Hafnium oxide-based single magnetoelectric coupling multiferroic material as well as preparation method and application thereof

Abstract

The invention relates to the field of multiferroic materials, in particular to a hafnium oxide-based single magnetoelectric coupling multiferroic material as well as a preparation method and application thereof. The chemical formula of the hafnium oxide-based single magnetoelectric coupling multiferroic material provided by the invention is (CoyFe < 1-y >) z (HfxZr < 1-x >) < 1-z > O2, x is equal to 0.2-0.4, y is equal to 0-0.48, and z is equal to 0.15-0.35. The hafnium oxide-based single magnetoelectric coupling multiferroic material provided by the invention is simple in preparation method, can be prepared by adopting a pulse laser co-deposition method, is applied to electronic devices, and can provide more choices for the preparation of the electronic devices.

Description

Technical Field

[0001] The present invention relates to the field of multiferroic materials, and in particular to a hafnium oxide-based single magnetoelectric coupling multiferroic material, a preparation method thereof, and applications thereof. Background Art

[0002] Multiferroic materials generally refer to materials containing two or more ferroic order parameters (such as ferroelectricity, ferromagnetism, and ferroelasticity). Efforts are underway to integrate these multiple order parameters into a single device, thereby enabling their interconnected control. Magnetoelectrically coupled multiferroic materials, for example, enable the mutual control of electrical and magnetic properties, such as the regulation of the electric polarization state through a magnetic field. These materials represent a new class of multifunctional materials with broad application prospects in spintronics, multistate storage, and electromagnetic sensors.

[0003] Magnetoelectrically coupled multiferroic materials are categorized into composite and single-phase types. Composite multiferroic materials are formed by combining ferroelectric and ferromagnetic phases, typically exhibiting a specific two-phase composite structure. Single-phase multiferroic materials are homogeneous materials with a single chemical composition or physical structure. Currently, there are relatively few single-phase multiferroic materials, and their magnetoelectric coupling effect is weak, which cannot meet the requirements of electronic devices. There is an urgent need to develop more types of single-phase multiferroic materials to provide more options for electronic device fabrication. Summary of the Invention

[0004] The present invention provides a hafnium oxide-based single magnetoelectric coupling multiferroic material and a preparation method and use thereof. The present invention provides a hafnium oxide-based single magnetoelectric coupling multiferroic material, which has good magnetoelectric coupling performance.

[0005] The present invention provides a hafnium oxide-based single magnetoelectric coupling multiferroic material, the chemical formula of which is (Co y Fe 1-y ) z (Hf x Zr 1-x ) 1-z O2, where x = 0.2-0.4, y = 0-0.48, z = 0.15-0.35.

[0006] Optionally, the X-ray diffraction spectrum of the hafnium oxide-based single magnetoelectric coupling multiferroic material has a characteristic peak at 30.2°.

[0007] Optionally, the macroscopic magnetoelectric coupling coefficient of the hafnium oxide-based single magnetoelectric coupling multiferroic material is 1×10 5 mV·cm -1 ·Oe -1 -4×10 5 mV·cm -1 ·Oe -1 .

[0008] Optionally, the thickness of the hafnium oxide-based single magnetoelectric coupling multiferroic material is 8-12 nm.

[0009] Optionally, x=0.3.

[0010] Optionally, z=0.17-0.23.

[0011] The present invention also provides a method for preparing a hafnium oxide-based single magnetoelectric coupling multiferroic material according to any one of the aforementioned technical solutions, comprising the following steps:

[0012] Using HfO2 target, ZrO2 target and CoFe2O4 target / Co3O4 target as target materials, pulsed laser co-deposition method was used to alternately deposit them on the substrate to obtain hafnium oxide-based single magnetoelectric coupled multiferroic material.

[0013] Optionally, the number of deposition pulses of the HfO2 target in a single growth cycle is 50, the number of deposition pulses of the ZrO2 target is 100, the number of deposition pulses of the CoFe2O4 target is 15-60, and the number of deposition pulses of the Co3O4 target is 15.

[0014] Optionally, the substrate comprises, from bottom to top, a strontium titanate substrate layer and a lanthanum strontium manganese oxide bottom electrode layer, and the hafnium oxide-based single magnetoelectrically coupled multiferroic material is deposited on the lanthanum strontium manganese oxide bottom electrode layer.

