Magnetic anti-vortex forming method, magnetic anti-vortex carrier and random number generator

Abstract

The invention relates to the technical field of magnetic materials, in particular to a magnetic anti-vortex forming method, a magnetic anti-vortex carrier and a random number generator. The invention provides a method for forming magnetic anti-vortex. The method comprises the following steps: providing a substrate material layer; the substrate material layer is made of a crystal material; performing epitaxial growth on the substrate material layer to form a magnetic structure layer, wherein the magnetic structure layer is provided with a plurality of magnetic structure units; the magnetic structure layer is made of a polycrystalline magnetic material; the substrate material layer and the magnetic structure layer form a magnetic anti-vortex carrier, and each magnetic structure unit is suitable for forming magnetic anti-vortex; wherein the polarity direction of the magnetic anti-vortex core of the magnetic anti-vortex formed by each magnetic structure unit is upward or downward perpendicular to the surface of the substrate material layer; the crystal structure of the substrate material layer has multiple rotational symmetry; the crystal orientation of the magnetic structure unit has multiple rotational symmetry orientation; the number of multiple rotational symmetry axes of the magnetic structural units is smaller than the number of multiple rotational symmetry axes of the substrate material layer.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging substrates, and particularly to a method for forming a magnetic antivortex, a magnetic antivortex carrier, and a random number generator. Background Art

[0002] With the rapid development of information technology, people increasingly rely on networked devices to manage vast amounts of digital confidential information and perform daily security-sensitive tasks. These widespread electronic devices can easily access various types of security information, such as biometric data, email passwords, credit card details, and authentication passwords for financial transactions. These electronic devices have become ideal targets for cyberterrorists, posing a great threat to information security. In the face of the escalating cyber threats, relying solely on software security is far from sufficient, which has promoted the development of hardware encryption solutions.

[0003] In recent years, the emergence of nanoelectronics and breakthroughs in new semiconductor materials and device configurations have provided computer engineers with new state variables, such as electron spin and resistance, to represent information. These technologies offer efficient and unique opportunities for the design of true random number generators. Magnetic antivortex memories are one of them, and the bit positions of the stored information can be dynamically encoded by using the polarity state change of the antivortex core. Since the two opposite polarity states of the antivortex core are energy-degenerate, this physical property can be used to dynamically generate random and unique bit sequences. Their secrecy stems from the unique random orientation of the magnetization vector direction at the position of the antivortex core during the manufacturing of magnetic antivortices, so that even the original manufacturer cannot predict and replicate them.

[0004] However, the existing technologies for constructing magnetic antivortices are not yet mature, and the harsh and cumbersome preparation conditions of magnetic antivortex carriers cannot meet the current industrial requirements for mass-producing, cheap, and convenient true random number generators. Magnetic antivortices are often observed to naturally occur between a pair of magnetic vortices with the same chirality, forming a vortex-antivortex-vortex structure. However, this magnetic structure is unstable and easily collapses into a single vortex state. Although researchers have artificially prepared single magnetic antivortices in materials with some carefully designed specific geometries. Typical shapes include: the "∞" shape structure, the "#" shape structure, the "φ" shape structure, and the "×" shape structure. However, a mask lithography process is required during the preparation process, and this preparation process can only be carried out in small batches in the laboratory. In addition, a certain external magnetic field sequence needs to be applied after the lithography process to induce the generation of magnetic antivortices. More importantly, the role of magnetic anisotropy energy is not considered in the above examples, which limits the magnetic materials that can be considered, and the successful cases are only limited to: metal films such as permalloy, cobalt film, and cobalt-iron-boron thin film. Moreover, the recognizability of the reported antivortex cores is poor and cannot be utilized. Therefore, a solution is needed to solve the problem that it is difficult to construct magnetic antivortex carriers and it is difficult to produce them in large quantities, cheaply, and conveniently. Summary of the Invention

[0005] In view of this, the present invention provides a method for forming a magnetic antivortex, a magnetic antivortex carrier, and a random number generator to solve the problem that it is difficult to construct a magnetic antivortex carrier and it is difficult to produce it in large quantities, cheaply, and conveniently.

[0006] In a first aspect of the present invention, the present invention provides a method for forming a magnetic antivortex, including the following steps: providing a substrate material layer; the material of the substrate material layer is a single crystal material; epitaxially growing a magnetic structure layer on the substrate material layer, the magnetic structure layer having a plurality of magnetic structure units; the material of the magnetic structure layer is a polycrystalline magnetic material; the substrate material layer provides a support platform and crystal symmetry limiting conditions for the formation of the magnetic structure layer; the substrate material layer and the magnetic structure layer constitute a magnetic antivortex carrier, and each magnetic structure unit is suitable for forming a magnetic antivortex; wherein, the polar direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit is upward or downward perpendicular to the surface of the substrate material layer; the crystal structure of the substrate material layer has multiple rotational symmetries; the crystal orientation of the magnetic structure unit has a multiple rotationally symmetric orientation; the number of multiple rotation axes of the magnetic structure unit is less than the number of multiple rotation axes of the substrate material layer.

[0007] The method for forming a magnetic antivortex provided by the present invention is as follows. The polycrystalline magnetic material with multiple symmetries has several fixed and symmetric equivalent low-energy orientation directions relative to the substrate material layer with multiple symmetries. Under the epitaxial growth conditions, the grains of the polycrystalline magnetic material will align and dock along these equivalent low-energy orientation directions, and finally a magnetic structure unit with a multiple symmetric structure with these equivalent low-energy orientation directions as multiple symmetry axes can be formed. These magnetic structure units with multiple symmetries have appropriate magnetocrystalline anisotropy constants and can be used as ideal carriers for constructing magnetic antivortices. The epitaxial growth can be carried out through general epitaxial growth steps, which are simple in steps, loose in conditions, easy to implement, and low in cost. In addition, for the magnetic antivortex carrier formed by the formation method provided by the present invention, due to the magnetic exchange interaction, the magnetic moments at the magnetic antivortex core tend to be parallelly arranged, so the magnetic moments at the core can easily curl to the direction perpendicular to the magnetic structure layer, generating a magnetic moment arrangement perpendicular to the surface of the magnetic structure layer. Therefore, the polar direction of the magnetic antivortex can be perpendicular to the surface of the substrate material layer. This is beneficial for subsequent detection and provides a basis for random number generation.

