Single-phase multiferroic material, single-phase multiferroic thin film, and preparation method and application thereof

Abstract

The present invention provides a single-phase multiferroic material, a single-phase multiferroic thin film, and their preparation methods and applications. The chemical formula of the single-phase multiferroic material is Dy 0.5 Ba 0.5 TiO3. A single-phase multiferroic thin film, the components of the thin film include Dy 0.5 Ba 0.5 TiO3, and the preparation method is as follows: preparing a Dy 0.5 Ba 0.5 TiO3 target by a solid-phase reaction method; using the Dy 0.5 Ba 0.5 TiO3 target as the target, using argon as the sputtering gas, and using a radio frequency power supply to perform magnetron sputtering on a single crystal substrate to obtain a single-phase multiferroic thin film. In the single-phase multiferroic material Dy 0.5 Ba 0.5 TiO3 of the present invention, the ferroelectric polarization and magnetism in the material are homologous and are both induced by magnetism, enhancing the magnetoelectric coupling effect in the material.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of new information materials, and particularly to a single-phase multiferroic material, a single-phase multiferroic thin film, and a preparation method and application thereof. Background Art

[0002] Multiferroic materials refer to materials that simultaneously possess two or more basic ferroic order parameters and can exhibit coupling effects between these ferroic order parameters. Due to the characteristics of multiferroic materials such as polarization controllable by electric field, magnetization controllable by magnetic field, and magnetoelectric cross-coupling effect, they have broad application prospects in the fields of magnetoelectric sensors, new information storage devices, spintronic devices, etc.

[0003] Single-phase multiferroic materials with a perovskite structure are a type of material that has received much attention in the multiferroic material family. Traditionally, the two ferroic order parameters of ferroelectricity and ferromagnetism are mutually exclusive. The conventional method for preparing single-phase multiferroic materials with a perovskite structure is to dope magnetic elements at the B site of perovskite ferroelectrics (ABO3). For example, Ba(Ti,Fe)O3, Ba(Ti,Mn)O3, Ba(Ti,Co)O3, etc. In such materials, ferroelectricity comes from the B ions (oxygen octahedron occupancy ions) themselves, such as Ti ions; ferromagnetism comes from the doped magnetic ions, such as Fe, Mn, Co ions. However, due to the different origins of ferroelectricity and ferromagnetism, the magnetoelectric coupling effect in the materials is often not significant, so the mutual regulation between ferroic order parameters is not sensitive. Summary of the Invention

[0004] Based on this, it is necessary to provide a single-phase multiferroic material, a single-phase multiferroic thin film, and a preparation method and application thereof. In this single-phase multiferroic material, ferroelectric polarization and magnetism are homologous and are both induced by magnetism, enhancing the magnetoelectric coupling effect in the material.

[0005] In the first aspect of the present invention, a single-phase multiferroic material is provided. The chemical formula of the single-phase multiferroic material is Dy 0.5 Ba 0.5 TiO3.

[0006] In the second aspect of the present invention, a single-phase multiferroic thin film is provided. The components of the single-phase multiferroic thin film include the aforementioned single-phase multiferroic material Dy 0.5 Ba 0.5 TiO3.

[0007] In some embodiments, the ferromagnetic Curie temperature of the single-phase multiferroic thin film is 100K.

[0008] In some embodiments, the crystal structure of the single-phase multiferroic thin film is a tetragonal perovskite structure, with the in-plane lattice constant the out-of-plane lattice constant

[0009] The third aspect of the present invention provides a method for preparing the aforementioned single-phase multiferroic thin film, comprising the following steps:

[0010] Prepare a Dy 0.5 Ba 0.5 TiO3 target by solid-state reaction method;

[0011] Using the Dy 0.5 Ba 0.5 TiO3 target as the target, using argon as the sputtering gas, and using a radio frequency power supply, perform magnetron sputtering on a single crystal substrate to obtain a single-phase multiferroic thin film.

[0012] In some embodiments, the single crystal substrate is any one selected from SrTiO3, LSAT, and LaAlO3.

[0013] In some embodiments, during magnetron sputtering, the temperature of the single crystal substrate is 650 °C to 900 °C.

[0014] In some embodiments, during magnetron sputtering, the argon gas pressure is 20 Pa to 80 Pa.

[0015] In some embodiments, during magnetron sputtering, the power of the radio frequency power supply is 30 W to 70 W.

[0016] The fourth aspect of the present invention provides the application of the aforementioned single-phase multiferroic material and the aforementioned single-phase multiferroic thin film in the preparation of electromagnetic devices.

[0017] The fifth aspect of the present invention provides an electromagnetic device, which includes the aforementioned single-phase multiferroic material and the aforementioned single-phase multiferroic thin film.

