Preparation method of two-dimensional ferromagnetic material and Hall device

Abstract

The application relates to a two-dimensional ferromagnetic material and a preparation method of a Hall device, and belongs to the technical field of electronic materials. 0.29 TaS2, electrode preparation through ultraviolet lithography and magnetron sputtering, and Hall device preparation through mechanical peeling and transferring. Single-crystal Fe 0.29 The preparation method of the single-crystal Fe TaS2 is not only high in efficiency, but also has less iodine and impurities remaining on the single-crystal surface. The prepared Hall device exhibits good ferromagnetism and air stability. Under the action of an applied magnetic field, a huge topological Hall effect can be observed in the Hall device. Notably, even after relaxation effect measurement, the topological Hall effect still stably exists, showing excellent stability and reliability. The "robust" chiral spin texture brought by the huge topological Hall effect has application value in the fields of magnetic storage and magnetic information transmission.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic materials, and relates to a two-dimensional ferromagnetic material and a preparation method of a Hall device. 0.29 TaS2, and a stable and reliable Hall device prepared by using the material. BACKGROUND

[0002] With the continuous miniaturization of electronic devices approaching the physical limit, unpredictable quantum effects pose a serious challenge to device stability. Further reduction in device size not only leads to a sharp increase in cost and manufacturing difficulty, but also gives rise to an urgent need for research on new electronic devices in the post-moore era.

[0003] Spintronic devices, which use electron spin as the carrier of information, open up new dimensions for information processing, and with their non-volatile, extremely high operating speed and relatively low power consumption, they have become a highly potential direction for the development of the next generation of information devices.

[0004] The outstanding performance of two-dimensional materials in electronic spin provides new opportunities for the exploration and progress of spintronic devices. These materials, due to the absence of dangling bonds on the surface, are easy to build van der Waals heterostructures, and can enhance device performance by improving charge-spin conversion efficiency and optimizing heterojunction interface quality. In addition, the rich interaction and coupling relationship of two-dimensional materials makes it possible to discover new physical phenomena and innovate property control mechanisms, thereby showing high application potential in the fields of spintronic devices and magnetic storage.

[0005] Although most known two-dimensional materials are non-magnetic by themselves, they can be made magnetic by doping with magnetic impurities or magnetic near-neighbor effect. In recent years, some two-dimensional materials with ferromagnetic, antiferromagnetic or other magnetic order have also been discovered, and the magnetism of these materials can be adjusted by adjusting the thickness, composition or applying external excitation (such as electric field and magnetic field).

[0006] In order to explore two-dimensional ferromagnetism, layered two-dimensional materials stand out because they can be reduced to one or two layers without compromising the ferromagnetic properties of the sample. In addition, the relatively large magnetic anisotropy makes it an ideal choice for studying two-dimensional magnetism. However, practical applications of spintronic devices still face many challenges, for example, the currently discovered two-dimensional ferromagnetic materials (such as CrI3, Cr2Ge2Te6, Fe3GeTe2) have poor air stability, which limits their practical application prospects.

[0007] Therefore, exploring layered two-dimensional ferromagnetic materials with strong anisotropy and high air stability is crucial for the study of two-dimensional intrinsic ferromagnetism and the realization of higher density and more stable data storage technology, and has a profound impact on the development of the next generation of spintronic devices. SUMMARY

[0008] The application aims to provide a two-dimensional ferromagnetic material and a preparation method of a Hall device. 0.29 TaS2, electrodes are prepared by ultraviolet lithography and magnetron sputtering, and the Hall device is prepared by mechanical peeling and transferring. The prepared Hall device exhibits excellent air stability, good magnetic properties and a large topological Hall effect.

