Single-phase alloy with low-temperature abnormal magnetic effect and preparation and application thereof

Abstract

The invention discloses a single-phase alloy with a low-temperature abnormal magnetic effect as well as preparation and application of the single-phase alloy. The chemical formula of the single-phase alloy with the low-temperature abnormal magnetic effect is REFe3-xGax, wherein x is greater than or equal to 0.3 and less than or equal to 0.6. The single crystal alloy crystal is of a rhombus PuNi3 type structure, the space group symbol is # imgabs0 #, the 3b and 18h sites are occupied by Fe, the 3a site is occupied by RE, the 6c site is occupied by RE and Fe together, and Ga randomly occupies the 3b, 6c and 18h sites. The hysteresis loop of the single-phase alloy at a low temperature is converted from a smooth curve to a jumping type stepped hysteresis loop. The magnetic storage medium has the beneficial effects that component design is carried out by adjusting the types and the contents of elements in the alloy, so that the magnetic storage medium has a stable single-phase structure and an abnormal magnetization behavior at a low temperature at the same time, can be used as a novel magnetic storage medium, and records more information in a unit volume by utilizing multiple magnetic states at the low temperature.

Description

Technical Field

[0001] The invention belongs to the field of functional materials, and in particular relates to a single-phase alloy with low-temperature anomalous magnetic effect and its preparation and application. Background Art

[0002] In 1996, B. Barbara et al. tested the low-temperature hysteresis loop of the first single-molecule magnet {Mn12} and found that the molecule exhibited a step-shaped hysteresis loop. Different from the Baghausen phenomenon, this step-shaped hysteresis loop is believed to be caused by the change of the degeneracy of different excited state energy levels under the induction of an external magnetic field, resulting in a tunneling effect of magnetization intensity. This magnetic effect may eventually be applied to high-density information storage devices and quantum computing.

[0003] Although a lot of research has been done in this field, most of the materials that can exhibit this type of magnetic effect are single-molecule magnets and random magnets. This is mainly because these magnetic materials have inherently low potential barriers, which is conducive to the tunneling of magnetic moments at low temperatures. However, in these materials, either the total number of magnetic moments that tunnel is very low, or the critical temperature is as low as the millikelvin level, which is difficult to achieve. Therefore, it is very important to explore other forms of magnetic materials with the same phenomenon, and a material that can achieve tunneling behavior of more magnetic moments at relatively high temperatures and ultimately show a stable step on the hysteresis loop is extremely valuable. Using this material, it is expected to achieve polymorphic storage within a limited temperature range. Summary of the invention

[0004] The present invention discloses a single-phase alloy with low-temperature anomalous magnetic effect and its preparation and application, so as to solve any of the above and other potential problems in the prior art.

[0005] In order to solve the above technical problems, the technical solution of the present invention is: adding defects in a strongly anisotropic lattice and using a strong magnetic field to weaken the potential barrier to finally establish a reversible magnetic behavior. The tunneling probability of the magnetic moment is mainly affected by the potential barrier. In magnetic materials, there are mainly intrinsic potential barriers caused by magnetic anisotropy and potential barriers caused by defects pinning domain walls, both of which can cause obvious metastable states of magnetic materials and manifest as hysteresis phenomena in macroscopic magnetism. The anisotropic potential barrier is generally H ∥ M0V order of magnitude, the pinning barrier is generally H c M0V order of magnitude, where M0 is the magnetic moment per unit volume, H c is the coercive field, and V is the volume involved in the tunneling process. This makes U / k B T c The order of magnitude is similar to (H ∥ / H ⊥ ) 1 / 2 J is equivalent to [Hc / (H ∥ / H ⊥ ) 1 / 2 ]J is equivalent to, J is the total spin of the tunneling. Therefore, when the number of spins in the tunneling is large, either the coercivity H of the material c Very small, or H ∥ H ⊥ , that is, the system has strong anisotropy. Although the critical temperature T c The size of is mainly determined by the distribution of energy barriers, but its value is usually similar to μ B (H ∥ / H ⊥ ) 1 / 2 In order to increase the total tunneling magnetic moment and obtain a higher critical temperature, the possibility of reducing the potential barrier by applying a magnetic field can be considered. The final result is a single-phase alloy with low-temperature anomalous magnetic effect. The atomic percentage expression of the single-phase alloy with low-temperature anomalous magnetic effect is REFe 3-x Ga x , where RE=Tb, Dy, Ho, Er, 0.3≤x≤0.6, that is, the doping amount is 7.5 at%-15 at%.