[0018] In some embodiments, the electromagnetic device is an electromagnetic sensor device or an electromagnetic storage device. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the crystal structure of the DBTO thin film in the present invention;

[0020] Figure 2 It is a high-resolution X-ray diffraction 2θ-ω scan diagram of the single-phase multiferroic thin films prepared in Examples 1-8 and Comparative Example 1 in the present invention (1#, Example 1; 2#, Example 2; 3#, Example 3; 4#, Example 4; 5#, Example 5; 6#, Example 6; 7#, Example 7; 8#, Example 8; 1##, Comparative Example 1);

[0021] Figure 3 It is an X-ray diffraction reciprocal space scan diagram of the single-phase multiferroic thin film prepared in Example 1 in the present invention;

[0022] Figure 4 These are the X-ray photoelectron spectroscopy diagrams of the DBTO thin film before and after etching in the present invention;

[0023] Figure 5 Among them, (a) is the temperature-dependent hysteresis regression line diagram of the DBTO thin film prepared in Example 1 of the present invention; (b) is the temperature-dependent hysteresis regression line diagram of the thin film prepared in Comparative Example 1 of the present invention;

[0024] Figure 6 This is the enlarged diagram of the hysteresis regression line of the DBTO thin film prepared in Example 1 of the present invention at 100K;

[0025] Figure 7 Using the second harmonic generation method, four configurations of the single-phase multiferroic thin film prepared in Example 1 of the present invention were tested at room temperature. Detailed implementation manners

[0026] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] In the present invention, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0029] In the present invention, regarding the numerical range, unless otherwise specified, the above numerical range is considered continuous and includes the minimum value and the maximum value of this range, as well as each value between such minimum value and maximum value. Further, when the range refers to an integer, it includes each integer between the minimum value and the maximum value of this range. In addition, when providing multiple ranges to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0030] In this article, regarding the unit of the data range, if there is only a unit after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 20~80Pa means that the units of the left endpoint "20" and the right endpoint "80" are both Pa (Pascal).

[0031] "B ions" in the present invention refer to "oxygen octahedron site ions".

[0032] In the present invention Figure 3 Q in x represents a vector in the X direction (in-plane) in reciprocal space; Q z represents a vector in the Z direction (out-of-plane) in reciprocal space.

[0033] In the present invention Figure 7 "S" represents vertically polarized light; "P" represents horizontally polarized light; "in" represents the input signal; "out" represents the output signal; "fitting" represents fitting.

[0034] In addition, the terms "first", "second", "third", "fourth", "fifth" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", "third", "fourth", "fifth" may explicitly or implicitly include at least one of such features. In the description of the invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined. In the description of the present invention, "several" means at least one, such as one, two, etc., unless otherwise specifically defined.

[0035] In a first aspect of the present invention, a single-phase multiferroic material is provided, and the chemical formula of the single-phase multiferroic material is Dy 0.5 Ba 0.5 TiO3.

[0036] The preparation of the single-phase multiferroic material in the present invention is based on BaTiO3, and the Ba ions at the A site in the barium titanate lattice are replaced by rare earth ions Dy through A-site doping. Using rare earth Dy ions with the most stable valence state of three, the Ti ions at the B site are induced from non-magnetic tetravalent to magnetic trivalent to maintain the conservation of positive and negative charges in the crystal, so that the Ti ions with spontaneous polarization in the material simultaneously generate 3d 1 electrons with spin polarization, obtaining magnetism, and thus obtaining a Dy 0.5 Ba 0.5 TiO3 single-phase multiferroic material with ferroelectric polarization and magnetism homologous.

[0037] In a second aspect of the present invention, a single-phase multiferroic thin film is provided, and the components of the thin film include the above-mentioned Dy 0.5 Ba 0.5 TiO3 single-phase multiferroic material. Hereinafter, the "single-phase multiferroic thin film" in the present invention is abbreviated as "DBTO thin film".

[0038] The third aspect of the present invention provides a method for preparing the above-mentioned DBTO thin film, which includes the following steps:

[0039] Prepare Dy 0.5 Ba 0.5 TiO3 target by solid-state reaction method;

[0040] Using Dy 0.5 Ba 0.5 TiO3 target as the target, argon as the sputtering gas, and a radio frequency power supply, perform magnetron sputtering on a single crystal substrate to obtain a DBTO thin film.

[0041] In some embodiments, the preparation of the Dy 0.5 Ba 0.5 TiO3 target includes the following steps S11 to S14:

[0042] S11. Weigh the initial raw materials Dy2O3, BaCO3 and TiO2 according to the stoichiometric ratio of 1:2:4, mix the ingredients to obtain a uniformly mixed powder.

[0043] S12. Calcinate the above-mentioned powder, and the calcination temperature for the calcination treatment is 1000°C to 1200°C, and the heat preservation time is 18h to 22h.

[0044] It can be understood that the calcination temperature can be 1000°C, 1050°C, 1100°C, 1150°C or 1200°C. Further, the calcination temperature can be 1050°C to 1150°C.

[0045] The heat preservation time can be 18h, 19h, 20h, 21h or 22h. Further, the heat preservation time can be 19h to 21h.

[0046] In some of these embodiments, heat up to the calcination temperature at a heating rate of 2°C / min to 4°C / min. Further, after reaching the heat preservation time, cool down to room temperature at a cooling rate of 4°C / min to 6°C / min.

