YIG / W heterojunction with enhanced interface spin mixed conductance and preparation method of YIG / W heterojunction

Abstract

The invention discloses a preparation method of a YIG / W heterojunction with enhanced interface spin mixed conductivity. The preparation method comprises the following steps: step 1, preparing a YIG thin film layer on a substrate; 2, preparing a W thin film layer on the YIG thin film layer prepared in the step 1 to obtain a YIG / W heterojunction; and step 3, carrying out annealing treatment on the YIG / W heterojunction obtained in the step 2. According to the preparation method, through annealing treatment, the beta phase W is converted into the alpha phase W, the interface matching degree of the non-magnetic layer and the ferromagnetic layer is improved, meanwhile, the non-magnetic layer is changed from the metastable state to the stable state, and enhancement of the spin mixed conductivity of the system interface is achieved. The invention further discloses the YIG / W heterojunction with the enhanced interface spin mixed conductance, which is prepared by the method.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic thin film materials, and particularly relates to a YIG / W heterojunction with enhanced interfacial spin mixing conductance, and also relates to a preparation method of the YIG / W heterojunction with enhanced interfacial spin mixing conductance. Background Art

[0002] Heterojunction thin films composed of ferromagnetic materials and non-magnetic heavy metal materials are the main components for spin current generation and detection in spintronic devices. During the transmission process of spin current, the physical quantity of interfacial spin mixing conductance determines the injection efficiency of spin current from the magnetic layer to the non-magnetic heavy metal layer. It quantifies the spin angular momentum transfer efficiency that occurs when spin current passes through the interface, especially the loss or transmission ability of spin current at the interface. Therefore, the interfacial spin mixing conductance is a key performance parameter directly affecting spin current-related spintronic devices such as spin-orbit torque (SOT) devices, and directly affects the energy consumption and speed of magnetic moment flipping. Thus, improving the interfacial spin mixing conductance and achieving efficient injection of spin current have important scientific significance and application value. Summary of the Invention

[0003] The first object of the present invention is to provide a preparation method of a YIG / W heterojunction with enhanced interfacial spin mixing conductance. Through annealing treatment, the β-phase W is transformed into α-phase W, the interfacial matching degree between the non-magnetic layer and the ferromagnetic layer is improved, and at the same time, the non-magnetic layer changes from a metastable state to a stable state, realizing the enhancement of the interfacial spin mixing conductance of the system.

[0004] The second object of the present invention is to provide a YIG / W heterojunction with enhanced interfacial spin mixing conductance.

[0005] The first technical solution adopted by the present invention is a preparation method of a YIG / W heterojunction with enhanced interfacial spin mixing conductance, including the following steps:

[0006] Step 1: Prepare a YIG thin film layer on a substrate;

[0007] Step 2: Prepare a W thin film layer on the YIG thin film layer prepared in Step 1 to obtain a YIG / W heterojunction;

[0008] Step 3: Anneal the YIG / W heterojunction obtained in Step 2.

[0009] The features of the present invention also lie in:

[0010] Specifically, Step 1 is:

[0011] Prepare a YIG thin film layer on a substrate by radio frequency magnetron sputtering. The base vacuum is 2*10-8 Torr - 5 * 10 - 8 Torr, the growth rate is 0.03 ± 0.01 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 20 nm - 100 nm; after preparation, the YIG thin film layer is annealed in an atmospheric atmosphere and then cooled in the furnace.

[0012] In step 1, the annealing temperature is 700 °C - 850 °C, and the annealing time is 5 minutes - 30 minutes.

[0013] In step 1, the substrate is gadolinium gallium garnet Gd3Ga5O 12 (GGG) with a thickness of 0.3 mm - 0.7 mm.

