A method for regulating spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction

Abstract

The present invention provides a method for regulating the spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction, including: introducing an antiferromagnetic insulating layer between the ferromagnetic metal layer and the substrate without changing the heavy metal material and without damaging the ferromagnetic / heavy metal interface, and regulating the reflection and absorption of the spin current of the ferromagnetic / heavy metal heterojunction by regulating the direction of the Néel vector of the antiferromagnetic insulating layer, so as to change the magnitude and sign of the spin Hall magnetoresistance.

Description

Technical Field

[0001] The present invention relates to the field of novel magnetoresistance technology, and in particular to a method for regulating the spin Hall magnetoresistance of ferromagnetic / heavy metal heterojunctions. Background Art

[0002] SMR is a novel magnetoresistance effect discovered in ferromagnetic / heavy metal heterojunction structures. Using SMR, the magnitude of the spin Hall angle of the heavy metal layer can be effectively extracted, and magnetic property parameters such as the magnetic anisotropy and interface magnetic structure of magnetic materials can be detected. In addition, the ferromagnetic / heavy metal heterojunction is the core structural unit for constructing the third-generation magnetic random access memory, and has very important research significance and potential application value in spintronics.

[0003] The so-called SMR is a magnetoresistance effect related to the magnetic moment direction of the ferromagnetic layer proposed based on the spin Hall effect (SHE) and inverse spin Hall effect (ISHE) of heavy metals. The principle is as follows: when an electric current flows through a heavy metal material, due to the spin Hall effect of the heavy metal material, a spin current perpendicular to the current direction will be generated. By adjusting the magnetic moment direction of the adjacent ferromagnetic layer, the magnitude of the spin current injected into the ferromagnetic layer can be regulated. When the polarization vector of the spin current is perpendicular to the magnetic moment of the adjacent ferromagnetic layer, the spin current will be almost completely absorbed by the ferromagnetic layer; when the polarization vector of the spin current is collinear with the magnetic moment of the adjacent ferromagnetic layer, most of the spin current will be reflected by the ferromagnetic layer. According to the inverse spin Hall effect, the net spin current in the heavy metal will induce a charge current in the opposite direction. Therefore, when the polarization vector of the spin current is perpendicular to the adjacent ferromagnetic layer, a larger additional current is generated, and the resistance of the heavy metal layer exhibits a high-resistance state; when the polarization vector of the spin current is parallel to the adjacent ferromagnetic layer, a smaller additional current is generated, and the resistance of the heavy metal layer exhibits a low-resistance state. The resistivity of the heavy metal layer and the magnetic moment direction of the adjacent ferromagnetic layer satisfy the following dependence relationship of formula (1):

[0004] ; (1)

[0005] wherein, is the resistivity independent of the magnetic moment direction, is the unit magnetic moment vector. SMR was first observed in the Pt / yttrium iron garnet (Y3Fe5O 12 , YIG) heterojunction, and was later confirmed in ferromagnetic / heavy metal and antiferromagnetic / heavy metal heterojunctions.

[0006] Ferromagnetic / heavy metal heterojunctions usually exhibit a positive spin Hall magnetoresistance effect. When the ferromagnetic metal exceeds a certain critical thickness, a negative spin Hall magnetoresistance effect appears due to the size effect. Controlling the spin Hall magnetoresistance of ferromagnetic / heavy metal heterojunctions is one of the important research contents in spintronics.

[0007] Currently, there are mainly two methods to control the spin Hall magnetoresistance of ferromagnetic / heavy metal heterojunctions: One is to replace the traditional single-component heavy metal material with a heavy metal alloy with a strong spin-orbit coupling effect, and regulate the alloy composition to optimize the conversion efficiency of spin current in the heavy metal layer, thereby increasing the spin Hall magnetoresistance of the heterojunction. Although this method can improve the conversion efficiency of spin current, it is very sensitive to the composition of heavy metals and has a high cost, and it cannot achieve the control of the sign of the spin Hall magnetoresistance of ferromagnetic / heavy metal heterojunctions. The other is to insert an ultrathin intermediate layer at the ferromagnetic metal / heavy metal interface to control the transmission efficiency of spin current at the ferromagnetic metal / heavy metal interface, thereby achieving the control of the spin Hall magnetoresistance. Although this method can achieve the control of the sign of the spin Hall magnetoresistance, it cannot effectively increase the spin Hall magnetoresistance of the heterojunction, and this method actually destroys the original ferromagnetic / heavy metal interface.

