Magnetic insulator epitaxial thin film based on Fe3Ga alloy and preparation method thereof

Abstract

The present application discloses a novel magnetic insulator epitaxial film based on Fe3Ga alloy and a preparation method thereof, which belongs to the field of spin storage and logic operation technology in spin electronics. First, the bulk Fe3Ga target is set to the DC power supply position, and the substrate is fixed to the center of the dial using high-temperature resistant silver glue so that the target corresponds to the substrate strontium tantalum aluminate (LSAT), and then vacuum is evacuated; then the DC power supply is turned on, and pre-sputtering preparation is performed on the surface of the target. After the glow is stable, formal sputtering begins. After the sputtering is completed, a magnetic insulator epitaxial film can be obtained. The magnetic insulator epitaxial film obtained in the present application has excellent electrical properties, and its resistivity reaches 400mΩ.cm at room temperature; through the measurement of the hysteresis loop, it is found that its in-plane saturation magnetization is about 1100emu / cm 3 , its effective magnetic anisotropy constant K eff Larger, about 0.6×10 7 erg / cm 3 .

Description

Technical Field

[0001] The present application relates to the technical field of spin storage and logic operation in spin electronics, and in particular to a novel magnetic insulator epitaxial film based on Fe3Ga alloy and a preparation method thereof. Background Art

[0002] Among magnetic thin film materials, magnetic thin film insulators have attracted the attention of many scholars because of their small magnetic damping coefficient, large dielectric constant and no shunt effect, making them suitable for the development of energy-efficient, high-density, ultra-fast next-generation spin electronics storage and logic operation devices. First, the rapid development of spin electronics has led to the demand for new materials to achieve efficient information storage and processing. Secondly, with the rise of quantum computing, researchers hope to use these materials to build more stable quantum bits. In addition, magnetic thin film insulators provide a rich experimental platform in basic physics research, especially in the study of magnetism, phase transitions and interface effects. Among them, Galfenol (Fe 100-x Ga x ) films have become a hot topic of research in recent years due to their excellent magnetic properties and more ideal mechanical properties, which make them have broader prospects in sensor and actuator applications (including high-frequency devices).

[0003] Artificially regulating the ferromagnetism of Fe3Ga is an important means to study this type of thin film material. Adrian Acosta et al. conducted a systematic study on this. They discussed in depth the influence of the substrate on the performance of Fe3Ga thin films, proved that the in-plane coercivity, anisotropy and Gilbert damping coefficient are significantly affected by the changes in the underlying materials, and found that using NiFe as the underlying material has a good effect in enhancing the soft magnetic properties of Fe3Ga thin films. Another related study is to control the growth power to affect the structural properties of Ga-rich Fe3Ga thin films. The researchers observed that the increase in growth power reduced the crystal size (medium magnitude) and promoted the reduction of the coercive field of the layer; at the same time, the growth power also determined the local order, indicating that the control of growth power can be used as another effective regulating factor for the performance of Fe3Ga thin films. In addition, D.Cao et al. also studied doping with other elements as a method to enhance the performance of Fe3Ga thin films. They doped B elements into Fe3Ga thin films, changed their structure and magnetic properties, improved the application characteristics of Fe3Ga thin films in high frequencies, and established the relationship between film composition and magnetic properties. The researchers also studied the conductivity of Fe3Ga. M. Mouas et al. studied the resistivity change caused by the phase change of Fe3Ga between L12 and D03, and found that the resistivity is very sensitive to the transition between closed stacking phases in Fe3Ga, and the resistivity change caused by the phase change is obvious. This discovery reveals new factors that affect the conductivity of Fe3Ga.

[0004] Although researchers have studied the magnetism and conductivity of Fe3Ga thin films, the real causes of many magnetic phenomena of Fe3Ga and the physical mechanisms behind them are not clear. At the same time, what means can be used to accurately control its magnetic and conductive properties needs further study. In addition, since magnetic insulators have excellent physical properties and huge application prospects, finding magnetic thin film insulators has always been one of the goals of researchers. The present invention aims to develop a new type of magnetic thin film insulator based on Fe3Ga alloy through the exploration of magnetron sputtering process. Summary of the invention

[0005] The purpose of the present application is to provide a new type of magnetic insulator epitaxial film based on Fe3Ga alloy and a preparation method thereof, so as to solve the technical problem of low resistivity and saturation magnetization intensity in magnetic thin film insulators in the prior art.

[0006] The present invention provides a method for preparing a novel magnetic insulator epitaxial film based on Fe3Ga alloy, comprising the following preparation steps:

[0007] Step 1: Set the bulk Fe3Ga target to the DC power supply position, fix the substrate to the center of the dial with high-temperature resistant silver glue, make the target correspond to the substrate, start the vacuum system, and evacuate;

[0008] Step 2: Turn on the DC power supply and perform pre-sputtering preparation on the target surface. After the glow is stable, formal sputtering begins. After sputtering is completed, a magnetic insulator epitaxial thin film can be obtained.

