Monocrystalline substrate / functioning oxide film / noble metal nanoparticle heterojunction, and preparation method and application thereof

Abstract

The application discloses a single crystal substrate / functioning oxide film / noble metal nanoparticle heterojunction and a preparation method and application thereof, and relates to the field of material technology applications.The method comprises the following steps: (1) depositing noble metal nanoparticles on the surface of a single crystal substrate / functioning oxide film heterojunction; (2) activating the noble metal nanoparticle-functioning oxide interface coupling effect through hydrogen plasma treatment, realizing rapid phase transition and magnetic order regulation, and obtaining a single crystal substrate / functioning oxide film / noble metal nanoparticle heterojunction.The method utilizes the synergistic effect of noble metal nanoparticles and hydrogen plasma, triggers rapid phase transition from a perovskite phase to a brownmillerite phase, realizes directional regulation of the phase state and magnetic order of a functioning oxide, and finally improves the saturation magnetization intensity and Curie temperature of the obtained heterojunction, and the crystal lattice is relatively stable, thereby providing key technical support for the development of high-performance spin electronic devices.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a single-crystal substrate / functional oxide thin film / noble metal nanoparticle heterostructure, its preparation method, and its application. Background Technology

[0002] In the field of phase transition modulation of functional oxide thin films, existing technologies mainly involve introducing heterogeneous elements to alter the electronic structure and lattice of the material, utilizing substrate / capping layer lattice mismatch or external stress to control oxygen octahedral distortion, thereby achieving phase transition effects. However, these technologies generally face two core challenges: first, the dynamic structural instability caused by oxygen vacancy diffusion and lattice mismatch in traditional processes; and second, the contradiction between phase transition rate and thermal stability. Furthermore, the aggregation problem of traditional noble metal nanoparticles due to oxygen erosion further weakens the ability of local electric fields to directionally control hydrogen ion penetration, making it difficult to achieve synergistic enhancement of deep phase transition and interfacial magnetic coupling.

[0003] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a single-crystal substrate / functional oxide film / noble metal nanoparticle heterojunction, its preparation method and application, aiming to solve the problems of limited phase transition rate and magnetic performance degradation at the interface of existing noble metal nanoparticles / functional oxides.

[0005] This invention provides a magnetic enhancement method for rapid phase transition synergistically induced by noble metal nanoparticles and hydrogen plasma. The method utilizes noble metal nanoparticles in conjunction with hydrogen plasma bombardment to induce an ultrafast transition from the perovskite (PV) phase to the Brown-Müllerite (BM) phase on the surface of a single-crystal substrate / functional oxide film heterojunction. The resulting heterojunction exhibits enhanced saturation magnetization and Curie temperature, providing an interface solution for high-density spintronic devices that combines strong magnetic order with wide-temperature stability.

[0006] To achieve the above effects, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a heterojunction of a single-crystal substrate / functional oxide thin film / noble metal nanoparticles, comprising the following steps: (1) Provide a single crystal substrate / functional oxide film heterojunction, wherein the single crystal substrate and the functional oxide film are stacked in the single crystal substrate / functional oxide film heterojunction; (2) Deposit noble metal nanoparticles on the surface of the functional oxide film of the single crystal substrate / functional oxide film heterojunction; (3) After step (2) is completed, hydrogen plasma treatment is performed to transform the perovskite phase of the functional oxide film into the Brown Miller stone phase, thus obtaining a single crystal substrate / functional oxide film / noble metal nanoparticle heterostructure.

[0007] Optionally, in step (1), the single crystal substrate is an SrTiO3 single crystal substrate.

[0008] Optionally, in step (1), the functional oxide film is La. 0.7 Sr 0.3 MnO3 film.

[0009] Optionally, in step (1), the thickness of the functional oxide film is 20-30 nm.

[0010] Optionally, in step (2), the noble metal nanoparticles are Pt nanoparticles with a diameter of less than 100 µm and a height of 10-100 nm.

[0011] Optionally, in step (3), a low-frequency inductively coupled plasma system is used for hydrogen plasma treatment. The conditions for hydrogen plasma treatment are: temperature of 30-500 ℃, time of 0-30 minutes, discharge power of 300-2000 W, hydrogen flux of 10-100 sccm, gas pressure of 1-30 Pa, and applied bias voltage of -80 V to -180 V.