[0008] Therefore, how to control the spin Hall magnetoresistance in the heterojunction without changing the heavy metal material and the ferromagnetic / heavy metal interface is one of the major challenges faced by the current spintronics field. Summary of the Invention

[0009] In view of this, embodiments of the present invention provide a method for controlling the spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction to eliminate or improve one or more defects existing in the prior art.

[0010] On the one hand, the present invention provides a method for controlling the spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction, and the method includes the following steps:

[0011] Put the pretreated substrate into the cavity of the first deposition system, and deposit a thin film on the substrate as an antiferromagnetic insulating layer based on the first preset deposition method; by setting the deposition parameters, control the thickness of the antiferromagnetic insulating layer. When the thickness of the antiferromagnetic insulating layer is less than the preset critical thickness, its Néel vector is perpendicular to the surface of the substrate, and when the thickness of the antiferromagnetic insulating layer is not less than the preset critical thickness, its Néel vector is parallel to the surface of the substrate;

[0012] Transfer the deposited antiferromagnetic insulating layer to the cavity of the second deposition system, and deposit a ferromagnetic metal / heavy metal heterojunction of a preset material with the epitaxially grown antiferromagnetic insulating layer as the bottom layer to obtain a multi-layer film structure sequentially from bottom to top as the antiferromagnetic insulating layer, the ferromagnetic metal layer, and the heavy metal layer;

[0013] By regulating the direction of the Néel vector of the antiferromagnetic insulating layer, the reflection and absorption of the spin current in the ferromagnetic / heavy metal heterojunction are regulated to change the magnitude and sign of the spin Hall magnetoresistance.

[0014] In some embodiments of the present invention, the antiferromagnetic insulating layer is made of an antiferromagnetic insulating oxide material, which at least includes nickel oxide, cobalt oxide, and chromium sesquioxide; the ferromagnetic metal layer is made of a magnetic metal material, which at least includes cobalt, cobalt iron boron alloy, cobalt iron alloy, and nickel iron alloy; the heavy metal layer is made of a heavy metal material, which at least includes platinum, tantalum, palladium, gold platinum alloy, and palladium platinum alloy.

[0015] In some embodiments of the present invention, the substrate is a single crystal magnesium oxide with a 001 orientation, and the substrate is cleaned to remove possible organic contamination and particles.

[0016] In some embodiments of the present invention, the first preset deposition method at least includes pulsed laser deposition, magnetron sputtering, and molecular beam epitaxy; when using the pulsed laser deposition method, the method further includes:

[0017] Put the pretreated substrate into the chamber of the first deposition system, use pulsed laser to strike the target, and deposit it on the substrate to form a thin film as the antiferromagnetic insulating layer; the thickness of the antiferromagnetic insulating layer is controlled by setting the number of pulses of the pulsed laser.

[0018] Among them, the deposition conditions include pumping the chamber of the first deposition system to a vacuum state, the repetition frequency of the pulsed laser is 1-5 Hz, the pulse energy is 300-350 mJ, the average power is 280-400 mW, and the voltage is 18-24 kV.

[0019] In some embodiments of the present invention, before transferring the deposited antiferromagnetic insulating layer to the chamber of the second deposition system, it further includes:

[0020] After the laser strike is completed, wait for the temperature in the chamber of the first deposition system to cool naturally to room temperature before transferring to ensure the stability of the deposited thin film.

[0021] In some embodiments of the present invention, the second preset deposition method at least includes pulsed laser deposition, magnetron sputtering, and molecular beam epitaxy; when using the magnetron sputtering method, its deposition conditions include:

[0022] Pump the chamber of the second deposition system to a vacuum state, the vacuum degree is 2.0×10 -5 Pa, the deposition temperature is room temperature, argon is introduced, and the argon gas pressure is maintained at 0.4-1.2 Pa.