[0008] In some alternative embodiments, the symmetry group of the crystal rotation symmetry of the magnetic structure layer is a subgroup of the symmetry group of the crystal rotation symmetry of the substrate material; the out-of-plane growth directions of the individual single crystals inside the polycrystal of the polycrystalline magnetic material are the same.

[0009] The method for forming a magnetic antivortex provided by the present invention. The polycrystalline magnetic material that meets the above conditions can construct the magnetic structure unit with a multiple symmetric structure with the equivalent low-energy orientation direction as the multiple symmetry axis, and then form a magnetic antivortex carrier.

[0010] In some alternative embodiments, in the step of epitaxially growing a magnetic structure layer on the substrate material layer, the epitaxial growth methods include chemical vapor deposition, molecular beam epitaxy, pulsed laser deposition, or magnetron sputtering deposition.

[0011] The method for forming a magnetic antivortex provided by the present invention. The above methods can be selected for the epitaxial growth process, which are all common methods in the field of epitaxial growth, simple in steps, loose in conditions, easy to implement, and low in cost.

[0012] In some alternative embodiments, in the step of epitaxially growing a magnetic structure layer on a substrate material layer, under the growth conditions, the crystal orientations of the individual grains of the polycrystalline magnetic material are parallel to the direction of the multiple rotation symmetry axes of the substrate material layer, and a multiple symmetric arrangement structure with each equivalent low-energy orientation direction as the symmetry axis is formed in the form of the lowest surface energy. In the method for forming a magnetic antivortex provided by the present invention, when the selected polycrystalline magnetic material meets the conditions, the above process will occur during the epitaxial growth process, so as to form a magnetic structure unit with a multiple symmetric structure having the equivalent low-energy orientation direction as the multiple symmetry axes, and further form a magnetic antivortex carrier.

[0013] In some alternative embodiments, the method for forming a magnetic antivortex of the present invention further includes the following steps: performing a magnetic moment perturbation on the magnetic antivortex carrier for the polycrystal, so that the magnetic moment arrangement of the polycrystal of the magnetic material is rearranged; the polarity direction at the magnetic antivortex core of the magnetic antivortex formed by the rearranged magnetic structure units is the same as or different from that before the rearrangement.

[0014] In the method for forming a magnetic antivortex provided by the present invention, after the initial magnetic antivortex carrier is formed by epitaxial growth, the magnetic moments inside the magnetic structure units are stably arranged in the magnetic structure form of the magnetic antivortex according to the principle of the lowest magnetic free energy. And after the magnetic moments are perturbed by changing the external conditions, the magnetic moments inside the magnetic structure units will be rearranged. The polarity direction of the magnetic antivortex newly formed after the rearrangement may be the same as or different from that before, so that the polarity directions of all the magnetic structure units of the magnetic antivortex as a whole are different from the original ones. Even if some are locally the same, it is impossible to be the same as a whole. Thus, a brand-new random number can be constructed.

[0015] In some alternative embodiments, the step of performing a magnetic moment perturbation on the magnetic antivortex carrier for the polycrystal includes: performing thermal annealing on the magnetic antivortex carrier, raising the temperature above the magnetic transition temperature to make the magnetic moments in the magnetic antivortex carrier disordered, and then cooling to room temperature to restore to a new magnetic antivortex ground state with an unknown polarity; or demagnetizing by using a demagnetizer, making the magnetic moments in the magnetic antivortex carrier disordered by using the alternating magnetic field generated after the demagnetizer is powered on, and then powering off and restoring to a new magnetic antivortex ground state with an unknown polarity under no external magnetic field.

[0016] In the method for forming a magnetic antivortex provided by the present invention, the magnetic moment perturbation can be realized by the above-listed methods or similar methods. All of them have simple steps, loose conditions, are easy to implement, and have low costs.

[0017] In another aspect of the present invention, the present invention provides a magnetic antivortex carrier, which is formed by the method for forming a magnetic antivortex provided by the present invention, and includes: a substrate material layer; the material of the substrate material layer is a single crystal material; a magnetic material layer; the magnetic material layer is disposed on one surface of the substrate material layer; the magnetic material layer includes a plurality of magnetic structure units; the material of the magnetic structure layer is a polycrystalline magnetic material; the substrate material layer provides a support platform and crystal symmetry limiting conditions for the formation of the magnetic structure layer; the substrate material layer and the magnetic structure layer constitute a magnetic antivortex carrier, and each magnetic structure unit is adapted to form a magnetic antivortex; wherein, the polar direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit is upward or downward perpendicular to the surface of the substrate material layer; the crystal structure of the substrate material layer has multiple rotational symmetries; the crystal orientation of the magnetic structure unit has a multiple rotationally symmetric orientation; the number of multiple rotation axes of the magnetic structure unit is less than the number of multiple rotation axes of the substrate material layer.

[0018] For the magnetic antivortex carrier provided by the present invention, the grains of the polycrystalline magnetic material form magnetic structure units with a multiple symmetric structure having these equivalent low-energy orientation directions as multiple symmetry axes. These multiple symmetric magnetic structure units have appropriate magnetocrystalline anisotropy constants and can be used as ideal carriers for constructing magnetic antivortices. The magnetic structure layer can be formed by epitaxial growth, and the epitaxial growth can be carried out through general epitaxial growth steps, with simple steps, loose conditions, easy implementation, and low cost.

[0019] In some optional embodiments, the symmetry group of the crystal rotational symmetry of the magnetic structure layer is a subgroup of the symmetry group of the crystal rotational symmetry of the substrate material; the out-of-plane growth directions of the individual single crystals inside the polycrystal of the polycrystalline magnetic material are the same.

