Rare earth magnetic material with spontaneous magnetic domain transformation, preparation method and application

Abstract

The invention provides a rare earth magnetic material with spontaneous magnetic domain transformation, a preparation method and application, and relates to the field of rare earth magnetic functions.The chemical formula of the rare earth magnetic material is RT2-xMnx, and R is one of Sm, Gd, Tb, Dy, Ho and Er; t is one of Fe, Co and Ni, and x is more than or equal to 0 and less than or equal to 1. According to the rare earth magnetic material capable of spontaneously transforming the magnetic domain, the preparation method and the application, a magnetic bubble type structure at the room temperature is achieved by applying a magnetic field, the shape of a magnetic bubble is changed by changing the temperature, and a new thought and method are provided for regulation and control of a magnetic domain structure. The magnetic domain transformation can be realized in two doping proportions, and the material is simple to prepare.

Description

Technical Field

[0001] The present invention relates to the field of rare earth magnetic functions, and in particular to a rare earth magnetic material with spontaneous magnetic domain transition, a preparation method and an application thereof. Background Art

[0002] With the advent of the information technology era, the explosive growth of data has placed higher demands on information processing and storage. Current magnetic storage media have reached a bottleneck in storage speed and storage density due to thermal effects caused by the small size limit. Spintronics introduces a new degree of freedom. The application of new magnetic materials to spintronic devices can significantly reduce storage density and power consumption. The characterization of the fine structure within magnetic materials can intuitively analyze the microstructure of magnetic domains. In-depth understanding of the microstructure is conducive to its application in spintronic devices. In particular, nonlinear spin textures such as magnetic skyrmions, magnetic bubbles and new magnetic domain walls are expected to become a new generation of small-scale information storage carriers. The discovery and effective regulation of such new magnetic structures are key issues for the application of magnetic materials.

[0003] Magnetic domain structure is often formed by the competition of multiple interactions. Intrinsic energy terms primarily include the Heisenberg exchange energy, anisotropy energy, dipole interaction energy, and, in special symmetry-broken systems, the Dzyaloshinskii-Moriya (DM) interaction energy. External excitations (magnetic fields, electric currents, lasers, and external stresses) can manipulate magnetic domain structure. Varying intrinsic parameters and external excitation conditions are the primary means of controlling magnetic domain structure.

[0004] Stress regulation is an intuitive way to control magnetic properties and magnetic structure, which can avoid the generation of Joule heating and reduce energy consumption during the regulation process. At present, the main method of stress regulation is mainly to conduct experiments with external stress equipment, including stretching, compression and bending. However, the complex equipment setup increases the difficulty of operation and is difficult to be compatible with electronic devices, which limits its application in devices. Therefore, exploring materials with inherent lattice stress and realizing the transformation and regulation of magnetic structure have important scientific significance and application prospects. Summary of the Invention

[0005] The purpose of the present invention is to provide a rare earth magnetic material with spontaneous magnetic domain transition, a preparation method, and an application. The lattice stress spontaneously generated by temperature change in the material with a high Curie temperature can achieve spontaneous transformation of the magnetic domain and change the shape of the bubble-like magnetic structure, overcoming the complex equipment required for stress regulation of the magnetic structure. The magnetic domain structure is regulated by changing the lattice parameters of the material itself, which can be regulated within a larger composition range, and the material preparation is simple.

[0006] To achieve the above object, the present invention provides a rare earth magnetic material with spontaneous magnetic domain transition, the chemical formula of the rare earth magnetic material is RT 2-x Mn x , 0≤x≤1wt%, R and T 2-x Mn x The mass ratio is 1:2, R is one of Sm, Gd, Tb, Dy, Ho, and Er; T is one of Fe, Co and Ni.

[0007] Preferably, Mn can also be replaced by other transition elements.

[0008] Preferably, R is Tb and T is Co.

[0009] A method for preparing a rare earth magnetic material with spontaneous magnetic domain transition, characterized by comprising the following steps: According to the chemical formula RT 2-x Mn x Weigh the R, T, and Mn raw materials with a purity of 99.9% respectively; Weighed R, T, and Mn are placed in a water-cooled crucible. Under the protection of Ar gas, arc melting is performed multiple times to heat and melt the raw materials. The melted product is turned over and then cooled to obtain an ingot. The resulting ingot is sealed in a quartz tube filled with a high-purity Ar gas atmosphere, and then heated and annealed at 1173.15K to 1273.15K for 7 days to obtain a polycrystalline block, i.e., a rare earth magnetic material; When x is equal to 0, the rare earth magnetic material undergoes magnetic domain transition within the magnetic domain transition temperature range; When x is not equal to 0, the rare earth magnetic material undergoes a magnetic domain transition within the magnetic domain transition temperature range, and is further regulated by an external magnetic field to produce bubble-like magnetic domains.

