GA-BASED VAN DER WAALS ROOM-TEMPERATURE FERROMAGNETIC CRYSTAL MATERIAL, PREPARATION AND USE THEREOF

Abstract

The present invention provides a Ga-based van der Waals room-temperature ferromagnetic crystal material, preparation and use thereof, which belong to the technical field of nano magnetic material preparation. The materials include Fe.sub.3-aGa.sub.bTe.sub.2 (a=?0.3 to 0.1, b=0.8 to 1.2) and Fe.sub.5-c GeGa.sub.dTe.sub.2 (c=?0.2 to 0.2, d=0.01 to 0.5). The growth method of Fe.sub.3-aGa.sub.bTe.sub.2 (a=?0.3 to 0.1, b=0.8 to 1.2) is a self-flux method, using excess Ga and Te as flux to grow crystals. The growth method of Fe.sub.5-c GeGa.sub.dTe.sub.2 (c=?0.2 to 0.2, d=0.01 to 0.5) uses iodine as a transport agent to grow crystals. The Ga-based van der Waals room-temperature ferromagnetic crystal Fe.sub.3-a Ga.sub.bTe.sub.2 (a=?0.3 to 0.1, b=0.8 to 1.2) and Fe.sub.5-cGeGa.sub.dTe.sub.2 (c=?0.2 to 0.2, d=0.01 to 0.5) materials have Curie temperature of 330 K to 367 K and 320 K to 345 K, and the saturation magnetic moments are 50 emu/g to 57.2 emu/g and 80 emu/g to 88.5 emu/g, respectively.

Claims

1. A Ga-based van der Waals ferromagnetic crystal material, wherein the ferromagnetic crystal material is a Fe.sub.3-a Ga.sub.bTe.sub.2 ferromagnetic crystal, wherein a=?0.3 to 0.1, b=0.8 to 1.2; or a Fe.sub.5-c Ga.sub.dTe.sub.2 ferromagnetic crystal, wherein c=?0.2 to 0.2, d=0.01 to 0.5; both a Fe.sub.3-aGa.sub.bTe.sub.2 compound of the Fe.sub.3-aGa.sub.bTe.sub.2 ferromagnetic crystal and a Fe.sub.5-c GeGa.sub.dTe.sub.2 compound of the Fe.sub.5-cGeGa.sub.dTe.sub.2 ferromagnetic crystal contain iron atoms with a valence of zero; Curie temperatures of the Fe.sub.3-aGa.sub.bTe.sub.2 ferromagnetic crystal and the Fe.sub.5-c GeGa.sub.dTe.sub.2 ferromagnetic crystal are 330 K to 367 K and 320 K to 345 K respectively, and the Fe.sub.3-a Ga.sub.bTe.sub.2 ferromagnetic crystal and the Fe.sub.5-c GeGa.sub.dTe.sub.2 ferromagnetic crystal exhibit ferromagnetism below their respective Curie temperatures.

2. The Ga-based van der Waals ferromagnetic crystal material according to claim 1, wherein saturation magnetic moments of the Fe.sub.3-a Ga.sub.bTe.sub.2 ferromagnetic crystal and the Fe.sub.5-c GeGa.sub.dTe.sub.2 ferromagnetic crystal are 50 emu/g to 57.2 emu/g and 80 emu/g to 88.5 emu/g, respectively.

3. A method for preparing a ferromagnetic crystal, comprising following steps: (1) mixing Fe powder, Ga block and Te powder thoroughly, a sum of an amount of the Fe powder and the Ga block is equal to an amount of the Te powder; the amount of the Fe powder accounts for 40% to 60% of the sum of the amount of the Fe powder and the Ga block; (2) vacuuming a container containing a mixture obtained in step (1); and (3) heating the mixture, a heating temperature is 950? C. to 1050? C., and then the heating temperature is reduced at a rate of 0.5? C./h to 1.5? C./h during a crystal growth process to obtain a Fe.sub.3-aGa.sub.bTe.sub.2 ferromagnetic crystal, wherein a=?0.3 to 0.1, b=0.8 to 1.2.

4. The method for preparing the ferromagnetic crystal according to claim 3, wherein a heating time is 24 hours to 48 hours.

