10 mm, a length of 200 mm, and a width of 200 mm.

[0016] According to a third aspect of the present invention, a method for regulating an artificial spin ice system is provided. The method is implemented based on the artificial spin ice system based on macroscopic magnets, and comprises the following steps: applying an external magnetic field to the artificial spin ice system; observing the arrangement, distribution and dynamic changes of the macroscopic magnets, and recording the dynamic phenomena and phase changes in the artificial spin ice system at different spacings when the external magnetic field is introduced.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention uses macroscopic magnets instead of nanomagnets, which can more intuitively observe the interaction between magnets, the generation of frustration and its behavior, and has high stability, avoiding the problem that the nanomagnets are difficult to enter the expected ground state due to thermal fluctuations, resulting in unstable experimental process;

[0019] 2. The present invention uses classical magnets and conducts experiments at room temperature. Changes in temperature and pressure have almost no effect on the structure. At the same time, the structure can remain stable for a long time, which can avoid the influence of temperature, pressure and size effects in traditional artificial spin ice systems, thereby better studying the collective dynamics between magnets.

[0020] 3. In the structure provided by the present invention, there are preset different spacings between adjacent empty wells, the height of the macroscopic magnet is less than the depth of the corresponding empty well to ensure that the magnet can move up and down in the empty well, and multiple macroscopic magnets are placed in the empty well in the same magnetic moment direction, one part of which is close to the bottom of the corresponding empty well, and the other part is close to the top of the corresponding empty well, forming an "up and down" state arrangement, which can be analogous to the two states of Ising spin. Combined with the control method, it can realize the study of frustration phenomenon in any lattice structure. At the same time, it is different from the Ising model, and it can consider the energy barrier of the movement of the macroscopic magnet in the empty well, and then consider the influence on the distribution of different configurations composed of frustrated bonds in the ground state. In the sample dominated by gravity, most of the macroscopic magnets fall, thereby increasing the frustration degree of the structure;

[0021] 4. The control method provided by the present invention adjusts the spacing between empty wells, that is, the spacing between magnets, and can accurately control the strength of the interaction in the artificial spin system. At the same time, an external magnetic field is applied to further study the influence of the external magnetic field and different empty well spacings on the frustration effect and ice phase formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic flow chart of the preparation method is provided for the present invention;

[0023] Figure 2 This is a schematic structural diagram of an artificial spin ice system based on macroscopic magnets of a triangular structure array provided in Example 1 of the present invention;

[0024] Figure 3 This is a schematic diagram of the arrangement of the macroscopic magnets provided in Example 1 of the present invention;

[0025] Wherein: 1. PMMA plate; 2. first macro magnet; 3. second macro magnet. DETAILED DESCRIPTION

[0026] In view of the problems existing in the existing artificial spin ice system, the present invention provides an artificial spin ice system based on macroscopic magnets, which aims to study and regulate the interaction between magnets in any lattice structure and the frustration effect caused by it, and can be widely used in spin ice, magnetic materials, condensed matter physics and related fields. The system includes an empty well array and a plurality of macroscopic magnets. The empty well array includes a plurality of empty wells, and there is a preset spacing between adjacent empty wells. The number of macroscopic magnets corresponds to the number of empty wells, and the height of the macroscopic magnet is less than the depth of the corresponding empty well. The plurality of macroscopic magnets are placed in the empty wells in the same magnetic moment direction, and one part of them is close to the bottom of the corresponding empty well, and the other part is close to the top of the corresponding empty well. Specifically, each micro empty well contains a magnet, and the magnet can move freely up and down in its corresponding empty well.

[0027] Optionally, the macroscopic magnet includes a cylindrical neodymium iron boron (NdFeB) magnet, and is placed in a cut empty well array, which can be obtained by the artificial spin ice system preparation method provided by the present invention. Based on the artificial spin ice system provided by the present invention, by adjusting the spacing between the empty wells, that is, the spacing between the magnets, empty well arrays of different geometric shapes, that is, different magnet arrangements, can be obtained. At the same time, a control method is provided to apply an external magnetic field to the prepared artificial spin ice system to adjust the interaction strength and position between the magnets, thereby simulating the frustration effect in the spin ice system. During the implementation of the control method, by adjusting the interaction and position between the magnets, the system can achieve energy minimization and observe state changes similar to those in the Ising spin model.

