Two-Dimensional Van der Waals Ga-Based Magnetic Crystals of Multielement Alloys, Preparation and Applications

Abstract

The present invention relates to a multi-component alloy two-dimensional van der Waals Ga-based magnetic crystal, its preparation and application, belonging to the technical field of nano-magnetic materials. The magnetic crystal material of the present invention is (Fe 1‑x A x ) a (Ga 1‑y B y ) b (Te 1‑z C z ) c , where x, y, and z are all greater than 0 and less than or equal to 0.9; a = 2 to 6, b = 0.1 to 2, c = 0.1 to 5; A is Ti, V, Cr, Mn, Cu, or Zn, B is Al or In, and C is S, Se, Br, I, or Sb. The multi-component alloy two-dimensional van der Waals Ga-based magnetic crystal provided by the present invention is a layered material, and the layers are connected by weak van der Waals forces. Multilayer to monolayer nanosheets can be obtained by mechanical exfoliation, which is easy to further prepare nano-scale spintronic devices. Depending on the type and proportion of doped elements, the crystal exhibits ferromagnetic or antiferromagnetic properties respectively, and has broad application prospects in spintronics.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of nano-magnetic materials, and more specifically, relates to a multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal, its preparation and application. Background Art

[0002] The discovery of two-dimensional magnetic materials has greatly promoted the development of two-dimensional spintronics and information technology. Due to the interlayer van der Waals interaction, two-dimensional magnetic materials are easy to mechanically exfoliate, have an atomically smooth surface and tunable physical properties, and can be used to construct van der Waals heterojunctions to prepare magnetic tunnel junctions, spin-orbit torque devices, spin-transfer torque devices, etc., so as to realize in-memory computing, neuromorphic computing, and stochastic computing based on non-volatile random access memory.

[0003] Spin functional devices with high performance and low power consumption usually rely on current drive. Therefore, compared with insulating magnetic materials, metallic magnetic materials have more advantages. However, the currently discovered metallic two-dimensional van der Waals magnetic materials have problems such as a magnetic transition temperature lower than room temperature, in-plane magnetic anisotropy, and a small coercive force of ferromagnetic materials, which greatly limit their practical applications. Summary of the Invention

[0004] The present invention provides a class of multi-element alloy two-dimensional van der Waals Ga-based magnetic crystals, and high-quality two-dimensional van der Waals Ga-based magnetic crystals can be prepared by using the present invention. The magnetic crystal material of the present invention is (Fe 1-x A x ) a (Ga 1-y B y ) b (Te 1-z C z ) c, where x, y, and z are all greater than 0 and less than or equal to 0.9; a = 2 - 6, b = 0.1 - 2, c = 0.1 - 5; A is Ti, V, Cr, Mn, Cu, or Zn, B is Al or In, and C is S, Se, Br, I, or Sb. In the present invention, the magnetic crystal material is a layered material, which is connected between layers by weak van der Waals forces and can be mechanically exfoliated to obtain nanosheets from multiple layers to single layers, making it easy to further fabricate spin electronic devices at the nanoscale. In addition, depending on the types and proportions of the doped elements A, B, and C, the material exhibits ferromagnetic or antiferromagnetic properties respectively. Correspondingly, its magnetic transition temperature is the Curie temperature or the Néel temperature respectively, which can be regulated within a large range. The Curie temperature is 300 - 500K, and the Néel temperature is 200 - 400K. The magnetic transition temperature is close to or higher than room temperature. When the magnetic crystal is ferromagnetic, it has out-of-plane magnetic anisotropy, and the coercivity is 0.4 - 2.5T, which can enhance the thermal stability in storage applications and improve the device reliability. The class of multi-element alloy two-dimensional van der Waals Ga-based magnetic crystals described in the present invention has metallicity, can be driven by current and achieve spin detection. The fully two-dimensional van der Waals heterojunction constructed by it has an atomically flat and smooth interface, enabling high-performance spin electronic devices. In addition, it has out-of-plane magnetic anisotropy, can construct a vertical heterojunction, and improves the device integration. Thus, the technical problems in the prior art that two-dimensional van der Waals magnetic materials have a magnetic transition temperature lower than room temperature, in-plane magnetic anisotropy, and a small coercivity when ferromagnetic are solved.