[0015] The present invention also provides the use of the hafnium oxide-based single magnetoelectrically coupled multiferroic material described in any one of the above technical solutions or the hafnium oxide-based single magnetoelectrically coupled multiferroic material prepared by the preparation method described in any one of the above technical solutions in electronic devices.

[0016] The present invention provides a hafnium oxide-based single magnetoelectric coupling multiferroic material, the chemical formula of which is (Co y Fe 1-y ) z (Hf x Zr 1-x ) 1-z O2, wherein x=0.2-0.4, y=0-0.48, z=0.15-0.34. 1-x Zr x Co and Fe were introduced into O2, and the resulting material has both room-temperature ferroelectricity and ferromagnetism, showing excellent magnetoelectric coupling.

[0017] In addition, the hafnium oxide-based single magnetoelectric coupling multiferroic material provided by the present invention has a simple preparation method and can be prepared by a pulsed laser co-deposition method.

[0018] The hafnium oxide-based single magnetoelectric coupling multiferroic material provided by the present invention is applied to electronic devices, which can provide more options for the preparation of electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present invention will be apparent from the following description of preferred embodiments illustrating the subject matter of the present invention and its use and the accompanying drawings, in which:

[0020] Figure 1 These are cross-sectional transmission electron microscopy (TEM) images of the hafnium oxide-based single magnetoelectrically coupled multiferroic material obtained in Example 2, wherein (a)-(c) are TEM images of the cross section along the [-110] crystal axis of the substrate at different magnifications, and (d)-(f) are TEM images of the cross section along the

[001] crystal axis of the substrate at different magnifications.

[0021] Figure 2 1 and 2 are XRD patterns of the hafnium oxide-based single magnetoelectrically coupled multiferroic materials obtained in Examples 1-4 and the thin film obtained in Comparative Example 1.

[0022] Figure 3 The in-plane and out-of-plane magnetization curves (MH curves) of the materials obtained in Examples 1-4 and Comparative Examples 1-2 are shown, where (a) is the in-plane MH curve of Examples 1-3 and Comparative Example 1, (b) is the out-of-plane MH curve of Examples 1-3 and Comparative Example 1, (c) is the in-plane MH curve of Examples 1, 4 and Comparative Example 2, and (d) is the out-of-plane MH curve of Examples 1, 4 and Comparative Example 2.

[0023] Figure 4 The hysteresis loop test results of the materials obtained in Examples 1 and 2 and Comparative Example 1 are shown.

[0024] Figure 5 The hysteresis loop test results of the thin film materials obtained in Examples 1 and 4 and Comparative Example 2 are shown.

[0025] Figure 6 This is a graph showing the variation of the amplitude curve of the material obtained in Example 1 with the in-plane magnetic field strength.

[0026] Figure 7 The results of the macroscopic magnetoelectric coupling test are shown, wherein (a) is a comparison of the PUND transient current test results of the material obtained in Example 1 with and without an external in-plane magnetic field (3 kOe), (b) is a graph showing the change in the remnant polarization intensity of the materials obtained in Examples 1, 2, 4 and Comparative Example 2 as a function of the in-plane magnetic field intensity, and (c) is a graph showing the change in the out-of-plane remnant polarization intensity of the material obtained in Example 1 as a function of the in-plane [-110] STO and

[001] STO (d) is a diagram showing the change in magnetic field intensity applied to the crystal direction, and (d) is a diagram showing the results of magnetic field cycle testing of the material obtained in Example 1. DETAILED DESCRIPTION

[0027] Below by specific embodiment, the present invention is described, those skilled in the art will appreciate that, below specific embodiment is only for illustrative purpose, and does not limit the scope of the present invention in any way.In addition, in the following embodiments, unless otherwise stated, employed reagent and equipment are all commercially available.If in the embodiment below, concrete treatment condition and treatment process are not clearly described, then can adopt condition and method well known in the art to process.