[0006] Furthermore, the single-phase alloy crystallizes into a rhombohedral PuNi3 structure with a space group symbol of , where the 3b and 18h ​​sites are occupied by Fe, the 3a site is occupied by RE, the 6c site is jointly occupied by RE and Fe, and Ga randomly occupies the 3b, 6c, and 18h ​​sites.

[0007] Furthermore, when RE = Tb and x = 0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is TbFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 5K is step-shaped, and there are 5 different magnetic states at 2K.

[0008] Furthermore, when RE = Dy and x = 0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is DyFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 5K is step-shaped, and there are 7 different magnetic states at 2K.

[0009] Furthermore, when RE = Ho and x = 0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is HoFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 2K is step-shaped, and there are three different magnetic states at 2K.

[0010] Furthermore, when RE = Er, x = 0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is ErFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 5K is step-shaped, and there are 6 different magnetic states at 2K.

[0011] Another object of the present invention is to provide a method for preparing the above-mentioned single-phase alloy with low-temperature anomalous magnetic effect, the method comprising the following steps: S1) According to the chemical composition of the designed alloy, weigh RE, Fe, and Ga raw materials respectively, where RE = Tb, Dy, Ho, and Er, and the purity of the raw materials is greater than 99.95%. For volatile rare earth elements, 0.1 wt%-1.0 wt% can be appropriately added; S2) placing the weighed RE, FE, and Ga raw materials in order according to the rule that the higher the melting point, the closer to the arc gun tip; S3) using a high vacuum arc furnace to melt the mixed raw materials multiple times under an argon protective atmosphere at a certain pressure with a suitable current to make them completely melted and evenly melted, and finally obtaining an alloy ingot with uniform composition; S4) grinding the obtained alloy ingot with 240-grit sandpaper to remove the surface oxide scale to avoid the influence of oxide as much as possible; S5) Wrapping the alloy ingot treated in S4) with molybdenum foil, marking the ingot with a serial number, and sealing the ingot in a quartz tube under an argon protective atmosphere at a certain pressure; S6) placing the sealed quartz tube with the sample in a muffle furnace and performing a heat treatment at 1273-1473 K for more than 48 hours; S7) The quartz tube containing the sample treated in S6) is taken out from the muffle furnace and quickly placed in liquid nitrogen for rapid cooling, and finally a single-phase alloy with low-temperature anomalous magnetic effect is obtained.

[0012] Furthermore, the smelting current in S3) is 120A≤I≤180A; the inert protective atmosphere is argon, and the smelting is repeated for more than 3 times, and the smelting time for each time is at least 1 minute.

[0013] The advantages of the present invention are: 1. The single-phase alloy with low-temperature anomalous magnetic effect disclosed in the present invention exhibits a step-shaped hysteresis loop whose critical temperature is higher than that of common molecular magnets and random magnets (functional materials with reported step-shaped hysteresis loops), and the number of states that can be used for magnetic recording is stable.

[0014] 2. The single-phase alloy with low-temperature anomalous magnetic effect involved in the present invention can greatly increase the storage density per unit volume, and the ratio (Br / Bm) of the residual magnetization intensity (Br) to the saturation magnetization intensity (Bm) of the material at low temperature is close to 1, which can meet the needs of being used as a memory element and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0016] Figure 1 This is a schematic diagram of the structure of a single-phase alloy with low-temperature anomalous magnetic effect prepared by the method of the present invention.

[0017] Figure 2 The single-phase alloy TbFe with low-temperature anomalous magnetic effect prepared by the method of the present invention is 2.6 Ga 0.4 ,DyFe 2.6 Ga 0.4 、HoFe 2.6 Ga 0.4 、ErFe 2.6 Ga 0.4 Schematic diagram of the structure.

[0018] Figure 3 The single-phase alloy TbFe with low-temperature anomalous magnetic effect prepared by the method of the present invention is 2.6 Ga 0.4 ,DyFe 2.6 Ga 0.4 、HoFe 2.6 Ga 0.4 、ErFe 2.6 Ga 0.4 Powder XRD pattern of .