[0014] Step 2 is specifically as follows:

[0015] A W thin film layer (2) is prepared on the prepared YIG thin film layer by DC magnetron sputtering. The background vacuum before preparation is 2 * 10 -8 Torr - 5 * 10 -8 Torr, the growth rate is 0.07 ± 0.01 nm / s, the thickness is 7 nm - 15 nm, and the preparation temperature is room temperature.

[0016] Step 3 is specifically as follows:

[0017] The prepared YIG / W heterojunction is subjected to in-situ annealing treatment in a high-vacuum environment. The vacuum degree before heating is 2 * 10 -8 Torr - 5 * 10 -8 Torr, the annealing temperature range is 200 °C - 600 °C, and the annealing time is 0.5 hour - 2 hours.

[0018] The second technical solution adopted by the present invention is a YIG / W heterojunction with enhanced interfacial spin mixing conductance, which is prepared by the above method.

[0019] The features of the present invention further lie in:

[0020] It includes a substrate, a YIG thin film layer, and a W thin film layer arranged in sequence from bottom to top.

[0021] The beneficial effects of the present invention are:

[0022] (1) In the method of the present invention, YIG is a yttrium iron garnet ferromagnetic insulator, W is a non-magnetic metal, and spin current can be injected from the ferromagnetic layer into the non-magnetic layer. Its injection efficiency depends on the interfacial spin mixing conductance; the W layer is in the metastable β phase when prepared at room temperature and becomes the stable α phase after high-temperature annealing; the YIG / W heterojunction is annealed to transform the β-phase W into α-phase W. At the same time, the non-magnetic layer changes from the metastable state to the stable state, improving the interfacial chemical state stability and interfacial matching degree, so as to enhance the interfacial spin mixing conductance of the YIG / W heterojunction system.

[0023] (2) The YIG / W heterojunction with enhanced interfacial spin mixing conductance prepared by the method of the present invention is a double-layer heterojunction thin film, which does not require special processing technology and has a simple structure. This method also provides new ideas for improving the spin current injection efficiency in spintronic devices; by enhancing the interfacial spin mixing conductance, efficient transmission of spin current is achieved, and Joule heat is reduced with spin current as the information carrier, which is helpful for the research and development of electronic devices based on spin current-related effects and has important scientific significance and application value. Description of the Drawings

[0024] Figure 1 is a schematic diagram of the YIG / W heterojunction structure in the present invention;

[0025] Figure 2 is the XRD pattern of the YIG / W heterojunction thin film corresponding to Comparative Examples 1-2 and Examples 1-5 in the present invention;

[0026] Figure 3 is a schematic diagram of ferromagnetic resonance measurement in the present invention;

[0027] Figure 4 is the relationship between the resonance linewidth of the YIG / W heterojunction thin film corresponding to Comparative Examples 1-2 and Examples 1-5 in the present invention and the magnetic field angle;

[0028] Figure 5 is the relationship between the interfacial spin mixing conductance of the YIG / W heterojunction thin film corresponding to Comparative Examples 1-2 and Examples 1-5 in the present invention and the annealing temperature of the YIG / W heterojunction.

[0029] In the figure, 1. Substrate, 2. YIG thin film layer, 3. W thin film layer. Detailed Embodiments

[0030] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0031] The present invention provides a method for preparing a YIG / W heterojunction with enhanced interfacial spin mixing conductance, which includes the following steps:

[0032] Step 1: Prepare a YIG thin film layer 2 on a substrate 1;

[0033] Step 1 specifically includes:

[0034] The YIG thin film layer 2 is prepared on the substrate 1 by radio frequency magnetron sputtering method, with a base vacuum of 2×10 -8 Torr - 5×10 -8 Torr, a growth rate of 0.03±0.01 nm / s, a preparation temperature of room temperature, and the thickness of the YIG ferromagnetic layer is 20 nm - 100 nm; after preparation, the YIG thin film layer 2 is annealed in an atmospheric atmosphere and then cooled in the furnace.

[0035] In Step 1, the annealing temperature is 700°C - 850°C, and the annealing time is 5 minutes - 30 minutes.