[0020] For the magnetic antivortex carrier provided by the present invention, a polycrystalline magnetic material that meets the above conditions can construct the magnetic structure units with a multiple symmetric structure having the equivalent low-energy orientation directions as multiple symmetry axes, and further form a magnetic antivortex carrier.

[0021] In some optional embodiments, the projected shape of the magnetic structure unit on the surface of the substrate material layer includes: a truncated triangle, a hexagon, or a cross-shaped wall shape.

[0022] In some optional embodiments, the magnetic structure unit has ferromagnetism or ferrimagnetism, and the magnetocrystalline anisotropy direction is parallel to the surface of the substrate material layer. The polycrystalline magnetic material includes ε-Fe 2 O 3 , and the material of the substrate material layer is mica.

[0023] In some alternative embodiments, the maximum dimension of the magnetic structure unit in the direction parallel to the surface of the substrate material layer is in the micrometer range; the maximum dimension of the magnetic structure unit in the direction perpendicular to the surface of the substrate material layer is in the nanometer range.

[0024] In some alternative embodiments, the magnetic moment of the magnetic structure unit is such that after the magnetic moment is perturbed by changing the external conditions, the magnetic moments inside the magnetic structure unit will rearrange. The polar direction of the magnetic antivortex formed after rearrangement may be the same as or different from the previous one. As a result, the polar directions of all the magnetic structure units of the magnetic antivortex as a whole are different from the original ones. Even if some local ones are the same, it is impossible for the whole to be the same. Thus, a brand-new random number can be constructed.

[0025] In another aspect of the present invention, the present invention provides a random number generator, comprising: the magnetic antivortex carrier provided by the present invention; a polarity detection module adapted to detect the polar direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit in the magnetic antivortex carrier; a data generation module communicatively connected to the polarity detection module and adapted to generate a random number according to the detection result of the polarity detection module.

[0026] For the random number generator provided by the present invention, the polar direction at the magnetic antivortex core of the magnetic antivortex formed by the magnetic structure units distributed on the magnetic antivortex carrier provided by the present invention is detected by the polarity detection module, and the data generation module can convert the detected result into a number of 0 or 1 according to the polar direction, and perform digital coding of 0 and 1 according to the distribution of the polar directions to realize the generation of random numbers.

[0027] In some alternative embodiments, the polarity detection module includes: a magnetic force microscope, a Lorentz transmission electron microscope, and a magneto-optical Kerr microscope.

[0028] In some alternative embodiments, the random number generator further includes: a magnetic moment perturbation module adapted to change the environmental conditions of the magnetic antivortex carrier to cause the magnetic moments of the magnetic structure units in the magnetic antivortex carrier to rearrange.

[0029] For the random number generator provided by the present invention, since the magnetic moments of the magnetic structure units are rearranged, the polar direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit may be the same as or different from that before rearrangement. Therefore, the polar distribution state on the entire magnetic antivortex carrier after rearrangement is different from that before rearrangement. Even if some local ones are the same, it is impossible for the whole to be the same. Thus, a brand-new random number can be constructed to realize the refresh of the random number.

[0030] In some alternative embodiments, the magnetic moment perturbation module includes: a heater or a demagnetizer. Description of the Drawings

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the related art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the related art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 Schematic flow diagram of a method for forming a magnetic antivortex according to an embodiment of the present invention.

[0033] Figure 2a Schematic diagram of the process of grain coalescence of a magnetic polycrystalline material to form a magnetic structure unit in a method for forming a magnetic antivortex according to an embodiment of the present invention;

[0034] Figure 2b Schematic diagram of the process of grain coalescence of a magnetic polycrystalline material to form a magnetic structure unit in a method for forming a magnetic antivortex according to another embodiment of the present invention;

[0035] Figure 3a Schematic diagram of simulation modeling of the process of grain coalescence of a magnetic polycrystalline material to form a magnetic structure unit in a method for forming a magnetic antivortex according to an embodiment of the present invention;

[0036] Figure 3b Schematic diagram of the epitaxial growth process of grain coalescence of a magnetic polycrystalline material to form a magnetic structure unit and corresponding optical micrographs at different growth stages in a method for forming a magnetic antivortex according to an embodiment of the present invention;

[0037] Figure 4 Schematic diagram of the state of epitaxial growth of a magnetic structure layer by a chemical vapor deposition process using a tube furnace device in a random number generator according to an embodiment of the present invention;

[0038] Figure 5a Atomic force microscope topography of a magnetic structure unit according to an embodiment of the present invention;

[0039] Figure 5b Magnetic force microscope phase diagram of a magnetic structure unit according to an embodiment of the present invention;

[0040] Figure 5c Magnetic force microscope phase diagram repeatedly measured by a magnetic probe with reverse magnetization of a magnetic structure unit according to an embodiment of the present invention;

[0041] Figure 5d Structure model diagram of a magnetic structure unit according to an embodiment of the present invention;

[0042] Figure 5e Simulated magnetization vector arrangement diagram of a magnetic structure unit according to an embodiment of the present invention;

[0043] Figure 5f Magnetic phase simulation diagram of the magnetic structure unit according to an embodiment of the present invention;

[0044] Figure 6 Comparison diagram of the thickness and magnetic force microscope phase of the magnetic structure unit according to different embodiments of the present invention;

[0045] Figure 7 Comparison diagram of the magnetic force microscope phase of the magnetic structure unit according to an embodiment of the present invention before and after standing in air for 10 months;

[0046] Figure 8a Schematic diagram of the magnetic antivortex carrier in the random number generator according to an embodiment of the present invention;

[0047] Figures 8b - 8e According to the magnetic antivortex carrier in the data generation module of the random number generator according to an embodiment of the present invention Figure 8a Schematic diagram of the process of random number encoding according to the polarity distribution of the magnetic antivortex of the magnetic antivortex carrier;

[0048] Figures 9a - 9b Schematic diagram of the crystal magnetic moment rearrangement process of the magnetic structure unit in the random number generator according to an embodiment of the present invention;

[0049] Figure 10 Magnetic force microscope phase diagram and corresponding magnetization arrangement simulation diagram of the same magnetic antivortex before and after multiple magnetic moment perturbation processes in the random number generator according to an embodiment of the present invention.