[0023] In some embodiments of the present invention, a multilayer film structure including, from bottom to top, the antiferromagnetic insulating layer, the ferromagnetic metal layer, and the heavy metal layer is obtained, and it includes:

[0024] The thickness of the ferromagnetic metal layer is 0.6 - 6.5 nm, and the thickness of the heavy metal layer is 1 - 10 nm.

[0025] In some embodiments of the present invention, after obtaining the multilayer film structure including, from bottom to top, the antiferromagnetic insulating layer, the ferromagnetic metal layer, and the heavy metal layer:

[0026] Characterize the multilayer film structure, and use one or more of X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy to verify the thin film, including at least the structure, thickness, and lattice arrangement of the thin film.

[0027] In some embodiments of the present invention, when the multilayer film structure is obtained and the thickness of the antiferromagnetic insulating layer of the multilayer film structure is less than a preset critical thickness:

[0028] Measure the multilayer film structure at a temperature of 5K - 400K. At low temperatures, a negative spin Hall magnetoresistance is presented; as the temperature increases, the spin Hall magnetoresistance changes from negative to positive.

[0029] In some embodiments of the present invention, when the multilayer film structure is obtained and the thickness of the antiferromagnetic insulating layer of the multilayer film structure is not less than a preset critical thickness:

[0030] Measure the multilayer film structure at a temperature of 5K - 400K. The spin Hall magnetoresistance always remains positive; as the temperature increases, the spin Hall magnetoresistance gradually tends to saturation and becomes stable near room temperature; when the temperature is further increased to 400K, the spin Hall magnetoresistance decreases.

[0031] The present invention provides a method for regulating the spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction, including: introducing an antiferromagnetic insulating layer between the ferromagnetic metal layer and the substrate without changing the heavy metal material and without damaging the ferromagnetic / heavy metal interface, and regulating the reflection and absorption of the spin current of the ferromagnetic / heavy metal heterojunction by regulating the direction of the Néel vector of the antiferromagnetic insulating layer, so as to change the magnitude and sign of the spin Hall magnetoresistance. The method provided by the present invention can regulate both the magnitude and the sign of the spin Hall magnetoresistance, which provides important guiding significance for the design of spin Hall magnetoresistance sensors and new magnetic random access memories.

[0032] Additional advantages, objects, and features of the present invention will be partly set forth in the description which follows, and will partly become obvious to those of ordinary skill in the art upon examination of the following, or may be learned by practice of the present invention. The objects and other advantages of the present invention may be realized and attained by the structure particularly pointed out in the specification and the drawings.

[0033] Those skilled in the art will understand that the objects and advantages that can be achieved by the present invention are not limited to those specifically described above, and the above and other objects that the present invention can achieve will be more clearly understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are for further understanding of the present invention, form a part of this application, and do not limit the present invention. In the drawings:

[0035] Figure 1 It is a schematic diagram of the steps of a method for regulating the spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction in an embodiment of the present invention.

[0036] Figure 2 It is a schematic diagram of the principle of a method for regulating the spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction in an embodiment of the present invention.

[0037] Figure 3 It is a measurement data graph of the angular magnetoresistance of a NiO (thin) / Co / Pt heterojunction at a temperature of 5K to 400K in an embodiment of the present invention.

[0038] Figure 4 It is a measurement data graph of the angular magnetoresistance of a NiO (thick) / Co / Pt heterojunction at a temperature of 5K to 400K in an embodiment of the present invention.

[0039] Figure 5 It is a measurement data graph of the angular magnetoresistance of a NiO (zero thickness) / Co / Pt heterojunction at a temperature of 5K to 400K in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] To make the objects, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention.

[0041] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, and other details less related to the present invention are omitted.

[0042] It should be emphasized that when the term "comprising / including" is used herein, it refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0043] Here, it should also be noted that if not otherwise specified, the term "connected" in this text can not only refer to direct connection, but also represent indirect connection with an intermediate.