[0036] In Step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O 12 (GGG) with an orientation of

[111] , and the thickness is 0.3 mm - 0.7 mm.

[0037] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0038] Step 2 specifically includes:

[0039] The W thin film layer 3 is prepared on the prepared YIG thin film layer 2 by direct current magnetron sputtering method. The base vacuum before preparation is 2×10 -8 Torr - 5×10 -8 Torr, a growth rate of 0.07±0.01 nm / s, a thickness of 7 nm - 15 nm, and a preparation temperature of room temperature.

[0040] Step 3: Anneal the YIG / W heterojunction obtained in Step 2.

[0041] Step 3 specifically includes:

[0042] The prepared YIG / W heterojunction is subjected to in-situ annealing treatment in a high vacuum environment. The vacuum degree before heating is 2×10 -8 Torr - 5×10 -8 Torr, the annealing temperature range is 200°C - 600°C, and the annealing time is 0.5 hour - 2 hours.

[0043] The present invention also provides a YIG / W heterojunction with enhanced interfacial spin mixing conductance, which is prepared by the above method.

[0044] As Figure 1 shown, the YIG / W heterojunction with enhanced interfacial spin mixing conductance includes a substrate 1, a YIG thin film layer 2, and a W thin film layer 3 arranged in sequence from bottom to top.

[0045] Reagents used in the following examples, equipment and models for sample preparation, structure and magnetic characterization:

[0046] Magnetron sputtering equipment: Kurt J. Lesker magnetron sputtering system (PVD 75Proline);

[0047] X-ray diffractometer: Rigaku, SmartLab SE;

[0048] Vibrating sample magnetometer: MicroSense, VSM-EZ9;

[0049] Tube annealing furnace: Hefei Kejing Materials Technology Co., Ltd., single-zone tube furnace OTF-1200X0S;

[0050] Ferromagnetic resonance measurement equipment: JEOL, Japan, model JES-FA300;

[0051] Reagents: YIG target, W target, GGG(111) single crystal substrate were all purchased from Hefei Kejing Materials Technology Co., Ltd.

[0052] Comparative Example 1

[0053] Step 1: Prepare a YIG thin film layer 2 on substrate 1;

[0054] Step 1 is specifically as follows:

[0055] A YIG thin film layer 2 was prepared on substrate 1 by radio frequency magnetron sputtering. The base vacuum was 5×10 -8 Torr, the growth rate was 0.03 nm / s, the preparation temperature was room temperature, and the thickness of the YIG ferromagnetic layer was 37 nm; after preparation, the YIG thin film layer 2 was annealed in an air atmosphere and then cooled with the furnace.

[0056] In Step 1, the annealing temperature was 750 °C and the annealing time was 10 minutes.

[0057] In Step 1, substrate 1 was gadolinium gallium garnet Gd3Ga5O with

[111] orientation 12 (GGG), with a thickness of 0.5 mm.

[0058] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0059] Step 2 is specifically as follows:

[0060] A W thin film layer 3 was prepared on the prepared YIG thin film layer 2 by DC magnetron sputtering. The base vacuum before preparation was 5×10 -8Torr, with a growth rate of 0.07 nm / s, a thickness of 10 nm, and a preparation temperature of room temperature.

[0061] Comparative Example 2

[0062] Step 1: Prepare a YIG thin film layer 2 on the substrate 1;

[0063] Step 1 is specifically as follows:

[0064] A YIG thin film layer 2 is prepared on the substrate 1 by radio frequency magnetron sputtering. The base vacuum is 5*10 -8 Torr, with a growth rate of 0.03 nm / s, a preparation temperature of room temperature, and the thickness of the YIG ferromagnetic layer is 37 nm; after preparation, the YIG thin film layer 2 is annealed in an air atmosphere and then cooled with the furnace.

[0065] In Step 1, the annealing temperature is 750 °C and the annealing time is 10 minutes.