[0012] Optionally, after step (3), the La 0.7 Sr 0.3 MnO3 film becomes La 0.7 Sr 0.3 MnO 2.5 film.

[0013] In a second aspect, the present invention provides a single-crystal substrate / functional oxide film / noble metal nanoparticle heterojunction, wherein the heterojunction is prepared by the preparation method described in the present invention.

[0014] A third aspect of the present invention provides an application of the single-crystal substrate / functional oxide thin film / noble metal nanoparticle heterojunction described herein in a spintronic device.

[0015] Optionally, the spintronic device includes at least one of a magnetic memory, a spin-orbit torque device, and a resistive switching memory. Beneficial Effects: This invention utilizes noble metal nanoparticles in conjunction with hydrogen plasma bombardment to induce an ultrafast transition from the PV phase to the BM phase on the surface of a single-crystal substrate / functional oxide thin film heterojunction, achieving directional control of the phase state and magnetic order of the functional oxide. The saturation magnetization and Curie temperature of the treated heterojunction are improved, and the lattice is more stable, providing key technical support for the development of high-performance spintronic devices. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 In the figure, 'a' represents the SrTiO3 / La from Embodiment 1 of the present invention. 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (-80 V), SrTiO3 / La (Comparative Example 1) 0.7 Sr 0.3 MnO 2.5 Heterojunction (-80 V) and Comparative Example 3 SrTiO3 / La 0.7 Sr 0.3 XRD test results of MnO3; Figure 1 b represents SrTiO3 / La from Example 2. 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (-180 V), Comparative Example 2: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 Heterojunction (-180 V) and Comparative Example 3 SrTiO3 / La 0.7 Sr 0.3 XRD test results of MnO3; Figure 2 In the figure, 'a' represents the SrTiO3 / La from Embodiment 1 of the present invention. 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (-80 V) and Comparative Example 1 SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 The 10 K hysteresis loop (MH curve) of a heterojunction (-80 V); Figure 2 b represents SrTiO3 / La from Example 2. 0.7 Sr 0.3 MnO2.5 / Pt heterojunction (-180 V) and Comparative Example 2 SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 The 10 K hysteresis loop (MH curve) of a heterojunction (-180 V); Figure 3 SrTiO3 / La as described in Embodiment 1 of the present invention 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (-80 V), SrTiO3 / La from Example 2 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (-180 V), SrTiO3 / La (Comparative Example 1) 0.7 Sr 0.3 MnO 2.5 Heterojunction (-80V) and Comparative Example 2: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 Saturation magnetization of a heterojunction (-180 V) from 10 to 400 K as a function of temperature (MT plot). Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] This invention addresses the technical bottleneck of low phase transition rates and magnetic property degradation at the interface between noble metal nanoparticles and functional oxides (primarily perovskite oxides), providing a method for rapid phase transitions and enhanced magnetic properties based on the synergistic regulation of high surface energy noble metal nanoparticles (such as Pt nanoparticles) and hydrogen plasma. Specifically, functional oxide thin films (such as La...) 0.7 Sr 0.3During high-temperature processing (such as annealing), oxygen atoms in the MnO3 thin film (LSMO thin film) gain sufficient energy to escape from their lattice sites. However, when functional perovskite oxides form heterojunctions with other oxide materials, oxygen interdiffusion occurs at the interface due to differences in chemical potentials. This may lead to oxygen deficiency in the region near the LSMO interface, resulting in lattice distortion, which in turn causes magnetization attenuation and limits the Curie temperature. This invention utilizes noble metal nanoparticles bombarded with hydrogen plasma to induce an ultrafast transition from the perovskite phase (PV phase) to the Brown-Millerite phase (BM phase), thereby improving saturation magnetization and Curie temperature, providing key technical support for the development of high-performance spintronic devices.

[0020] Specifically, embodiments of the present invention provide a method for preparing a heterojunction of a single-crystal substrate / functional oxide thin film / noble metal nanoparticles, comprising the following steps: (1) Provide a single crystal substrate / functional oxide film heterojunction, wherein the single crystal substrate and the functional oxide film are stacked in the single crystal substrate / functional oxide film heterojunction; (2) Deposit noble metal nanoparticles on the surface of the functional oxide film of the single crystal substrate / functional oxide film heterojunction; (3) After step (2) is completed, hydrogen plasma treatment is performed to transform the perovskite phase of the functional oxide film into the Brown Miller stone phase, thus obtaining a single crystal substrate / functional oxide film / noble metal nanoparticle heterostructure. This embodiment utilizes the synergistic effect of noble metal nanoparticles and hydrogen plasma to trigger a rapid phase transition from the PV phase to the BM phase, achieving directional control of the phase state and magnetic order of functional oxides. This mechanism simultaneously increases the saturation magnetization and Curie temperature of the single-crystal substrate / functional oxide film / noble metal nanoparticle heterojunction, making it suitable for interface optimization of spintronic devices such as magnetic storage devices, spin-orbit torque devices, and resistive switching memories, providing a novel solution for the high-temperature stable operation of spintronic devices.

