CN113667934A - Two-dimensional magnetic composite material with controllable magnetism and preparation method thereof - Google Patents
Two-dimensional magnetic composite material with controllable magnetism and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/24—Vacuum evaporation
- C23C14/28—Vacuum evaporation by wave energy or particle radiation
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
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- C23C14/083—Oxides of refractory metals or yttrium
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- H—ELECTRICITY
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- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/0036—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity
- H01F1/009—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity bidimensional, e.g. nanoscale period nanomagnet arrays
Abstract
The invention relates to the field of magnetic materials, and discloses a two-dimensional magnetic composite material with controllable magnetism and a preparation method thereof, aiming at overcoming the defects of low controllability and poor repeatability of the magnetic regulation of the conventional magnetic material. The bottom lining layer is connected with the magnetic layer through coupling acting force, the change of the internal state of the bottom lining layer can be influenced when the temperature changes, the bottom lining layer is acted by internal force, and further stress can be applied to the magnetic layer, and the stress acts on the magnetic layer, so that the change of the magnetic property can be shown. The reversibility of the action process of the force can be achieved only by controlling the temperature, so that the regulation and control of the magnetic strength of the magnetic layer from the temperature regulation and control perspective can be realized.
Description
Technical Field
The invention relates to the field of magnetic materials, in particular to a two-dimensional magnetic composite material with controllable magnetism and a preparation method thereof.
Background
The two-dimensional material is an ultrathin material with two-dimensional macroscopic dimensions and one-dimensional nanometer dimensions. Two-dimensional materials are novel materials which are born at the beginning of the twenty-first century and rise rapidly, and have wide application prospects in the fields of photoelectric converters, catalysis, sensing, medicine and the like because the two-dimensional materials show a series of special structures and properties such as unique optical, mechanical, electromagnetic and air-sensitive characteristics compared with blocks.
One class of systems with magnetic properties (i.e., two-dimensional magnetic materials) in the two-dimensional material family is receiving extensive attention from both academic and industrial industries. Such as a two-dimensional iron germanium tellurium material (Fe)3GeTe2) The material not only has the common characteristic of two-dimensional materials, but also has higher ferromagnetic phase transition Curie temperature (about 220K), and is expected to be applied to the next generation of spintronics devices. From 2018 development to the present, magnetic regulation of iron-germanium-tellurium materials is always a hot spot of current research, and scientists are led to explore a new round of two-dimensional magnetic field from an experimental angle. The regulation and control method currently comprises component regulation and control, doping regulation and control, strain regulation and control, electric field regulation and control, illumination regulation and control and the like, but the methods still have a plurality of defects, such as poor repeatability, magnetic second phase interference, unobvious Curie temperature increase and the like, so that a novel method for regulating and controlling the magnetic characteristics is needed to be developed.
Since Morin discovered the phase transition characteristics of vanadium dioxide in 1959, research on vanadium dioxide has never been interrupted. When the temperature is reduced to be below a phase change point, the process can be carried out reversibly, and the vanadium dioxide film is a phase change material with excellent performance.
Theoretical research shows that the strain can significantly improve the magnetic performance of the two-dimensional magnetic material, but repeated modulation is difficult to achieve by applying the strain manually, so a new stress transfer mode needs to be developed. The characteristics of the two-dimensional layered ferromagnetic material formed by van der waals force bonding ensure that the iron, germanium and tellurium and other materials can still be coupled by van der waals force to generate strong close-proximity interaction, and the effectiveness and controllability of the process are still urgently sought.
Chinese patent publication No. CN111681691A discloses a phase change auxiliary disk medium, a disk, a device, and a method, which is characterized in that a phase change auxiliary disk medium, comprising: a substrate; the phase change material layer is formed on the substrate and undergoes phase change under a preset condition; the magnetic material layer is formed on the phase change material layer, wherein the magnetic material layer is in an unmagnetized state when the phase change material layer is in a phase change state, and has a first magnetization direction and a second magnetization direction under the magnetic field condition of the first direction and the second direction respectively when the phase change material layer is not in the phase change state; and a clad layer formed on the magnetic material layer. The magnetic material has the disadvantages that an external magnetic field is required to obtain a first magnetization direction and a second magnetization direction, and the strength of the magnetism depends on the strength of the external magnetic field; the magnetization state changes in an on-off state when strained, and the controllability is low.