[0028] On the one hand, the present invention provides a hafnium oxide-based single magnetoelectric coupling multiferroic material, the chemical formula of which is (Co y Fe 1-y ) z (Hf x Zr 1-x ) 1-z O2, wherein x = 0.2-0.4, y = 0-0.48, z = 0.15-0.35. The material provided by the present invention is Co-doped or Co / Fe co-doped Hf x Zr 1-x O2(HZO) material, by introducing Co and Fe, introduces room-temperature ferromagnetism while maintaining the room-temperature ferroelectricity of the material. At the same time, the material exhibits excellent magnetoelectric coupling.

[0029] In some embodiments of the present invention, the X-ray diffraction spectrum of the hafnium oxide-based single magnetoelectrically coupled multiferroic material has a characteristic peak at 30.2°. In the present invention, having a characteristic peak at 30.2° means having a characteristic peak near 30.2°, such as 30.2°±0.3°.

[0030] In some embodiments of the present invention, the macroscopic magnetoelectric coupling coefficient of the hafnium oxide-based single magnetoelectric coupling multiferroic material is 1×10 5 mV·cm -1 ·Oe -1 -4×10 5 mV·cm -1 ·Oe -1 .

[0031] In some embodiments of the present invention, the thickness of the hafnium oxide-based single magnetoelectrically coupled multiferroic material is 8-12 nm, specifically 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, etc.

[0032] In some embodiments of the present invention, x=0.2-0.4, specifically 0.2, 0.3, 0.4, etc.; z=0.15-0.35, preferably 0.17-0.23.

[0033] In some embodiments of the present invention, the hafnium oxide-based single magnetoelectrically coupled multiferroic material is in thin film form and is located on a substrate comprising, from bottom to top, a strontium titanate (STO) substrate layer and a lanthanum strontium manganese oxide (LSMO) bottom electrode layer.

[0034] Another aspect of the present invention further provides a method for preparing the hafnium oxide-based single magnetoelectric coupling multiferroic material according to any one of the above technical solutions, comprising the following steps:

[0035] Using HfO2 target, ZrO2 target and CoFe2O4 target / Co3O4 target as target materials, pulsed laser co-deposition method was used to alternately deposit them on the substrate to obtain hafnium oxide-based single magnetoelectric coupled multiferroic material.

[0036] The hafnium oxide-based single magnetoelectric coupling multiferroic material provided by the present invention can be prepared by a relatively mature and widely applicable pulsed laser co-deposition method, and the preparation method is simple and easy to implement.

[0037] In some embodiments of the present invention, the number of deposition pulses in a single growth cycle for the HfO2 target is 50, the number of deposition pulses for the ZrO2 target is 100, the number of deposition pulses for the CoFe2O4 target is 15-60, and the number of deposition pulses for the Co3O4 target is 15. In the present invention, those skilled in the art can adjust the number of deposition pulses for the CoFe2O4 target according to the desired amount of Co and Fe co-doping.

[0038] In some embodiments of the present invention, the substrate comprises, from bottom to top, a strontium titanate underlayer and a lanthanum strontium manganese oxide bottom electrode layer. The hafnium oxide-based single magnetoelectrically coupled multiferroic material is deposited on the lanthanum strontium manganese oxide bottom electrode layer. The strontium titanate underlayer is a single crystal strontium titanate underlayer. In some embodiments of the present invention, the thickness of the lanthanum strontium manganese oxide bottom electrode layer is 8-12 nm, for example, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, etc. Those skilled in the art may adjust the thickness as needed.

[0039] The present invention also provides the use of the hafnium oxide-based single magnetoelectrically coupled multiferroic material described in any of the above technical solutions or the hafnium oxide-based single magnetoelectrically coupled multiferroic material prepared by the preparation method described in any of the above technical solutions in electronic devices.

[0040] In some embodiments of the present invention, the electronic devices include magnetoelectric sensors, magnetoelectric memories, tunable inductors and filters, energy recoverers, and storage-computing integrated logic devices.

[0041] The following will be combined with the accompanying drawings and embodiments to clearly and completely describe the technical solutions of the present invention. The embodiments of this application are only for example, and all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0042] The STO / LSMO substrates used in the embodiments of the present invention were prepared by the following method:

[0043] A 10 nm thick LSMO bottom electrode layer was deposited on an STO single crystal substrate using pulsed laser deposition (PLD) with LSMO as the target. This resulted in an STO / LSMO substrate. The deposition temperature was 800°C, the oxygen partial pressure was 100 mTorr, and the laser energy density was 1.5 J / cm. 2 , the number of pulses is 2000, and the pulse frequency is 5Hz.