[0021] Furthermore, in step (1), the single crystal substrate is an SrTiO3 single crystal substrate.

[0022] Furthermore, in step (1), the thickness of the single crystal substrate is 0.1-0.8 mm, such as 0.5 mm.

[0023] Furthermore, in step (1), the functional oxide thin film is La. 0.7 Sr 0.3 MnO3 film.

[0024] Furthermore, in step (1), the thickness of the functional oxide film is 20-30 nm, such as 25 nm.

[0025] Furthermore, in step (1), the single crystal substrate is an SrTiO3 single crystal substrate, and the functional oxide thin film is La. 0.7 Sr 0.3 MnO3 thin film, SrTiO3 lattice constant and La 0.7 Sr 0.3 The MnO3 matching degree reached 99.2%.

[0026] Furthermore, the La 0.7 Sr 0.3 The method for preparing MnO3 thin films includes the following steps: bombarding La on a SrTiO3 single-crystal substrate with a pulsed laser. 0.7 Sr 0.3 MnO3 target material, La deposition was obtained 0.7 Sr 0.3 MnO3 film; The pulsed laser source is a KrF excimer laser with a wavelength of 248 nm, a pulse width of 10 ns, and an energy density of 1.0–3.0 J / cm². 2 The laser frequency is 2-5 Hz, La 0.7 Sr 0.3 The deposition temperature of MnO3 thin films is 600-800℃, and the deposition oxygen pressure is 5-100 Pa.

[0027] Furthermore, in step (2), a magnetron sputtering instrument is used to deposit noble metal nanoparticles on the surface of the functional oxide film of the single crystal substrate / functional oxide film heterojunction using a mask.

[0028] Furthermore, in step (2), the noble metal nanoparticles are Pt nanoparticles with a diameter of less than 100 µm and a height of 10-100 nm, such as 20 nm, 40 nm, 50 nm, 80 nm, etc.

[0029] Furthermore, in step (3), a low-frequency inductively coupled plasma (LFICP) system is used to perform hydrogen plasma treatment on the interface between noble metal nanoparticles and functional oxides to activate the coupling effect between the interface between noble metal nanoparticles and functional oxides, thereby achieving rapid phase transition and magnetically ordered control.

[0030] Furthermore, in step (3), the conditions for hydrogen plasma treatment are as follows: temperature is 30-500 ℃, time is 0-30 minutes, discharge power is 300-2000 W, hydrogen flux is 10-100 sccm (e.g., 10 sccm, 20 sccm, 40 sccm, 50 sccm, 80 sccm, 100 sccm, etc.), gas pressure is 1-30 Pa (e.g., 1 Pa, 3 Pa, 5 Pa, 10 Pa, 20 Pa, 30 Pa, etc.), and applied bias voltage is -80 V to -180 V (e.g., -80 V, -100 V, -120 V, -140 V, -160 V, -180 V, etc.).

[0031] Furthermore, after step (3), La 0.7 Sr 0.3 MnO3 film becomes La 0.7 Sr 0.3 MnO 2.5 Thin film. A phase transition occurs, resulting in an increase in saturation magnetization and Curie temperature.

[0032] This invention provides a magnetically enhanced single-crystal substrate / functional oxide film / noble metal nanoparticle heterojunction, which is prepared by the method described in this invention.

[0033] The embodiments of the present invention provide the application of the above-described single-crystal substrate / functional oxide thin film / noble metal nanoparticle heterojunction in spintronic devices such as magnetic memory, spin-orbit torque device and resistive switching memory.

[0034] The present invention will be further described in detail below through specific embodiments.