Disclosure of Invention
The invention discloses a magnetically controllable two-dimensional magnetic composite material with high controllability and strong repeatability and a preparation method thereof, aiming at overcoming the defects of low controllability and poor repeatability of magnetic regulation of the conventional magnetic material.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
the two-dimensional magnetic composite material with controllable magnetism is formed by coupling a bottom lining layer and a magnetic layer, and the magnetism of the two-dimensional magnetic composite material with controllable magnetism is changed by adjusting the temperature.
The bottom lining layer is connected with the magnetic layer through coupling acting force, the change of the internal state of the bottom lining layer can be influenced when the temperature changes, the bottom lining layer is acted by internal force, and further stress can be applied to the magnetic layer, and the stress acts on the magnetic layer, so that the change of the magnetic property can be shown. The reversibility of the action process of the force can be achieved only by controlling the temperature, so that the regulation and control of the magnetic strength of the magnetic layer from the temperature regulation and control perspective can be realized.
Further, the bottom lining layer is a monoclinic crystal vanadium dioxide film which is weak ferromagnetic at room temperature.
Vanadium dioxide of the monoclinic crystal has no ferromagnetism or weak ferromagnetism above room temperature, can generate structural phase change at the temperature of higher than 68 ℃ to become rutile tetragonal crystal, and can be converted into the monoclinic crystal at the temperature of lower than 68 ℃ to change lattice constant.
Furthermore, the thickness of the bottom lining layer is 20-30 nm.
Further, the magnetic layer is an iron-germanium-tellurium nanosheet.
The iron-germanium-tellurium nanosheets are ferromagnetic at low temperature, but gradually weaken in magnetism with temperature rise, and completely disappear at 220K. The inventor finds that, in an experimental process, under a room temperature state, a neighbor effect exists when the iron germanium tellurium nanosheets are coupled with the weak ferromagnetic vanadium dioxide thin film, namely, the vanadium element and the iron element in the iron germanium tellurium generate spin-orbit coupling, the weak ferromagnetic vanadium dioxide can induce the non-ferromagnetic iron germanium tellurium to show ferromagnetic characteristics, and along with temperature rise, the crystal form of the vanadium dioxide is changed, the ferromagnetic characteristics of the iron germanium tellurium are further influenced due to stress transmission on a contact surface, and the magnetic characteristics of the iron germanium tellurium are gradually enhanced. The possibility of maintaining and enhancing the magnetic characteristics of the iron-germanium-tellurium at normal temperature even at higher temperature is realized. The Van der Waals force belongs to weak intermolecular interaction, so that the force transfer effect on the iron germanium tellurium nanosheets can be ensured when the vanadium dioxide film undergoes phase change, the integral structure of the iron germanium tellurium nanosheets cannot be damaged by too much force applied on the iron germanium tellurium nanosheets, and the practical value of the iron germanium tellurium is widened.
Furthermore, the average thickness of the magnetic layer is 10-50 nm, and the transverse dimension is 1-20 μm.
A method for manufacturing a two-dimensional magnetic composite material with controllable magnetism comprises the following steps:
(1) depositing and preparing a bottom lining film on a substrate;
(2) stripping the magnetic material crystal to obtain a magnetic layer nanosheet;
(3) transferring the magnetic layer nanosheets to the prepared bottom lining film to form a two-dimensional magnetic composite material combining the magnetic layer nanosheets and the bottom lining film;
(4) and (4) regulating and controlling the temperature of the two-dimensional magnetic composite material obtained in the step (3) so as to regulate and control the magnetic characteristics of the two-dimensional magnetic composite material.
Further, in the step (1), the substrate is sapphire, and the thickness of the sapphire substrate is 1-2 mm.
Further, in the step (1), the deposition method is a Pulsed Laser Deposition (PLD) method, the film-forming temperature of the PLD is 500-700 ℃, the oxygen pressure is 5-15 mTorr, the pulse wavelength is 248nm, the pulse width is 10-30 ns, the pulse repetition frequency is 1-20 Hz, and the energy density is 2-4J/cm2The distance between the pulse laser target and the substrate is 40-50 mm.