[0010] Preferably, the magnetic domain transition temperature ranges from 200 K to 280 K.

[0011] Application of a rare earth magnetic material with spontaneous magnetic domain transition in spintronic devices.

[0012] Therefore, the present invention adopts the above-mentioned rare earth magnetic material with spontaneous magnetic domain transition, preparation method, and application, and the technical effects are as follows: Spontaneous magnetic domain transformation can occur in magnetic materials with lattice strain. Magnetic domains with different crystal orientations exhibit distinct magnetic domain configurations, all influenced by internal stress, shifting from ordinary domain walls to charge domain walls. Furthermore, leveraging internal stress to achieve this transition to a bubble-like structure overcomes the complex equipment required to manipulate magnetic structures using stress. By altering the material's own lattice parameters, the magnetic domain structure can be manipulated over a wide composition range. Furthermore, the material is simple to prepare, facilitating its application in spintronics devices.

[0013] Compared with the rare earth transition metal alloy materials that have been invented and use temperature-induced spin reorientation to control magnetic domains, the alloy in the present invention has a larger magnetoelastic effect and magnetostrictive effect, which enables the rare earth material system to undergo magnetic moment rotation under lattice stress, providing a new dimension for controlling the magnetic domain structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the TbCo obtained in the embodiment 2-x Mn x Room temperature X-ray diffraction refinement pattern of (x=0, 0.2) alloy; Figure 2 is the TbCo obtained in the embodiment 2-x Mn x Magnetization intensity-temperature curve of the alloy (x=0, 0.2); Figure 3 is the TbCo obtained in the embodiment 2-x Mn x Magnetization intensity-magnetic field curves of the alloy at different temperatures (x=0, 0.2); Figure 3 (a) Magnetization intensity-magnetic field curves of TbCo2 alloy at different temperatures; Figure 3 (b) TbCo 1.8 Mn 0.2 Magnetization intensity-magnetic field curves of the alloy at different temperatures; Figure 4 In Example 2, the Lorentz transmission electron microscope was used to observe the 2-x Mn x The spontaneous transformation process of magnetic domains with different crystal orientations was observed in the (x=0) alloy; Figure 4 (a) Lorentz transmission electron microscopy in TbCo2 alloy at 226K Observe the spontaneous transformation process of magnetic domains with different crystal orientations on the crystal plane; Figure 4 (b) Lorentz transmission electron microscopy in TbCo2 alloy at 220K Observe the spontaneous transformation process of magnetic domains with different crystal orientations on the crystal plane; Figure 4 (c) Lorentz transmission electron microscopy in TbCo2 alloy at 150K Observe the spontaneous transformation process of magnetic domains with different crystal orientations on the crystal plane; Figure 4 (d) is the analytical diagram of the spin distribution in the box of Figure (c); Figure 4 (e) Lorentz transmission electron microscopy in TbCo2 alloy at 226K Observe the spontaneous transformation process of magnetic domains with different crystal orientations on the crystal plane; Figure 4 (f) Lorentz transmission electron microscopy in TbCo2 alloy at 220K Observe the spontaneous transformation process of magnetic domains with different crystal orientations on the crystal plane; Figure 4 (g) Lorentz transmission electron microscopy in TbCo2 alloy at 150K Observe the spontaneous transformation process of magnetic domains with different crystal orientations on the crystal plane; Figure 4 (h) is the analytical diagram of the spin distribution in the box of Figure (g); Figure 5 This is a micromagnetic simulation diagram of the effective anisotropy of stress change of the rare earth magnetic material prepared according to the raw materials in Example 2; Figure 5 (a) 180° magnetic domain in the stress-free state; Figure 5 (b) Charge domain wall after adding stress conditions; Figure 5 (c) The expansion of the charge domain wall under stress conditions increases the saturation magnetization, which corresponds to the experimental results during the cooling process. Figure 5 (d) The expansion of the charge domain wall under stress conditions increases the saturation magnetization, which corresponds to the result during the cooling process in the experiment. Figure 6 In Example 1, the Lorentz transmission electron microscope was used to observe the 2-x Mn x (x=0.2)Observe the magnetic domain transition process in the alloy; Figure 6 (a) is the TbCo crystal structure obtained by Lorentz transmission electron microscopy at 300K in Example 1. 1.8 Mn 0.2 Observe the magnetic domain transition process in the alloy; Figure 6 (b) is the TbCo 1.8 Mn 0.2 Observe the magnetic domain transition process in the alloy; Figure 6 (c) is the TbCo image obtained by Lorentz transmission electron microscopy at 150K in Example 1. 1.8 Mn 0.2 Observe the magnetic domain transition process in the alloy; Figure 6 (d) is the analytical diagram of the spin arrangement in the box of Figure (c); Figure 7 In Example 1, an external vertical magnetic field is applied to the TbCo 2-x Mnx Realization of room-temperature magnetic bubble-like structures in (x=0, 0.2) alloys; Figure 8 Figure 8(a) is a diagram showing the control of the shape of bubble-like magnetic domains by using a Lorentz transmission electron microscope during the cooling process in Example 1; Figure 8(b) is a diagram showing the control of the shape of bubble-like magnetic domains by using a Lorentz transmission electron microscope at 300K in Example 1; Figure 8(c) is a diagram showing the control of the shape of bubble-like magnetic domains by using a Lorentz transmission electron microscope at 180K in Example 1. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0016] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0017] Example 1 A method for preparing a rare earth magnetic material with spontaneous magnetic domain transition comprises the following steps: According to TbCo 2-x Mn x Chemical formula, x = 0.2, Tb and Co 1.8 Mn 0.2 The mass ratio of Tb, Co and Mn raw materials with a purity of 99.9% were weighed in a 1:2 ratio. In order to compensate for the non-proportional loss of Mn during arc melting and annealing, an additional Mn of 3% of the total mass was first added.