[0035] Example 1: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (-80 V) (1) Select crystal plane orientation as <001> SrTiO3 (STO) was used as a single-crystal substrate with a lattice constant of 3.905 Å. La was bombarded onto the STO single-crystal substrate using a pulsed laser. 0.7 Sr 0.3 Preparation of La using MnO3 target material 0.7 Sr 0.3 MnO3 thin films (LSMO films for short) were used to obtain SrTiO3 / La 0.7 Sr 0.3 MnO3 thin film heterojunction (abbreviated as STO / LSMO heterojunction, hereinafter the same); The pulsed laser uses a KrF excimer laser as its source, with a wavelength of 248 nm, a pulse width of 10 ns, and a laser energy density of 1.0 J / cm². 2 The laser frequency was 2 Hz. The deposition temperature of the LSMO film was 700 ℃, and the deposition oxygen pressure was 30 Pa. The thickness of the LSMO film was 30 nm.

[0036] (2) In SrTiO3 / La 0.7 Sr 0.3 La-type MnO3 thin film heterostructure 0.7 Sr 0.3 Pt nanoparticles (diameter less than 100 µm and height 50 nm) are deposited on the surface of the MnO3 film to obtain SrTiO3 / La 0.7 Sr 0.3 MnO3 / Pt heterojunction; (3) Using a low-frequency inductively coupled plasma (LFICP) system to process SrTiO3 / La 0.7 Sr 0.3 The MnO3 / Pt heterojunction was subjected to hydrogen plasma treatment. The hydrogen plasma treatment temperature was 450 °C, the time was 10 minutes, the discharge power was 1800 W, the hydrogen flux was 20 sccm, the gas pressure was 6 Pa, and the applied bias voltage was -80 V, to obtain SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction.

[0037] Example 2: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (-180 V) The difference between Example 2 and Example 1 is that in step (3), the bias voltage applied is -180 V, while the other conditions are the same.

[0038] Comparative Example 1: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 Heterojunction (-80 V) Compared with Example 1, Comparative Example 1 is different in that step (2) was not performed, while all other conditions are the same.

[0039] Comparative Example 2: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 Heterojunction (-180 V) Compared with Example 2, Comparative Example 2 is different in that step (2) was not performed, while all other conditions are the same.

[0040] Compared with Comparative Example 1, Comparative Example 2 differs in that in step (3), the bias voltage applied is -180 V, while the other conditions are the same.

[0041] Comparative Example 3: SrTiO3 / La 0.7 Sr 0.3 MnO3 heterojunction Compared with Examples 1 and 2, Comparative Example 3 is different in that step (2) and step (3) are not performed, while all other conditions are the same.

[0042] For SrTiO3 / La in Example 1 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (denoted as STO / LSMO / Pt@-80 V), SrTiO3 / La from Example 2 0.7 Sr 0.3 MnO 2.5 / Pt heterojunction (denoted as STO / LSMO / Pt@-180 V), Comparative Example 1: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 Heterojunction (denoted as STO / LSMO@-80 V), Comparative Example 2: SrTiO3 / La 0.7 Sr 0.3 MnO 2.5 Heterojunction (denoted as STO / LSMO@-180 V) and Comparative Example 3: SrTiO3 / La 0.7 Sr 0.3 XRD tests were performed on the MnO3 heterojunction (denoted as STO / LSMO), and the XRD test results are as follows: Figure 1 As shown in a and b. From Figure 1 As can be seen in Figure a, compared with the original STO / LSMO sample (Comparative Example 3), the hydrogen plasma-treated sample STO / LSMO / Pt@-80 V (Example 1) and STO / LSMO@-80 V (Comparative Example 1) undergo a phase transition, with the characteristic peak increasing from 47.2° to 43.7° and the lattice constant expanding from 3.854 Å to 4.14 Å. In contrast, the STO / LSMO / Pt@-80 V (Example 1) sample with deposited Pt nanoparticles exhibits a Pt structural characteristic peak around 40°, and the BM phase characteristic peak increases by 0.1° compared to STO / LSMO@-80 V (Comparative Example 1), while the lattice constant decreases by 0.1 Å.

[0043] Figure 1Figure b shows that the samples with larger bias, STO / LSMO / Pt@-180 V (Example 2) and STO / LSMO@-180 V (Comparative Example 2), also exhibited a phase transition, and the experimental phenomena were basically consistent with those described above. It should be noted that the characteristic peak of STO / LSMO / Pt@-180 V (Example 2) is shifted to a higher angle by about 0.2° compared to STO / LSMO / Pt@-80 V (Example 1), and the lattice constant is smaller.