[0009] Preferably, the substrate is a LSAT substrate.

[0010] Preferably, in step 1, the distance between the target and the substrate is set to 90 mm, and the vacuum is evacuated to a vacuum degree of 1.3×10 -5 Pa.

[0011] Preferably, in step 1, during the thin film growth process, the substrate temperature is maintained at 550° C. and the pressure of the Ar gas is kept constant at 1.3 Pa.

[0012] Preferably, in step 1, before preparing the film, the dial is polished clean with sandpaper.

[0013] Preferably, in step 2, the pre-sputtering preparation time is 3 minutes.

[0014] Preferably, in step 2, during the formal sputtering, the growth rate is set to 0.15 nm / s and the sputtering time is set to 10 minutes.

[0015] The present application provides a magnetic insulator epitaxial film prepared by the method for preparing the novel magnetic insulator epitaxial film based on Fe3Ga alloy.

[0016] Therefore, the present application provides a novel magnetic insulator epitaxial film based on Fe3Ga alloy and a preparation method thereof, which has the following beneficial effects:

[0017] 1. Magnetic insulator epitaxial thin films can be directly deposited on LSAT substrates using DC magnetron sputtering, and the prepared films have excellent crystalline quality.

[0018] 2. The magnetic insulator epitaxial film obtained in this application has excellent electrical properties. Its resistivity reaches 400 mΩ.cm at room temperature, which is several orders of magnitude higher than the resistivity (17-80 μΩ.cm) of Fe3Ga alloy prepared by the furnace method in previous studies.

[0019] 3. The magnetic insulator epitaxial film prepared in this experiment has a large saturation magnetization and significant magnetic anisotropy. The measurement of the hysteresis loop shows that its in-plane saturation magnetization is about 1100 emu / cm 3 , its effective magnetic anisotropy constant K eff Larger, about 0.6×10 7 erg / cm 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD diffraction patterns of Fe3Ga magnetic films grown at three different N2 flow rates in Example 1 and Comparative Examples 1-2 of the present invention;

[0021] Figure 2 The XRR spectra of the Fe3Ga magnetic films grown in Example 1 and Comparative Examples 1-2 of the present invention at three different N2 flow rates (XRR, X-ray reflectivity has obvious oscillation peaks, indicating that the grown films have atomic-level flatness and high quality);

[0022] Figure 3 The in-plane (IP) hysteresis loops MH of the Fe3Ga magnetic films grown at three different N2 flow rates in Example 1 and Comparative Examples 1-2 of the present invention;

[0023] Figure 4 The resistivity (ρ) curves of Fe3Ga magnetic films grown with three different N2 flow rates in Example 1 and Comparative Examples 1-2 of the present invention are plotted as a function of temperature (T). DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further illustrated by the following examples.

[0025] Example 1

[0026] The magnetic insulator epitaxial thin film is prepared by DC magnetron sputtering technology. The specific steps are as follows:

[0027] 1. Fix the bulk Fe3Ga target at the DC magnetron target position. Before preparing the film, polish the dial clean with sandpaper. Use high-temperature resistant silver glue to fix the (001) oriented LSAT substrate in the center of the tray. The distance between the target and the substrate is set to 90 mm.

[0028] 2. Close the vacuum chamber door and pump the vacuum to 1.3×10 -5 Pa.

[0029] 3. Set the dial speed to 10 r / min, and increase the temperature to 550 ℃ at a rate of 10 ℃ / min and maintain it for 20 minutes to ensure that the tray temperature reaches a uniform state.

[0030] 4. Only 50 sccm of Ar gas was introduced and the gas pressure was controlled at 1.3 Pa.

[0031] 5. Turn on the DC sputtering power supply, adjust the power to 60 W, pre-sputter for 3 minutes, and formally sputter after confirming that the glow is stable. Sputter at a high temperature of 550 °C for 10 minutes to obtain a magnetic insulator epitaxial film.

[0032] 6. After sputtering, turn off the DC sputtering power supply and the heating power supply to allow the tray to cool down naturally. At the same time, the mechanical pump and molecular pump continue to work to maintain the vacuum degree of the sputtering chamber.

[0033] Comparative Example 1

[0034] The magnetic insulator epitaxial thin film is prepared by DC magnetron sputtering technology. The specific steps are as follows:

[0035] 1. Fix the bulk Fe3Ga target at the DC magnetron target position. Before preparing the film, polish the dial clean with sandpaper. Use high-temperature resistant silver glue to fix the (001) oriented LSAT substrate in the center of the tray. The distance between the target and the substrate is set to 90 mm.