[0050] Reference numerals:

[0051] 100 - crystal grain; 200 - magnetic structure unit. Detailed implementation manners

[0052] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0053] In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention. Various schematic structural diagrams according to embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art can additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs. In the context of the present invention, when a layer / component is referred to as being "on" another layer / component, the layer / component can be directly on the other layer / component, or there can be an intermediate layer / component between them. Additionally, if a layer / component is "on" another layer / component in one orientation, then when the orientation is reversed, the layer / component can be "under" the other layer / component.

[0054] Embodiment 1

[0055] Reference Figure 1 , this embodiment provides a method for forming a magnetic antivortex, including the following steps:

[0056] Provide a substrate material layer; the material of the substrate material layer is a single crystal material;

[0057] Epitaxially grow a magnetic structure layer on the substrate material layer, and the magnetic structure layer has a number of magnetic structure units; the material of the magnetic structure layer is a polycrystalline magnetic material;

[0058] The substrate material layer provides a physical platform and crystal symmetry constraint conditions for the formation of the magnetic structure layer; the substrate material layer and the magnetic structure layer constitute a magnetic antivortex carrier, and each magnetic structure unit is suitable for forming a magnetic antivortex;

[0059] Among them, the polar direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit is upward or downward perpendicular to the surface of the substrate material layer;

[0060] The crystal structure of the substrate material layer has multiple rotational symmetries;

[0061] The crystal orientation of the magnetic structure unit has an orientation with multiple rotational symmetries;

[0062] The number of multiple rotational symmetry axes of the magnetic structure unit is less than the number of multiple rotational symmetry axes of the substrate material layer.

[0063] The method for forming a magnetic antivortex provided in this embodiment. The polycrystalline magnetic material with multiple symmetries has several fixed and symmetrically arranged equivalent low-energy orientation directions with respect to the substrate material layer with multiple symmetries. Under epitaxial growth conditions, the crystal orientations of the individual grains of the polycrystalline magnetic material are parallel to the direction of the multiple rotational symmetry axes of the substrate material layer. The grains align and butt-joint along these equivalent low-energy orientation directions and finally form magnetic structure units with a multiple-symmetry structure having these equivalent low-energy orientation directions as the multiple rotational symmetry axes in the form of the lowest surface energy. These magnetic structure units with multiple symmetries have appropriate magnetocrystalline anisotropy constants and can serve as ideal carriers for constructing magnetic antivortices. Epitaxial growth can be carried out through general epitaxial growth steps, with simple steps, loose conditions, easy implementation, and low cost.

[0064] It should be noted that: The epitaxial growth of the magnetic structure units in the magnetic structure layer on the substrate layer starts from several small nucleation points and they are discrete from the very beginning of nucleation. Due to the symmetry relationship between the epitaxial layer (magnetic structure layer) and the substrate, the adjacent nucleation points will be arranged and spliced at a certain misorientation angle to form polycrystals with a specific shape after growth. The crystals formed by the nucleation points far away will be at their respective nucleation point positions. Overall, the grown crystals (i.e., magnetic structure units) are controlled to be discrete by controlling the epitaxial growth time. If the growth time is too long, the crystals may grow and connect all the discrete crystals on the entire substrate as they become larger. However, a magnetic antivortex cannot be formed in the entire magnetic structure.

[0065] Meanwhile, for the magnetic antivortex carrier formed by the formation method provided in this embodiment, the growth directions within each single crystal plane of the magnetic antivortex constructed by its magnetic structure units are misoriented due to rotational symmetry, so the in-plane growth directions are different. And due to the magnetic exchange interaction, the magnetic moments at the magnetic antivortex core tend to be parallelly arranged, so the magnetic moments at the core can easily curl to the direction perpendicular to the magnetic structure layer, generating a magnetic moment arrangement perpendicular to the surface of the magnetic structure layer, either upward or downward. Therefore, the polar direction of the magnetic antivortex can be perpendicular to the surface of the matrix material layer. This is conducive to subsequent detection and provides a basis for random number generation.

[0066] In addition, magnetocrystalline anisotropy means that the magnetization curves measured when a single crystal is magnetized along different crystal axis directions and the ease of magnetization to saturation are different. That is, the crystal is easy to magnetize along certain crystal axis directions, while it is not easy to magnetize along certain crystal axis directions. This phenomenon is called magnetocrystalline anisotropy. The magnetocrystalline anisotropy of a material or structure is determined by its own material. When the material is determined, the magnetocrystalline anisotropy of its structure is also determined accordingly.

[0067] Specifically, refer to Figure 2a and Figure 2b , Figure 2aOn a substrate material with six-fold symmetry, the square grains 100 with four-fold symmetry have approximately three states, namely 0°, rotated 30°, and rotated 60° as shown in the figure. Rotating 90° coincides with 0°, so there are three states. Due to the effect of the six-fold symmetric substrate material, the grains 100 with three equivalent low-energy orientations are distributed on it and will necessarily approximately present these three states. Under epitaxial growth conditions, the grains 100 will naturally arrange closely in these three states, and finally present a truncated triangular magnetic structure unit 200 aggregated and arranged along the directions of these 3 equivalent low-energy orientations as the symmetry axes. Similarly, on a four-fold symmetric substrate material, the triangular grains 100 with three-fold symmetry have approximately four states, namely 0°, rotated 30°, rotated 60°, and rotated 90°. Rotating 120° coincides with 0°, so there are four states. Due to the effect of the four-fold symmetric substrate material, the grains 100 with four equivalent low-energy orientations are distributed on it and will necessarily approximately present these four states. Under epitaxial growth conditions, the grains 100 will naturally arrange closely in these four states, and finally present a cross-shaped magnetic structure unit 200 aggregated and arranged along the directions of these 4 equivalent low-energy orientations as the symmetry axes. Such a magnetic structure unit 200 is a suitable carrier structure for forming a magnetic antivortex. In addition, for the magnetic antivortex carrier formed by the formation method provided in this embodiment, the magnetic antivortex constructed by its magnetic structure unit has the polar direction at the magnetic antivortex core perpendicular to the surface of the substrate material layer, which is beneficial for subsequent detection and provides a basis for random number generation.