[0047] In some of these embodiments, it further includes a step of pulverizing the powder after the calcination treatment.

[0048] S13. Press the powder after the calcination treatment into a green body.

[0049] In some of these embodiments, the pressure for pressing into a green body is 30MPa to 50Mpa.

[0050] It can be understood that the pressure for pressing into a green body can be 30MPa, 35MPa, 40MPa, 45MPa or 50MPa. Further, the pressure for pressing into a green body can be 35MPa to 45Mpa.

[0051] In a specific example, the powder is placed in a mold and pressed with a hydraulic press.

[0052] S14. Calcinate the above green body, where the calcination temperature for the calcination treatment is 1200°C to 1300°C, and the holding time is 7h to 9h, to obtain the Dy 0.5 Ba 0.5 TiO3 target.

[0053] It is understandable that the calcination temperature can be 1200°C, 1210°C, 1220°C, 1230°C, 1240°C, 1250°C, 1260°C, 1270°C, 1280°C, 1290°C or 1300°C. Further, the calcination temperature can be 1220°C to 1280°C.

[0054] The holding time can be 7h, 7.5h, 8h, 8.5h or 9h. Further, the holding time can be 7.5h to 8.5h.

[0055] In some of these embodiments, the temperature is raised to the calcination temperature at a heating rate of 2°C / min to 4°C / min. Further, after reaching the holding time, the temperature is lowered to room temperature at a cooling rate of 4°C / min to 6°C / min.

[0056] In some of these embodiments, it further includes the step of double-sided polishing the target obtained after the calcination treatment.

[0057] In some embodiments, the DBTO thin film is deposited and prepared by a magnetron sputtering method, including steps S21 to S25:

[0058] S21. Clean the single crystal substrate and send it into the sputtering chamber.

[0059] In a specific example, the single crystal substrate is placed in an acetone and ethanol solution and ultrasonically cleaned for 5 min to 15 min, dried, and then sent into the sputtering chamber.

[0060] It is understandable that the cleaning time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min or 15 min. Further, the cleaning time can be 10 min to 15 min.

[0061] S22. Evacuate the sputtering chamber and heat-treat the above single crystal substrate, where the temperature of the single crystal substrate is 650°C to 900°C.

[0062] It is understandable that the temperature of the single crystal substrate can be 650°C, 700°C, 750°C, 800°C, 850°C or 900°C. Further, the temperature of the single crystal substrate can be 700°C to 800°C.

[0063] In some of these embodiments, the background vacuum degree of the sputtering chamber is 10 -3 Pa.

[0064] S23. Gas washing: Introduce argon gas, control the argon gas flow rate to be 2 sccm to 3 sccm, and the argon gas pressure to be 20 Pa to 80 Pa.

[0065] It can be understood that the argon gas flow rate can be 2 sccm, 2.1 sccm, 2.2 sccm, 2.3 sccm, 2.4 sccm, 2.5 sccm, 2.6 sccm, 2.7 sccm, 2.8 sccm, 2.9 sccm or 3 sccm. Further, the argon gas flow rate can be 2.3 sccm to 2.5 sccm.

[0066] The argon gas pressure can be 20 Pa, 25 Pa, 30 Pa, 35 Pa, 40 Pa, 45 Pa, 50 Pa, 55 Pa, 60 Pa, 65 Pa, 70 Pa, 75 Pa or 80 Pa. Further, the argon gas pressure can be 30 Pa to 70 Pa.

[0067] S24. Set the pre-sputtering power supply power to 30 W. After pre-sputtering for 10 min to 30 min, set the power of the radio frequency power supply to 30 W to 70 W, and formally sputter and grow the DBTO film.

[0068] It can be understood that the power of the radio frequency power supply can be 30 W, 35 W, 40 W, 45 W, 50 W, 55 W, 60 W, 65 W or 70 W. Further, the power of the radio frequency power supply can be 40 W to 60 W.

[0069] The pre-sputtering time can be 10 min, 15 min, 20 min, 25 min or 30 min. Further, the pre-sputtering time can be 20 min to 30 min.

[0070] S25. Turn off the radio frequency power supply, keep the original argon gas pressure unchanged, cool down, and obtain the DBTO film.

[0071] In some of these embodiments, after formally sputtering and growing the DBTO film for 4 h, turn off the radio frequency power supply.

[0072] In some of these embodiments, cool down at a rate of 50 °C / min. After cooling down to 200 °C, cool down naturally.

[0073] In step S22, the single-crystal substrate is heated to a temperature in the range of 650 °C to 900 °C, preferably 700 °C to 800 °C. In this temperature range, not only can the residual organic reagents on the single-crystal substrate be effectively removed, and the impurity gases desorbed on the single-crystal substrate be removed, providing a highly clean substrate for the growth of the DBTO thin film; moreover, this temperature range provides sufficient kinetic energy for the sputtering clusters adsorbed on the substrate surface to form a high-quality continuous film.

[0074] In step S24, pre-sputtering is carried out to completely remove the contaminated part on the surface of the target and desorb the impurity gases on the target.