[0066] In Step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O with a

[111] orientation 12 (GGG), with a thickness of 0.5 mm.

[0067] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0068] Step 2 is specifically as follows:

[0069] A W thin film layer 3 is prepared on the prepared YIG thin film layer 2 by direct current magnetron sputtering. The base vacuum before preparation is 5*10 -8 Torr, with a growth rate of 0.07 nm / s, a thickness of 10 nm, and a preparation temperature of room temperature.

[0070] Step 3 is specifically as follows:

[0071] The prepared YIG / W heterojunction is subjected to in-situ annealing treatment in a high vacuum environment. The vacuum degree before heating is 5*10 -8 Torr, the annealing temperature range is 100 °C, and the annealing time is 1 hour.

[0072] Example 1

[0073] Step 1: Prepare a YIG thin film layer 2 on the substrate 1;

[0074] Step 1 is specifically as follows:

[0075] A YIG thin film layer 2 is prepared on the substrate 1 by radio frequency magnetron sputtering. The base vacuum is 5*10 -8Torr, the growth rate is 0.03 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 37 nm; after preparation, the YIG thin film layer 2 is annealed in an atmospheric atmosphere and then cooled in the furnace.

[0076] In step 1, the annealing temperature is 750 °C and the annealing time is 10 minutes.

[0077] In step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O with a

[111] orientation 12 (GGG), with a thickness of 0.5 mm.

[0078] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in step 1 to obtain a YIG / W heterojunction;

[0079] Step 2 is specifically as follows:

[0080] The W thin film layer 3 is prepared on the prepared YIG thin film layer 2 by DC magnetron sputtering. The background vacuum before preparation is 5×10 -8 Torr, the growth rate is 0.07 nm / s, the thickness is 10 nm, and the preparation temperature is room temperature.

[0081] Step 3 is specifically as follows:

[0082] The prepared YIG / W heterojunction is subjected to in-situ annealing treatment in a high-vacuum environment. The vacuum degree before heating is 5×10 -8 Torr, the annealing temperature range is 200 °C, and the annealing time is 1 hour.

[0083] Example 2

[0084] Step 1: Prepare a YIG thin film layer 2 on the substrate 1;

[0085] Step 1 is specifically as follows:

[0086] The YIG thin film layer 2 is prepared on the substrate 1 by radio frequency magnetron sputtering. The background vacuum is 5×10 -8 Torr, the growth rate is 0.03 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 37 nm; after preparation, the YIG thin film layer 2 is annealed in an atmospheric atmosphere and then cooled in the furnace.

[0087] In step 1, the annealing temperature is 750 °C and the annealing time is 10 minutes.

[0088] In step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O with a

[111] orientation 12 (GGG), with a thickness of 0.5 mm.

[0089] Step 2: Deposit a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0090] Specifically, Step 2 is as follows:

[0091] Deposit the W thin film layer 3 on the prepared YIG thin film layer 2 by DC magnetron sputtering. The background vacuum before deposition is 5×10 -8 Torr, the growth rate is 0.07 nm / s, the thickness is 10 nm, and the deposition temperature is room temperature.

[0092] Specifically, Step 3 is as follows:

[0093] Anneal the prepared YIG / W heterojunction in situ under a high-vacuum environment. The vacuum degree before heating is 5×10 -8 Torr, the annealing temperature range is 300 °C, and the annealing time is 1 hour.

[0094] Example 3

[0095] Step 1: Deposit a YIG thin film layer 2 on a substrate 1;

[0096] Specifically, Step 1 is as follows:

[0097] Deposit the YIG thin film layer 2 on the substrate 1 by RF magnetron sputtering. The background vacuum is 5×10 -8 Torr, the growth rate is 0.03 nm / s, the deposition temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 37 nm. After preparation, anneal the YIG thin film layer 2 in an air atmosphere and then cool it in the furnace.