[0005] According to the first aspect of the present invention, there is provided a multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal, and the magnetic crystal material is (Fe 1-x A x ) a (Ga 1-y B y ) b (Te 1-z C z ) c , where x, y, and z are all greater than 0 and less than or equal to 0.9; a = 2 - 6, b = 0.1 - 2, c = 0.1 - 5; A is Ti, V, Cr, Mn, Cu, or Zn, B is Al or In, and C is S, Se, Br, I, or Sb.

[0006] Preferably, the multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal exhibits ferromagnetism below the Curie temperature or antiferromagnetism below the Néel temperature; the range of the Curie temperature is 300 - 500K, and the range of the Néel temperature is 200 - 400K.

[0007] Preferably, when the multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal exhibits ferromagnetism, the coercivity is 0.4 - 2.5T.

[0008] According to another aspect of the present invention, there is provided an application of the multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal described in any one of the above in ferromagnetic or antiferromagnetic spintronics.

[0009] Preferably, the application is specifically an application in a magnetic tunnel junction device, a spin-orbit torque device, a spin-transfer torque device, or an electrically controlled magnetic device.

[0010] Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention mainly have the following technical advantages:

[0011] (1) A class of multi-element alloy two-dimensional van der Waals Ga-based magnetic crystals in the present invention exhibit ferromagnetic or antiferromagnetic properties respectively according to the types and proportions of the doped elements. Correspondingly, their magnetic transition temperatures are the Curie temperature or the Néel temperature respectively, and both can be regulated within a large range. The Curie temperature is 300 - 500K, and the Néel temperature is 200 - 400K, which are higher than most of the known two-dimensional van der Waals metallic ferromagnetic or antiferromagnetic materials.

[0012] (2) When a class of multi-element alloy two-dimensional van der Waals Ga-based magnetic crystals in the present invention are ferromagnetic, they have a large coercivity. The coercivity of the material is 0.4 - 2.5T, which is higher than most of the known two-dimensional van der Waals magnetic materials, can enhance the thermal stability in storage applications, and improve the reliability of the device.

[0013] (3) The magnetic crystal material in the present invention is a two-dimensional van der Waals metal material, with good crystallinity, high purity, and is easy to mechanically exfoliate.

[0014] (4) Due to its two-dimensional van der Waals property, the magnetic crystal material in the present invention has a small surface roughness, can achieve seamless stacking with other two-dimensional materials, has no lattice mismatch problem, can construct a van der Waals heterojunction with high interface quality, and can be used to prepare magnetic tunnel junctions, spin-orbit torque devices, spin-transfer torque devices, etc., so as to realize in-memory computing, neuromorphic computing, and stochastic computing based on non-volatile random access memory. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is (Fe 0.9 Cu 0.1 ) 3 Ga 0.8 Al 0.2 (Te 0.9 Se 0.1 ) 2 Zero-field cooled, field-cooled curves and low-temperature hysteresis loops of the crystal under an out-of-plane magnetic field.

[0016] Figure 2 is (Fe 0.8 Mn 0.2 ) 5(Ga 0.9 In 0.1 ) 2 (Te 0.7 Sb 0.3 ) 3 Zero-field-cooled, field-cooled curves and low-temperature hysteresis loops of the crystal under an out-of-plane magnetic field.

[0017] Figure 3 is (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 Zero-field-cooled, field-cooled curves and low-temperature hysteresis loops of the crystal under an out-of-plane magnetic field.

[0018] Figure 4 is based on (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 Performance curves of the magnetic tunnel junction device of two-dimensional nanosheets at 190 K. Detailed implementation manners

[0019] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] A novel type of multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal and preparation thereof in the present invention, the material (Fe 1-x A x ) a (Ga 1-y B y ) b (Te 1-z C z ) c(x = 0 to 0.9, y = 0 to 0.9, z = 0 to 0.9; a = 2 to 6, b = 0.1 to 2, c = 0.1 to 5; A is Ti, V, Cr, Mn, Cu or Zn, B is Al or In, C is S, Se, Br, I or Sb) is a two-dimensional van der Waals material, and multi-layer to single-layer nanosheets can be obtained by mechanical exfoliation, which is easy to further prepare nano-scale spintronic devices.

[0021] The preparation method of the multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal of the present invention is the molten salt method, chemical vapor transport method, magnetron sputtering method or molecular beam epitaxy method.