[0009] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0010] Firstly, the application provides a preparation method of a two-dimensional ferromagnetic material, and the prepared two-dimensional ferromagnetic material is Fe 0.29 TaS2. The preparation method specifically comprises the following steps:

[0011] 1.1): Fe, Ta and S are mixed uniformly according to the molar ratio, placed at the bottom of a quartz tube, and I2 is added as a transport agent. The quartz tube is vacuumized and sealed;

[0012] 1.2): single crystal Fe 0.29 TaS2 is grown in a double-temperature-zone tube furnace, and the growth is completed after cooling;

[0013] 1.3): the quartz tube is broken, the sample is taken out, washed, dried, and a sheet-shaped single crystal sample is obtained, which is Fe 0.29 TaS2.

[0014] As a preferred technical scheme of the application, in the preparation method of the two-dimensional ferromagnetic material:

[0015] In step 1.1), the molar ratio of Fe, Ta and S is 0.45:1:2, and the transport agent I2 accounts for 15% of the total mass of the raw materials. The reaction zone and the growth zone of the quartz tube are necked in the middle to avoid contamination of the growth zone during the sealing process. An ice bag is used to cool the bottom of the quartz tube during the sealing process to prevent the transport agent from volatilizing.

[0016] In step 1.2), the reaction zone is at the high-temperature end and is set to 980℃, and the growth zone is at the low-temperature end and is set to 920℃. The temperature rising rate of the reaction zone and the growth zone is less than 1℃ / min. After the temperature is raised to the set temperature, it is maintained at a constant temperature for 144h, and then naturally cooled after the growth is completed.

[0017] In step 1.3), the sample is cleaned with alcohol ultrasonically for 2-3 times to remove the residual I2 and impurities on the surface, and finally dried on a hot plate at 60℃ for 10-20min.

[0018] Secondly, the application also provides a Hall device prepared by the two-dimensional ferromagnetic material. 0.29The method for preparing a Hall device from TaS2 specifically comprises the following steps:

[0019] 2.1): UV lithography is performed on a clean Si / SiO2 substrate to form a Hall bar pattern, and a W / Pt electrode is grown by magnetron sputtering;

[0020] 2.2): Mechanical exfoliation is performed, the sample is transferred to the center of the Hall electrode, and a Hall device is prepared.

[0021] As a preferred technical solution of the present application, in the method for preparing a Hall device:

[0022] The Hall bar pattern formed by UV lithography in step 2.1) has six electrodes, and the center is not connected, so that the magnetoresistance and anomalous Hall effect tests can be performed, and the thickness of the W / Pt electrode formed by magnetron sputtering is 10 nm.

[0023] In step 2.2), the sample is repeatedly folded 5-6 times on the adhesive tape and then stuck to the PDMS, and the heat release condition of the PDMS is 85 DEG C for 7 min.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The present application uses iron (Fe), tantalum (Ta) and sulfur (S) as raw materials, mixes them according to a certain molar ratio, and adds iodine (I2) as a transport agent to prepare a two-dimensional single crystal material. This preparation method not only has high efficiency, but also has less iodine and impurities remaining on the surface of the single crystal. In addition, the selected materials are easy to obtain, the process steps are simple, the repeatability is high, and the requirements for equipment are low.

[0026] 2. The single crystal material Fe 0.29 TaS2 constructed Hall device, showing good ferromagnetic and air stability. Under the action of an external magnetic field, a large topological Hall effect can be observed in the Hall device. It is worth noting that even after the relaxation effect measurement, the topological Hall effect still exists stably, showing excellent stability and reliability. The "robust" chiral spin texture brought by the large topological Hall effect has application value in the fields of magnetic storage and magnetic information transmission. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Fe 0.29 TaS2 growth and Hall device preparation flow chart.

[0028] Figure 2 Fe 0.29 TaS2 Hall device measurement configuration diagram.

[0029] Figure 3 Fe 0.29 Optical image of TaS2 Hall device.

[0030] Figure 4 Fe 0.29 EDS spectrum of TaS2.

[0031] Figure 5 Fe 0.29 XRD spectrum of TaS2.

[0032] Figure 6 Magnetoresistance as a function of magnetic field when the magnetic field is perpendicular to the surface of the Hall device.