[0098] In Step 1, the annealing temperature is 750 °C and the annealing time is 10 minutes.

[0099] In Step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O 12 (GGG) with an orientation of

[111] and a thickness of 0.5 mm.

[0100] Step 2: Deposit a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0101] Specifically, Step 2 is as follows:

[0102] Deposit the W thin film layer 3 on the prepared YIG thin film layer 2 by DC magnetron sputtering. The background vacuum before deposition is 5×10 -8 Torr, the growth rate is 0.07 nm / s, the thickness is 10 nm, and the deposition temperature is room temperature.

[0103] Specifically, Step 3 is as follows:

[0104] The prepared YIG / W heterojunction was subjected to in-situ annealing treatment in a high-vacuum environment. The vacuum degree before heating was 5*10 -8 Torr, the annealing temperature range was 400 °C, and the annealing time was 1 hour.

[0105] Example 4

[0106] Step 1: Prepare a YIG thin film layer 2 on the substrate 1;

[0107] Step 1 is specifically as follows:

[0108] A YIG thin film layer 2 was prepared on the substrate 1 by radio frequency magnetron sputtering. The base vacuum was 5*10 -8 Torr, the growth rate was 0.03 nm / s, the preparation temperature was room temperature, and the thickness of the YIG ferromagnetic layer was 37 nm; after preparation, the YIG thin film layer 2 was annealed in an atmospheric atmosphere and then cooled in the furnace.

[0109] In Step 1, the annealing temperature was 750 °C and the annealing time was 10 minutes.

[0110] In Step 1, the substrate 1 was gadolinium gallium garnet Gd3Ga5O with a

[111] orientation 12 (GGG), with a thickness of 0.5 mm.

[0111] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0112] Step 2 is specifically as follows:

[0113] A W thin film layer 3 was prepared on the prepared YIG thin film layer 2 by direct current magnetron sputtering. The base vacuum before preparation was 5*10 -8 Torr, the growth rate was 0.07 nm / s, the thickness was 10 nm, and the preparation temperature was room temperature.

[0114] Step 3 is specifically as follows:

[0115] The prepared YIG / W heterojunction was subjected to in-situ annealing treatment in a high-vacuum environment. The vacuum degree before heating was 5*10 -8 Torr, the annealing temperature range was 500 °C, and the annealing time was 1 hour.

[0116] Example 5

[0117] Step 1: Prepare a YIG thin film layer 2 on the substrate 1;

[0118] Step 1 is specifically as follows:

[0119] A YIG thin film layer 2 was prepared on the substrate 1 by radio frequency magnetron sputtering. The base vacuum was 5*10 -8Torr, the growth rate is 0.03 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 37 nm. After preparation, the YIG thin film layer 2 is annealed in an atmospheric atmosphere and then cooled in the furnace.

[0120] In step 1, the annealing temperature is 750 °C and the annealing time is 10 minutes.

[0121] In step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O 12 (GGG) with a thickness of 0.5 mm.

[0122] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in step 1 to obtain a YIG / W heterojunction;

[0123] Step 2 is specifically as follows:

[0124] The W thin film layer 3 is prepared on the prepared YIG thin film layer 2 by DC magnetron sputtering. The background vacuum before preparation is 5×10 -8 Torr, the growth rate is 0.07 nm / s, the thickness is 10 nm, and the preparation temperature is room temperature.

[0125] Step 3 is specifically as follows:

[0126] The prepared YIG / W heterojunction is subjected to in-situ annealing treatment in a high-vacuum environment. The vacuum degree before heating is 5×10 -8 Torr, the annealing temperature range is 600 °C, and the annealing time is 1 hour.

