Methods for achieving phase transitions between different topological magnetic structures based on magnetic heterostructure materials
By utilizing the topological magnetic structure phase transition based on magnetic heterojunction materials and controlling the ferroelectric polarization state with an external electric field, the stability and crosstalk problems of small-scale magnetic storage devices are solved, achieving low-power, high-density information storage.
Patent Information
- Application Number
- CN202411013606.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-26
- Publication Date
- 2025-10-31
- Estimated Expiration
- 2044-07-26
AI Technical Summary
Existing magnetic storage devices suffer from reduced magnetic domain stability at small scales, and stray fields lead to increased crosstalk, limiting the improvement of storage density. Furthermore, traditional control methods are complex or consume high power, making it difficult to achieve high-density, low-power information storage.
By using magnetic heterojunction materials, first-principles calculations and micromagnetic simulations, the phase transition between magnetic skyrmions and magnetic bismerons is achieved by manipulating magnetic interactions. The topological magnetic structure is changed by controlling the ferropolar polarization state using an external electric field, thus realizing low-power information encoding.
It realizes spintronic devices with low power consumption, high read/write speed and high storage density, simplifies device structure, reduces power consumption and increases storage density.
Smart Images
Figure CN119047142B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of spintronic device technology, and particularly relates to a method for realizing phase transitions between different topological magnetic structures based on magnetic heterojunction materials. Background Technology
[0002] In today's era of big data, people have higher demands for information storage and processing carriers with lower energy consumption, higher speed, and higher density. Major technological powers worldwide attach great importance to the development of new magnetic storage materials and technologies. For magnetic memories based on mundane magnetic domain structures, when ferromagnetic domains are too small (e.g., ~10 nm), the demagnetizing field significantly reduces domain stability. Furthermore, the stray fields accompanying ferromagnetic domains can cause crosstalk to neighboring domains, and this crosstalk increases with decreasing domain size. This limits the increase in storage density and reduces the reliability of the memory. Magnetic skyrmions are topologically protected quasi-particles with non-collinear magnetic vortex structures and excellent stability. Their size can reach the 10 nm range, far smaller than existing magnetic information storage units, which can significantly increase magnetic information storage density. They possess many advantages such as nanoscale size, easy control, and low driving threshold current, and are expected to become the next generation of high-capacity, high-speed read / write, low-power, non-volatile information storage and logic operation carriers.
[0003] Currently, the most studied magnetic skyrmion systems are ferromagnetic / heavy metal multilayer films. In recent years, with the rapid development of two-dimensional magnets (such as CrI3, CrGeTe3, and Fe3GeTe2), realizing topological magnetic structures in two-dimensional systems is a remarkable research area for achieving ultrathin, low-power spintronic devices. When the system has perpendicular magnetic anisotropy, the topological magnetic structure tends to exhibit a magnetic skyrmion state; when the magnetic anisotropy is in-plane, the topological magnetic structure exhibits a magnetic bismerin state. By controlling the direction of the magnetocrystalline anisotropy, a phase transition between these two topological magnetic states can be achieved, resulting in two different magnetic states corresponding to "1" and "0" in information encoding. Applying an external magnetic field or current can control these two magnetic states, but the former complicates the device, while the latter leads to significant Joule heating, which is detrimental to power consumption reduction. Therefore, a new technology is urgently needed to realize novel magnetic storage devices that are simple and have low power consumption. Summary of the Invention
[0004] This invention addresses the shortcomings of existing technologies by providing a method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials. It achieves the mutual conversion between magnetic skyrmions and magnetic bismerons by manipulating magnetic interactions, and utilizes two different magnetic media to achieve different information encoding, thereby realizing different magnetic storage signals.
[0005] This invention is achieved through the following technical solution: a method for realizing phase transitions between different topological magnetic structures based on magnetic heterojunction materials, comprising the following steps:
[0006] (1) Two-dimensional magnets are preliminarily screened, searched, designed and predicted through a two-dimensional material database, and compared with existing two-dimensional non-magnetic ferroelectric materials by single-cell lattice or supercell lattice to ensure that the lattice mismatch rate of the heterojunction is less than 5%.
[0007] (2) Calculate the magnetic parameters of the polarization-up configuration in the magnetic heterostructure using the first-principles software package. The magnetic parameters include magnetic exchange J, magnetocrystalline anisotropy K, DM interaction d, and double secondary exchange B; and solve for the corresponding values of the four parameters.
[0008] (3) Using the magnetic parameters calculated by first principles, perform micromagnetic simulation or atomic-level simulation on the magnetic heterojunction system to obtain magnetic skyrmion state or damaren state.
