Cage structure ferromagnet with large abnormal Hall effect and preparation method thereof

Abstract

The invention provides a cage-mesh-structure ferromagnet with a large anomalous Hall effect and a preparation method thereof.The preparation method comprises the steps that raw materials including Tb, Mg, Mn and Sn elementary substances are contained in an Al2O3 crucible, sealed in a quartz tube in a vacuum mode and smelted in a muffle furnace, and finally the cage-mesh-structure ferromagnet with the large anomalous Hall effect is obtained through centrifugal separation of a fluxing agent Sn; the Tb-xMgxMn6Sn6 has the structural characteristic that Tb in TbMn6Sn6 is substituted by Mg, and the expression of the Tb1-xMgxMn6Sn6 is Tb1-xMgxMn6Sn6, xlt; and 0.2 part. The Tb < 1-x > Mg < x > Mn < 6 > Sn < 6 > is a hexagonal crystal system, the space group is P6 / mmm, the Tb < 1-x > Mg < x > Mn < 6 > Sn < 6 > has metallic luster, the thickness is 0.1-0.5 mm, and the side length of the hexagon is 1-3mm; the single crystal shows ferrimagnetism at room temperature and has a large abnormal Hall effect at low temperature. Abnormal Hall resistivity of Tb0. 986Mg0. 014Mn6Sn6 at 3K is about # imgabs0. Abnormal Hall conductivity of # imgabs1 # imgabs2 # Tb0. 96Mg0. 04Mn6Sn6 at 3K is about # imgabs3 # imgabs4 #, and abnormal Hall conductivity of # imgabs5 # is about 1 # imgabs2 # Tb0. 96Mg0. 04Mn6Sn6 at 3K

Description

Technical Field

[0001] The present invention belongs to the field of condensed matter physics and specifically relates to a cage-structured ferrimagnet with large anomalous Hall effect and a preparation method thereof. Background Art

[0002] Ferrimagnets are unique magnetic materials whose magnetic structure consists of magnetic moments of different sizes and arranged in opposite directions. Due to this special magnetic structure, ferimagnets have the advantages of both ferromagnets and antiferromagnets, such as ultrafast spin dynamics similar to antiferromagnets and net magnetization like ferromagnets. Therefore, ferimagnets are expected to produce spin polarization and large anomalous Hall effect. Theoretical studies have shown that the anomalous Hall effect is one of the important electrical transport properties in spin electronics. It refers to a physical phenomenon in which when current passes through a magnetic conductor, an unbalanced accumulation of charges in the lateral direction perpendicular to the current is generated to form a transverse voltage. This phenomenon plays a vital role in anomalous Hall sensors and spin electronics applications. Therefore, ferimagnets with large anomalous Hall effect provide an ideal platform for realizing spin electronics devices with ultrafast spin dynamics.

[0003] RMn6Sn6 (R = Gd, Tb, Dy, Ho, Er) is a cage-structured ferrimagnet with a cage layer composed of Mn atoms in its crystal structure. Due to this unique crystal structure, RMn6Sn6 has a special band structure and can produce a series of unique physical properties. For example, TbMn6Sn6 has a Chern gap Dirac point, which can theoretically obtain a large anomalous Hall effect and has the advantages of both antiferromagnets and ferromagnets, so it is expected to be used in spin electronics devices. Therefore, in recent years, the development and application of cage-structured ferrimagnets with large anomalous Hall effects have received widespread attention. With the deepening of research, researchers have found that the anomalous Hall effect in RMn6Sn6 is relatively small. At present, there is still no research report on the growth method and related properties of cage-structured ferrimagnets with large anomalous Hall effects.

[0004] In view of this, there is an urgent need for new cage-structured ferrimagnetic products with large anomalous Hall effect and their synthesis methods. Summary of the invention

[0005] The main purpose of the present invention is to provide a new cage-structured ferrimagnet with a large anomalous Hall effect and a preparation method thereof. The preparation method of the present invention is simple and low in cost. The cage-structured ferrimagnet prepared by the method of the present invention exhibits ferrimagnetism at room temperature and has a large anomalous Hall effect at low temperatures.

[0006] The above-mentioned object of the present invention is achieved through the following technical solutions.