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments. The macro magnets used in the following embodiments are all cylindrical neodymium iron boron (NdFeB) magnets with dimensions of 5.89 mm in height, 3.97 mm in diameter, and 0.557 g in mass.

[0029] Embodiment 1:

[0030] like Figure 1 As shown, this embodiment first provides a method for preparing an artificial spin ice system. The method specifically includes:

[0031] Step S1, determine the empty well array according to the preset geometric shape, and insert the circular hole pattern at the vertex of the geometric shape to obtain the geometric array and the corresponding program file. The circular hole pattern is used to determine the position of the empty wells, and there is a preset different spacing d between adjacent empty wells. Optionally, the design of the empty well array and the insertion of the circular hole pattern are completed in the auto CAD software, and the program file corresponding to the geometric array composed of circular holes is a dwg file. In addition, the geometric array has periodic symmetry and can be composed of geometric shapes including triangles. The restricted area when preparing the geometric array is 20×20cm 2 plane.

[0032] Step S2, importing the program file into a preset laser cutting machine program. Optionally, in the auto CAD software, converting the dwg file obtained in step S1 into a dxf file and importing it into the laser cutting machine program.

[0033] Step S3, cutting the geometric array into a preset acrylic sheet. Optionally, a laser cutting machine is used to cut the geometric array in step S2 into a square acrylic sheet; the laser cutting machine uses a continuous wave with a wavelength of λ=10.6 μm for cutting.

[0034] Step S4, placing the pre-acquired macroscopic magnets in the corresponding empty well positions in the geometric array vertically and row by row in the same magnetic moment direction, and covering them with acrylic sheets. The vertical refers to the direction perpendicular to the plane, and placing them in the corresponding empty well positions, that is, placing them on the cut acrylic sheet obtained in step S3, and covering them with a thin acrylic sheet, the thickness of the thin acrylic sheet is, for example, 2mm. Among them, the acrylic sheet (i.e., polymethyl methacrylate, PMMA) used to constrain the magnets in steps S3 to S4 has a thickness of 10mm, and the complete size of the entire plate is 200×200×10mm 3 , the empty well size is slightly larger than the diameter of the magnet.

[0035] Step S5, punch holes around the current acrylic sheet and fix it with non-magnetic screws to obtain an artificial spin ice system. Optionally, a puncher is used to punch holes. The upper and lower surfaces of the artificial spin ice system (sample) obtained in steps S4 to S5 are covered with a 2 mm thick PMMA plate and fixed with non-magnetic copper screws.

[0036] Based on the above-mentioned preparation method, this embodiment provides a triangular structure array with an empty well spacing of d as a geometric array of an artificial spin ice system, such as Figure 2 In this triangular structure array, the specific spacing values ​​include 0.5mm, 0.9mm, 1mm, 1.5mm, 1.9mm, 3mm, 5mm, 7mm and 9mm, and the array is cut into 20×20cm 2 The PMMA plate 1 is cut by a CO2 laser with a wavelength of 10.6 μm, and cylindrical empty wells with a diameter of 4.13 mm and a depth of 10 mm are cut in sequence to form a triangular lattice array with different empty well spacings d. The empty well diameter is slightly larger than the magnet diameter to ensure that the magnet can move freely up and down in the empty well.

[0037] Place the macro magnets in the cut empty wells in rows in the same magnetic moment direction and in the vertical plane direction, and cover them with a thin acrylic plate. Figure 3 As shown, the height of the macro magnet is less than the depth of the corresponding empty well, wherein a part of the macro magnet is close to the bottom of the corresponding empty well, namely the first macro magnet 2, and another part of the macro magnet is close to the top of the corresponding empty well, namely the second macro magnet 3, and the second macro magnet 3 and the first macro magnet 2 form an "up and down" arrangement. Then, a puncher is used to punch holes around the acrylic plate, and it is fixed with non-magnetic screws to ensure that the magnets are stably arranged in the empty well.