[0044] The STO / LSMO / Pt@-80 V of Example 1, the STO / LSMO / Pt@-180 V of Example 2, the STO / LSMO@-80 V of Comparative Example 1, and the STO / LSMO@-180 V of Comparative Example 2 were placed in a comprehensive physical property measurement system for corresponding magnetic performance tests. Their hysteresis loops (MH curves) at 10 K are shown below. Figure 2 As shown in Figures a and b, the saturation magnetization intensity varies with temperature from 10 K to 400 K (MT plot). Figure 3 As shown. The MH curve further verifies the synergistic effect of Pt nanoparticles and high bias voltage treatment: at 10 K, the saturation magnetization of the sample STO / LSMO / Pt@-180 V (Example 2) reaches 80 emu / cc, and the coercivity (H c The value is 260 Oe, compared to the STO / LSMO / Pt@-80 V (Example 1) sample (45 emu / cc, H). c =150 Oe) performance improved by 78%, and significantly higher than the sample without Pt (<35 emu / cc). MT curves show that the Curie temperature of the high bias voltage (-180 V) treated samples STO / LSMO / Pt@-180 V (Example 2) and STO / LSMO@-180 V (Comparative Example 2) is significantly improved, with a magnetization of approximately 15 emu / cc at 400 K; while the Curie temperature of the lower bias voltage (-80 V) treated samples STO / LSMO / Pt@-80 V (Example 1) and STO / LSMO@-80 V (Comparative Example 1) is approximately 350 K, and the Curie temperature of the STO / LSMO (Comparative Example 3) sample is approximately 300 K, showing an increase in Curie temperature.

[0045] In summary, this invention utilizes the synergistic effect of high surface energy noble metal nanoparticles (such as Pt nanoparticles) and hydrogen plasma to induce an ultrafast transition from the PV phase to the BM phase, thereby improving the saturation magnetization and Curie temperature. This provides a heterogeneous interface solution for high-temperature spintronic devices that combines high magnetic performance, wide temperature range stability, and rapid phase transition dynamics.

[0046] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0047] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a heterojunction of a single-crystal substrate / functional oxide thin film / noble metal nanoparticles, characterized in that, Includes the following steps: (1) Provide a single crystal substrate / functional oxide film heterojunction, wherein the single crystal substrate and the functional oxide film are stacked in the single crystal substrate / functional oxide film heterojunction; (2) Deposit noble metal nanoparticles on the surface of the functional oxide film of the single crystal substrate / functional oxide film heterojunction; (3) After step (2) is completed, hydrogen plasma treatment is performed to transform the perovskite phase of the functional oxide film into the Brown Miller stone phase, thus obtaining a single crystal substrate / functional oxide film / noble metal nanoparticle heterostructure.

2. The preparation method according to claim 1, characterized in that, In step (1), the single crystal substrate is an SrTiO3 single crystal substrate.

3. The preparation method according to claim 1, characterized in that, In step (1), the functional oxide thin film is La. 0.7 Sr 0.3 MnO3 film.

4. The preparation method according to claim 1 or 3, characterized in that, In step (1), the thickness of the functional oxide film is 20-30 nm.

5. The preparation method according to claim 1, characterized in that, In step (2), the noble metal nanoparticles are Pt nanoparticles with a diameter of less than 100 µm and a height of 10-100 nm.

6. The preparation method according to claim 1, characterized in that, In step (3), a low-frequency inductively coupled plasma system is used to perform hydrogen plasma treatment. The conditions for hydrogen plasma treatment are: temperature of 30-500 ℃, time of 0-30 minutes, discharge power of 300-2000 W, hydrogen flux of 10-100 sccm, gas pressure of 1-30 Pa, and applied bias voltage of -80 V to -180 V.

7. The preparation method according to claim 3, characterized in that, After step (3), the La 0.7 Sr 0.3 MnO3 film becomes La 0.7 Sr 0.3 MnO 2.5 film.

8. A heterojunction of single-crystal substrate / functional oxide thin film / noble metal nanoparticles, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The application of the single-crystal substrate / functional oxide film / noble metal nanoparticle heterojunction as described in claim 8 in spintronic devices.

10. The application as described in claim 9, characterized in that, The spintronic device includes at least one of a magnetic memory, a spin-orbit torque device, and a resistive switching memory.

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