[0007] The first aspect of the present invention provides a method for preparing a kagome - structured ferrimagnet with a large anomalous Hall effect, including the following specific steps:

[0008] (1) According to the molar ratio of Tb:Mg:Mn:Sn being 1 - y:y:6:10 - 30, weigh the raw materials of elemental Tb, Mg, Mn, and Sn and place them in an Al2O3 crucible. Subsequently, vacuum - seal the Al2O3 crucible in a quartz tube;

[0009] (2) Put the sealed quartz tube in step (1) into a muffle furnace to subject the mixture to smelting, and finally separate the flux Sn by centrifugation to obtain a kagome - structured ferrimagnet with a large anomalous Hall effect.

[0010] Preferably, in the method of the present invention, 0 < y < 0.2 in step (1).

[0011] Preferably, in the method of the present invention, the raw materials in step (1) are all elemental substances and the purity is greater than or equal to 99.9%.

[0012] Preferably, in the method of the present invention, the vacuum degree of the vacuum seal in step (1) is above 4×10 -4 Pa.

[0013] Preferably, in the method of the present invention, the weighing error of the raw materials in step (1) is less than or equal to 0.01%.

[0014] Preferably, in the method of the present invention, the smelting of the mixture in step (2) is carried out under the following conditions: the mixture is heated to 1050°C at a uniform rate of 10 h, held for 20 h, and then the mixture is slowly cooled to 600°C at a rate of 3°C - 5°C / h.

[0015] The second aspect of the present invention provides a kagome - structured ferrimagnet with a large anomalous Hall effect prepared by the above - mentioned method, which has the structural feature of Mg substituting for Tb in TbMn6Sn6, and the expression is: Tb 1-x Mg x Mn6Sn6, where 0 < x < 0.2, and preferably x = 0.014 or x = 0.04.

[0016] In the present invention, the x value of Mg substituting for Tb is calculated by the change in saturation magnetization.

[0017] Preferably, the kagome - structured ferrimagnet Tb 1-x Mg x Mn6Sn6 of the present invention is a hexagonal crystal system, with a space group of P6 / mmm, having a metallic luster, being a hexagonal sheet with a thickness of 0.1 - 0.5 mm and a hexagonal side length of 1 - 3 mm.

[0018] The inventors of the present application unexpectedly discovered that the cage-structured ferrimagnet Tb with large anomalous Hall effect described in the present invention 1-x Mg x Mn6Sn6 exhibits ferrimagnetism at room temperature and has a large anomalous Hall effect at low temperatures. The low temperature refers to 3-20K, and preferably, the low temperature refers to 3K.

[0019] In the cage-structured ferrimagnet with large anomalous Hall effect described in the present invention, when x=0.014, Tb 0.986 Mg 0.014 The anomalous Hall resistivity of Mn6Sn6 at 3K is approximately The anomalous Hall conductivity is approximately When x = 0.04, Tb 0.96 Mg 0.04 The anomalous Hall resistivity of Mn6Sn6 at 3K is approximately The anomalous Hall conductivity is approximately

[0020] Preferably, in the cage-structured ferrimagnet with large anomalous Hall effect described in the present invention, Cu target Kα diffraction is used, and its X-ray powder diffraction pattern expressed in 2θ angles has diffraction peaks at 19.72°~19.82°, 29.70°~29.90°, and 40.00°~40.06°, and the 2θ angle measurement error is ±0.01°.

[0021] The cage-structured ferrimagnet with large anomalous Hall effect described in the present invention is prepared by adopting the above method.

[0022] The third aspect of the present invention provides the application of the above-mentioned cage-structured ferrimagnet with large anomalous Hall effect in a Hall device. The manufacturing method of the Hall device is: the current is parallel to the ab plane of the prepared single crystal, and the external magnetic field is perpendicular to the ab plane to obtain a Hall element.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention provides a method for preparing a cage-structured ferrimagnet with a large anomalous Hall effect by flux, which is simple and low-cost.

[0025] 2. The cage-structured ferrimagnet Tb with large anomalous Hall effect prepared by the method of the present invention 1- x Mg x Mn6Sn6 single crystal exhibits ferrimagnetism at room temperature.