[0009] (4) By applying an external electric field, the polarization state of the two-dimensional non-magnetic ferroelectric material is changed, thereby changing the polarization direction, and new magnetic parameters are recalculated using first principles.
[0010] (5) Perform micromagnetic simulation or atomic-level simulation again, input the new calculated magnetic parameters to obtain magnetic bismerin state or magnetic skyrmion state.
[0011] Furthermore, the first principle software package is VASP, and the atomic-level magnetic simulation software package is Vampire.
[0012] Furthermore, the two-dimensional material database is selected from any one or more of LiCrTe2 / In2Se3, MnBi2Se2Te2 / In2Se3, or LaCl / In2Se3.
[0013] Specifically, the magnetic exchange effect J is solved by setting different magnetic configurations in the same supercell and solving the Heisenberg equation under different magnetic configurations.
[0014] Specifically, the magnetocrystalline anisotropy K is the magnetocrystalline anisotropy K of the system along different magnetization directions, considering the spin-orbit coupling effect, and is expressed as: K = E (100) -E (001) E(100) is the total energy when the magnetization direction is in-plane, and E(001) is the total energy when the magnetization direction is out-of-plane.
[0015] Specifically, the DM interaction d is solved using the real-space spin-helix method, and its expression is: Where n is the period of spin rotation, ECW and E ACW These are the total energy of the system in the clockwise and counterclockwise spin states, respectively.
[0016] Specifically, the value of the biquadratic exchange action B is obtained by solving multiple equations for the magnetic states corresponding to different high-symmetry points on different high-symmetry paths using the reciprocal space spin-helical method.
[0017] This invention also provides a device for realizing phase transitions between different topological magnetic structures based on magnetic heterojunction materials, comprising the following steps:
[0018] Preliminary screening and comparison module: Through a two-dimensional material database, preliminary screening is conducted to find, design, and predict two-dimensional magnets, and the single-cell or supercell lattice of existing two-dimensional non-magnetic ferroelectric materials is compared to ensure that the lattice mismatch rate of the heterojunction is less than 5%.
[0019] Parameter calculation module: Calculates various magnetic parameters of the polarization-up configuration in the magnetic heterostructure using a first-principles software package. These magnetic parameters include magnetic exchange J, magnetocrystalline anisotropy K, DM interaction d, and double secondary exchange B; and solves for the corresponding values of the four parameters.
[0020] Computational simulation module: Using the magnetic parameters calculated by first principles, it performs micro-magnetic simulation or atomic-level simulation of the magnetic heterojunction system to obtain magnetic skyrmion state or bismerin state;
[0021] New parameter calculation module: By applying an external electric field to change the ferroelectric polarization state of a two-dimensional non-magnetic ferroelectric material, the polarization direction is changed, and new magnetic parameters are recalculated using first-principles calculations.
[0022] Resimulation module: Perform micromagnetic simulation or atomic-level simulation again, input new calculated magnetic parameters to obtain magnetic bismerin states or magnetic skyrmion states.
[0023] An electronic device, comprising:
[0024] One or more processors;
[0025] Memory, used to store one or more programs;
[0026] When the one or more programs are executed by the one or more processors, the one or more processors implement the method for phase transition between different topological magnetic structures based on magnetic heterojunction materials.
[0027] A computer-readable storage medium storing computer instructions that, when executed by a processor, implement the steps of the method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials.
[0028] The beneficial effects of this invention are as follows:
[0029] This invention involves searching for magnetic multiferroic heterostructure materials capable of realizing magnetic skyrmions or magnetic bis-merrens. Through first-principles calculations, it presents detailed magnetic parameters of the material system, including the Heisenberg exchange coupling constant, DM interaction, magnetic anisotropy, and double second-order exchange energy. Based on atomic-level magnetic simulations, it achieves stable magnetic skyrmion states (or magnetic bis-merren states). By applying an electric field to the system, it utilizes the ferroelectric effect to modulate the competition between various magnetic interaction energies. Again, it utilizes atomic-level simulations to realize magnetic bis-merren states (or magnetic skyrmion states). Compared to traditional magnetic domain-based storage media, this invention's spintronic devices (such as magnetic skyrmion track memories) using magnetic skyrmions and magnetic bis-merrens as basic units can achieve low power consumption, high read / write speeds, and high storage density. Attached Figure Description
[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0031] Figure 1 This is a diagram showing the most stable stacking configuration under different polarization states calculated by the present invention;
[0032] Figure 2 The graph shows the magnetic parameter data calculated under different polarization states according to the present invention; the left graph is a schematic diagram of the DM interaction calculated using the real space spin-helical algorithm; the right graph is a comparison of the magnetic parameters calculated under the polarization-up and polarization-down states.