[0033] Figure 7 Hall resistance as a function of magnetic field when the magnetic field is perpendicular to the surface of the Hall device.

[0034] Figure 8 Hall resistance as a function of magnetic field at 10 K (squares) and relaxation effect test fitting plot (circles). DETAILED DESCRIPTION

[0035] The present application is further described in connection with the following examples and drawings.

[0036] As Figure 1 shown, the embodiment of the present application provides a preparation method of a two-dimensional ferromagnetic material and a Hall device, comprising the following steps:

[0037] 1) : 125.65 mg (2.25 mmol) of elemental Fe, 904.75 mg (5 mmol) of elemental Ta, and 320.6 mg (10 mmol) of elemental S were weighed and uniformly mixed, the mixture was placed at the bottom of a quartz tube using a paper chute, and 202.65 mg (15% of the total mass of the raw materials) of elemental I2 was added as a transport agent. The quartz tube was vacuumed and sealed by a hydrogen-oxygen flame. In order to prevent the transport agent from volatilizing, an ice bag was used to cool the bottom of the quartz tube during the whole sealing process.

[0038] 2) : The quartz tube was horizontally placed in a double-zone tube furnace (the side with the sample was placed at the high-temperature end), the high-temperature end (reaction zone) was raised to 980°C, and the low-temperature end (growth zone) was raised to 920°C. The temperature was raised at a rate of less than 1°C / min for about 16 h, and the growth was maintained for 144 h before natural cooling.

[0039] 3) : The quartz tube was broken, and the sheet-shaped sample grown at the low-temperature end was taken out, ultrasonically cleaned with alcohol twice to remove the residual I2 and impurities on the surface, and finally dried on a hot plate at 60°C.

[0040] 4) : The pattern of the Hall bar was photoetched on the cleaned Si / SiO2 substrate (as Figure 2As shown in the figure), the Hall bar has six electrodes, the center of which is not connected. The W / Pt electrodes with a thickness of 10 nm are grown by magnetron sputtering.

[0041] 5) After drying, the sheet sample is placed on the blue tape, and the blue tape is repeatedly folded for 5 times. The sample on the blue tape is transferred to the PDMS, and a smooth film on the PDMS is found and transferred to the center of the electrode on a two-dimensional transfer platform (as shown in the figure). Figure 3 As shown in the figure), the thermal release condition of the PDMS is 85 DEG C, and 7 min.

[0042] 6) The six-terminal Hall device after the transfer is characterized, including an energy dispersive X-ray spectrometer (EDS), an X-ray diffraction spectrum (XRD), and a test of magnetoresistance, Hall resistance, and relaxation effect in a comprehensive physical property measurement system (PPMS).

[0043] Preparation of Fe 0.29 Performance characterization of TaS2 single crystal and Hall device:

[0044] Figure 4 Fe 0.29 The energy dispersive X-ray spectrometer (EDS) scanning sheet sample of TaS2 shows that the sheet material synthesized by the application contains Fe, Ta and S three elements, and the ratio of the three elements is about 0.29:1:2, which is consistent with the chemical formula Fe 0.29 TaS2.

[0045] Figure 5 Fe 0.29 The X-ray diffraction spectrum (XRD) of TaS2 shows that the diffraction peaks in the spectrum are (00l) crystal phase, and there is no other impurity phase, which shows that the Fe 0.29 TaS2 bulk material is a single crystal phase.

[0046] Figure 6 When the magnetic field is perpendicular to the surface of the Hall device, the magnetoresistance changes with the magnetic field at different temperatures, and a peak appears at about 40K.

[0047] Figure 7 When the magnetic field is perpendicular to the surface of the Hall device, the Hall resistance changes with the magnetic field, and as the temperature decreases, the Hall value appears to rise first and then decrease, and the system gradually becomes a magnetic ordered state, and the longitudinal resistance decreases with the temperature.