[0026] 3. Cage-structured ferrimagnet Tb with large anomalous Hall effect prepared by the method of the present invention 1- x Mg x Mn6Sn6 single crystal has a large anomalous Hall effect at low temperature, with the best x=0.04, followed by x=0.014. Tb 0.986 Mg 0.014 The anomalous Hall resistivity of Mn6Sn6 at room temperature is approximately The maximum anomalous Hall conductivity is approximately The anomalous Hall resistivity at 3K is approximately The anomalous Hall conductivity is approximately Tb 0.96 Mg 0.04 The anomalous Hall resistivity of Mn6Sn6 at room temperature is approximately The maximum anomalous Hall conductivity is approximately The anomalous Hall resistivity at 3K is approximately The anomalous Hall conductivity is approximately BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is Tb in Examples 1-5 of the present invention 1-x Mg x Related parameter diagram of Mn6Sn6 single crystal:

[0028] (a) is Tb 1-x Mg x Optical photo of Mn6Sn6 single crystal, (b) Tb 1-x Mg x XRD diffraction pattern of Mn6Sn6 single crystal on the (001) plane.

[0029] Figure 2 is Tb in Examples 1-5 of the present invention 1-x Mg x The basic magnetoelectric characterization results of Mn6Sn6 single crystal: (a) single crystal Tb at low temperature 1-x Mg x The magnetization intensity curve of Mn6Sn6; (b) is Tb 1-x Mg x The resistivity curve of Mn6Sn6 single crystal changes with temperature.

[0030] Figure 3 This is the Hall signal output curve of the Hall device manufactured using the single crystal obtained in Examples 1-5 of the present invention.

[0031] Figure 4Graph showing the anomalous Hall conductivity intensity at different Mg contents of the Hall device manufactured using the single crystals obtained in Examples 1-5 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with specific embodiments. The given examples are only for illustrating the present invention, but not for limiting the scope of the present invention.

[0033] Example 1

[0034] Cage-like ferrimagnet Tb with large anomalous Hall effect grown by flux method 1-x Mg x The specific preparation method of Mn6Sn6 single crystal comprises the following steps:

[0035] (1) According to the molar ratio of Tb:Mg:Mn:Sn of 0.95:0.05:6:20, the weighed raw materials are placed in an Al2O3 crucible, the Al2O3 crucible is placed in a quartz tube, and then sealed in the quartz tube under vacuum;

[0036] (2) placing the sealed quartz tube in step (1) into a muffle furnace to subject the mixture to smelting. The muffle furnace growth temperature program is as follows: heating the mixture to 1050° C. at a constant rate of 10 h, keeping the temperature for 20 h, then slowly cooling the mixture to 600° C. at a rate of 3° C. / h, and finally separating the flux Sn by centrifugation to obtain caged ferrimagnet Tb with large anomalous Hall effect. 0.986 Mg 0.014 Mn6Sn6 single crystal.

[0037] Example 2

[0038] In this embodiment, the molar ratio of Tb:Mg:Mn:Sn is 0.9:0.1:6:20, and the caged ferrimagnet Tb with large anomalous Hall effect is obtained. 0.972 Mg 0.028 Mn6Sn6 single crystal. The rest is the same as in Example 1.

[0039] Example 3

[0040] In this embodiment, the molar ratio of Tb:Mg:Mn:Sn is 0.85:0.15:6:20, and the caged ferrimagnet Tb with large anomalous Hall effect is obtained. 0.96 Mg 0.04 Mn6Sn6 single crystal. The rest is the same as in Example 1.

[0041] Example 4

[0042] In this embodiment, the molar ratio of Tb:Mg:Mn:Sn is 0.8:0.2:6:20, and the caged ferrimagnet Tb with large anomalous Hall effect is obtained.0.945 Mg 0.055 Mn6Sn6 single crystal. The rest is the same as in Example 1.

[0043] Example 5

[0044] In this embodiment, the molar ratio of Tb:Mg:Mn:Sn is 1:0:6:20, and a cage-shaped ferrimagnetic TbMn6Sn6 single crystal is obtained. The rest is the same as in embodiment 1.