When the laser frequency is too high, the particles deposited on the film do not move away, and the particles of the next batch fall off, so that accumulation is caused to form an uneven film; when the frequency is too low, the interval time becomes long, and impurities enter the film, thereby degrading the quality of the bottom lining film. The laser energy is too low to obtain a film or the deposition speed is slow, the deposition rate, the average particle size and the spatial distribution of plasma plume of the film are changed along with the increase of the energy, but when the energy is too high, large particles appear, and the surface smoothness of the film is also reduced. When the distance between the target and the substrate is too large, ions in the plume can be compounded into large particles; when the distance is too small, the ion energy of the plume is large, the speed is high, the quality of the film is influenced, and even the substrate is damaged.
Due to the adoption of the technical scheme, the invention has the following beneficial effects: on the premise that the coupling acting force exists between the bottom lining layer and the magnetic layer, the two-dimensional magnetic composite material enables the bottom lining layer to generate structural change by changing the temperature, so that stress is applied to the magnetic layer, the magnetism of the magnetic layer is changed, and the controllability adjustment of the magnetism of the two-dimensional magnetic composite material is realized; in the process of magnetic adjustment, the change of the influencing factors is reversible, so that the magnetic adjustment of the two-dimensional magnetic composite material has repeatability; in addition, in the process of adjusting the magnetism of the two-dimensional magnetic composite material, the inventor finds that the ferromagnetism of the iron, germanium and tellurium is obviously improved after the two-dimensional magnetic composite material is subjected to phase change; the Curie temperature of the iron, germanium and tellurium is increased, the applicable temperature range of the iron, germanium and tellurium is improved, and the application prospect of the two-dimensional magnetic composite material is effectively expanded.
Drawings
FIG. 1 is a schematic diagram of an iron germanium tellurium nanosheet coupled to a vanadium dioxide thin film and stressed by a temperature control method.
FIG. 2 is an optical micrograph of a vanadium dioxide thin film coupled with an iron germanium tellurium nanosheet of the present invention.
FIG. 3 is a graph of magnetization versus temperature at 4-300K for the iron-germanium-tellurium single crystal of comparative example 1.
FIG. 4 is a graph of magnetization intensity-temperature of 4-300K of a target sample prepared by compounding iron-germanium-tellurium nanosheets on a silicon wafer with an oxide layer in comparative example 2.
FIG. 5 is a graph of magnetization versus temperature at 4-300K for the vanadium dioxide film of comparative example 3.
Fig. 6 is a graph of magnetization versus temperature under an applied magnetic field 1000Oe for a two-dimensional magnetic composite material prepared by example 1, comparative example 4 and comparative example 5, in which iron-germanium-tellurium nanosheets are coupled to a vanadium dioxide thin film.
Fig. 7 is a graph of magnetization versus magnetic field strength at 300K and 340K for the two-dimensional magnetic composite of example 1.
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings.
A two-dimensional magnetic composite material with controllable magnetism is disclosed, as shown in figure 1 (a), and is formed by coupling a bottom lining layer vanadium dioxide film and a magnetic layer iron germanium tellurium nanosheet, wherein the magnetism of the two-dimensional magnetic composite material with controllable magnetism is changed by adjusting the temperature, as shown in figure 1 (b), the iron germanium tellurium nanosheet is coupled on the surface of the vanadium dioxide film, the crystal form of the vanadium dioxide film is changed along with the rise of the temperature, so that phase change occurs, and the iron germanium tellurium nanosheet is stretched by the neighbor effect due to the neighbor effect, so that the magnetism of the composite iron germanium tellurium nanosheet is adjusted.
Example 1
(1) Adding 10ml methanol into 10g analytically pure vanadium dioxide powder to obtain suspension, standing at 80 deg.C for 30min, taking out, and grinding into powderAnd finally, putting the mixture into a pressurizing machine for pressurizing to obtain the vanadium dioxide target material. And (3) putting the prepared target material into a high-temperature furnace, and annealing for 4 hours in an argon atmosphere at 1000 ℃ to prepare the target material for the test. Fixing the target material for test in a PLD instrument, adopting sapphire with the thickness of 1mm as a substrate, adopting an excimer pulse laser as the laser, controlling the film forming temperature at 600 ℃, the oxygen pressure at 10mTorr, the control wavelength at 248nm, the pulse width at 20ns, the pulse repetition frequency at 2Hz, and the energy density at 3J/cm2The distance from the target to the substrate was controlled at 40 mm. Depositing to obtain the vanadium dioxide film with the thickness of 20 nm.