[0019] Figure 4 The single-phase alloy TbFe with low-temperature anomalous magnetic effect prepared by the method of the present invention 2.6 Ga 0.4 ,DyFe 2.6 Ga 0.4 、HoFe 2.6 Ga 0.4 、ErFe 2.6 Ga 0.4 Hysteresis loop at 2K.

[0020] Figure 5 The single-phase alloy TbFe with low-temperature anomalous magnetic effect prepared by the method of the present invention 2.6 Ga 0.4Stability of the step-like hysteresis loop after repeated magnetization at 2K.

[0021] Figure 6 The single-phase alloy TbFe with low-temperature anomalous magnetic effect prepared by the method of the present invention 2.6 Ga 0.4 Variable temperature hysteresis loop diagram.

[0022] Figure 7 The single-phase alloy TbFe with low-temperature anomalous magnetic effect prepared by the method of the present invention 2.6 Ga 0.4 Dependence of the AC magnetic susceptibility on temperature. DETAILED DESCRIPTION

[0023] In order to better understand the technical solution of the present invention, the embodiments of the present invention are further described below with reference to the accompanying drawings.

[0024] The present invention provides a single-phase alloy with low-temperature anomalous magnetic effect and a preparation method thereof. The chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is REFe 3-x Ga x , where RE = Tb, Dy, Ho, Er, 0.3≤x≤0.6, that is, the doping amount is 7.5 at%-15 at%. The single-phase alloy has a single-phase crystallization of rhombohedral PuNi3 structure, and the space group symbol is , where 3b and 18h ​​sites are occupied by Fe, 3a site is occupied by RE, 6c site is occupied by RE and Fe, and Ga randomly occupies 3b, 6c and 18h ​​sites. 2.6 Ga 0.4 The hysteresis loop of the alloy below 5K changes from a smooth curve to a step-like hysteresis loop, such as Figure 1 The present invention designs the composition by adjusting the element types and contents in the alloy so that it has both a stable single-phase structure and abnormal magnetization behavior at low temperatures. It can be used as a new type of magnetic storage medium, and can record more information per unit volume by using multiple magnetic states at low temperatures.

[0025] The present invention provides a method for preparing a single-phase alloy having a low-temperature anomalous magnetic effect, the method comprising the following steps: S1) According to the alloy chemical composition of the designed alloy, RE, Fe, Ga raw materials, where RE = Tb, Dy, Ho, Er, the purity of the raw materials is greater than 99.95%, and the volatile rare earth elements can be appropriately increased by 0.1 wt%-1.0 wt%; S2) placing the weighed RE, Fe, and Ga raw materials in order according to the rule that the higher the melting point, the closer to the arc gun tip; S3) using a high vacuum arc furnace to melt the mixed raw materials multiple times under an argon protective atmosphere at a certain pressure with a suitable current to make them completely melted and evenly melted, and finally obtaining an alloy ingot with uniform composition; S4) grinding the obtained alloy ingot with 240-grit sandpaper to remove the surface oxide scale to avoid the influence of oxide as much as possible; S5) Wrapping the alloy ingot treated in S4) with molybdenum foil, marking the ingot with a serial number, and sealing the ingot in a quartz tube under an argon protective atmosphere at a certain pressure; S6) placing the sealed quartz tube with the sample in a muffle furnace and performing a heat treatment at 1273 K for more than 48 hours; S7) The quartz tube containing the sample treated in S6) is taken out from the muffle furnace and quickly placed in liquid nitrogen for rapid cooling, and finally a single-phase alloy with low-temperature anomalous magnetic effect is obtained.

[0026] Embodiment 1: The single-phase alloy with low-temperature anomalous magnetic effect is prepared by vacuum arc furnace melting, and its expression is TbFe 2.6 Ga 0.4 .

[0027] The specific operation is as follows: Weigh 5 g of Tb, Fe and Ga raw materials with a molar ratio of 1:2.6:0.4; place the weighed Tb, Fe and Ga raw materials in order according to the rule that the higher the melting point, the closer to the arc gun tip; use a current of 120 A to melt the alloy under an argon protective atmosphere; repeat the melting for 4 times, each melting time is 1.5 min; use 240 mesh sandpaper to grind off the oxide scale on the surface of the ingot, wrap it with molybdenum foil, mark the serial number, and seal it in a quartz tube under an argon protective atmosphere at a certain pressure; place the quartz tube in a muffle furnace and perform heat treatment at 1353 K for 50 hours; finally, take the quartz tube out of the muffle furnace and quickly put it into liquid nitrogen for rapid cooling to finally obtain the target alloy.