[0045] Test example:

[0046] (1) Morphology and structure characterization:

[0047] Figure 1 is Tb in Examples 1-5 of the present invention 1-x Mg x Related parameter diagram of Mn6Sn6 single crystal: (a) is Tb 1-x Mg x Optical photo of Mn6Sn6 single crystal, (b) Tb 1-x Mg x XRD diffraction pattern of Mn6Sn6 single crystal on the (001) plane.

[0048] like Figure 1 As shown in (a), millimeter-scale Tb 1-x Mg x Mn6Sn6 hexagonal wafer, hexagonal sheet with thickness of 0.1-0.5mm and hexagonal side length of 1-3mm.

[0049] like Figure 1 (b) shows that the Tb prepared by the present invention 1-x Mg x Mn6Sn6 crystal, its (001) surface was tested by XRD diffractometer. The results show that Tb 1-x Mg x Mn6Sn6 single crystal is hexagonal, belongs to P6 / mmm space group, all diffraction peaks are

[001] oriented, no impurity peaks. With the increase of Mg content, the diffraction peaks gradually move to high diffraction angles, and the c-axis lattice constant decreases.

[0050] (2) Characterization of basic magnetoelectric properties:

[0051] Figure 2 is Tb in Examples 1-5 of the present invention 1-x Mg x Characterization results of the basic magnetoelectric properties of Mn6Sn6 single crystal: (a) single crystal Tb 1-x Mg x Magnetization curve of Mn6Sn6; (b) Tb 1-x Mg xThe relationship between the resistivity of Mn6Sn6 single crystal and temperature.

[0052] like Figure 2 As shown in (a), Tb 1-x Mg x The magnetization curve of Mn6Sn6 single crystal shows that since Mg is non-magnetic relative to Tb, the saturation magnetic moment increases with the increase of Mg content. The increase in saturation magnetic moment can be used to obtain the number of Mg replacing Tb in the single crystal, and the obtained single crystals all exhibit ferrimagnetism.

[0053] like Figure 2 (b) shows that single crystal Tb 1-x Mg x The resistivity curve of Mn6Sn6 shows that its magnetization transition temperature T SR Around 315K.

[0054] In the present invention, Figure 1 (b) and Figure 2 (a) The structural characteristics of Mg replacing Tb in TbMn6Sn6 can be obtained. The Mg ion radius is smaller than that of Tb, so Mg replacing Tb will cause the c-axis lattice constant of the compound to become smaller, such as Figure 1 (b) shows that the XRD diffraction peak gradually moves to a higher diffraction angle. In addition, Mg has no magnetic properties relative to Tb, so the substitution of Mg for Tb will increase the saturation magnetization intensity in the compound, as shown in Figure 2 (a) shows the saturation magnetization enhancement. The ratio of Mg replacing Tb is calculated by the change in magnetization. 1-x Mg x The increase in the saturation magnetization of Mn6Sn6 relative to TbMn6Sn6 is divided by the magnetic moment of Tb atoms to obtain the value of x in the expression.

[0055] Expression Tb 1-x Mg x Mn6Sn6 means that 1 Tb is replaced by x Mg, where x = 0.014-0.055, and after the substitution, the number of Tb is (1-x).

[0056] (3) Application in Hall Effect Devices

[0057] Figure 3 : is the Hall signal output curve of the Hall device manufactured by the present invention using the single crystal with x of 0, 0.014, and 0.04 obtained in the embodiment. Figure 3 As shown in (a), the Hall resistivity of TbMn6Sn6 at room temperature is approximately Tb 0.986 Mg 0.014 The Hall resistivity of Mn6Sn6 at room temperature is approximately Tb 0.96 Mg 0.04 The Hall resistivity of Mn6Sn6 at room temperature is approximately like Figure 3 As shown in (b), the Hall resistivity of TbMn6Sn6 at 3K is approximately Tb 0.986 Mg 0.014 The Hall resistivity of Mn6Sn6 at 3K is approximately Tb 0.96 Mg 0.04 The Hall resistivity of Mn6Sn6 at 3K is approximately