[0033] Figure 3 The figures show the atomic-level micromagnetic simulation results obtained from the magnetic parameters calculated based on the polarization-up and polarization-down states, respectively; the left and right figures are the magnetic skyrmion state and the magnetic bismerin state, respectively. Detailed Implementation
[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.
[0035] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.
[0036] The first-principles software package used in this scheme is VASP (Vienna Ab-initio Simulation Package), an atomic-level magnetic simulation software package called Vampire.
[0037] (1) A preliminary screening was conducted using a two-dimensional material database to find and predict two-dimensional magnets, and the single-cell or supercell lattice of existing two-dimensional non-magnetic ferroelectric materials was compared to ensure that the lattice mismatch rate was less than 5%.
[0038] (2) Calculate the magnetic interaction parameters of polarization-up configuration in magnetic heterojunction using first-principles software, including magnetic exchange, magnetocrystalline anisotropy, DM interaction and double secondary exchange.
[0039] (3) Using the magnetic parameters calculated by first principles, perform micromagnetic simulation or atomic-level simulation on the magnetic heterojunction system to obtain the magnetic skyrmion state (or duomerin state).
[0040] (4) By applying an external electric field to change the ferroelectric polarization state of the non-magnetic material, the polarization direction is changed, and new magnetic parameters are recalculated using first principles.
[0041] (5) Perform micromagnetic simulation or atomic-level simulation again, input the new calculated magnetic parameters to obtain the magnetic bismerin state (magnetic skyrmion state).
[0042] In some embodiments of the present invention, the material system may be selected from, but is not limited to, one or more of, LiCrTe2 / In2Se3, MnBi2Se2Te2 / In2Se3, LaCl / In2Se3, and MnTe2 / ZrS2 / In2Se3.
[0043] This invention provides a two-dimensional material heterostructure with magnetoelectric multiferroic (ferromagnetic + ferroelectric) properties. We first modify a two-dimensional CrTe2 magnet with alkali metal Li on one side (Li-CrTe2) to break the spatial inversion symmetry of the system. The lattice constants of Li-CrTe2 and two-dimensional ferroelectric In2Se3 are 4.08 and 4.10 Å, respectively, with a lattice mismatch rate of only 0.5%, far below the required 5%. It should be noted that the technique of modifying two-dimensional materials with alkali metal Li is a commonly used experimental method, and Li-CrTe2 has been experimentally synthesized, while two-dimensional ferroelectric In2Se3 is a synthesized two-dimensional ferroelectric material that can be produced over large areas. The combination of these two materials ensures experimental feasibility. Furthermore, by calculating and comparing the relative energies of different stacking configurations, the most stable configuration under two polarization states is determined. Figure 1 ).
[0044] For the two most thermodynamically stable configurations, we first calculate the magnetic parameters of the polarization-upward configuration.
[0045] This includes the Heisenberg exchange involving the nearest neighbor (J1) and the second nearest neighbor (J2), the DM interaction (d), magnetocrystalline anisotropy (K), the double quadratic exchange (B), and the empirical value d / J1, which measures whether the system can exhibit topological magnetism. For the calculation of the DM interaction in this case, the value of DM can be obtained by calculating the energies under the clockwise and counterclockwise spin configurations. This invention employs a real-space spin-helical algorithm (…). Figure 2 (Left figure). For the polarization-down configuration, the value of d / J1 is equal to 0.11, and its K is out-of-plane magnetization (K = 0.25 meV), which meets the conditions for producing stable magnetic skyrmions, i.e., d / J1 should be approximately in the range of 0.1 to 0.2 and K should be out-of-plane magnetization. Next, we used the same method to calculate the magnetic parameters of the polarization-down configuration, from... Figure 2 As shown in the right figure, compared to the magnetic parameters of the polarization-up configuration, when the system is polarized downwards, the magnetocrystalline anisotropy changes from a positive value to a negative value (K = -0.22 meV). This means that the change in polarization direction causes the easy magnetization axis to change from out-of-plane to in-plane. However, other magnetic parameters do not change much. At the same time, when the polarization is downwards, its d / J1 value (0.2) is still within the range that allows for the formation of a topological magnetic structure. Figure 3The figures show the atomic-level micromagnetic simulation results obtained from the magnetic parameters calculated based on polarization-up and polarization-down states, respectively. The left and right figures represent the magnetic skyrmion state and the magnetic double merren state, respectively. That is, changes in the anisotropy of the magnetocrystalline material will lead to the emergence of a magnetic skyrmion state with in-plane magnetization, which is the magnetic double merren state. Finally, using atomic-level micromagnetic simulation technology, by inputting magnetic parameters under two different polarization states, we further confirmed that the system exhibits a magnetic skyrmion state when polarization is up, and a stable magnetic double merren state when the polarization state is changed to down. Thus, we have achieved a field-controlled topological magnetic phase transition from magnetic skyrmions to magnetic double merren.