[0028] The X-ray diffraction results of the target alloy show that the space group is , the single-phase, hysteresis loop test results are Figure 3 It is shown that the hysteresis loop of the target alloy in the temperature range of 2 K-5 K is step-shaped, and there are 5 different magnetic states at 2K.

[0029] Embodiment 2: The single-phase alloy with low-temperature anomalous magnetic effect is prepared by vacuum arc furnace melting, and its expression is DyFe 2.6 Ga 0.4 .

[0030] The specific operation is as follows: Weigh 5 g of Dy, Fe and Ga raw materials with a molar ratio of 1:2.6:0.4; place the weighed Dy, Fe and Ga raw materials in order according to the rule that the higher the melting point, the closer to the arc gun head; use a current of 150 A to smelt the alloy under an argon protective atmosphere; repeat the smelting for 5 times, each smelting time is 2 min; use 240 mesh sandpaper to grind off the oxide scale on the surface of the ingot, wrap it with molybdenum foil, mark the serial number, and seal it in a quartz tube under an argon protective atmosphere at a certain pressure; place the quartz tube in a muffle furnace and perform heat treatment at 1473 K for 52 hours; finally, take the quartz tube out of the muffle furnace and quickly put it into liquid nitrogen for rapid cooling, and finally obtain the target alloy.

[0031] The X-ray diffraction results of the target alloy show that the space group is , the single-phase, hysteresis loop test results are Figure 4 It is shown that the hysteresis loop of the target alloy at 2K is step-shaped and there are 7 different magnetic states at 2K.

[0032] Embodiment 3: The single-phase alloy with low-temperature anomalous magnetic effect is prepared by vacuum arc furnace melting, and its expression is HoFe 2.6 Ga 0.4 .

[0033] The specific operation is as follows: Weigh 5 g of Ho, Fe and Ga raw materials with a molar ratio of 1:2.6:0.4; place the weighed Ho, Fe and Ga raw materials in order according to the rule that the higher the melting point, the closer it is to the tip of the arc gun; use a current of 180 A to smelt the alloy under an argon protective atmosphere; repeat the smelting for 5 times, each smelting time is 3 min; use 240 mesh sandpaper to grind off the oxide scale on the surface of the ingot, wrap it with molybdenum foil, mark the serial number, and seal it in a quartz tube under an argon protective atmosphere at a certain pressure; place the quartz tube in a muffle furnace and perform heat treatment at 1373 K for 60 hours; finally, take the quartz tube out of the muffle furnace and quickly put it into liquid nitrogen for rapid cooling, and finally obtain the target alloy.

[0034] The X-ray diffraction results of the target alloy show that the space group is , the test results of the single-phase hysteresis loop are Figure 4 It is shown that the hysteresis loop of the target alloy at 2 K is step-shaped and there are three different magnetic states at 2K.

[0035] Embodiment 4: The single-phase alloy with low-temperature anomalous magnetic effect is prepared by vacuum arc furnace melting, and its expression is ErFe 2.6 Ga 0.4 .

[0036] The specific operation is as follows: Weigh 5 g of Er, Fe and Ga raw materials with a molar ratio of 1:2.6:0.4; place the weighed Er, Fe and Ga raw materials in order according to the rule that the higher the melting point, the closer to the arc gun head; use a current of 160 A to smelt the alloy under an argon protective atmosphere; repeat the smelting for 7 times, and each smelting time is 3.5 min; use 240 mesh sandpaper to grind off the oxide scale on the surface of the ingot, wrap it with molybdenum foil, mark the serial number, and seal it in a quartz tube under an argon protective atmosphere at a certain pressure; place the quartz tube in a muffle furnace and perform heat treatment at 1273 K for 48 hours; finally, take the quartz tube out of the muffle furnace and quickly put it into liquid nitrogen for rapid cooling, and finally obtain the target alloy.

[0037] The X-ray diffraction results of the target alloy show that the space group is , the test results of the single-phase hysteresis loop are Figure 4 It is shown that the hysteresis loop of the target alloy at 2 K is step-shaped and there are 6 different magnetic states at 2K.