[0068] In some embodiments of the present invention, the symmetry group of the crystal rotation symmetry of the magnetic structure layer is a subgroup of the symmetry group of the crystal rotation symmetry of the substrate material; the out-of-plane growth directions of the single crystals inside the polycrystal of the polycrystalline magnetic material are the same.

[0069] The formation method of the magnetic antivortex provided in this embodiment, for the polycrystalline magnetic material that meets the above conditions, can construct the magnetic structure unit of the multiple symmetric structure with the equivalent low-energy orientation direction as the multiple symmetry axes, and then form a magnetic antivortex carrier.

[0070] In some embodiments of the present invention, in the step of epitaxially growing a magnetic structure layer on the substrate material layer, the epitaxial growth methods include chemical vapor deposition, molecular beam epitaxy, pulsed laser deposition, or magnetron sputtering deposition.

[0071] For the formation method of the magnetic antivortex provided in this embodiment, the above methods can be selected for the epitaxial growth process. They are all common methods in the field of epitaxial growth, with simple steps, loose conditions, easy to implement, and low cost.

[0072] In some embodiments of the present invention, in the step of epitaxially growing a magnetic structure layer on a substrate material layer, under the growth conditions, the crystal orientations of the individual grains of the polycrystalline magnetic material are parallel to the direction of the multiple rotation symmetry axes of the substrate material layer, and a multiple symmetric arrangement structure with the equivalent low-energy orientation directions as the symmetry axes is formed in the form of the lowest surface energy.

[0073] In a specific embodiment, the polycrystalline magnetic material is selected as ε-Fe 2 O 3 , and the material of the substrate material layer is mica. Referring to Figure 3a and Figure 3b , as well as Figure 4 , in the tube furnace equipment for the chemical vapor deposition process, on the six-fold symmetric mica substrate material, the two-fold symmetric ε-Fe 2 O 3 grains 100 preferentially grow by selecting three equivalent low-energy orientations with counterclockwise orientation angles of 0°, 60°, and 120° respectively. These grains with different orientations nucleate within a limited range. During the subsequent growth process, due to the edges of these grains coming into contact with each other, three flat grain boundaries are formed. In a small area of the substrate, the chemical environment is usually uniform, which means that the growth rates of the three types of grains are almost equal. Finally, the polycrystalline island grows into a truncated triangular nanosheet, containing three grain boundaries that are 120° apart from each other. Under the epitaxial growth conditions, they coalesce into magnetic structure units 200 in the form of a truncated triangle with the equivalent low-energy orientation directions as the multiple symmetry axes.

[0074] It should be particularly noted that: among them Figure 3b the small black-bottomed graphics are experimental optical micrographs, and the large graphics are the corresponding model diagrams. Figure 3b In , the three adjacent small rectangles are in the early stage of epitaxial growth in the experiment and are difficult to capture from an optical microscope. The schematic diagram selects a rectangular single-crystalline grain to represent a single growth unit participating in the splicing at the initial growth stage.

[0075] For the method for forming a magnetic antivortex provided by the present invention, when the selected polycrystalline magnetic material meets the conditions, the above process will occur during the epitaxial growth process, thereby forming magnetic structure units with a multiple symmetric structure having the equivalent low-energy orientation directions as the multiple symmetry axes, and further forming a magnetic antivortex carrier.

[0076] In some alternative embodiments, the method for forming a magnetic antivortex of the present invention further includes the following steps: performing a magnetic moment perturbation on the magnetic antivortex carrier to cause rearrangement of the magnetic moment arrangement of the polycrystal of the magnetic material; the polarity direction at the magnetic antivortex core of the magnetic antivortex formed by the rearranged magnetic structure units is the same as or different from that before rearrangement.

[0077] The method for forming a magnetic antivortex provided by the present invention forms an initial magnetic antivortex carrier through epitaxial growth. Then, the magnetic moments inside the magnetic structure units are stably arranged in the magnetic structure form of the magnetic antivortex according to the principle of the lowest magnetic free energy, and the magnetic structure of the magnetic antivortex is formed by natural arrangement. After disturbing the magnetic moments by changing external conditions, the magnetic moments inside the magnetic structure units will rearrange. Specifically, referring to Figure 9a and Figure 9b After the magnetic moment perturbation, for example, Figure 9a during the annealing process, the magnetic moment arrangement of the magnetic structure unit 200 is disrupted, reaching a metastable magnetic state with a higher energy, and then naturally relaxing to a new magnetic antivortex ground state with a stable energy. And this process from the high-energy state to the low-energy state is a completely spontaneous process without external condition interference. Therefore, the final state of the magnetic antivortex formed after rearrangement may be the same as or different from the previous one, and the polarity may be the same or reversed. Since the polarity direction after rearrangement may be the same as or different from the previous one, the polarity directions of all the magnetic structure units of the magnetic antivortex as a whole are different from the original ones. Even if some parts are the same, it is impossible to be the same as a whole. Thus, a brand-new random number can be constructed.

[0078] In some alternative embodiments, the step of performing magnetic moment perturbation on the magnetic antivortex carrier includes: performing thermal annealing on the magnetic antivortex carrier, raising the temperature above the magnetic transition temperature to make the magnetic moments in the magnetic antivortex carrier disordered, and then cooling down to room temperature to restore to a new magnetic antivortex ground state with an unknown polarity; or using a demagnetizer for demagnetization. After the demagnetizer is powered on, the alternating magnetic field generated by it is used to make the magnetic moments in the magnetic antivortex carrier disordered, and then after power-off, it can restore to a new magnetic antivortex ground state with an unknown polarity under no external magnetic field.