[0038] By experimentally recording the arrangement of macroscopic magnets in artificial spin ice system samples prepared at different spacings, it can be found that the behavior of macroscopic magnets remains stable over long time scales, and a ground state consisting of low-energy configurations can be achieved in small-spacing samples. At the same time, the artificial spin ice system prepared in this embodiment is different from the Ising model. There is an energy barrier to the movement of magnets in an empty well, which affects the distribution of different configurations composed of frustrated bonds in the ground state. In samples dominated by gravity, most of the magnets fall, increasing the degree of frustration of the system.

[0039] On this basis, the artificial spin ice system samples based on triangular structure arrays at different prepared spacings were regulated, similar to "magnetic annealing". Specifically, the arrangement of magnets was adjusted by an external magnetic field, and the arrangement behavior of magnets under different magnetic field strengths was observed. An optical camera was used to capture the distribution and dynamic changes of magnets, and to record the dynamic phenomena and phase changes that occurred in the artificial spin ice system based on macroscopic magnets at different spacings when an external magnetic field was introduced, to achieve the transition from a high-energy disordered structure to a low-energy ordered structure.

[0040] Embodiment 2:

[0041] Based on the preparation method provided in Example 1, this embodiment provides a compressed triangular structure array with an empty well spacing of d as a geometric array of an artificial spin ice system. In the compressed triangular structure array, specific spacing values ​​include 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 7mm and 9mm. Specifically, in 20×20cm 2 On the PMMA plate, a CO2 laser with a wavelength of 10.6 μm is used to sequentially cut cylindrical empty wells with a diameter of 4.13 mm and a depth of 10 mm to form a compressed triangular lattice array with different empty well spacings d. The empty well diameter is slightly larger than the magnet diameter to ensure that the magnet can move freely up and down in the empty well. The magnet placement process and system packaging process are the same as those in Example 1, and will not be repeated here.

[0042] Similarly, by experimentally recording the arrangement of magnets in artificial spin ice system samples prepared at different spacings, it can be found that the behavior of magnets remains stable over long time scales, and phase transitions of ordered structures can be observed in samples with different spacings. In this artificial spin ice system based on a compressed triangular structure array, there are energy barriers and the effects of gravity on frustration. At the same time, this system is different from the Ising model. There is an energy barrier to the movement of magnets in an empty well, which affects the distribution of different configurations composed of frustrated bonds in the ground state. In samples dominated by gravity, most of the magnets fall, increasing the degree of frustration of the system.

[0043] On this basis, the artificial spin ice system samples based on the compressed triangular structure array at different prepared spacings were regulated. The specific process and conclusion are basically the same as those in Example 1, and will not be repeated here.

[0044] Embodiment 3:

[0045] Based on the preparation method provided in Example 1, this embodiment provides a quasi-crystal structure array with an empty well spacing of d as a geometric array of an artificial spin ice system. In the quasi-crystal structure array, specific spacing values ​​include 0.9 mm, 1 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm and 5 mm. The process of preparing an artificial spin ice system sample based on the quasi-crystal structure array is the same as that in Example 1, and will not be repeated here.

[0046] Similarly, by experimentally recording the arrangement of magnets in samples of artificial spin ice systems prepared at different spacings, it can be found that the behavior of magnets remains stable over long time scales, and long-range ordered structures are observed in samples with different spacings. In this artificial spin ice system based on a quasicrystal structure array, there are energy barriers and the influence of gravity on frustration. At the same time, this system is different from the Ising model. There is an energy barrier to the movement of magnets in an empty well, which affects the distribution of different configurations composed of frustrated bonds in the ground state. In samples dominated by gravity, most of the magnets fall, increasing the degree of frustration of the system.

[0047] On this basis, the artificial spin ice system samples based on the quasicrystal structure array at different prepared spacings were regulated. The specific process and conclusion are basically the same as those in Example 1, and will not be repeated here.

[0048] Embodiment 4:

[0049] Based on the preparation method provided in Example 1, this embodiment provides a square structure array with an empty well spacing of d as a geometric array of an artificial spin ice system. In the square structure array, specific spacing values ​​include 0.2 mm, 0.5 mm, 1 mm, 1.2 mm, 1.5 mm, 1.9 mm, 2.2 mm, 2.5 mm and 3 mm. The process of preparing an artificial spin ice system sample based on the square structure array is the same as that in Example 1, and will not be repeated here.