[0018] The weighed raw materials were placed in a water-cooled crucible, and under the protection of Ar gas, arc melting was used to heat and melt the raw materials and maintain the temperature for 60-70 seconds.

[0019] The heated and molten product was turned over and cooled for five minutes, and then melted again in an electric arc furnace and kept for 60-70 seconds. This was repeated four times to obtain an ingot.

[0020] The obtained ingot is sealed in a quartz tube filled with a high-purity Ar gas atmosphere, and then heated and annealed at 1173.15K-1273.15K for 7 days to obtain a polycrystalline block, namely a rare earth magnetic material.

[0021] Focused ion beam scanning electron microscopy (FIB-SEM) was used to analyze the TbCo 2-x Mn x Single crystal slices with different crystal orientations were prepared from polycrystalline alloys for observation. The spontaneous transformation of the magnetic structure inside the material was tested using a Lorentz transmission electron microscope. This was achieved by temperature regulation and applying a perpendicular magnetic field along the crystal plane to generate bubble-like magnetic domains.

[0022] Example 2 A method for preparing a rare earth magnetic material with spontaneous magnetic domain transition comprises the following steps: According to TbCo 2-x Mn x The chemical formula is x=0, the mass ratio of Tb:Co=1:2, and the Tb and Co raw materials with a purity of 99.9% are weighed.

[0023] The weighed raw materials were placed in a water-cooled crucible and, under the protection of Ar gas, arc melting was used to heat and melt the raw materials and maintain the temperature for 60-70 seconds.

[0024] The heated and molten product was turned over and cooled for five minutes, and then melted again in an electric arc furnace and kept for 60-70 seconds. This was repeated four times to obtain an ingot.

[0025] The obtained ingot is sealed in a quartz tube filled with a high-purity Ar gas atmosphere, and then heated and annealed at 1173.15K-1273.15K for 7 days to obtain a polycrystalline block, namely a rare earth magnetic material.

[0026] Focused ion beam scanning electron microscopy (FIB-SEM) was used to prepare single crystal slices of TbCo2 polycrystalline alloy with different crystal orientations for observation. Lorentz transmission electron microscopy was used to investigate the spontaneous transition of the material's internal magnetic structure. Rare earth magnetic materials undergo magnetic domain transitions at a temperature ranging from 200 K to 280 K.

[0027] The process of magnetic domain transition was reproduced by micromagnetic simulation. The MuMax3 software package based on the Landau–Lifshitz–Gilbert equation (LLG equation) was used for simulation. The simulation size was 1200 nm × 1200 nm × 60 nm (the simulation was performed according to the raw material ratio in Example 2).

[0028] Simulation results: Saturation magnetization of rare earth magnetic materials obtained The range is 600 to 1200 , the uniaxial anisotropy constant 150 The action of stress changes the anisotropy direction of the system, and the simulation obtains the magnetic domain transition phenomenon consistent with the experiment, revealing the essential role of stress regulation, such as Figure 5 shown.

[0029] Rare earth magnetic materials prepared by doping with Mn elements (transition elements) or not doping with Mn elements (transition elements) (i.e., x is equal to 0 or x is not equal to 0) can change the lattice constant of the rare earth magnetic materials by changing the temperature, and generate stress inside the rare earth magnetic materials, thereby changing the magnetic domain structure; By adding Mn or other transition elements (i.e., x is not equal to 0) to rare earth magnetic materials, the Curie temperature is increased (i.e., the magnetic domain transition temperature is increased), thereby realizing the transformation of the stress magnetic domain structure. For rare earth magnetic materials doped with Mn or other transition elements, the external magnetic field is further used to control the generation of bubble-like magnetic domains, providing an experimental basis for the control of storage units.