[0079] The method for forming a magnetic antivortex provided by the present invention can realize the magnetic moment perturbation in the above-listed ways or similar ways. All the steps are simple, the conditions are loose, it is easy to implement, and the cost is relatively low.

[0080] A specific implementation process is as follows:

[0081] Select antiferromagnetic ε-Fe with an orthorhombic crystal structure 2 O 3 to generate a magnetic antivortex. Synthesize a magnetic structure layer formed by polycrystalline ε-Fe 2 O 3 on a mica substrate by spatial-confined CVD method.

[0082] A newly cut mica substrate (10 mm × 10 mm × 0.2 mm) is provided, stacked face to face and placed above the source powder to construct a confined synthesis environment as the substrate material layer. Before growth, the quartz reaction tube is flushed with 200 sccm of argon for 20 minutes. The temperature of the growth zone is raised to 700 °C within 25 minutes and maintained for 10 minutes at a flow rate of 2 / 198 sccm in an argon / oxygen mixed atmosphere. Finally, the system is naturally cooled to room temperature under an argon flow rate of approximately 60 sccm. The prepared ε-Fe 2 O 3 has a geometric shape of a truncated triangle.

[0083] Example 2

[0084] This example provides a magnetic antivortex carrier formed by the method for forming a magnetic antivortex provided in Example 1 above, including:

[0085] A substrate material layer; the material of the substrate material layer is a single crystal material;

[0086] A magnetic material layer; the magnetic material layer is disposed on one surface of the substrate material layer; the magnetic material layer includes a plurality of magnetic structure units; the material of the magnetic structure layer is a polycrystalline magnetic material;

[0087] The substrate material layer provides a support platform and crystal symmetry constraint conditions for the formation of the magnetic structure layer; the substrate material layer and the magnetic structure layer constitute a magnetic antivortex carrier, and each magnetic structure unit is suitable for forming a magnetic antivortex;

[0088] Among them, the polar direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit is upward or downward perpendicular to the surface of the substrate material layer; the crystal structure of the substrate material layer has multiple rotational symmetries; the crystal orientation of the magnetic structure unit has a rotationally symmetric orientation with multiple folds; the number of multiple rotational symmetry axes of the magnetic structure unit is less than the number of multiple rotational symmetry axes of the substrate material layer.

[0089] For the magnetic antivortex carrier provided in this example, the grains of the polycrystalline magnetic material form magnetic structure units with a multiple symmetric structure having these equivalent low-energy orientation directions as multiple symmetry axes. These magnetically multi-symmetric structure units have appropriate magnetocrystalline anisotropy constants and can be used as ideal carriers for constructing magnetic antivortices. The magnetic structure layer can be formed by epitaxial growth, and the epitaxial growth can be carried out through general epitaxial growth steps, with simple steps, loose conditions, easy implementation, and low cost.

[0090] In some alternative embodiments, the symmetry group of the crystal rotational symmetry of the magnetic structure layer is a subgroup of the symmetry group of the crystal rotational symmetry of the substrate material; the out-of-plane growth directions of the individual single crystals inside the polycrystal of the polycrystalline magnetic material are the same.

[0091] The magnetic antivortex carrier provided by this embodiment, a polycrystalline magnetic material that meets the above conditions, can construct the magnetic structure unit of the above-mentioned multiple symmetric structure with the equivalent low-energy orientation direction as the multiple symmetry axis, and then form a magnetic antivortex carrier.

[0092] In some alternative embodiments, the projected shape of the magnetic structure unit on the surface of the substrate material layer includes: a truncated triangle, a hexagon, or a cross-shaped wall.

[0093] In some alternative embodiments, the magnetic structure unit has ferromagnetic or ferrimagnetic properties, and the magnetocrystalline anisotropy direction is parallel to the surface of the substrate material layer.

[0094] In some alternative embodiments, the maximum dimension of the magnetic structure unit in the direction parallel to the surface of the substrate material layer is on the micron scale; the maximum dimension of the magnetic structure unit in the direction perpendicular to the surface of the substrate material layer is on the nanometer scale.

[0095] In some alternative embodiments, the magnetic moment of the magnetic structure unit is such that after the magnetic moment is perturbed by changing external conditions, the magnetic moments inside the magnetic structure unit will rearrange. The polarity direction of the magnetic antivortex newly formed after rearrangement may be the same as or different from the previous one. As a result, the polarity directions of all the magnetic structure units of the magnetic antivortex as a whole are different from the original ones. Even if some local ones are the same, it is impossible for the whole to be the same. Thus, a brand-new random number can be constructed.

[0096] Figures 5a - 5f Shows an ε-Fe prepared by the formation method according to the above-mentioned Embodiment 1 2 O 3 Experimental observation and theoretical simulation of the magnetic antivortex constructed by the magnetic structure units in the magnetic antivortex carrier as the magnetic material layer. Figure 5a and Figure 5b are respectively the topography image and the magnetic force microscope phase image of the magnetic structure unit of ε-Fe 2 O 3 . The dark contrast and the light contrast respectively represent the magnetic attractive and repulsive interactions between the probe and the surface of the nanosheet. On the three edges of the magnetic structure unit nanosheet, the light and dark contrasts are alternately distributed, and there is a core with the magnetization curling out of the plane at the center. They conform to the magnetic antivortex structure. Repeated tests with the reversed probe magnetization intensity obtained the same reverse contrast, indicating that the phase contrast is completely due to magnetic interaction rather than short-range Coulomb repulsion ( Figure 5c ). The structural model of the truncated triangle ε-Fe 2 O 3 magnetic structure unit nanosheet is as shown in Figure 5d . Using this structural model and ε-Fe 2 O 3General parameters, the magnetic antivortex structure was successfully reproduced through micromagnetic simulations. Figure 5e and Figure 5f are respectively the simulated magnetization vector arrangement and the corresponding magnetic phase simulation image, which are consistent with the experimental observations.