[0127] The sample information obtained from Comparative Examples 1-2 and Examples 3-6 is shown in the following table:

[0128] Sample serial number Sample composition Annealing temperature Comparative example 1 YIG / β-W Not annealed Comparative example 2 YIG / β-W 100 Example 1 YIG / α-W 200 Example 2 YIG / α-W 300 Example 3 YIG / α-W 400 Example 4 YIG / α-W 500 Example 5 YIG / α-W 600

[0129] In the heterojunction thin film materials prepared from Comparative Examples 1-2 and Examples 1-5, the crystal structure of the W layer changes with the annealing temperature. As Figure 2 shown in the X-ray diffraction (XRD) pattern of the thin film material, it can be seen that the characteristic peaks of β-W appear in both unannealed W and W annealed at 100 °C, namely the β-W(200) peak, the β-W(210) peak, and the β-W(211) peak. As the annealing temperature increases to 200 °C, all the characteristic peaks of β-W disappear, and the characteristic peak of α-W(110) appears instead. It can be seen that after high-temperature annealing at at least 200 °C or above, the crystal structure of the W thin film can be transformed from the β phase to the α phase.

[0130] Measurement of interfacial spin - mixing conductance: For the heterojunction thin - film materials prepared in Comparative Examples 1 - 2 and Examples 1 - 5, their interfacial spin - mixing conductance gradually increases with the increase of the annealing temperature of the YIG / W heterojunction. The interfacial spin - mixing conductance of this series of samples is calculated using the following formula:

[0131]

[0132] where the gyromagnetic ratio γ = 17.56 GHz / kOe, the saturation magnetization M s = 116 emu / cm 3 , the thickness t FM of the YIG thin - film layer = 37 nm, the Landé g - factor g = 2.0, μ B is the Bohr magneton, the angular frequency ω = 2πf, f is the microwave frequency 9.37 GHz, and all of the above are known quantities. ΔH FM / NM and ΔH FM are the resonance linewidths of the heterojunction and the ferromagnetic single - layer film respectively, which are the key factors determining the interfacial spin - mixing conductance.

[0133] The interfacial spin - mixing conductance is proportional to the difference between the resonance linewidth of the YIG / W bilayer film and the resonance linewidth of the YIG single - layer film. In order to accurately obtain the interfacial spin - mixing conductance, the resonance linewidths of the YIG / W heterojunction and the YIG single - layer film at different in - plane angles are measured, and their respective average values are taken to calculate the interfacial spin - mixing conductance.

[0134] The schematic diagram of the resonance linewidth measurement is as shown in Figure 3 . The measurement process is as follows: At room temperature, the sample is placed in a cylindrical resonant cavity and located at the center of the magnetic field. Microwaves of a certain frequency enter the resonant cavity to maintain the resonant state of the cavity, and the resonant cavity is in the TE 011 mode. In the experiment, the microwave frequency is f = 9.37 GHz. By changing the magnitude of the external magnetic field, ferromagnetic resonance of the sample occurs, and thus the resonance linewidth is measured. An in - plane magnetic field is applied in different directions of the thin film, and the ferromagnetic resonance spectra are measured to obtain the resonance linewidths at different magnetic field angles. The average resonance linewidth ΔH FM of YIG is measured to be 8.6 Oe. The variation relationships of the resonance linewidths of Comparative Examples 1 - 2 and Examples 1 - 5 with the magnetic field angle are as shown in Figure 4 . The average resonance linewidths are 13.5 Oe, 14.0 Oe, 15.6 Oe, 17.2 Oe, 21.3 Oe, 25.3 Oe, 27.8 Oe respectively. The finally calculated results of the interfacial spin - mixing conductance are as shown in Figure 5As shown, it can be clearly seen that as the annealing temperature of the YIG / W heterojunction increases, the interfacial spin mixing conductance gradually increases. This is because as the annealing temperature increases, the metastable β-W gradually transforms into the stable α-W, and at the same time, the interfacial chemical state of YIG / W becomes more stable with the increase of the annealing temperature, which is more conducive to the transmission of spin current at the interface.