[0022] The present invention relates to the preparation of a novel multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal. Now, in combination with the following specific embodiments and drawings, the present invention will be further described in detail.

[0023] Example 1

[0024] 1) Prepare (Fe 0.9 Cu 0.1 ) 3 Ga 0.8 Al 0.2 (Te 0.9 Se 0.1 ) 2 ;

[0025] 2) Mix evenly Fe powder, Cu powder, Ga particles, Al particles, Te powder and Se powder with a molar ratio of Fe:Cu:Ga:Al:Te:Se = 2.7:0.3:0.8:0.2:1.8:0.2, place them in an ampoule bottle, and evacuate and seal after washing with Ar gas three times repeatedly;

[0026] 3) Place the sealed ampoule bottle in a muffle furnace, quickly heat it to 1000 °C, and then slowly cool it at a rate of 1.5 °C / h after sufficient reaction, and thus obtain (Fe 0.9 Cu 0.1 ) 3 Ga 0.8 Al 0.2 (Te 0.9 Se 0.1 ) 2 magnetic crystal.

[0027] Example 2

[0028] 1) Prepare (Fe 0.7 Cr 0.3 ) 3 Ga 0.9 Al 0.1 (Te 0.9 Se 0.1 ) 2 ;

[0029] 2) Select Te, Se, FeCl 2 , CrCl 3 , GaI 3 and AlCl 3 powders as precursors, and SiO 2 / Si with a diameter of 1 inch as the substrate. In a three-zone CVD tube furnace, place Se powder in the upstream zone 1 at a temperature of 200 °C, place Te powder in the middle zone 2 at a temperature of 420 °C, and place a mixture of FeCl 2 , CrCl 3 , GaI 3 and AlCl 3 powders in the downstream zone 3 at a temperature of 600 °C, and place the substrate downstream of zone 3;

[0030] 3) Introduce 100 sccm of Ar gas. After purging, introduce the H 2 / Ar mixed gas at 5 / 50 sccm. Rapidly heat the three-zone tube furnace to the target temperature, with a heating time of 30 min. After natural cooling, the (Fe 2 Cr 0.7 ) 0.3 ) 3 Ga 0.9 Al 0.1 (Te 0.9 Se 0.1 ) 2 crystal deposited on the SiO

[0031] Example 3

[0032] 1) Prepare (Fe 0.8 Ti 0.2 ) 4 Ga 0.7 In 0.3 (Te 0.8 I 0.2 ) 2 by the self-assembly solvent method;

[0033] 2) Mix Fe powder, Ti powder, Ga particles, In powder, Te powder and I 2 granules with a molar ratio of Fe:Ti:Ga:In:Te:I 2 = 3.2:0.8:0.7:0.3:1.6:0.2 evenly, place them in an ampoule, and repeatedly purge with Ar gas three times and then evacuate and seal;

[0034] 3) Place the sealed ampoule in a muffle furnace, rapidly heat it to 1000 °C, and slowly cool it at a rate of 1.5 °C / h after sufficient reaction, then the (Fe 0.8 Ti0.2 ) 4 Ga 0.7 In 0.3 (Te 0.8 I 0.2 ) 2 Magnetic crystal.

[0035] Example 4

[0036] 1) Prepare (Fe 0.8 Mn 0.2 ) 5 (Ga 0.9 In 0.1 ) 2 (Te 0.7 Sb 0.3 ) 3 ;

[0037] 2) Mix evenly Fe powder, Mn powder, Ga particles, In powder, Te powder, Sb powder with a molar ratio of Fe:Mn:Ga:In:Te:Sb = 4:1:1.8:0.2:2.1:0.9 and 0.2 g of I 2 granules, place them in a 15 cm quartz tube, wash with Ar gas three times repeatedly and then evacuate and seal.

[0038] 3) Place the sealed quartz tube in a two-zone tube furnace, heat the high-temperature zone and the low-temperature zone to 1000 °C and 750 °C respectively within 1 h, keep warm for 2 weeks, let the raw materials react fully and then cool naturally to room temperature, and thus obtain (Fe 0.8 Mn 0.2 ) 5 (Ga 0.9 In 0.1 ) 2 (Te 0.7 Sb 0.3 ) 3 magnetic crystal.