[0046] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.
[0047] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.
Claims
1. A method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials, characterized in that, Includes the following steps: (1) Two-dimensional magnets are preliminarily screened, searched, designed and predicted through a two-dimensional material database, and compared with existing two-dimensional non-magnetic ferroelectric materials by single-cell lattice or supercell lattice to ensure that the lattice mismatch rate of the heterojunction is less than 5%. (2) Calculate the magnetic parameters of the polarization-up configuration in the magnetic heterostructure using the first-principles software package. The magnetic parameters include magnetic exchange J, magnetocrystalline anisotropy K, DM interaction d, and double secondary exchange B; and solve for the corresponding values of the four parameters. (3) Using the magnetic parameters calculated by first principles, perform micromagnetic simulation or atomic-level simulation on the magnetic heterojunction system to obtain magnetic skyrmion state or damaren state. (4) By applying an external electric field, the polarization state of the two-dimensional non-magnetic ferroelectric material is changed, thereby changing the polarization direction, and new magnetic parameters are recalculated using first principles. (5) Perform micromagnetic simulation or atomic-level simulation again, input the new calculated magnetic parameters to obtain magnetic bismerin state or magnetic skyrmion state.
2. The method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials according to claim 1, characterized in that, The first principle software package is VASP, and the atomic-level magnetic simulation software package is Vampire.
3. The method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials according to claim 1, characterized in that, The two-dimensional material database is selected from any one or more of LiCrTe2 / In2Se3, MnBi2Se2Te2 / In2Se3, or LaCl / In2Se3.
4. The method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials according to claim 1, characterized in that, The solution to the magnetic exchange effect J is obtained by setting different magnetic configurations in the same supercell and solving the Heisenberg equation under different magnetic configurations.
5. The method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials according to claim 1, characterized in that, The magnetocrystalline anisotropy K is the total energy of the system along different magnetization directions, considering the spin-orbit coupling effect, and its expression is: K = E (100) -E (001) E(100) is the total energy when the magnetization direction is in-plane, and E(001) is the total energy when the magnetization direction is out-of-plane.
6. The method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials according to claim 1, characterized in that, The solution for the DM interaction d is obtained using the real-space spin-helix method, and its expression is as follows: Where n is the period of spin rotation, E CW and E ACW These are the total energy of the system in the clockwise and counterclockwise spin states, respectively.
7. The method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials according to claim 1, characterized in that, The value of the biquadratic exchange action B is obtained by solving multiple equations for the magnetic states corresponding to different high-symmetry points on different high-symmetry paths using the reciprocal spin-helical method.
8. A device for realizing phase transition between different topological magnetic structures based on magnetic heterojunction materials, characterized in that, Includes the following steps: Preliminary screening and comparison module: Through a two-dimensional material database, preliminary screening is conducted to find, design, and predict two-dimensional magnets, and the single-cell or supercell lattice of existing two-dimensional non-magnetic ferroelectric materials is compared to ensure that the lattice mismatch rate of the heterojunction is less than 5%. Parameter calculation module: Calculates various magnetic parameters of the polarization-up configuration in the magnetic heterostructure using a first-principles software package. These magnetic parameters include magnetic exchange J, magnetocrystalline anisotropy K, DM interaction d, and double secondary exchange B; and solves for the corresponding values of the four parameters. Computational simulation module: Using the magnetic parameters calculated by first principles, it performs micro-magnetic simulation or atomic-level simulation of the magnetic heterojunction system to obtain magnetic skyrmion state or bismerin state; New parameter calculation module: By applying an external electric field to change the ferroelectric polarization state of a two-dimensional non-magnetic ferroelectric material, the polarization direction is changed, and new magnetic parameters are recalculated using first-principles calculations. Resimulation module: Perform micromagnetic simulation or atomic-level simulation again, input new calculated magnetic parameters to obtain magnetic bismerin states or magnetic skyrmion states.
9. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials as described in any one of claims 1-7.
10. A computer-readable storage medium storing computer instructions thereon, characterized in that, When executed by the processor, this instruction implements the steps of the method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials as described in any one of claims 1-7.