[0135] Example 6

[0136] A preparation method of a YIG / W heterojunction with enhanced interfacial spin mixing conductance includes the following steps:

[0137] Step 1: Prepare a YIG thin film layer 2 on a substrate 1;

[0138] Specifically, Step 1 is as follows:

[0139] Prepare a YIG thin film layer 2 on the substrate 1 by radio frequency magnetron sputtering. The base vacuum is 2×10 -8 Torr, the growth rate is 0.02 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 20 nm; after preparation, the YIG thin film layer 2 is annealed in an air atmosphere and then cooled in the furnace.

[0140] In Step 1, the annealing temperature is 700 °C and the annealing time is 5 minutes.

[0141] In Step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O 12 (GGG) with an orientation of

[111] and a thickness of 0.3 mm.

[0142] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0143] Specifically, Step 2 is as follows:

[0144] Prepare a W thin film layer 3 on the prepared YIG thin film layer 2 by direct current magnetron sputtering. The base vacuum before preparation is 2×10 -8 Torr - 5×10 -8 Torr, the growth rate is 0.07 nm / s, the thickness is 7 nm, and the preparation temperature is room temperature.

[0145] Step 3: Anneal the YIG / W heterojunction obtained in Step 2.

[0146] Specifically, Step 3 is as follows:

[0147] The prepared YIG / W heterojunction is subjected to in-situ annealing treatment in a high-vacuum environment. The vacuum degree before heating is 2×10 -8 Torr, the annealing temperature range is 200 °C, and the annealing time is 0.5 hours.

[0148] Example 7

[0149] A method for preparing a YIG / W heterojunction with enhanced interfacial spin - mixing conductance includes the following steps:

[0150] Step 1: Prepare a YIG thin - film layer 2 on a substrate 1;

[0151] Step 1 is specifically as follows:

[0152] Prepare the YIG thin - film layer 2 on the substrate 1 by radio - frequency magnetron sputtering. The base vacuum is 5×10 -8 Torr, the growth rate is 0.04 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 100 nm. After preparation, anneal the YIG thin - film layer 2 in an air atmosphere and then cool it in the furnace.

[0153] In step 1, the annealing temperature is 850 °C and the annealing time is 30 minutes.

[0154] In step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O 12 (GGG) with a thickness of 0.7 mm.

[0155] Step 2: Prepare a W thin - film layer 3 on the YIG thin - film layer 2 prepared in step 1 to obtain a YIG / W heterojunction;

[0156] Step 2 is specifically as follows:

[0157] Prepare the W thin - film layer 3 on the prepared YIG thin - film layer 2 by direct - current magnetron sputtering. The base vacuum before preparation is 5×10 -8 Torr, the growth rate is 0.08 nm / s, the thickness is 15 nm, and the preparation temperature is room temperature.

[0158] Step 3: Anneal the YIG / W heterojunction obtained in step 2.

[0159] Step 3 is specifically as follows:

[0160] In - situ anneal the prepared YIG / W heterojunction in a high - vacuum environment. The vacuum degree before heating is 5×10 -8 Torr, the annealing temperature range is 600 °C, and the annealing time is 2 hours.

[0161] Example 8

[0162] A method for preparing a YIG / W heterojunction with enhanced interfacial spin - mixing conductance includes the following steps:

[0163] Step 1: Prepare a YIG thin - film layer 2 on a substrate 1;

[0164] Step 1 is specifically as follows:

[0165] On the substrate 1, a YIG thin film layer 2 is prepared by radio frequency magnetron sputtering method. The base vacuum is 4×10 -8 Torr, the growth rate is 0.03 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 80 nm. After preparation, the YIG thin film layer 2 is annealed in an atmospheric atmosphere and then cooled in the furnace.

[0166] In Step 1, the annealing temperature is 800 °C and the annealing time is 20 minutes.