[0039] Example 5

[0040] 1) Prepare (Fe 0.7 Zn 0.3 ) 5 (Ga 0.8 In 0.2 ) 1.5 (Te 0.9 Br 0.1 ) 2 ;

[0041] 2) Mix evenly Fe powder, Zn powder, Ga particles, In powder, Te powder, Br powder with a molar ratio of Fe:Zn:Ga:In:Te:Br = 3.5:1.5:1.2:0.3:1.8:0.2 and 0.2 g of I 2 granules, place them in a 15-cm quartz tube, wash with Ar gas three times repeatedly and then evacuate and seal;

[0042] 3) Place the sealed quartz tube in a two-zone tube furnace, heat the high-temperature zone and the low-temperature zone to 980 °C and 750 °C respectively within 1 h, hold for 2 weeks, let the raw materials react fully and then cool naturally to room temperature to obtain (Fe 0.7 Zn 0.3 ) 5 (Ga 0.8 In 0.2 ) 1.5 (Te 0.9 Br 0.1 ) 2 magnetic crystal.

[0043] Example 6

[0044] 1) Prepare (Fe 0.8 Cr 0.2 ) 5 (Ga 0.7 Al 0.3 ) 2 (Te 0.6 I 0.4 ) 2 ;

[0045] 2) Place the bulk target of (Fe 0.8 Cr 0.2 ) 5 (Ga 0.7 Al 0.3 ) 2 (Te 0.6 I 0.4 ) 2 in the magnetron sputtering cavity, introduce Ar gas for washing, evacuate repeatedly three times, and the vacuum degree is 3×10 -5 mbar;

[0046] 3) Place the silicon wafer in the sample cavity and then start sputtering. The sputtering power is 13 W and the time is 3 minutes. Then place the sputtered silicon wafer in a tube furnace and anneal at 450 °C to obtain (Fe 0.8 Cr 0.2 ) 5 (Ga 0.7 Al 0.3 ) 2 (Te 0.6 I 0.4 )2 Magnetic crystal

[0047] Example 7

[0048] 1) Prepare (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 ;

[0049] 2) Place the sapphire substrate in the sample chamber, anneal at 600 °C for 30 min, and then lower the temperature to the growth temperature of 340 °C;

[0050] 3) Co-evaporate high-purity Fe, V, Ga, In, Te, and Se sources at temperatures of 1200 °C, 1900 °C, 30 °C, 160 °C, 280 °C, and 220 °C respectively to obtain the (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 crystal

[0051] Example 8

[0052] 1) Prepare (Fe 0.9 Cr 0.1 ) 3 Ga 0.9 Al 0.1 (Te 0.9 S 0.1 ) 2 ;

[0053] 2) Place the mica substrate in the sample chamber, anneal at 600 °C for 30 min, and then lower the temperature to the growth temperature of 340 °C;

[0054] 3) Co-evaporate high-purity Fe, Cr, Ga, Al, Te, and S sources at temperatures of 1200 °C, 1900 °C, 30 °C, 660 °C, 280 °C, and 180 °C respectively to obtain the (Fe 0.9 Cr 0.1 ) 3 Ga 0.9 Al 0.1 (Te 0.9 S 0.1 ) 2 crystal

[0055] Example 9

[0056] 1) Prepare (Fe 0.7 Cr 0.3 ) 5 (Ga 0.7 Al 0.3 ) 3 (Te 0.6 Sb 0.4 ) 2 ;

[0057] 2) Mix evenly Fe powder, Cr powder, Ga particles, Al particles, Te powder and Sb powder with a molar ratio of Fe:Cr:Ga:Al:Te:Sb = 3.5:1.5:2.1:0.9:1.2:0.8, place them in an ampoule bottle, and after washing with Ar gas three times repeatedly, evacuate and seal;

[0058] 3) Place the sealed ampoule bottle in a muffle furnace, quickly heat it up to 1000 °C, and then slowly cool it at a rate of 1.5 °C / h after sufficient reaction, thus obtaining (Fe 0.7 Cr 0.3 ) 5 (Ga 0.7 Al 0.3 ) 3 (Te 0.6 Sb 0.4 ) 2 magnetic crystal.