5. The method for preparing the ferromagnetic crystal according to claim 3, wherein first the heating temperature is reduced rapidly to 880? C. at a rate of 70? C./h to 170? C./h, then reduced slowly to 780? C. at a rate of 0.5? C./h to 1.5? C./h, and then cooled naturally.

6. A method for preparing a ferromagnetic crystal, comprising following steps: (1) mixing Fe powder, Ge powder, Ga block, Te powder and I.sub.2 particles thoroughly, a ratio of an amount of the Fe powder, a sum of an amount of the Ge powder and the Ga block, and an amount of the Te powder is 4:1:2, the amount of the Ge powder accounts for 40% to 60% of the sum of the amount of the Ge powder and the Ga block; (2) vacuuming a container containing a mixture obtained in step (1); and (3) placing a part of the container containing the mixture in a high-temperature raw material zone in a dual-temperature zone tube furnace and placing a part of the container not containing the mixture in a low-temperature crystallization zone in the dual-temperature zone tube furnace, a temperature in the high-temperature raw material zone is 950? C. to 1050? C., and a temperature in the low-temperature crystallization zone is 600? C. to 700? C.; the I.sub.2 particles serve as a transport agent; and transporting the mixture to the low-temperature crystallization zone for reaction to obtain a Fe.sub.5-c GeGa.sub.dTe.sub.2 ferromagnetic crystal, wherein c=?0.2 to 0.2, d=0.01 to 0.5.

7. The method for preparing the ferromagnetic crystal according to claim 6, wherein in step (3), a time of the reaction is 168 hours to 330 hours.

8. The method for preparing the ferromagnetic crystal according to claim 6, wherein a ratio of a mass of the I.sub.2 particles to a volume of the container is 3 mg/cm.sup.3 to 9 mg/cm.sup.3.

9. A use of the Ga-based van der Waals ferromagnetic crystal material in a two-dimensional quantum device according to claim 1.

10. The use according to claim 9, wherein the two-dimensional quantum device is an anomalous Hall device or an electrically regulated magnetic device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is an X-ray diffraction spectrum of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.3GaTe.sub.2 single crystal of Example 1.

[0033] FIG. 2 is an X-ray diffraction spectrum of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal in Example 4.

[0034] FIG. 3 is an energy spectrum element distribution diagram of Ga-based two-dimensional van der Waals room-temperature ferromagnetic crystal Fe.sub.3GaTe.sub.2 nanosheets in Example 1.

[0035] FIG. 4 is an energy spectrum element distribution diagram of Ga-based two-dimensional van der Waals room-temperature ferromagnetic crystal Fe.sub.5GeGa.sub.0.1Te.sub.2 nanosheets in Example 4.

[0036] FIG. 5 shows a spontaneous magnetization curve, and hysteresis loops under out-of-plane magnetic field at different temperatures of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.3GaTe.sub.2 single crystal of Example 1.

[0037] FIG. 6 shows a spontaneous magnetization curve, and hysteresis loops under out-of-plane magnetic field at different temperatures of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal of Example 4.

[0038] FIG. 7 shows an anomalous Hall device and above-room-temperature anomalous Hall effect based on a Ga-based two-dimensional van der Waals room-temperature ferromagnetic crystal Fe.sub.3GaTe.sub.2 nanosheets in Example 1.

[0039] FIG. 8 shows an anomalous Hall device and above-room-temperature anomalous Hall effect based on Ga-based two-dimensional van der Waals room-temperature ferromagnetic crystal Fe.sub.5GeGa.sub.0.1Te.sub.2 nanosheets in Example 4.

[0040] FIG. 9 shows a hysteresis loop under in-plane magnetic field at 300K of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.3GaTe.sub.2 single crystal in Example 1.

[0041] FIG. 10 shows an electrically regulated magnetism curve graph of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.3GaTe.sub.2 single crystal in Example 4.

DESCRIPTION OF THE EMBODIMENTS

[0042] In order to make the purpose, technical solution and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present disclosure, not to limit the present disclosure. In addition, the technical features involved in the various embodiments of the present disclosure described below can be combined with each other as long as they do not constitute a conflict with each other.

[0043] With regard to a type of Ga-based van der Waals room-temperature ferromagnetic crystal material and preparation of the same in the present disclosure, the preparation method of the material is as follows.