(2) And mechanically stripping the iron germanium tellurium monocrystal by using a mechanical stripping special adhesive tape, wherein the average thickness of the obtained iron germanium tellurium nanosheet is 40nm, and the transverse size of the obtained iron germanium tellurium nanosheet is 10 mu m.
(3) And transferring the stripped iron-germanium-tellurium nanosheets to a vanadium dioxide thin film, and coupling the nanosheets together under the action of van der Waals force to obtain the two-dimensional magnetic composite material. As shown in fig. 2, the optical micrographs of the iron-germanium-tellurium nanosheets before and after being transferred to the vanadium dioxide film are shown.
(4) And (3) placing the transferred two-dimensional magnetic composite material into a superconducting quantum interference device SQUID instrument, measuring the magnetic change of the iron-germanium-tellurium nanosheets before and after the phase change of the vanadium dioxide film at the temperature range of 300-360K with the external magnetic field of 1000 Oe.
Comparative example 1
And mechanically stripping the iron germanium tellurium monocrystal by using a special mechanical stripping adhesive tape to obtain an iron germanium tellurium nanosheet with the thickness average value of 40nm and the transverse size of 10 mu m, putting the stripped iron germanium tellurium nanosheet into an SQUID instrument, and measuring the change of the magnetism of the iron germanium tellurium nanosheet within the temperature range of 4K-300K. As shown in fig. 3, the fe-ge-te completely loses its magnetic properties when the temperature reaches 300K.
Comparative example 2
Selecting a commercial silicon wafer with the surface oxidation layer thickness of 300nm, mechanically stripping the iron germanium tellurium monocrystal by using a mechanical stripping special adhesive tape to obtain iron germanium tellurium nanosheets with the average thickness of 40nm and the transverse size of 10 mu m, transferring the stripped iron germanium tellurium nanosheets onto the surface oxidized silicon wafer to couple the iron germanium tellurium nanosheets and the surface oxidized silicon wafer together, putting the transferred experimental sample into a SQUID instrument, and measuring the change of the magnetism of the iron germanium tellurium nanosheets on the surface oxidized silicon wafer within the temperature range of 4K-300K.
As can be seen from fig. 4, the variation trend of the magnetization-temperature curve of the silicon wafer with oxidized surface is similar to that of the fe-ge-te single crystal in fig. 3, and the number of the nano sheets transferred to the silicon wafer is small, so the magnetization is reduced and the curie transition temperature is slightly reduced.
Comparative example 3
Adding 10ml of methanol into 10g of analytically pure vanadium dioxide powder to prepare a suspension, standing at the constant temperature of 80 ℃ for 30min, taking out, grinding into powder, and then putting into a press to pressurize to obtain the vanadium dioxide target material. And (3) putting the prepared target material into a high-temperature furnace, and annealing for 4 hours in an argon atmosphere at 1000 ℃ to prepare the target material for the test. Fixing the target material for test in a PLD instrument, adopting sapphire with the thickness of 1mm as a substrate, adopting an excimer pulse laser as the laser, controlling the film forming temperature at 600 ℃, the oxygen pressure at 10mTorr, the control wavelength at 248nm, the pulse width at 20ns, the pulse repetition frequency at 2Hz, and the energy density at 3J/cm2The distance from the target to the substrate was controlled at 40 mm. Depositing to obtain the vanadium dioxide film with the thickness of 20 nm.
And (3) putting the prepared vanadium dioxide film into a SQUID instrument, and measuring the magnetic change of the vanadium dioxide film before and after phase change within the temperature range of 4-300K when the external magnetic field is 1000 Oe. As shown in fig. 5, the magnetization of vanadium dioxide gradually decreases as the temperature increases to 300K, but does not reach the curie transition point, and thus is weakly ferromagnetic at room temperature.