[0167] In Step 1, the substrate 1 is gadolinium gallium garnet Gd3Ga5O with a

[111] orientation 12 (GGG), and the thickness is 0.5 mm.

[0168] Step 2: Prepare a W thin film layer 3 on the YIG thin film layer 2 prepared in Step 1 to obtain a YIG / W heterojunction;

[0169] Step 2 is specifically as follows:

[0170] A W thin film layer 3 is prepared on the prepared YIG thin film layer 2 by direct current magnetron sputtering method. The base vacuum before preparation is 4×10 -8 Torr, the growth rate is 0.07 nm / s, the thickness is 9 nm, and the preparation temperature is room temperature.

[0171] Step 3: Anneal the YIG / W heterojunction obtained in Step 2.

[0172] Step 3 is specifically as follows:

[0173] The prepared YIG / W heterojunction is subjected to in-situ annealing treatment in a high vacuum environment. The vacuum degree before heating is 4×10 -8 Torr, the annealing temperature range is 400 °C, and the annealing time is 1 hour.

Claims

1. Preparation method of YIG / W heterojunction with enhanced interfacial spin mixing conductance, characterized in that, It includes the following steps: Step 1: Prepare a YIG thin film layer (2) on a substrate (1); Step 2: Prepare a W thin film layer (3) on the YIG thin film layer (2) prepared in Step 1 to obtain a YIG / W heterojunction; Step 3: Anneal the YIG / W heterojunction obtained in Step 2.

2. The preparation method of the YIG / W heterojunction with enhanced interfacial spin mixing conductance according to claim 1, characterized in that, Specifically, Step 1 is as follows: The YIG thin film layer (2) is prepared on the substrate (1) by radio frequency magnetron sputtering method. The base vacuum is 2*10 -8 Torr - 5*10 - 8 Torr, the growth rate is 0.03 ± 0.01 nm / s, the preparation temperature is room temperature, and the thickness of the YIG ferromagnetic layer is 20 nm - 100 nm. After preparation, the YIG thin film layer (2) is annealed in an atmospheric atmosphere and then cooled in the furnace.

3. The preparation method of the YIG / W heterojunction with enhanced interfacial spin mixing conductance according to claim 2, wherein, In Step 1, the annealing temperature is 700°C - 850°C, and the annealing time is 5 minutes - 30 minutes.

4. The preparation method of the YIG / W heterojunction with enhanced interfacial spin mixing conductance according to claim 1, characterized in that, In Step 1, the substrate (1) is a [111]-oriented gadolinium gallium garnet Gd3Ga5O 12 , with a thickness of 0.3 mm to 0.7 mm.

5. The preparation method of the YIG / W heterojunction with enhanced interfacial spin mixing conductance according to claim 1, characterized in that, Specifically, Step 2 is as follows: The W thin film layer (3) is prepared on the prepared YIG thin film layer (2) by DC magnetron sputtering. The background vacuum before preparation is 2×10 -8 Torr - 5×10 -8 Torr, the growth rate is 0.07 ± 0.01 nm / s, the thickness is 7 nm - 15 nm, and the preparation temperature is room temperature.

6. The preparation method of the YIG / W heterojunction with enhanced interfacial spin mixing conductance according to claim 1, characterized in that, Specifically, Step 3 is as follows: The prepared YIG / W heterojunction was subjected to in-situ annealing treatment in a high-vacuum environment. The vacuum degree before heating was 2×10 - 8 Torr - 5×10 -8 Torr. The annealing temperature range was 200°C - 600°C, and the annealing time was 0.5 hour - 2 hours.

7. A YIG / W heterojunction with enhanced interfacial spin mixing conductance, characterized in that, It is prepared by using the method described in any one of claims 1 - 6.

8. The YIG / W heterojunction with enhanced interfacial spin mixing conductance according to claim 7, characterized in that, It includes a substrate (1), a YIG thin film layer (2), and a W thin film layer (3) which are sequentially arranged from bottom to top.

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