[0044] Example 1

[0045] Using HfO2, ZrO2, and CoFe2O4 (CFO) targets as targets, pulsed laser co-deposition was used to alternately deposit 10 nm of hafnium oxide-based single magnetoelectrically coupled multiferroic material on an STO / LSMO substrate. The deposition temperature was 850°C, the oxygen partial pressure was 100 mTorr, and the laser energy density was 1.5 J / cm 2 In a single growth cycle, the deposition pulse number of the HfO2 target is 50, the deposition pulse number of the ZrO2 target is 100, the deposition pulse number of the CoFe2O4 target is 15, and the pulse frequency is 2Hz. The material was subjected to X-ray photoelectron spectroscopy (XPS) test, and the chemical formula of the material was obtained as (Co 0.47 Fe 0.53 ) 0.17 (Hf 0.3 Zr 0.7 ) 0.83 O2, denoted as HZO-L.

[0046] Example 2

[0047] The hafnium oxide-based single magnetoelectric coupled multiferroic material was prepared by the method shown in Example 1, except that the number of deposition pulses of the CoFe2O4 target was 35. The material was subjected to XPS testing, and the chemical formula of the material was obtained as (Co 0.48 Fe 0.52 ) 0.23 (Hf 0.3 Zr 0.7 ) 0.77 O2, denoted as HZO-M.

[0048] Example 3

[0049] The hafnium oxide-based single magnetoelectric coupled multiferroic material was prepared by the method shown in Example 1, except that the number of deposition pulses of the CoFe2O4 target was 60. The material was subjected to XPS testing, and the chemical formula of the material was obtained as (Co 0.47 Fe 0.53 ) 0.35 (Hf 0.3 Zr 0.7 ) 0.65 O2, denoted as HZO-H.

[0050] Example 4

[0051] The hafnium oxide-based single magnetoelectric coupled multiferroic material was prepared by the method shown in Example 1, except that the CoFe2O4 target was replaced by a Co3O4 target, and the number of deposition pulses of the Co3O4 target was 15. The material was subjected to XPS testing, and the chemical formula of the material was obtained to be Co 0.17 (Hf 0.3 Zr 0.7 ) 0.83 O2, recorded as HZO-Co.

[0052] Comparative Example 1

[0053] The film was prepared by the method of Example 1, except that the CFO target was not used. The film material was subjected to XPS test, and the chemical formula of the material was obtained to be Hf 0.3 Zr 0.7 O2, denoted as undoped-HZO.

[0054] Comparative Example 2

[0055] The film was prepared by the method of comparative example 1, except that the CFO target was replaced by Fe3O4 target. The film material was subjected to XPS test, and the chemical formula of the material was obtained as Fe 0.17 (Hf 0.3 Zr 0.7 ) 0.83 O2, denoted as HZO-Fe.

[0056] 1. Microstructure characterization

[0057] The cross section of the hafnium oxide-based single magnetoelectric coupled multiferroic material obtained in Example 2 was characterized using a transmission electron microscope (TEM). Figure 1 As shown, (a)-(c) are TEM images of different magnifications of the cross section along the substrate [-110] crystal axis, and (d)-(f) are TEM images of different magnifications of the cross section along the substrate

[001] crystal axis. Figure 1It can be seen that the film obtained in Example 2 is a single continuous film with a smooth and neat interface with LSMO. The materials obtained in other examples also have similar morphologies.

[0058] 2. X-ray diffraction (XRD) characterization

[0059] XRD analysis was performed on the hafnium oxide-based single magnetoelectric coupled multiferroic materials obtained in Examples 1-4 and the film obtained in Comparative Example 1. The results are as follows: Figure 2 As shown, Cu-Kα radiation is used and the characteristic peaks are expressed in 2θ diffraction angles. Figure 2 It can be seen that the hafnium oxide-based single magnetoelectrically coupled multiferroic materials obtained in Examples 1-4 and Comparative Example 1 both showed characteristic peaks at around 30.2, but the characteristic peaks shifted slightly with changes in the doping amount, indicating that the crystal structure of the hafnium oxide-based single magnetoelectrically coupled multiferroic material provided by the present invention will change to a certain extent with changes in the doping amount.