[0030] Figure 1 The structural properties of the sample at room temperature were obtained using X-ray diffraction technology. The crystal belongs to a cubic Laves phase structure. During the cooling process, the lattice parameter a gradually decreases and the lattice parameter c gradually increases. The change in lattice parameters leads to the generation of internal stress.

[0031] Figure 2 The Curie temperature of rare earth magnetic materials was obtained by magnetic measurement, and with the doping of Mn elements, the Curie temperature reached above room temperature.

[0032] Figure 3 Figure 1 is the magnetization intensity-magnetic field curve of rare earth magnetic materials at different temperatures. It can be seen that the saturation magnetization intensity increases with decreasing temperature.

[0033] Figure 4 The Lorentz electron microscope images of TbCo2 thin films with different crystal orientations during the cooling process show the transition from ordinary domain walls to Z-shaped charge domain walls.

[0034] Figure 5 In order to reproduce the process of magnetic domain transition using micromagnetic simulation, the magnetic domain transition is formed due to the anisotropic transition caused by lattice stress.

[0035] Figure 6 The change in magnetic domains of the rare earth magnetic material prepared in Example 2 during the cooling process from room temperature is similar to that of the rare earth magnetic material system not doped with Mn element, and still undergoes a transformation from ordinary domain walls to zigzag charge domain walls.

[0036] Figure 7 In order to regulate the magnetic bubble structure of the material prepared in Example 1, a magnetic bubble structure at room temperature can be formed by applying an external magnetic field. Preferably, the direction of the magnetic field is perpendicular to the sample plane.

[0037] Figure 8 This is the change of a single magnetic bubble structure during the cooling process. For a closed elliptical magnetic bubble structure, the shape of the bubble is elongated in the long axis direction during the cooling process, which is also caused by the change of lattice stress.

[0038] Application of a rare earth magnetic material with spontaneous magnetic domain transition in spintronic devices.

[0039] Therefore, the present invention adopts the above-mentioned rare earth magnetic material, preparation method, and application of spontaneous magnetic domain transition. The lattice stress spontaneously generated by temperature change in the material with a high Curie temperature can realize the spontaneous transition of magnetic domains and the shape change of the bubble-like magnetic structure, overcoming the complex equipment required for stress regulation of the magnetic structure. The magnetic domain structure is regulated by changing the lattice parameters of the material itself, which can be regulated within a larger composition range, and the material preparation is simple.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A rare earth magnetic material with spontaneous magnetic domain transition, characterized in that: The chemical formula of rare earth magnetic materials is RT 2-x Mn x , 0≤x≤1wt%, R and T 2-x Mn x The mass ratio is 1:2, R is one of Sm, Gd, Tb, Dy, Ho and Er; T is one of Fe, Co and Ni.

2. The rare earth magnetic material with spontaneous magnetic domain transition according to claim 1, characterized in that: Mn can also be replaced by other transition group elements.

3. The rare earth magnetic material with spontaneous magnetic domain transition according to claim 1, characterized in that: R is Tb and T is Co.

4. The method for preparing a rare earth magnetic material with spontaneous magnetic domain transition according to claim 1, characterized in that: The following steps are involved: According to the chemical formula RT 2-x Mn x Weigh the R, T and Mn raw materials with a purity of 99.9% respectively; The weighed R, T, and Mn are placed in a water-cooled crucible, and arc melting is performed multiple times under the protection of Ar gas to heat and melt the raw materials, and the melted product is turned over and cooled to obtain an ingot; The obtained ingot is sealed in a quartz tube filled with a high-purity Ar gas atmosphere, and then heated and annealed at 1173.15K to 1273.15K for 7 days to obtain a polycrystalline block, i.e., a rare earth magnetic material; When x is equal to 0, the rare earth magnetic material undergoes magnetic domain transition within the magnetic domain transition temperature range; When x is not equal to 0, the rare earth magnetic material undergoes a magnetic domain transition within the magnetic domain transition temperature range, and further utilizes an external magnetic field to control the generation of bubble-like magnetic domains.

5. The method for preparing a rare earth magnetic material with spontaneous magnetic domain transition according to claim 4, characterized in that: The magnetic domain transition temperature ranges from 200 K to 280 K.

6. Use of the rare earth magnetic material with spontaneous magnetic domain transition according to any one of claims 1 to 3 in spintronic devices.

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