[0038] The schematic diagram of the structure of the single-phase alloy with low-temperature anomalous magnetic effect prepared in Example 1-4 is as follows Figure 1 As shown; X-ray diffraction pattern as Figure 2 As shown; the hysteresis loop at 2K is as follows Figure 3 The stability of the abnormal magnetic effect of the target alloy prepared in Example 1 at low temperature is shown in Figure 4 The temperature-dependent hysteresis curve test results of the target alloy prepared in Example 1 are shown in Figure 5 The AC magnetic susceptibility test results of the target alloy prepared in Example 1 are shown in Figure 6 The aging effect test results of the target alloy prepared in Example 1 are shown in Figure 7 shown.

[0039] X-ray diffraction test and phase analysis: The phase composition of the samples ground into powder was analyzed using a Cu target X-ray diffractometer. The scanning angle 2θ ranged from 20° to 60° and the scanning speed was 5° / min. The four alloy powders obtained all showed space groups of Single-phase rhombohedral PuNi3 structure.

[0040] The above is a detailed introduction to a single-phase alloy with low-temperature anomalous magnetic effect and a preparation method provided in the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0041] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0042] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0043] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0044] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A single-phase alloy with low-temperature anomalous magnetic effect, characterized in that: The chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is REFe 3-x Ga x , wherein RE = Tb, Dy, Ho, Er, 0.3≤x≤0.6, i.e. the doping amount is 7.5 at%-15 at%; the single-phase alloy crystal with low-temperature anomalous magnetic effect is a rhombohedral PuNi3 structure, and the space group symbol is , where the 3b and 18h ​​sites are occupied by Fe, the 3a site is occupied by RE, the 6c site is jointly occupied by RE and Fe, and Ga randomly occupies the 3b, 6c, and 18h ​​sites.

2. The single-phase alloy with low-temperature anomalous magnetic effect according to claim 1, characterized in that: When RE=Tb, x=0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is TbFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 5K is step-shaped, and there are 5 different magnetic states at 2K.

3. The single-phase alloy with low-temperature anomalous magnetic effect according to claim 1, characterized in that: When RE=Dy and x=0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is DyFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 5K is step-shaped, and there are 7 different magnetic states at 2K.

4. The single-phase alloy with low-temperature anomalous magnetic effect according to claim 1, characterized in that: When RE=Ho and x=0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is HoFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 2K is step-shaped, and there are three different magnetic states at 2K.

5. The single-phase alloy with low-temperature anomalous magnetic effect according to claim 1, characterized in that: When RE = Er, x = 0.4, the chemical formula of the single-phase alloy with low-temperature anomalous magnetic effect is ErFe 2.6 Ga 0.4 The hysteresis loop of the alloy in the temperature range below 5K is step-shaped, and there are 6 different magnetic states at 2K.

6. A method for preparing a single-phase alloy having a low-temperature anomalous magnetic effect as claimed in any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1) According to the alloy chemical composition of the designed alloy, weigh RE, Fe, and Ga raw materials respectively, the purity of the raw materials is greater than 99.95%, and the volatile rare earth elements are increased by 0.1 wt%-1.0 wt%; S2) placing the weighed RE, Fe, and Ga raw materials in order according to the rule that the higher the melting point, the closer to the arc gun tip; S3) using a high vacuum arc furnace to melt the mixed raw materials multiple times under an argon protective atmosphere at a certain pressure with a suitable current to make them completely melted and evenly melted, and finally obtaining an alloy ingot with uniform composition; S4) grinding the obtained alloy ingot with 240-grit sandpaper to remove the surface oxide scale to avoid the influence of oxide as much as possible; S5) Wrapping the alloy ingot treated in S4) with molybdenum foil, marking the ingot with a serial number, and sealing the ingot in a quartz tube under an argon protective atmosphere at a certain pressure; S6) placing the sealed quartz tube with the sample in a muffle furnace and performing a heat treatment at a temperature of 1273-1473 K for more than 48 hours; S7) The quartz tube containing the sample treated in S6) is taken out from the muffle furnace and quickly placed in liquid nitrogen for rapid cooling, and finally a single-phase alloy with low-temperature anomalous magnetic effect is obtained.

7. The method according to claim 6, characterized in that The smelting current in said S3) is 120A≤I≤180A; the inert protective atmosphere is argon, and the smelting is repeated for at least 3 times, and the smelting time for each time is at least 1 minute.

8. A single-phase alloy with low-temperature anomalous magnetic effect as claimed in any one of claims 1 to 5, used in the fields of information storage devices and quantum computing.

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