[0097] Figure 6 It is a comparison diagram of the morphology map and the magnetic force microscope phase map of a single magnetic structure unit in multiple magnetic structure layers of the same material but different thicknesses. There are 9 embodiments a, b, c, d, e, f, g, h, i with different thicknesses. The thickness dimension (longitudinal dimension) ranges from 6 nm to 42 nm, and the maximum dimension parallel to the surface of the substrate material layer (transverse dimension) ranges from 3 μm to 16 μm. The magnetic antivortex structure can be stably presented in these embodiments. It shows that the morphological control of the magnetic structure unit can have a large tolerance within a large range, providing great flexibility for the integration process.

[0098] In addition, for the magnetic antivortex carrier provided in this embodiment, the comparison diagram of the magnetic force microscope phase maps before and after the magnetic antivortex formed by the magnetic structure units therein is statically placed in the air for 10 months can be referred to Figure 7 . As Figure 7 shown, it can be seen that there is no obvious change in the force microscope phase maps before and after static placement, which can prove that the air stability of the magnetic antivortex carrier provided in this embodiment is good.

[0099] Embodiment 3

[0100] This embodiment provides a random number generator, including:

[0101] The magnetic antivortex carrier provided in the above Embodiment 2;

[0102] A polarity detection module, adapted to detect the polarity direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit in the magnetic antivortex carrier;

[0103] A data generation module, communicatively connected to the polarity detection module, adapted to generate random numbers according to the detection results of the polarity detection module.

[0104] For the random number generator provided in this embodiment, the polarity direction at the magnetic antivortex core of the magnetic antivortex formed by the magnetic structure units distributed on the magnetic antivortex carrier provided by the present invention is detected by the polarity detection module, and the data generation module can convert the detected results into numbers of 0 or 1 according to the polarity direction, and perform digital encoding of 0 and 1 according to the distribution of the polarity direction to realize the generation of random numbers.

[0105] Specifically, referring to Figures 8a - 8d , for the entire magnetic antivortex carrier, the polarity direction at the magnetic antivortex core of the magnetic antivortex formed by each magnetic structure unit thereon can be measured by the polarity detection module. Referring toFigure 8b and Figure 8c , according to the polarity direction, for example, upward perpendicular to the base material layer is labeled as "1", and downward perpendicular to the base material layer is labeled as "0", several "1"s and "0"s arranged according to the arrangement positions of the magnetic structure units can be obtained. Thus, in the manner as Figure 8d , the encoded random numbers of "1" and "0" can be obtained by the self-defined number-taking rule. When the magnetic antivortex carrier changes, mainly due to the change of the magnetic structure units resulting in the change of the magnetic antivortex, the arrangement of the "1" and "0" also changes. Thus, in the manner as Figure 8e shown, new random numbers can be obtained according to the same number-taking rule.

[0106] In addition, it should be noted that: Figure 8b 、 Figure 8c and Figure 9b are both cases of truncated triangles. The magnetic moment here shows the local magnetic moment arrangement at the center core of the truncated triangle. The magnetic moment at the antivortex core is upward or downward, and the magnetic moments near the periphery of the core flow into the center from one direction and flow out from the other direction. This is to emphasize the upward or downward arrangement at the core, so only the magnetic moment arrangement near the core at the center is shown.

[0107] In some alternative embodiments, the polarity detection module includes: a magnetic force microscope, a Lorentz transmission electron microscope, and a magneto-optical Kerr microscope.

[0108] In some alternative embodiments, the random number generator further includes: a magnetic moment perturbation module, adapted to change the environmental conditions of the magnetic antivortex carrier, so that the magnetic moments of the magnetic structure units in the magnetic antivortex carrier are rearranged.

[0109] For the random number generator provided by the present invention, due to the rearrangement of the magnetic moments of the magnetic structure units, the polarity direction at the magnetic antivortex core of the magnetic antivortex constructed by each magnetic structure unit may be the same as or different from that before the rearrangement. Therefore, the polarity distribution state on the entire magnetic antivortex carrier after the rearrangement is different from that before the rearrangement. Even if some local parts are the same, it is impossible to be the same as a whole. Thus, a brand-new random number can be constructed to realize the refresh of the random number.

[0110] Specifically, for the magnetic antivortex constructed by a single magnetic structure unit, the magnetic moment perturbation process is as in Figure 9a and Figure 9b the process, and the magnetic antivortex is as in Figure 10 shown. After multiple magnetic moment perturbations, each perturbation is rearranged again to form a new magnetic antivortex state, and the polarity direction may change or remain unchanged. Thus, on the entire magnetic antivortex carrier, the distribution state of the polarity orientation direction changes after the magnetic moment perturbation, so as to realize the refresh. Furthermore, the new random numbers can be obtained by adopting the number-taking rule of Figure 8e .

[0111] In some alternative embodiments, the magnetic moment perturbation module includes: a heater or a demagnetizer. The heater can be, for example: a tube furnace or a heating stage, or other heating devices.

[0112] In the description of this specification, the descriptions with reference to the terms "this embodiment", "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0113] The above is only the preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the above specific embodiments, and various obvious changes, re-adjustments, combinations with each other, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the protection scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for forming a magnetic anti-vortex, characterized in that: The following steps are involved: Providing a base material layer; the base material layer is made of single crystal material; Epitaxially growing a magnetic structure layer on the base material layer, wherein the magnetic structure layer has a plurality of magnetic structure units; the material of the magnetic structure layer is a polycrystalline magnetic material; The base material layer provides a supporting platform and crystal symmetry restriction conditions for the formation of the magnetic structure layer; the base material layer and the magnetic structure layer constitute a magnetic anti-vortex carrier, and each of the magnetic structure units is suitable for forming a magnetic anti-vortex; Wherein, the polarity direction of the magnetic anti-vortex core of the magnetic anti-vortex formed by each of the magnetic structural units is vertical to the surface of the base material layer and upward or downward; The crystal structure of the base material layer has multiple rotational symmetries; The crystal orientation of the magnetic structural unit has a multi-rotationally symmetric orientation; The number of multiple rotational symmetry axes of the magnetic structure unit is smaller than the number of multiple rotational symmetry axes of the base material layer.