[0044] With respect to Fe.sub.3-aGa.sub.bTe.sub.2 (a=?0.3?0.1, b=0.8?1.2):

[0045] 1) Step 1: Fe powder (99.99%), Ga block (99.999%), and Te powder (99.999%) with a particular molar ratio are put into the bottom of a quartz ampoule. A particular molar ratio refers to that the sum of the amount Fe powder substance and Ga block substance is equal to the amount of Te powder substance; the amount of the Fe powder substance accounts for 40% to 60% of the sum of the amount of Fe powder substance and Ga block substance.

[0046] 2) Step 2: The ampoule is vacuumized and sealed.

[0047] 3) Step 3: The ampoule is placed in a muffle furnace. The temperature is raised to a range from 950? C. to 1050? C. within 1 hour to 5 hours and kept warm for 1 day to 2 days, then rapidly cooled down to 880? C. and slowly cooled down to 780? C. at a rate of 0.5? C./h to 1.5? C./h. Then the program ends, and the ampoule is naturally cooled to room temperature with the furnace.

[0048] With respect to Fe.sub.5-cGeGa.sub.dTe.sub.2 (c=?0.2?0.2, d=0.01?0.5):

[0049] 1) Step 1: Fe powder (99.99%), Ge powder (99.999%), Ga block (99.999%), Te powder (99.999%) with a particular molar ratio and I.sub.2 particles (99.99%) with a particular mass are put into the bottom of the quartz ampoule. A particular molar ratio refers to that the ratio of the amount of the Fe powder substance, the sum of the amount of the Ge powder substance and the Ga block substance, and the amount of the Te powder substance is 4:1:2, and the amount of the Ge powder substance accounts for 40% to 60% of the sum of the amount of Ge powder substance and Ga block substance.

[0050] 2) Step 2: The ampoule is vacuumized and sealed.

[0051] 3) Step 3: The ampoule bottle is placed in a dual-temperature zone tube furnace, the raw material end is a high-temperature raw material zone, and the other end is a low-temperature crystallization zone. The high-temperature zone and the low-temperature zone are respectively heated to 950? C. to 1050? C. and 600? C. to 700? C. within 1 hour to 5 hours and kept warm for 1 week to 2 weeks and cooled down to room temperature naturally.

[0052] In some embodiments, the size of the Ga blocks is 1 mm to 10 mm, and the volume is 0.1 cm.sup.3 to 0.5 cm.sup.3; the diameter of the I.sub.2 particles is 1 mm to 3 mm, and the ratio of the mass of the I.sub.2 particles to the volume of the container is 3 mg/cm.sup.3 to 9 mg/cm.sup.3, the powder size of the Fe, Ge, Te is 100 mesh to 300 mesh.

[0053] In some embodiments, the vacuum sealing process of the quartz tube is as follows: a mechanical pump is pumped to a vacuum below 1 Pa, then washed with argon gas with a purity of 99.999% for thee times to remove the oxygen from the quartz tube, and finally sealed with oxyhydrogen flame.

[0054] In some embodiments, the quartz ampoule for growing Fe.sub.3-aGa.sub.bTe.sub.2 (a=?0.3?0.1, b=0.8?1.2) has a diameter of 2 cm and a length of 10 cm. The quartz ampoule for growing Fe.sub.5-cGeGa.sub.dTe.sub.2 (c=?0.2?0.2, d=0.01?0.5) has a diameter of 2 cm to 5 cm and a length of 40 cm.

[0055] In some embodiments, the crystal material sizes of the Fe.sub.3-aGa.sub.bTe.sub.2 (a=?0.3?0.1, b=0.8?1.2) and Fe.sub.5-cGeGa.sub.dTe.sub.2 (c=?0.2?0.2, d=0.01?0.5) are 2?3 ?1?2?0.1?0.5 mm and 6?4?0.1?0.5 mm.