[0058] Figure 4 The anomalous Hall conductivity intensity diagram of the Hall devices made of single crystals with x of 0, 0.014, and 0.04 obtained in the present invention. The maximum anomalous Hall conductivity of TbMn6Sn6 at room temperature is about The anomalous Hall conductivity at 3K is approximately Tb 0.986 Mg 0.014 The maximum anomalous Hall conductivity of Mn6Sn6 at room temperature is about The anomalous Hall conductivity at 3K is approximately Tb 0.96 Mg 0.04 The maximum anomalous Hall conductivity of Mn6Sn6 at room temperature is about The anomalous Hall conductivity at 3K is approximately

Claims

1. A method for preparing a cage-structured ferrimagnetic material having a large anomalous Hall effect, characterized in that: The specific steps include: (1) According to the molar ratio of Tb:Mg:Mn:Sn of 1-y:y:6:10-30, weighed raw materials Tb, Mg, Mn and Sn are placed in an Al2O3 crucible, and then the Al2O3 crucible is vacuum-sealed in a quartz tube under 1 / 3 argon conditions; the value range of y is: 0 <y<0.2; (2) placing the sealed quartz tube in step (1) into a muffle furnace, subjecting the mixture to smelting, and finally separating the flux Sn by centrifugation to obtain a cage-structured ferrimagnet with a large anomalous Hall effect.

2. The method for preparing a cage-structured ferrimagnetic material having a large anomalous Hall effect according to claim 1, characterized in that: In the step (1), the raw materials are all simple substances with a purity greater than or equal to 99.9%, and the raw material weighing error is less than or equal to 0.01%; the vacuum degree of the vacuum seal is 4×10 -4 Pa or above.

3. The method for preparing a cage-structured ferrimagnetic material with a large anomalous Hall effect according to claim 1, characterized in that: The smelting of the mixture in step (2) is carried out under the following conditions: the mixture is heated to 1050°C at a constant rate of 10 hours, kept at that temperature for 20 hours, and then the mixture is slowly cooled to 600°C at a rate of 3°C to 5°C / h.

4. A cage-structured ferrimagnet with a large anomalous Hall effect, characterized in that: The cage-structured ferrimagnet with large anomalous Hall effect has the structural feature that Mg replaces Tb in TbMn6Sn6, and the expression is: Tb 1-x Mg x Mn6Sn6, where 0 <x<0.2。 5. The cage-structured ferrimagnet with large anomalous Hall effect according to claim 4, characterized in that: Using Cu target Kα diffraction, its X-ray powder diffraction pattern expressed in 2θ angle has diffraction peaks at 19.72°-19.82°, 29.70°-29.90°, and 40.00°-40.06°, and the 2θ angle measurement error is ±0.01°.

6. The cage-structured ferrimagnet with large anomalous Hall effect according to claim 4, characterized in that: Tb 1- x Mg x Mn6Sn6 is a hexagonal crystal with a space group of P6 / mmm, a metallic luster, a hexagonal sheet with a thickness of 0.1-0.5 mm and a hexagonal side length of 1-3 mm.

7. The cage-structured ferrimagnet with large anomalous Hall effect according to claim 4, characterized in that: Tb 1- x Mg x Mn6Sn6 exhibits ferrimagnetism at room temperature and has a large anomalous Hall effect at low temperatures, where low temperatures refer to 3-20K.

8. The cage-structured ferrimagnet with large anomalous Hall effect according to claim 4, characterized in that: When x = 0.014, Tb 0.986 Mg 0.014 The anomalous Hall resistivity of Mn6Sn6 at 3K is approximately =4.61×10 -3 μΩcm, and the anomalous Hall conductivity is approximately When x = 0.04, Tb 0.96 Mg 0.04 The anomalous Hall resistivity of Mn6Sn6 at 3K is approximately The anomalous Hall conductivity is approximately 9. The cage-structured ferrimagnet with large anomalous Hall effect according to any one of claims 4 to 8, characterized in that: The cage-structured ferrimagnet with large anomalous Hall effect is prepared by the method described in any one of claims 1-3.

10. Application of the cage-structured ferrimagnet with large anomalous Hall effect as claimed in any one of claims 4 to 8 in a Hall device, wherein the manufacturing method of the Hall device is as follows: the current is parallel to the ab plane of the prepared single crystal, and the external magnetic field is perpendicular to the ab plane to obtain the Hall element.

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