[0075] In some embodiments, the single-crystal substrate can be but is not limited to SrTiO3 (STO), (La,Sr)(Al,Ta)O3 (LSAT), or LaAlO3 (LAO). Preferably, the single-crystal substrate is SrTiO3.

[0076] In some embodiments, the single-crystal substrate can be cleaned by ultrasonic cleaning to remove the particulate matter on the surface of the substrate. The cleaning result of the substrate will affect the uniformity, density, and performance of the thin film, and then affect the performance and reliability of the electronic device prepared through the thin film. The cleaned single-crystal substrate should be immediately placed in the sputtering chamber and cannot be stored in the air for a long time.

[0077] In some embodiments, the argon gas pressure is controlled to be maintained in the range of 20 Pa to 80 Pa, preferably 30 Pa to 70 Pa. In this argon gas pressure range, the kinetic energy of the sputtering atomic clusters is moderate, which is beneficial to improving the crystallization quality of the DBTO thin film.

[0078] In some embodiments, the radio frequency power supply power is set in the range of 30 W to 70 W, preferably 40 W to 60 W. In this power supply power range, the sputtering rate of the target is moderate, which is beneficial to the epitaxial growth of the DBTO thin film.

[0079] In the fourth aspect of the present invention, there is provided an application of a single-phase multiferroic material and a DBTO thin film in the preparation of electromagnetic devices.

[0080] In the fifth aspect of the present invention, there is provided an electromagnetic device, which includes the aforementioned single-phase multiferroic material and the aforementioned single-phase multiferroic thin film.

[0081] In some embodiments, the electromagnetic device is an electromagnetic sensor device or an electromagnetic storage device.

[0082] Hereinafter, the implementation schemes of the present application will be described in detail with reference to specific embodiments.

[0083] Example 1

[0084] Target preparation: Dy is prepared by the solid-phase reaction method 0.5 Ba 0.5TiO3 target.

[0085] Substrate cleaning: The SrTiO3 substrates were ultrasonically cleaned in analytical pure acetone and ethanol solutions for 10 min, then dried with a nitrogen gas gun, and the dried single-crystal substrates were mounted on a heating stage and sent into the sputtering chamber.

[0086] Magnetron sputtering: The mechanical pump and molecular pump were started in sequence, and the background vacuum of the sputtering chamber was pumped down to 10 -3 Pa. The heating was turned on and the temperature was set to 800 °C. After the temperature of the single-crystal substrate stabilized at 800 °C, it was baked continuously for 20 min. At the same time, the argon gas flow rate was set to 2.4 sccm, and the gas valve was adjusted to keep the argon gas pressure in the sputtering chamber stable at 50 Pa.

[0087] After the temperature and pressure were stable, the radio frequency power supply was turned on. The pre-sputtering power supply power was set to 30 W. With the heating stage baffle closed, after pre-sputtering for 30 min, the power of the radio frequency power supply was set to 40 W, and the heating stage baffle was opened to start sputtering officially. After sputtering for 4 h, the radio frequency power supply was turned off, and the original argon gas pressure was kept unchanged. The temperature was decreased at a rate of 50 °C / min. After decreasing to 200 °C, it was cooled naturally to prepare the DBTO film.

[0088] As Figure 1 shown, it is a schematic diagram of the crystal structure of the DBTO film, and its crystal structure is a tetragonal perovskite structure.

[0089] The obtained DBTO film was subjected to X-ray diffraction (XRD) experiment. As Figure 2 shown in 1# in the figure, it is the high-resolution X-ray diffraction 2θ-ω scan pattern of the DBTO film. Only the Dy 0.5 Ba 0.5 TiO3 (001), (002) and (003) characteristic peaks appeared in the figure, indicating that the DBTO film grew along a single (001) orientation and there were no other impurity phases.

[0090] As Figure 3 shown, a high-resolution X-ray diffraction reciprocal space scan was performed near the (103) diffraction of the obtained DBTO film. The diffraction spot of Dy 0.5 Ba 0.5 TiO3 is at the lower left corner of the figure, and the diffraction spot of the substrate SrTiO3 is at the upper right corner. According to the position of the Dy 0.5 Ba 0.5 TiO3 diffraction spot in the figure, the in-plane lattice constant of the DBTO film was calculated out-of-plane lattice constant

[0091] As Figure 4As shown, it is the X-ray photoelectron spectroscopy diagram of the DBTO thin film before and after etching in the present invention. The line located Figure 4 below is the X-ray photoelectron spectroscopy diagram of the DBTO thin film before, and the line located Figure 4 above is the X-ray photoelectron spectroscopy diagram of the DBTO thin film after etching. According to Figure 4 it can be found that except for the disappearance of the absorption peak of C, the characteristic absorption peaks of Dy, Ba, Ti, and O do not change before and after the etching of the DBTO thin film, indicating that the rare earth element dysprosium (Dy) is doped on the surface and inside of the DBTO thin film.