[0036] 2. Close the vacuum chamber door and pump the vacuum to 1.3×10 -5 Pa.

[0037] 3. Set the dial speed to 10 r / min, and increase the temperature to 550 ℃ at a rate of 10 ℃ / min and maintain it for 20 minutes to ensure that the tray temperature reaches a uniform state.

[0038] 4. Introduce 50 sccm of Ar gas and 6 sccm of nitrogen gas and control the gas pressure at 1.3 Pa.

[0039] 5. Turn on the DC sputtering power supply, adjust the power to 60 W, pre-sputter for 3 minutes, and start formal sputtering after confirming that the glow is stable. Sputter at a high temperature of 550 °C for 10 minutes to obtain a magnetic epitaxial film.

[0040] 6. After sputtering, turn off the DC sputtering power supply and the heating power supply to allow the tray to cool down naturally. At the same time, the mechanical pump and molecular pump continue to work to maintain the vacuum degree of the sputtering chamber.

[0041] Comparative Example 2

[0042] 1. Fix the bulk Fe3Ga target at the DC magnetron target position. Before preparing the film, polish the dial clean with sandpaper. Use high-temperature resistant silver glue to fix the (001) oriented LSAT substrate in the center of the tray. The distance between the target and the substrate is set to 90 mm.

[0043] 2. Close the vacuum chamber door and pump the vacuum to 1.3×10 -5 Pa.

[0044] 3. Set the dial speed to 10 r / min, and increase the temperature to 550 ℃ at a rate of 10 ℃ / min and maintain it for 20 minutes to ensure that the tray temperature reaches a uniform state.

[0045] 4. Introduce 50 sccm of Ar gas and 10 sccm of nitrogen gas and control the gas pressure at 1.3 Pa.

[0046] 5. Turn on the DC sputtering power supply, adjust the power to 60 W, pre-sputter for 3 minutes, and start formal sputtering after confirming that the glow is stable. Sputter at a high temperature of 550 °C for 10 minutes to obtain a magnetic epitaxial film.

[0047] 6. After the sputtering is completed, turn off the DC sputtering power supply and the heating power supply to allow the tray to cool down naturally. At the same time, the mechanical pump and molecular pump continue to work to maintain the vacuum degree of the sputtering chamber. When the flow rate of N2 is 0 sccm, the grown sample has insulating properties.

[0048] Therefore, the present application provides a novel magnetic insulator epitaxial film based on Fe3Ga alloy and a preparation method thereof. The magnetic insulator epitaxial film can be directly deposited on an LSAT substrate by using a DC magnetron sputtering method, and the prepared film has excellent crystalline quality.

[0049] In the description of this specification, the description with reference to the terms "an experimental example", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the experimental example or example are included in at least one experimental example or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same experimental example or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more experimental examples or examples in a suitable manner.

[0050] Finally, it should be noted that the above experimental examples are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred experimental examples, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a magnetic insulator epitaxial thin film based on Fe3Ga alloy, characterized in that: The method comprises the following preparation steps: Step 1: Set the bulk Fe3Ga target to the DC power supply position, fix the substrate to the center of the dial with high-temperature resistant silver glue, make the target correspond to the substrate, start the vacuum system, and evacuate; Step 2: Turn on the DC power supply, perform pre-sputtering preparation on the target surface, and start formal sputtering after the glow is stable. After the sputtering is completed, a magnetic insulator epitaxial film based on Fe3Ga alloy can be obtained; The substrate is a LSAT substrate; In step 1, the distance between the target and the substrate was set to 90 mm, and the vacuum was evacuated to a vacuum degree of 1.3×10 -5 Pa; In step 1, during the film growth process, the substrate temperature was maintained at 550 °C, the pressure of the Ar gas was constant at 1.3 Pa, the flow rate of the Ar gas was 50 sccm, and the flow rate of the N2 was 0 sccm.

2. The method for preparing a magnetic insulator epitaxial thin film based on Fe3Ga alloy according to claim 1, characterized in that: In step 1, the dial was cleaned with sandpaper before preparing the film.

3. The method for preparing a magnetic insulator epitaxial thin film based on Fe3Ga alloy according to claim 1, characterized in that: In step 2, the pre-sputtering preparation time is 3 minutes.

4. The method for preparing a magnetic insulator epitaxial thin film based on Fe3Ga alloy according to claim 1, characterized in that: In step 2, during the formal sputtering, the growth rate was set to 0.15 nm / s and the sputtering time was set to 10 minutes.

5. A magnetic insulator epitaxial film prepared according to the method for preparing a magnetic insulator epitaxial film based on Fe3Ga alloy according to any one of claims 1 to 4.

Images