[0048] Figure 8The final Hall resistance extracted from the variation of Hall resistance with magnetic field (square) and the relaxation effect (set the initial magnetic field to 2T / -2T, then reverse the direction of the magnetic field, observe the change of Hall resistance with time under different holding magnetic fields until the Hall resistance tends to be stable) test at 10K, the relationship between the final Hall resistance and the holding field (circle). At 10K, the Hall device can observe the giant topological Hall effect under the applied magnetic field (hatched part). The topological Hall effect still exists by fitting the final Hall resistance of the relaxation effect test.

[0049] In summary: the present application is prepared by chemical vapor transport monocrystalline Fe 0.29 TaS2, the preparation process is simple, the preparation efficiency is high, and the surface impurities are few. The W / Pt electrode and Fe 0.29 The Hall device prepared by the monocrystalline TaS2 sample exhibits excellent air stability, good magnetic properties and giant topological Hall effect, and the topological Hall effect still exists through the relaxation effect test for the first time. The "robust" chiral spin texture brought by the giant topological Hall effect has application value in the fields of magnetic storage and magnetic information transmission.

[0050] The above is only an example and description of the concept of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as the modifications or supplements do not deviate from the concept of the present application or exceed the scope defined by the present application, and should belong to the protection scope of the present application.

Claims

1. A method of preparing a two-dimensional ferromagnetic material, characterized by, The prepared two-dimensional ferromagnetic material is Fe 0.29 TaS2, the preparation method specifically comprises the following steps: 1.1): Fe, Ta, S were mixed uniformly in a molar ratio of 0.45:1:2, and were placed in the bottom of a quartz tube, and a transport agent I2 was added, the quartz tube was vacuumed and sealed; 1.2): Growth of single crystal Fe in a double-temperature-zone tube furnace 0.29 TaS2, the reaction zone was at the high-temperature end, and the setting temperature was 980 ℃; the growth zone was at the low-temperature end, and the setting temperature was 920 ℃; the reaction zone and the growth zone were both heated to the setting temperature at a heating rate of less than 1 ℃ / min and then maintained at constant temperature for 144 h, and after the growth was completed, the sample was naturally cooled; 1.3): Break open the quartz tube, remove the sample, clean, dry, and obtain a sheet of single crystal sample, which is Fe 0.29 TaS2.

2. The method of claim 1, wherein the two-dimensional ferromagnetic material is prepared by a method comprising: The transport agent I2 in step 1.1) accounts for 15% of the total mass of raw materials.

3. The method for preparing the two-dimensional ferromagnetic material as described in claim 1, characterized in that, In step 1.1), the reaction zone and the growth zone of the quartz tube are necked in the middle to avoid contamination of the growth zone during the sealing process, and an ice bag is used to cool the bottom of the quartz tube during the sealing process to prevent the transport agent from volatilizing.

4. The method for preparing the two-dimensional ferromagnetic material as described in claim 1, characterized in that, In step 1.3), the sample is cleaned with alcohol ultrasonically for 2-3 times to remove the residual I2 and impurities on the surface, and finally dried on a hot plate at 60°C for 10-20 min.

5. A method for the preparation of a Hall device using a two-dimensional ferromagnetic material prepared by the method according to any one of claims 1 to 4, characterized in that, Specifically comprising the following steps: 2.1): The pattern of Hall bar is etched by ultraviolet light on the cleaned Si / SiO2 substrate, and W / Pt electrodes are grown by magnetron sputtering; 2.2): The sample is transferred to the center of the Hall electrode by mechanical exfoliation to prepare a Hall device; during mechanical exfoliation, the sample is repeatedly folded 5-6 times on the tape and then stuck to the PDMS, and the heat release condition of the PDMS is 85°C for 7 min.

6. The method of producing a Hall device according to claim 5, wherein The Hall bar pattern etched by ultraviolet light in step 2.1) has six electrodes, and the center is not connected, which can be used for magnetoresistance and anomalous Hall effect test, and the thickness of the W / Pt electrode grown by magnetron sputtering is 10 nm.

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