[0092] As Figure 5 shown in (a) of it, it is the temperature-dependent hysteresis loop diagram of the DBTO thin film. As the temperature decreases, the saturation magnetization intensity of the DBTO thin film increases from 0.2 emu / cc at 300K to 6.4 emu / cc at 100K, and increases to 187.3 emu / cc after reaching 2K, and its saturation magnetic field is close to 2T at 2K. And in the Figure 6 amplified diagram of the hysteresis loop of the DBTO thin film at 100K shown, it can be seen that the DBTO thin film still has an obvious hysteresis phenomenon at 100K, proving that the DBTO thin film still has magnetism at 100K. In other words, the ferromagnetic Curie temperature of the DBTO thin film is 100K. Compared with the ferromagnetic Curie temperature of 60K of the pure-phase DyTiO3 thin film, the ferromagnetic Curie temperature has been significantly improved.

[0093] As Figure 7 shown, using the second harmonic generation method, four configurations of the DBTO thin film were tested at room temperature. Figure 7 In (a), the polarization of the output light is fixed, Figure 7 and in (b), the polarization of the input light is fixed. The results show that the second harmonic signal caused by ferroelectric polarization is very obvious, indicating that there is a strong centrosymmetry breaking (i.e., ferroelectric polarization) in Dy 0.5 Ba 0.5 TiO3. The solid line part in the figure is the fitting of the experimental data. It can be seen that the fitting curve and the experimental data have a very high degree of coincidence. The ratio of the second-order nonlinear coefficients of Dy 0.5 Ba 0.5 TiO3 was calculated from the fitting data, which are d33 / d31 = 1.12 and d33 / d15 = 0.86 respectively. Compared with the ratio of the second-order nonlinear coefficients of the pure-phase BaTiO3 bulk material, which is d33 / d31 = 0.43 and d33 / d15 = 0.4, the out-of-plane polarization of Dy 0.5 Ba 0.5 TiO3 is greatly enhanced.

[0094] Example 2

[0095] Target preparation: Prepare Dy 0.5 Ba 0.5 TiO3 target.

[0096] Substrate cleaning: Place the SrTiO3 substrate in acetone and ethanol solutions of analytical purity respectively and ultrasonically clean for 10 min. Then blow dry with a nitrogen gas gun, and install the dried single crystal substrate on the heating stage and send it into the sputtering chamber.

[0097] Magnetron sputtering: Start the mechanical pump and molecular pump in sequence, pump the background vacuum of the sputtering chamber to 10 -3 Pa, turn on the heating, set the temperature to 650 °C, and keep baking for 20 min after the temperature of the single crystal substrate is stable at 650 °C. At the same time, set the argon gas flow rate to 2.4 sccm, adjust the gas valve, and keep the argon gas pressure in the sputtering chamber stable at 50 Pa.

[0098] After the temperature and pressure are stable, turn on the RF power supply, set the pre-sputtering power supply power to 30 W, and pre-sputter for 30 min with the heating stage baffle closed. Then set the power of the RF power supply to 40 W, open the heating stage baffle and start sputtering officially. After sputtering for 4 h, turn off the RF power supply, keep the original argon gas pressure unchanged, cool down at a rate of 50 °C / min, and cool down naturally after reaching 200 °C to prepare the DBTO thin film.

[0099] The obtained DBTO thin film was subjected to X-ray diffraction (XRD) experiment. As Figure 2 shown in Figure 2#, it is the high-resolution X-ray diffraction 2θ-ω scan pattern of the DBTO thin film. Only the Dy 0.5 Ba 0.5 TiO3 (001), (002) and (003) characteristic peaks appear in the figure, indicating that the DBTO thin film grows along a single (001) orientation and there are no other impurity phases.

[0100] Example 3

[0101] Target preparation: Prepare Dy 0.5 Ba 0.5 TiO3 target.

[0102] Substrate cleaning: Place the SrTiO3 substrate in acetone and ethanol solutions of analytical purity respectively and ultrasonically clean for 10 min. Then blow dry with a nitrogen gas gun, and install the dried single crystal substrate on the heating stage and send it into the sputtering chamber.

[0103] Magnetron sputtering: Start the mechanical pump and molecular pump in sequence, pump the background vacuum of the sputtering chamber to 10 -3Set Pa to turn on heating, set the temperature to 700 °C, and keep baking for 20 min after the temperature of the single crystal substrate stabilizes at 700 °C. Meanwhile, set the argon gas flow rate to 2.4 sccm, adjust the gas valve, and keep the argon gas pressure in the sputtering chamber stable at 50 Pa.

[0104] After the temperature and pressure are stable, turn on the RF power supply, set the pre-sputtering power supply power to 30 W. With the heating stage baffle closed, after pre-sputtering for 30 min, set the power of the RF power supply to 40 W, and open the heating stage baffle to start sputtering officially. After sputtering for 4 h, turn off the RF power supply, keep the original argon gas pressure unchanged, cool down at a rate of 50 °C / min, and let it cool naturally after reaching 200 °C to prepare the DBTO thin film.