[0056] With regard to a type of Ga-based van der Waals room-temperature ferromagnetic crystal material and preparation method for the same in the present disclosure, the Fe.sub.3-aGa.sub.bTe.sub.2 (a=?0.3?0.1, b=0.8?1.2) and Fe.sub.5-cGeGa.sub.dTe.sub.2 (c=?0.2?0.2, d=0.01?0.5) crystal materials are all high-quality room-temperature ferromagnetic compounds, which have a van der Waals structure and are easily exfoliated mechanically. The crystal materials are silvery white, and may be exfoliated into flat and thin sheet-like two-dimensional nanocrystals, which may be used to prepare various multifunctional two-dimensional quantum devices; the materials are all single crystals.

[0057] A type of Ga-based van der Waals room-temperature ferromagnetic crystal material and preparation method for the same in the present disclosure will now be further described in detail in conjunction with the following specific examples and accompanying drawings.

Example 1

[0058] 1) The high-purity Fe powder, Ga block and Te powder were weighted with a molar ratio of 1:1:2, and poured into the bottom of the quartz ampoule respectively and vacuumed for sealing.

[0059] 2) The sealed ampoule was placed in the muffle furnace. The temperature was raised to 1000? C. within 1 hour and kept warm for 1 day, then quickly cooled down to 880? C. at a rate of 100? C./h and slowly cooled down to 780? C. at a rate of 1? C./h. Then the program was finished, and the ampoule was naturally cooled to room temperature with the furnace to obtain Fe.sub.3GaTe.sub.2 single crystal.

Example 2

[0060] 1) The high-purity Fe powder, Ga block and Te powder were weighted with a molar ratio of 0.8:1.2:2, and poured into the bottom of the quartz ampoule respectively and vacuumed for sealing.

[0061] 2) The sealed ampoule was placed in the muffle furnace. The temperature was raised to 1000? C. within 1 hour and kept warm for 1 day, then quickly cooled down to 880? C. at a rate of 100? C./h and slowly cooled down to 780? C. at a rate of 1? C./h. Then the program was finished, and the ampoule was naturally cooled to room temperature with the furnace to obtain Fe.sub.2.9Ga.sub.1.2Te.sub.2 single crystal.

Example 3

[0062] 1) The high-purity Fe powder, Ga block and Te powder were weighted with a molar ratio of 1.2:0.8:2, and poured into the bottom of the quartz ampoule respectively and vacuumed for sealing.

[0063] 2) The sealed ampoule was placed in the muffle furnace. The temperature was raised to 1000? C. within 1 hour and kept warm for 1 day, then quickly cooled down to 880? C. at a rate of 100? C./h and slowly cooled down to 780? C. at a rate of 1? C./h. Then the program was finished, and the ampoule was naturally cooled to room temperature with the furnace to obtain Fe.sub.3.3Ga.sub.0.8Te.sub.2 single crystal.

Example 4

[0064] 1) The high-purity Fe powder, Ge powder, Ga block and Te powder were weighted with a molar ratio of 8:1:1:4, the I.sub.2 particles were weighted with a mass of 0.3 g, and poured into the bottom of the quartz ampoule respectively and vacuumed for sealing.

[0065] 2) The sealed ampoule bottle was placed in a dual-temperature zone tube furnace, the raw material end is a high-temperature raw material zone, and the other end is a low-temperature crystallization zone. The high-temperature zone and the low-temperature zone were respectively heated to 1000? C. and 650? C. within 1 hour and kept warm for 2 weeks and cooled down to room temperature naturally, and Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal was obtained in low-temperature crystallization zone.

Example 5

[0066] 1) The high-purity Fe powder, Ge powder, Ga block and Te powder were weighted with a molar ratio of 8:1.2:0.8:4, the I.sub.2 particles were weighted with a mass of 0.3 g, and poured into the bottom of the quartz ampoule respectively and vacuumed for sealing.

[0067] 2) The sealed ampoule bottle was placed in a dual-temperature zone tube furnace, the raw material end is a high-temperature raw material zone, and the other end is a low-temperature crystallization zone. The high-temperature zone and the low-temperature zone were respectively heated to 1000? C. and 650? C. within 1 hour and kept warm for 2 weeks and cooled down to room temperature naturally, and Fe.sub.5.2GeGa.sub.0.01Te.sub.2 single crystal was obtained in low-temperature crystallization zone.