[0060] 3. Ferromagnetic characterization

[0061] The in-plane and out-of-plane magnetization curves (MH curves) of the materials obtained in Examples 1-4 and Comparative Examples 1-2 were measured at room temperature using a vibrating sample magnetometer (VSM). Figure 3 As shown, where M is the magnetization intensity, H is the external magnetic field intensity, (a) is the in-plane MH curve of Examples 1-3 and Comparative Example 1, (b) is the out-of-plane MH curve of Examples 1-3 and Comparative Example 1, (c) is the in-plane MH curve of Examples 1, 4 and Comparative Example 2, and (d) is the out-of-plane MH curve of Examples 1, 4 and Comparative Example 2. Figure 3 It can be seen that for the HZO film, almost no magnetization intensity signal was detected in both aspects, while the thin film materials obtained in Examples 1-4 and Comparative Example 2 all detected magnetization intensity signals, and when Co and Fe were co-doped, as the ratio of Co to Fe increased, the saturation magnetization intensity increased, indicating that Co doping alone or co-doping with Fe gave the material room temperature ferromagnetism.

[0062] 4. Ferroelectric characterization

[0063] The materials obtained in Examples 1, 2 and Comparative Example 1 were made into metal-ferroelectric layer-metal (MFM) two-terminal devices, and hysteresis loop tests were performed using the Positive-Up-Negative-Down (PUND) method. The results are shown in FIG. Figure 4 As shown. Figure 4 It can be seen that with the increase of Co / Fe doping concentration, the remanent polarization intensity of the material decreases significantly.

[0064] The hysteresis loop test of the thin film materials obtained in Examples 1, 4 and Comparative Example 2 was obtained by PUND method. The results are as follows: Figure 5 As shown. Figure 5 It can be seen that the HZO films doped with Fe and Co have similar remnant polarization and coercive field to those of Co / Fe co-doped HZO films.

[0065] 5. Characterization of magnetoelectric coupling performance

[0066] (1) Microscopic magnetoelectric coupling test

[0067] The piezoelectric response of the material obtained in Example 1 was analyzed in situ under a magnetic field by piezoelectric force microscopy (SS-PFM). Figure 6 As shown. Figure 6 It can be seen that the amplitude of the piezoelectric response increases significantly with the increase of the in-plane magnetic field strength. This shows that the in-plane magnetic field strength has a significant enhancement effect on the ferroelectric polarization strength of the HZO-L in the out-of-plane direction, and the material has obvious magnetoelectric coupling behavior. The magnetoelectric coupling coefficient (α 31 ) is 1.37×10 5 mV·cm -1 ·Oe -1 .

[0068] (2) Macroscopic magnetoelectric coupling test

[0069] The material obtained in Example 1 was subjected to PUND transient current test (such as Figure 7 (a) in the figure), by Figure 7 As shown in (a), the current intensity under the first positive and negative pulses is contributed by both the polarization reversal current and the leakage current, while the current intensity under the second pulse signal is entirely contributed by the leakage current. The result of subtracting the time integral of the two is the current intensity contributed by the polarization reversal, which is an important reference for the magnitude of the ferroelectric polarization. From the transient current test results, it can be seen that under the action of the in-plane magnetic field, the total current inside the sample under the positive and negative pulse signals increases significantly, while the current intensity contributed by the leakage current remains almost unchanged. This shows that at the macroscopic scale, the in-plane magnetic field intensity can cause an enhancement effect on the out-of-plane ferroelectric polarization intensity, a phenomenon consistent with the amplitude results measured in the microscopic SS-PFM.

[0070] The residual polarization intensity variation (ΔPr(e.g. Figure 7 (b) in the figure), Figure 7 As shown in (b), in the magnetic field range of 0-3k Oe, the changes in the remanent polarization intensity of HZO-L, HZO-M, and HZO-Co all show a monotonically increasing trend with the increase of magnetic field intensity, showing an obvious magnetoelectric coupling effect at the macro scale, while the magnetoelectric coupling effect is almost not observed in HZO-Fe.31 About 1×10 5 mV·cm -1 ·Oe -1 , which is roughly equivalent to the result measured by SS-PFM, while HZO-M with higher doping concentration, α 31 The value is higher, reaching 3×10 5 mV·cm -1 ·Oe -1 , α of HZO-Co 31 The value is 4×10 5 mV·cm -1 ·Oe -1 This indicates that the Co-doped and Co / Fe co-doped materials have significant room-temperature magnetoelectric coupling effects.