[0105] X-ray diffraction (XRD) experiments were carried out on the obtained DBTO thin film, as Figure 2 shown in 3# in the figure, which is the high-resolution X-ray diffraction 2θ-ω scan pattern of the DBTO thin film. Only the characteristic peaks of Dy 0.5 Ba 0.5 TiO3 (001), (002) and (003) appear in the figure, indicating that the DBTO thin film grows along a single (001) orientation and there are no other impurity phases.

[0106] Example 4

[0107] Target preparation: Prepare the Dy 0.5 Ba 0.5 TiO3 target by the solid-state reaction method.

[0108] Substrate cleaning: Place the SrTiO3 substrate in analytical pure acetone and ethanol solutions respectively and ultrasonically clean for 10 min, then dry it with a nitrogen gas gun, and install the dried single crystal substrate on the heating stage and send it into the sputtering chamber.

[0109] Magnetron sputtering: Start the mechanical pump and molecular pump in sequence, pump the background vacuum of the sputtering chamber to 10 -3 Pa, turn on heating, set the temperature to 900 °C, and keep baking for 20 min after the temperature of the single crystal substrate stabilizes at 900 °C. Meanwhile, set the argon gas flow rate to 2.4 sccm, adjust the gas valve, and keep the argon gas pressure in the sputtering chamber stable at 50 Pa.

[0110] After the temperature and pressure are stable, turn on the RF power supply, set the pre-sputtering power supply power to 30 W. With the heating stage baffle closed, after pre-sputtering for 30 min, set the power of the RF power supply to 40 W, and open the heating stage baffle to start sputtering officially. After sputtering for 4 h, turn off the RF power supply, keep the original argon gas pressure unchanged, cool down at a rate of 50 °C / min, and let it cool naturally after reaching 200 °C to prepare the DBTO thin film.

[0111] X-ray diffraction (XRD) experiments were carried out on the obtained DBTO thin films. As Figure 2 shown in No. 4# in 0.5 Dy 0.5 Ba

[0112] Example 5

[0113] Target preparation: Dy 0.5 Ba 0.5 TiO3 target was prepared by solid-state reaction method.

[0114] Substrate cleaning: The SrTiO3 substrates were ultrasonically cleaned in acetone and ethanol solutions of analytical purity for 10 min respectively, and then dried with a nitrogen gas gun. The dried single-crystal substrates were installed on a heating stage and sent into the sputtering chamber.

[0115] Magnetron sputtering: The mechanical pump and the molecular pump were started in sequence to pump the background vacuum of the sputtering chamber to 10 -3 Pa, the heating was turned on, and the temperature was set to 800 °C. After the temperature of the single-crystal substrate was stabilized at 800 °C, it was baked continuously for 20 min. At the same time, the argon gas flow rate was set to 2.4 sccm, and the gas valve was adjusted to keep the argon gas pressure in the sputtering chamber stable at 30 Pa.

[0116] When the temperature and the pressure were stabilized, the radio frequency power supply was turned on. The power of the pre-sputtering power supply was set to 30 W. With the heating stage baffle closed, after pre-sputtering for 30 min, the power of the radio frequency power supply was set to 40 W, and the heating stage baffle was opened to start sputtering officially. After sputtering for 4 h, the radio frequency power supply was turned off, and the original argon gas pressure was kept unchanged. The temperature was decreased at a rate of 50 °C / min. After decreasing to 200 °C, it was cooled naturally to prepare the DBTO thin film.

[0117] X-ray diffraction (XRD) experiments were carried out on the obtained DBTO thin films. As Figure 2 shown in No. 5# in 0.5 Dy 0.5 Ba

[0118] Example 6

[0119] Target preparation: Dy 0.5 Ba 0.5TiO3 target.

[0120] Substrate cleaning: The SrTiO3 substrates were ultrasonically cleaned in analytical pure acetone and ethanol solutions for 10 min, then dried with a nitrogen gas gun, and the dried single-crystal substrates were mounted on a heating stage and sent into the sputtering chamber.

[0121] Magnetron sputtering: The mechanical pump and the molecular pump were started in sequence to pump the background vacuum of the sputtering chamber down to 10 -3 Pa, heating was turned on, the temperature was set to 800 °C, and after the temperature of the single-crystal substrate stabilized at 800 °C, it was baked continuously for 20 min. At the same time, the argon gas flow rate was set to 2.4 sccm, and the gas valve was adjusted to keep the argon gas pressure in the sputtering chamber stable at 70 Pa.

[0122] When the temperature and pressure were stable, the RF power supply was turned on, the pre-sputtering power supply power was set to 30 W, and under the condition that the heating stage baffle was closed, after pre-sputtering for 30 min, the power of the RF power supply was set to 40 W, and the heating stage baffle was opened to officially start sputtering. After sputtering for 4 h, the RF power supply was turned off, and the original argon gas pressure was kept unchanged, and the temperature was decreased at a rate of 50 °C / min until it reached 200 °C and then cooled naturally to prepare the DBTO thin film.