Comparative example 4
(1) And (3) uniformly mixing 10g of vanadium dioxide powder (analytically pure), adding the mixture into 10ml of methanol solution to prepare suspension, standing at the constant temperature of 80 ℃ for 30min, taking out, grinding into powder, and then putting the powder into a press to pressurize to obtain the vanadium dioxide target. And (3) putting the prepared target material into a high-temperature furnace, and annealing for 4 hours in an argon atmosphere at 1000 ℃ to prepare the target material for the test. Fixing the target material for test in a PLD instrument, and collectingSapphire with the thickness of 1mm is used as a substrate, an excimer pulse laser is adopted as the laser, the film forming temperature is 600 ℃, the oxygen pressure is 15mTorr, the control wavelength is 248nm, the pulse width is 20ns, the pulse repetition frequency is 2Hz, and the energy density is 3J/cm2The distance from the target to the substrate was controlled at 40 mm. Depositing to obtain the vanadium dioxide film with the thickness of 20 nm.
(2) And mechanically stripping the iron germanium tellurium monocrystal by using a mechanical stripping special adhesive tape, wherein the average thickness of the obtained iron germanium tellurium nanosheets is 30nm, and the transverse size of the obtained iron germanium tellurium nanosheets is 20 micrometers.
(3) And transferring the stripped iron-germanium-tellurium nanosheets to a vanadium dioxide thin film, and coupling the nanosheets together under the action of van der Waals force to obtain the two-dimensional magnetic composite material.
(4) And (3) placing the transferred two-dimensional magnetic composite material into a SQUID instrument, measuring the magnetic change of the iron germanium tellurium nanosheets before and after the phase change of the vanadium dioxide film at the temperature range of 300-360K with the external magnetic field of 1000 Oe.
Comparative example 5
(1) And (3) uniformly mixing 10g of vanadium dioxide powder (analytically pure), adding the mixture into 10ml of methanol solution to prepare suspension, standing at the constant temperature of 80 ℃ for 30min, taking out, grinding into powder, and then putting the powder into a press to pressurize to obtain the vanadium dioxide target. And (3) putting the prepared target material into a high-temperature furnace, and annealing for 4 hours in an argon atmosphere at 1000 ℃ to prepare the target material for the test. Fixing the target material for test in a PLD instrument, adopting sapphire with the thickness of 1mm as a substrate, adopting an excimer pulse laser as the laser, controlling the film forming temperature at 500 ℃, the oxygen pressure at 10mTorr, the control wavelength at 248nm, the pulse width at 20ns, the pulse repetition frequency at 2Hz, and the energy density at 3J/cm2The distance from the target to the substrate was controlled at 40 mm. Depositing to obtain the vanadium dioxide film with the thickness of 20 nm.
(2) And mechanically stripping the iron germanium tellurium monocrystal by using a mechanical stripping special adhesive tape to obtain an iron germanium tellurium nanosheet with the average thickness of 30nm and the transverse size of 10 mu m.
(3) And transferring the stripped iron-germanium-tellurium nanosheets to a vanadium dioxide thin film, and coupling the nanosheets together under the action of van der Waals force to obtain the two-dimensional magnetic composite material.
(4) And (3) placing the transferred two-dimensional magnetic composite material into a SQUID instrument, measuring the external magnetic field to be 1000Oe, and measuring the magnetic change of the iron-germanium-tellurium nanosheets before and after the phase change of the vanadium dioxide film in the temperature range of 300K-360K.