[0071] The material obtained in test example 1 is along the in-plane [-110] STO and

[001] STO The effect of the change in the out-of-plane remanent polarization intensity when a magnetic field is applied to the crystal direction (such as Figure 7 (c) in the figure), Figure 7 As can be seen from (c) in FIG, the coupling effect is independent of the direction of the applied in-plane magnetic field.

[0072] The material obtained in Example 1 was subjected to a magnetic field cycle test (e.g. Figure 7 As shown in (d) in the figure, it can be seen that when the magnetic field is repeatedly cycled between 0-3k Oe, the out-of-plane ferroelectric remnant polarization intensity also shows a reversible reciprocating change, indicating that the above-mentioned magnetoelectric coupling effect has good cyclability and repeatability at room temperature.

[0073] In summary, the hafnium oxide-based single magnetoelectric coupling multiferroic material provided by the present invention has a good magnetoelectric coupling effect and can be applied to electronic devices such as magnetoelectric sensors, magnetoelectric memories, tunable inductors and filters, energy recovery devices, and storage and computing integrated logic devices.

[0074] While preferred embodiments of the invention have been shown and described, it is contemplated that those skilled in the art may devise various modifications of the invention within the spirit and scope of the appended claims.

Claims

1. A hafnium oxide-based single magnetoelectric coupling multiferroic material, the chemical formula of which is (Co y Fe 1-y ) z (Hf x Zr 1-x ) 1-z O2, where x = 0.2-0.4, y = 0-0.48, z = 0.15-0.

35.

2. The hafnium oxide-based single magnetoelectric coupled multiferroic material according to claim 1, wherein: The X-ray diffraction spectrum of the hafnium oxide-based single magnetoelectric coupling multiferroic material has a characteristic peak at 30.2°.

3. The hafnium oxide-based single magnetoelectric coupled multiferroic material according to claim 1, wherein: The macroscopic magnetoelectric coupling coefficient of the hafnium oxide-based single magnetoelectric coupling multiferroic material is 1×10 5 mV·cm -1 ·Oe -1 -4×10 5 mV·cm -1 ·Oe -1 .

4. The hafnium oxide-based single magnetoelectric coupled multiferroic material according to claim 1, wherein: The thickness of the hafnium oxide-based single magnetoelectric coupling multiferroic material is 8-12 nm.

5. The hafnium oxide-based single magnetoelectric coupled multiferroic material according to claim 1, wherein: x＝0.3。 6. The hafnium oxide-based single magnetoelectric coupled multiferroic material according to claim 1, wherein: z＝0.17-0.23。 7. A method for preparing the hafnium oxide-based single magnetoelectrically coupled multiferroic material according to any one of claims 1 to 6, comprising the following steps: Using HfO2 target, ZrO2 target and CoFe2O4 target / Co3O4 target as target materials, pulsed laser co-deposition method was used to alternately deposit them on the substrate to obtain hafnium oxide-based single magnetoelectric coupled multiferroic material.

8. The preparation method according to claim 7, characterized in that The number of deposition pulses in a single growth cycle is 50 for the HfO2 target, 100 for the ZrO2 target, 15-60 for the CoFe2O4 target, and 15 for the Co3O4 target.

9. The preparation method according to claim 7 or 8, characterized in that The substrate comprises a strontium titanate substrate layer and a lanthanum strontium manganese oxide bottom electrode layer from bottom to top, and the hafnium oxide-based single magnetoelectric coupling multiferroic material is deposited on the lanthanum strontium manganese oxide bottom electrode layer.

10. Use of the hafnium oxide-based single magnetoelectrically coupled multiferroic material according to any one of claims 1 to 6 or the hafnium oxide-based single magnetoelectrically coupled multiferroic material prepared by the preparation method according to any one of claims 7 to 9 in electronic devices.

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