[0123] The obtained DBTO thin film was subjected to X-ray diffraction (XRD) experiment. As Figure 2 shown in 6# in the figure, it is the high-resolution X-ray diffraction 2θ-ω scan pattern of the DBTO thin film. Only the characteristic peaks of Dy 0.5 Ba 0.5 TiO3 (001), (002) and (003) appear in the figure, indicating that the DBTO thin film grows along a single (001) orientation and there are no other impurity phases.

[0124] Example 7

[0125] Target preparation: Dy 0.5 Ba 0.5 TiO3 target was prepared by the solid-state reaction method.

[0126] Substrate cleaning: The SrTiO3 substrates were ultrasonically cleaned in analytical pure acetone and ethanol solutions for 10 min, then dried with a nitrogen gas gun, and the dried single-crystal substrates were mounted on a heating stage and sent into the sputtering chamber.

[0127] Magnetron sputtering: The mechanical pump and the molecular pump were started in sequence to pump the background vacuum of the sputtering chamber down to 10 -3 Pa, heating was turned on, the temperature was set to 800 °C, and after the temperature of the single-crystal substrate stabilized at 800 °C, it was baked continuously for 20 min. At the same time, the argon gas flow rate was set to 2.4 sccm, and the gas valve was adjusted to keep the argon gas pressure in the sputtering chamber stable at 50 Pa.

[0128] After the temperature and air pressure were stabilized, the radio frequency power supply was turned on, and the power of the pre-sputtering power supply was set to 30 W. With the heating stage baffle closed, after pre-sputtering for 30 min, the power of the radio frequency power supply was set to 60 W, and the heating stage baffle was opened to officially start sputtering. After sputtering for 4 h, the radio frequency power supply was turned off, the air pressure of the original argon gas was kept unchanged, and the temperature was decreased at a rate of 50 °C / min. After decreasing to 200 °C, it was naturally cooled to prepare the DBTO thin film.

[0129] X-ray diffraction (XRD) experiments were carried out on the obtained DBTO thin film, as Figure 2 shown in 7# in the figure, which is the high-resolution X-ray diffraction 2θ-ω scan pattern of the DBTO thin film. Only the characteristic peaks of Dy 0.5 Ba 0.5 TiO3(001), (002) and (003) appeared in the figure, indicating that the DBTO thin film grew along a single (001) orientation and there were no other impurity phases.

[0130] Example 8

[0131] Target preparation: Dy 0.5 Ba 0.5 TiO3 target was prepared by the solid-phase reaction method.

[0132] Substrate cleaning: The SrTiO3 substrate was ultrasonically cleaned in analytical pure acetone and ethanol solutions for 10 min respectively, and then dried with a nitrogen gas gun. The dried single crystal substrate was installed on the heating stage and sent into the sputtering chamber.

[0133] Magnetron sputtering: The mechanical pump and the molecular pump were started in sequence, and the background vacuum of the sputtering chamber was pumped to 10 -3 Pa. Heating was turned on, and the temperature was set to 800 °C. After the temperature of the single crystal substrate was stabilized at 800 °C, it was baked continuously for 20 min. At the same time, the argon gas flow rate was set to 2.4 sccm, and the gas valve was adjusted to keep the argon gas pressure in the sputtering chamber stable at 50 Pa.

[0134] After the temperature and air pressure were stabilized, the radio frequency power supply was turned on, and the power of the pre-sputtering power supply was set to 30 W. With the heating stage baffle closed, after pre-sputtering for 30 min, the power of the radio frequency power supply was set to 70 W, and the heating stage baffle was opened to officially start sputtering. After sputtering for 4 h, the radio frequency power supply was turned off, the air pressure of the original argon gas was kept unchanged, and the temperature was decreased at a rate of 50 °C / min. After decreasing to 200 °C, it was naturally cooled to prepare the DBTO thin film.

[0135] X-ray diffraction (XRD) experiments were carried out on the obtained DBTO thin film, as Figure 2 shown in 8# in the figure, which is the high-resolution X-ray diffraction 2θ-ω scan pattern of the DBTO thin film. Only the characteristic peaks of Dy 0.5 Ba0.5 The characteristic peaks of TiO3(001), (002) and (003) indicate that the DBTO thin film grows along a single (001) orientation and there are no other impurity phases.

[0136] The experimental parameters in Examples 1 to 8 are summarized in Table 1 below:

[0137] Table 1

[0138]

[0139]

[0140] Comparative Example 1

[0141] This comparative example is different from Example 1 in terms of the target material. Others are the same, specifically as follows:

[0142] Target material preparation: Prepare the Dy 0.2 Ba 0.8 TiO3 target material by the solid-phase reaction method.

[0143] Substrate cleaning: Place the SrTiO3 substrate in analytical pure acetone and ethanol solutions respectively and ultrasonically clean for 10 min, then blow dry with a nitrogen gas gun. Install the dried single-crystal substrate on the heating stage and send it into the sputtering chamber.

[0144] Magnetron sputtering: Start the mechanical pump and molecular pump in sequence, pump the background vacuum of the sputtering chamber to 10 -3 Pa, turn on the heating, set the temperature to 800 °C, and continuously bake for 20 min after the temperature of the single-crystal substrate stabilizes at 800 °C. At the same time, set the argon gas flow rate to 2.4 sccm, adjust the gas valve, and keep the argon gas pressure in the sputtering chamber stable at 50 Pa.