From comparative examples 1 and 3, it can be seen that the independent fe-ge-te nanosheets and the independent vanadium dioxide thin films have no magnetic characteristics or exhibit weak ferromagnetism at room temperature; as can be seen from comparative example 2, when the iron germanium tellurium nanosheets are composited onto a silicon oxide surface which cannot undergo spin-orbit coupling with iron germanium tellurium, the magnetic properties of iron germanium tellurium are not affected. After the iron germanium tellurium nanosheets are coupled with the vanadium dioxide thin film, as shown in fig. 6, the magnetization intensity of the two-dimensional magnetic composite material changes along with the temperature within the temperature range of 300-360K, so that the curie temperature of the iron germanium tellurium is effectively improved, the iron germanium tellurium shows strong magnetic characteristics at room temperature and high temperature, and the application prospect of the iron germanium tellurium material is widened. As shown in fig. 6 (a), in example 1, the variation of the magnetization intensity of the two-dimensional magnetic composite material is shown when the applied magnetic field is 1000Oe and the temperature is in the range of 300-360K, it can be seen that at 300K, the ferromagnetism-free iron germanium tellurium nanosheet and the weak ferromagnetism vanadium dioxide thin film are compounded to show a certain magnetization intensity, and the magnetization intensity of the two-dimensional magnetic composite material shows an increasing trend in the temperature range of 300-340K and continues to be stable at 340-360K, and according to the trend of the magnetization intensity of example 1 changing with the temperature, the control of the magnetism of the two-dimensional magnetic composite material through adjusting the temperature can be realized. As shown in fig. 6 (b), in comparative example 4, the magnetization of the two-dimensional magnetic composite material changes in the applied magnetic field of 1000Oe and at a temperature of 300 to 360K, and it can be seen that the two-dimensional magnetic composite material of comparative example 4 has a certain magnetization at a temperature of 300K, but the magnetization is significantly lower than that of the two-dimensional magnetic composite material of example 1, and the magnetization tends to decrease after the temperature rises to 300K or more. This is because in the preparation process of the two-dimensional magnetic composite material of comparative example 4, the oxygen pressure in the preparation process of the vanadium dioxide thin film is relatively large, and the oxygen vacancies in the formed vanadium dioxide thin film are relatively few, which may result in a decrease in the coupling ability of the vanadium dioxide thin film and the iron germanium tellurium nanosheet, a decrease in the spin coupling effect of the vanadium dioxide and the iron germanium tellurium, and a corresponding weaker initial magnetic characteristic at 300K than that of example 1. The stress effect applied to the surface iron germanium tellurium nanosheet during subsequent vanadium dioxide phase transition is correspondingly reduced, and finally the neighbor effect is weakened, so that the magnetic property cannot be enhanced through phase transition stretching as in embodiment 1. As shown in fig. 6 (c), in the case of comparative example 5, the magnetization intensity of the two-dimensional magnetic composite material changes in the range of the applied magnetic field of 1000Oe and the temperature of 300 to 360K, it can be seen that the two-dimensional magnetic composite material of comparative example 5 has a certain magnetization intensity at the temperature of 300K, but the magnetization intensity is significantly weaker than that of example 1, and the magnetization intensity shows a similar decrease tendency as that of comparative example 4 after the temperature reaches 300K or more. In the preparation process of the two-dimensional magnetic composite material of comparative example 5, the film forming temperature is relatively low, the formed vanadium dioxide thin film has poor quality and uneven thickness, which can cause the coupling capacity of the vanadium dioxide thin film to the surface iron germanium tellurium nanosheets to be reduced, so the initial magnetization intensity of the vanadium dioxide thin film at 300K is weaker than that of example 1, the effect of applying stress to the surface iron germanium tellurium nanosheets is reduced during the phase transition of vanadium dioxide, the neighbor effect is also weakened, the magnetic property is poorer than that of example 1, and the magnetic property cannot be enhanced through phase transition stretching as in example 1. Meanwhile, comparing the example 1 with the comparative examples 4 and 5, it can be found that the oxygen pressure and the film forming temperature in the process of manufacturing the vanadium dioxide thin film have direct influence on the quality of the vanadium dioxide thin film, and the quality of the vanadium dioxide thin film determines the magnetic characteristics of the two-dimensional magnetic composite material. Among them, the film forming temperature of example 1 is preferably 600 ℃ and the oxygen pressure is preferably 10 mTorr. As shown in fig. 7, the magnetization versus magnetic field strength plots for the two-dimensional magnetic composite of example 1 at 300K and 340K. It can be seen that compared with the temperature variation curve of magnetization intensity at 300K, at 340K, i.e. the phase transition temperature at which the vanadium dioxide changes from a monoclinic phase structure to a high-temperature tetragonal phase structure, the loop of the temperature variation curve of magnetization intensity of the two-dimensional magnetic composite material is obviously increased, and the magnetic hysteresis is obviously enhanced, i.e. after the vanadium dioxide changes from monoclinic crystal to tetragonal crystal, the magnetization intensity of the iron germanium tellurium nanosheet is obviously increased under the stretching effect of the neighbor effect, and the magnetism is obviously enhanced.