[0059] Example 10

[0060] 1) Prepare (Fe 0.9 Cu 0.1 ) 4 (Ga 0.9 Al 0.1 ) 2 (Te 0.8 I 0.2 ) 2 ;

[0061] 2) Mix evenly Fe powder, Cu powder, Ga particles, Al particles, Te powder and I 2 = 3.6:0.4:1.8:0.2:1.6:0.2 of Fe powder, Cu powder, Ga particles, Al particles, Te powder and I 2 particles, place them in an ampoule bottle, and after washing with Ar gas three times repeatedly, evacuate and seal;

[0062] 3) Place the sealed ampoule bottle in a muffle furnace, quickly heat it up to 1000 °C, and then slowly cool it at a rate of 1.5 °C / h after sufficient reaction, thus obtaining (Fe 0.9 Cu 0.1 )4 (Ga 0.9 Al 0.1 ) 2 (Te 0.8 I 0.2 ) 2 Magnetic crystal.

[0063] Table 1 is a summary table of the chemical formulas, preparation methods, magnetism, Curie temperature T C or Néel temperature T N and coercive force at ferromagnetic state, showing that the novel multi - element alloy two - dimensional van der Waals Ga - based magnetic crystal described in the present invention exhibits ferromagnetic and antiferromagnetic properties respectively according to different types and ratios of doping elements.

[0064] Table 1: Chemical formulas of different examples and corresponding preparation methods, magnetism, Curie temperature T C or Néel temperature T N and coercive force

[0065]

[0066]

[0067] Figure 1 is (Fe 0.9 Cu 0.1 ) 3 Ga 0.8 Al 0.2 (Te 0.9 Se 0.1 ) 2 Zero - field - cooled, field - cooled curves and low - temperature hysteresis loops of the crystal in an out - of - plane magnetic field. It shows the room - temperature ferromagnetism and extremely large coercive force of (Fe 0.9 Cu 0.1 ) 3 Ga 0.8 Al 0.2 (Te 0.9 Se 0.1 ) 2 . Figure 2 is (Fe 0.8 Mn 0.2 ) 5 (Ga 0.9 In 0.1 ) 2 (Te 0.7 Sb 0.3 ) 3 Zero - field - cooled, field - cooled curves and low - temperature hysteresis loops of the crystal in an out - of - plane magnetic field. It shows the room - temperature ferromagnetism of (Fe 0.8 Mn 0.2 ) 5 (Ga 0.9 In 0.1) 2 (Te 0.7 Sb 0.3 ) 3 The antiferromagnetism and relatively high Néel temperature of the crystal. Figure 3 is (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 The zero-field cooled, field-cooled curves and low-temperature hysteresis loop of the (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 The antiferromagnetism and relatively high Néel temperature of the crystal. Figure 4 is based on (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 The performance curves of the magnetic tunnel junction device based on two-dimensional nanosheets at 190 K. It shows the application potential of (Fe 0.6 V 0.4 ) 5 (Ga 0.5 In 0.5 ) 1.2 (Te 0.7 Se 0.3 ) 2 crystals in two-dimensional van der Waals antiferromagnetic spintronics.

[0068] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal, characterized in that: The magnetic crystal material is (Fe 1-x A x ) a (Ga 1-y B y ) b (Te 1-z C z ) c , wherein x, y and z are all greater than 0 and less than or equal to 0.9; a=2-6, b=0.1-2, c=0.1-5; A is Ti, V, Cr, Mn, Cu or Zn, B is Al or In, and C is S, Se, Br, I or Sb; The multi-alloy two-dimensional van der Waals Ga-based magnetic crystal exhibits ferromagnetism below the Curie temperature or antiferromagnetism below the Neel temperature; the Curie temperature ranges from 300 to 500K, and the Neel temperature ranges from 200 to 400K.

2. The multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal according to claim 1, characterized in that: When the multi-element alloy two-dimensional van der Waals Ga-based magnetic crystal exhibits ferromagnetism, the coercive force is 0.4-2.5T.

3. Application of the multi-alloy two-dimensional van der Waals Ga-based magnetic crystal as described in any one of claims 1-2 in ferromagnetic or antiferromagnetic spin electronics.

4. The use according to claim 3, characterized in that The application is specifically an application in a magnetic tunnel junction device, a spin-orbit torque device, a spin-transfer torque device or an electrically controlled magnetic device.

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