[0145] After the temperature and pressure are stable, turn on the RF power supply, set the pre-sputtering power supply power to 30 W, pre-sputter for 30 min with the heating stage baffle closed, then set the power of the RF power supply to 40 W, and turn on the heating stage baffle to start sputtering officially. After sputtering for 4 h, turn off the RF power supply, keep the original argon gas pressure unchanged, cool down at a rate of 50 °C / min, and naturally cool down after reaching 200 °C to prepare the thin film.

[0146] The thin film obtained in Comparative Example 1 was subjected to X-ray diffraction (XRD) experiment. As Figure 2 shown in 1## in the figure, it is the high-resolution X-ray diffraction 2θ-ω scan pattern of the thin film obtained in this Comparative Example 1. It can be seen from the figure that except for the characteristic peaks of STO, there are no other characteristic peaks, indicating that the crystal quality of the thin film obtained in Comparative Example 1 is poor or polycrystalline and amorphous structures are generated.

[0147] As Figure 5As shown in (b), it is the temperature-dependent hysteresis loop diagram of the thin film in Comparative Example 1. It can be seen from the figure that when the Dy doping amount is 20%, the obtained thin film is superparamagnetic and does not have ferromagnetism, and there is no Curie temperature point within the measured range. That is, the ferromagnetic Curie temperature of this thin film is significantly lower than the ferromagnetic Curie temperature of 100 K of the DBTO thin film with a Dy doping content of 50%. As the temperature decreases, the saturation magnetization of the thin film is the highest at 139 emu / cc at 5 K.

[0148] The DBTO thin film prepared by the method of the present invention is subjected to the substrate strain effect, resulting in tetragonal distortion of the DBTO thin film. Its magnetic structure is an antiferromagnetic coupling of the tilted dysprosium magnetic moment and the titanium magnetic moment, expressing ferrimagnetism externally. Its ferroelectric polarization direction is the <001> direction. Compared with the Curie temperature (Tc = 60 K) of the pure-phase DyTiO3 thin film, its ferromagnetic Curie temperature has been significantly increased to 100 K; compared with the pure-phase BaTiO3 bulk material, its out-of-plane ferroelectric polarization has also been enhanced.

[0149] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0150] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A single-phase multiferroic thin film, characterized in that, The components of the single-phase multiferroic thin film include the single-phase multiferroic material Dy 0.5 Ba 0.5 TiO3; the crystal structure of the single-phase multiferroic thin film is a tetragonal perovskite structure, and the in-plane lattice constant The out-of-plane lattice constant 2. The single-phase multiferroic thin film according to claim 1, characterized in that, The ferromagnetic Curie temperature of the single-phase multiferroic thin film is 100 K.

3. A method for preparing the single-phase multiferroic thin film according to claim 1, characterized in that, It includes the following steps: Preparation of Dy 0.5 Ba 0.5 BaTiO3 target by solid-phase reaction method; wherein, the Dy 0.5 Ba 0.5 preparation of BaTiO3 target includes the following steps: Weigh the initial raw materials Dy2O3, BaCO3 and TiO2 according to the stoichiometric ratio of 1:2:4, and after mixing and processing, obtain a mixed powder. Carry out a calcination treatment on the mixed powder, where the temperature of the calcination treatment is 1000 °C to 1200 °C, and the heat preservation time is 18 h to 22 h. Press the powder after the calcination treatment into a green body. The embryo is calcined at a calcination temperature of 1200 °C to 1300 °C and a holding time of 7 h to 9 h to produce a Dy 0.5 Ba 0.5 TiO3 target; Using the Dy 0.5 Ba 0.5 TiO3 target as the target, argon as the sputtering gas, and a radio frequency power supply, magnetron sputtering is carried out on a single crystal substrate to obtain a single-phase multiferroic thin film; specifically, the following steps are included: Vacuum the sputtering chamber, and carry out a heating treatment on the single crystal substrate, where the temperature of the single crystal substrate is 650 °C to 900 °C. Introduce argon into the sputtering chamber, control the argon gas flow rate to be 2 sccm to 3 sccm, and the argon gas pressure to be 20 Pa to 80 Pa. Set the pre-sputtering power supply power to 30 W. After pre-sputtering for 10 min to 30 min, set the power of the radio frequency power supply to 30 W to 70 W, and formally sputter and grow a single-phase multiferroic thin film. Among them, the single crystal substrate is any one selected from SrTiO3, LSAT and LaAlO3.

4. Application of the single-phase multiferroic thin film according to any one of claims 1 to 2 or the single-phase multiferroic thin film prepared by the preparation method according to claim 3 in the preparation of electromagnetic devices.

5. An electromagnetic device, characterized in that, It includes the single-phase multiferroic thin film according to any one of claims 1 to 2 or the single-phase multiferroic thin film prepared by the preparation method according to claim 3.

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