Example 6

[0068] 1) The high-purity Fe powder, Ge powder, Ga block and Te powder were weighted with a molar ratio of 8:0.8:1.2:4, the I.sub.2 particles were weighted with a mass of 0.3 g, and poured into the bottom of the quartz ampoule respectively and vacuumed for sealing.

[0069] 2) The sealed ampoule bottle was placed in a dual-temperature zone tube furnace, the raw material end is a high-temperature raw material zone, and the other end is a low-temperature crystallization zone. The high-temperature zone and the low-temperature zone were respectively heated to 1000? C. and 650? C. within 1 hour and kept warm for 2 weeks and cooled down to room temperature naturally, and Fe.sub.4.8GeGa.sub.0.5Te.sub.2 single crystal was obtained in low-temperature crystallization zone.

[0070] FIG. 1 is an X-ray diffraction spectrum of Fe.sub.3GaTe.sub.2 single crystal. After comparing FIG. 1 with the theoretical X-ray diffraction spectrum, it can be seen that the equidistant diffraction peaks in the X-ray diffraction spectrum of Fe.sub.3GaTe.sub.2 single crystal correspond to the (001) crystal plane, and no impurity peaks are observed, which indicates that the synthesized Fe.sub.3GaTe.sub.2 single crystal has high crystal quality and strict growth orientation. FIG. 2 is an X-ray diffraction spectrum of Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal. After comparing FIG. 2 with the theoretical X-ray diffraction spectrum, it can be seen that the equidistant diffraction peaks in the X-ray diffraction spectrum of Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal correspond to the (001) crystal plane, and no impurity peaks are observed, which indicates that the synthesized Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal has high crystal quality and strict growth orientation. FIG. 3 is an energy spectrum element distribution diagram of Fe.sub.3GaTe.sub.2 nanosheets, and energy spectrum analysis shows that Fe, Ga, and Te elements are evenly distributed in Fe.sub.3GaTe.sub.2. FIG. 4 is an energy spectrum element distribution diagram of Fe.sub.5GeGa.sub.0.1Te.sub.2 nanosheets, and energy spectrum analysis shows that the Fe, Ge, Ga, and Te elements are evenly distributed in Fe.sub.5GeGa.sub.0.1Te.sub.2. FIG. 5 shows a spontaneous magnetization curve, and hysteresis loops under out-of-plane magnetic field at different temperatures of Fe.sub.3GaTe.sub.2 single crystal, which shows intrinsic above-room-temperature ferromagnetism and large saturation magnetic moment of Fe.sub.3GaTe.sub.2 single crystal. FIG. 6 shows a spontaneous magnetization curve, and hysteresis loops under out-of-plane magnetic field at different temperatures of Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal, which shows intrinsic above-room-temperature ferromagnetism and large saturation magnetic moment of Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal. FIG. 7 shows an anomalous Hall device and above-room-temperature anomalous Hall effect of Fe.sub.3GaTe.sub.2 nanosheets, which shows the easy-exfoliating characteristics of Fe.sub.3GaTe.sub.2 single crystal, intrinsic above-room-temperature ferromagnetism and the application potential of two-dimensional quantum devices. FIG. 8 shows an anomalous Hall device and above-room-temperature anomalous Hall effect of Fe.sub.5GeGa.sub.0.1Te.sub.2 nanosheets, which shows the easy-exfoliating characteristics of Fe.sub.5GeGa.sub.0.1Te.sub.2 single crystal, intrinsic above-room-temperature ferromagnetism and the application potential of two-dimensional quantum devices. FIG. 9 shows a hysteresis loop under in-plane magnetic field at 300 K of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.3GaTe.sub.2 single crystal in Example 1. Based on FIG. 9, it can be calculated that the perpendicular magnetic anisotropy energy of Fe.sub.3GaTe.sub.2 at 300 K is as high as 4.79?10.sup.5 J/m.sup.3. FIG. 10 shows an electrically regulated magnetism curve graph of a Ga-based two-dimensional van der Waals room-temperature ferromagnetic Fe.sub.3GaTe.sub.2 single crystal in Example 1. FIG. 10 shows that the current flowing through the device has an obvious adjustment effect on the Hall resistance of the sample, exhibiting an application prospect thereof in the field of two-dimensional quantum devices.

[0071] It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present disclosure should all be included within the protection scope of the present disclosure.