2. The method for forming a magnetic anti-vortex according to claim 1, characterized in that: The symmetry group of the crystal rotational symmetry of the magnetic structure layer is a subgroup of the symmetry group of the crystal rotational symmetry of the substrate material; The out-of-plane growth directions of the single crystals inside the polycrystalline magnetic material are the same.

3. The method for forming a magnetic anti-vortex according to claim 1, characterized in that: In the step of epitaxially growing a magnetic structure layer on the base material layer, Epitaxial growth methods include chemical vapor deposition, molecular beam epitaxy, pulsed laser deposition or magnetron sputtering deposition.

4. The method for forming a magnetic anti-vortex according to claim 1, characterized in that: In the step of epitaxially growing a magnetic structural layer on the base material layer, under the growth conditions, the crystal orientation of each grain of the polycrystalline magnetic material is parallel to the direction of the multiple rotational symmetry axes of the base material layer, forming a multiple symmetrical arrangement structure with the equivalent low-energy orientation directions as symmetry axes in the form of lowest surface energy.

5. The method for forming a magnetic anti-vortex according to any one of claims 1 to 4, characterized in that: The following steps are also included: Performing magnetic moment disturbance on the polycrystalline magnetic anti-vortex carrier to rearrange the magnetic moment arrangement of the polycrystalline magnetic material; The polarity direction of the magnetic anti-vortex core of the magnetic anti-vortex formed by the magnetic structural units after rearrangement is the same as or different from that before rearrangement.

6. The method for forming a magnetic anti-vortex according to claim 5, characterized in that: The step of perturbing the magnetic moment of the polycrystalline material on the magnetic anti-vortex carrier comprises: The magnetic anti-vortex carrier is thermally annealed to increase the temperature above the magnetic transition temperature so that the magnetic moment in the magnetic anti-vortex carrier is disordered, and then the temperature is cooled to room temperature to recover to a new magnetic anti-vortex ground state with unknown polarity; or a demagnetizer is used for demagnetization, and after the demagnetizer is powered on, the alternating magnetic field generated by it is used to achieve magnetic moment disorder in the magnetic anti-vortex carrier, and then after the power is turned off, it can be recovered to a new magnetic anti-vortex ground state with unknown polarity in the absence of an external magnetic field.

7. A magnetic anti-vortex carrier, formed by the forming method according to any one of claims 1 to 6, characterized in that: include: a base material layer; The material of the base material layer is a single crystal material; A magnetic material layer; The magnetic material layer is arranged on one side surface of the base material layer; the magnetic material layer comprises a plurality of magnetic structural units; the material of the magnetic structural layer is a polycrystalline magnetic material; The base material layer provides a supporting platform and crystal symmetry restriction conditions for the formation of the magnetic structure layer; the base material layer and the magnetic structure layer constitute a magnetic anti-vortex carrier, and each of the magnetic structure units is suitable for forming a magnetic anti-vortex; Wherein, the polarity direction of the magnetic anti-vortex core of the magnetic anti-vortex formed by each of the magnetic structural units is vertical to the surface of the base material layer and upward or downward; The crystal structure of the base material layer has multiple rotational symmetries; The crystal orientation of the magnetic structural unit has a multi-rotationally symmetric orientation; The number of multiple rotational symmetry axes of the magnetic structure unit is smaller than the number of multiple rotational symmetry axes of the base material layer.

8. The magnetic anti-vortex carrier according to claim 7, characterized in that: The symmetry group of the crystal rotational symmetry of the magnetic structure layer is a subgroup of the symmetry group of the crystal rotational symmetry of the substrate material; The out-of-plane growth directions of the single crystals inside the polycrystalline magnetic material are the same.

9. The magnetic anti-vortex carrier according to claim 8, characterized in that: The projection shape of the magnetic structure unit on the surface of the base material layer includes: a truncated triangle, a hexagon or a cross-wall shape.

10. The magnetic anti-vortex carrier according to claim 8, characterized in that: The magnetic structural unit has ferromagnetism or ferrimagnetism, and its magnetocrystalline anisotropy direction is parallel to the surface of the base material layer; The polycrystalline magnetic material includes ε-Fe2O3, and the material of the base material layer is mica.

11. The magnetic anti-vortex carrier according to claim 7, characterized in that: The maximum dimension of the magnetic structure unit in a direction parallel to the surface of the base material layer is in the micrometer order; The maximum size of the magnetic structure unit in a direction perpendicular to the surface of the base material layer is in nanometer order.

12. The magnetic anti-vortex carrier according to claim 7, characterized in that: The magnetic moment of the magnetic structural unit is suitable for rearrangement after magnetic moment disturbance, and the polarity direction of the magnetic antivortex core of the magnetic antivortex formed by the magnetic structural unit after rearrangement is the same as or different from that before rearrangement.

13. A random number generator, characterized in that: include: The magnetic anti-vortex carrier according to any one of claims 7 to 12; A polarity detection module, adapted to detect the polarity direction of the magnetic anti-vortex core of the magnetic anti-vortex formed by each of the magnetic structural units in the magnetic anti-vortex carrier; The data generation module is in communication connection with the polarity detection module and is suitable for generating a random number according to the detection result of the polarity detection module.

14. The random number generator according to claim 13, characterized in that: The polarity detection module comprises: Magnetic force microscope, Lorentz transmission electron microscope, magneto-optical Kerr microscope.

15. The random number generator according to claim 13, characterized in that: Also includes: The magnetic moment disturbance module is suitable for changing the environmental conditions of the magnetic anti-vortex carrier to rearrange the magnetic moments of the magnetic structural units in the magnetic anti-vortex carrier.

16. The random number generator according to claim 15, characterized in that The magnetic moment disturbance module comprises: Heater or demagnetizer.

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