Claims (8)
1. The two-dimensional magnetic composite material with controllable magnetism is characterized by being formed by coupling a bottom lining layer and a magnetic layer, and changing magnetism of the two-dimensional magnetic composite material with controllable magnetism by adjusting temperature.
2. A magnetically controllable two-dimensional magnetic composite as claimed in claim 1 wherein said underlayer is a monoclinic vanadium dioxide film that is weakly ferromagnetic at room temperature.
3. A magnetically controllable two-dimensional magnetic composite as claimed in claim 1 or claim 2 wherein the substrate is 20 to 30nm thick.
4. The magnetically controllable two-dimensional magnetic composite material as claimed in claim 1, wherein the magnetic layer is an iron germanium tellurium nanosheet.
5. A magnetically controllable two-dimensional magnetic composite as claimed in claim 1 or claim 4, wherein the mean thickness of the magnetic layer is from 10 to 50nm and the transverse dimension is from 1 to 20 μm.
6. A method for making a magnetically controllable two-dimensional magnetic composite material as claimed in any of claims 1 to 5, comprising the steps of:
(1) depositing and preparing a bottom lining film on a substrate;
(2) stripping the magnetic material crystal to obtain a magnetic layer nanosheet;
(3) transferring the magnetic layer nanosheets to the prepared bottom lining film to form a two-dimensional magnetic composite material combining the magnetic layer nanosheets and the bottom lining film;
(4) and (4) regulating and controlling the temperature of the two-dimensional magnetic composite material obtained in the step (3) so as to regulate and control the magnetic characteristics of the two-dimensional magnetic composite material.
7. The method of claim 6, wherein in step (1), the substrate is sapphire, and the thickness of the sapphire substrate is 1-2 mm.
8. The method for preparing a two-dimensional magnetic composite material according to claim 6, wherein in the step (1), the deposition method is a Pulsed Laser Deposition (PLD) method, the PLD film-forming temperature is 500-700 ℃, the oxygen pressure is 5-15 mTorr, the pulse wavelength is 248nm, the pulse width is 10-30 ns, the pulse repetition frequency is 1-20 Hz, and the energy density is 2-4J/cm2The distance between the pulse laser target and the substrate is 40-50 mm.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20150207060A1 (en) * | 2013-12-13 | 2015-07-23 | The Regents Of The University Of California | Magnetic and electrical control of engineered materials |
| CN107574454A (en) * | 2017-09-19 | 2018-01-12 | 河北工业大学 | It is a kind of to mix tungsten Vanadium dioxide nanometer rod/molybdenum disulfide composite and preparation method thereof for electrochemistry liberation of hydrogen |
| CN109768157A (en) * | 2018-07-02 | 2019-05-17 | 中国科学院金属研究所 | A method of two-dimensional magnetic semiconductor material magnetic property is regulated and controled by gate voltage |
| CN112591718A (en) * | 2021-01-12 | 2021-04-02 | 南开大学 | Two-dimensional material Fe3GeTe2Preparation method of nanosheet |
| CN113089100A (en) * | 2021-03-22 | 2021-07-09 | 华中科技大学 | Two-dimensional ferromagnetic Cr sensitive to strain2Te3Nanosheet and preparation method thereof |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20150207060A1 (en) * | 2013-12-13 | 2015-07-23 | The Regents Of The University Of California | Magnetic and electrical control of engineered materials |
| CN107574454A (en) * | 2017-09-19 | 2018-01-12 | 河北工业大学 | It is a kind of to mix tungsten Vanadium dioxide nanometer rod/molybdenum disulfide composite and preparation method thereof for electrochemistry liberation of hydrogen |
| CN109768157A (en) * | 2018-07-02 | 2019-05-17 | 中国科学院金属研究所 | A method of two-dimensional magnetic semiconductor material magnetic property is regulated and controled by gate voltage |
| CN112591718A (en) * | 2021-01-12 | 2021-04-02 | 南开大学 | Two-dimensional material Fe3GeTe2Preparation method of nanosheet |
| CN113089100A (en) * | 2021-03-22 | 2021-07-09 | 华中科技大学 | Two-dimensional ferromagnetic Cr sensitive to strain2Te3Nanosheet and preparation method thereof |
Non-Patent Citations (1)
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| YUWANG: ""Strain-Sensitive Magnetization Reversal of a van der Waals Magnet"" * |
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