[0050] Similarly, by experimentally recording the arrangement of magnets in samples of artificial spin ice systems prepared at different spacings, it can also be found that the behavior of magnets remains stable over long time scales, and low-energy configurations are observed to occupy most of the vertices in samples with different spacings. In this artificial spin ice system based on a square structure array, there are energy barriers and the influence of gravity on frustration. At the same time, this system is different from the Ising model. There is an energy barrier to the movement of magnets in an empty well, which affects the distribution of different configurations composed of frustrated bonds in the ground state. In samples dominated by gravity, most of the magnets fall, increasing the degree of frustration of the system.

[0051] On this basis, the artificial spin ice system samples based on square structure arrays with different prepared spacings were regulated. The specific process and conclusion are basically the same as those in Example 1, and will not be repeated here.

[0052] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. An artificial spin ice system based on macroscopic magnets, characterized in that: It comprises an empty well array and a plurality of macroscopic magnets, wherein the empty well array comprises a plurality of empty wells, adjacent empty wells have preset different spacings, the number of the macroscopic magnets corresponds to the number of the empty wells, and the height of the macroscopic magnets is less than the depth of the corresponding empty wells; the plurality of macroscopic magnets are placed in the empty wells in the same magnetic moment direction, with a part of them close to the bottom of the corresponding empty wells and another part close to the top of the corresponding empty wells.

2. The macroscopic magnet-based artificial spin ice system according to claim 1, characterized in that: The macroscopic magnet includes a cylindrical neodymium iron boron magnet.

3. The macroscopic magnet-based artificial spin ice system according to claim 1, characterized in that: The empty well array is a triangular structure array, and the spacing includes 0.5mm, 0.9mm, 1mm, 1.5mm, 1.9mm, 3mm, 5mm, 7mm and 9mm.

4. The macroscopic magnet-based artificial spin ice system according to claim 1, characterized in that: The empty well array is a compressed triangular structure array, and the spacing includes 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 7mm and 9mm.

5. The macroscopic magnet-based artificial spin ice system according to claim 1, characterized in that: The empty well array is a quasi-crystal structure array, and the spacing includes 0.9 mm, 1 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm and 5 mm.

6. The macroscopic magnet-based artificial spin ice system according to claim 1, characterized in that: The empty well array is a square structure array, and the spacing includes 0.2mm, 0.5mm, 1mm, 1.2mm, 1.5mm, 1.9mm, 2.2mm, 2.5mm and 3mm.

7. The artificial spin ice system based on macroscopic magnets according to any one of claims 1 to 6, characterized in that: The empty well array has periodic symmetry.

8. A method for preparing an artificial spin ice system, characterized in that: The preparation method is used to obtain the artificial spin ice system according to any one of claims 1 to 6, comprising the following steps: S1, determining an empty well array according to a preset geometric shape, and inserting a circular hole pattern at the vertices of the geometric shape to obtain a geometric array and a corresponding program file, wherein the circular hole pattern is used to determine the position of the empty wells, and there are preset different spacings between adjacent empty wells, and the spacings are used to determine the geometric shape corresponding to the empty well array; S2, importing the program file into a preset laser cutting machine program; S3, cutting the geometric array into a preset acrylic sheet; S4, placing the pre-acquired macroscopic magnets vertically and row by row in the corresponding empty well positions in the geometric array in the same magnetic moment direction, and covering them with acrylic sheets; S5, holes are punched around the current acrylic sheet and fixed with non-magnetic screws to obtain an artificial spin ice system.

9. The preparation method according to claim 8, characterized in that: In step S3, the acrylic sheet has a thickness of 10 mm, a length of 200 mm, and a width of 200 mm.

10. A method for controlling an artificial spin ice system, characterized in that: The control method is implemented based on the artificial spin ice system based on macroscopic magnets as described in any one of claims 1 to 6, and comprises the following steps: applying an external magnetic field to the artificial spin ice system; The arrangement, distribution and dynamic changes of macroscopic magnets were observed, and the dynamic phenomena and phase transitions in the artificial spin ice system at different distances when an external magnetic field was introduced were recorded.

Images