[0044] In the following, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0045] It should be emphasized here that the step marks mentioned hereinafter do not limit the sequence of each step. Instead, it should be understood that the steps can be executed in the order mentioned in the embodiments, or different from the order in the embodiments, or several steps can be executed simultaneously.

[0046] To solve the problem that the existing methods for regulating the spin Hall magnetoresistance of ferromagnetic / heavy metal heterojunctions need to change the heavy metal material or damage the original ferromagnetic / heavy metal interface, the present invention provides a method for regulating the spin Hall magnetoresistance of ferromagnetic / heavy metal heterojunctions. Without changing the heavy metal material and the ferromagnetic / heavy metal interface, a buffer layer is introduced between the ferromagnetic metal layer and the substrate. This buffer layer is an oxide insulating material with antiferromagnetic properties, which is called an antiferromagnetic insulating layer in the present invention. Its spin structure can be regulated by substrate stress, local electric field, and spin current. By regulating the absorption and reflection of spin current at the antiferromagnetic insulating layer / ferromagnetic layer interface, modulation of the spin Hall magnetoresistance of ferromagnetic / heavy metal can be achieved. As Figure 1 shown, the method includes the following steps S101 to S103:

[0047] Step S101: Place the pretreated substrate into the cavity of the first deposition system. Based on the first preset deposition method, deposit a thin film on the substrate as the antiferromagnetic insulating layer. By setting the deposition parameters, control the thickness of the antiferromagnetic insulating layer. When the thickness of the antiferromagnetic insulating layer is less than the preset critical thickness, its Néel vector is perpendicular to the substrate surface. When the thickness of the antiferromagnetic insulating layer is not less than the preset critical thickness, its Néel vector is parallel to the substrate surface.

[0048] Step S102: Transfer the deposited antiferromagnetic insulating layer to the cavity of the second deposition system. Based on the second preset deposition method, use the epitaxially grown antiferromagnetic insulating layer as the bottom layer, and deposit a ferromagnetic metal / heavy metal heterojunction of a preset material to obtain a multi-layer film structure including, from bottom to top, an antiferromagnetic insulating layer, a ferromagnetic metal layer, and a heavy metal layer.

[0049] Step S103: By regulating the direction of the Néel vector of the antiferromagnetic insulating layer, the reflection and absorption of the spin current in the ferromagnetic / heavy-metal heterojunction are regulated to change the magnitude and sign of the spin Hall magnetoresistance.

[0050] In step S101, the substrate is first pre-treated.

[0051] In some embodiments, the substrate is a single crystal of magnesium oxide (MgO) with a 001 orientation. Herein, "001 orientation" refers to a specific crystal plane direction of the crystal, and "001" represents the crystal plane parallel to the z-axis and perpendicular to the x and y axes.

[0052] In some embodiments, the substrate is cleaned to remove possible organic contamination and particles. The cleaning method may include using solvents (such as isopropyl alcohol or acetone, etc.) and ultrasonic cleaning.

[0053] Then, the pre-treated substrate is placed into the chamber of the first deposition system, and a thin film is deposited on the substrate based on the first preset deposition method to serve as the antiferromagnetic insulating layer.

[0054] In some embodiments, the first preset deposition method includes at least pulsed laser deposition, magnetron sputtering, and molecular beam epitaxy.

[0055] In some embodiments, when using pulsed laser deposition (PLD), the pre-treated substrate is placed into the chamber of the first deposition system, and a pulsed laser is used to strike the target, and the deposition on the substrate forms a thin film to serve as the antiferromagnetic insulating layer.

[0056] When using pulsed laser deposition, the deposition conditions include: evacuating the chamber of the first deposition system (pulsed laser deposition system) to a vacuum state, and controlling the thin film quality by setting appropriate deposition parameters, including: the repetition frequency of the pulsed laser is 1 - 5 Hz, the pulse energy is 300 - 350 mJ, the average power is 280 - 400 mW, and the voltage is 18 - 24 kV.

[0057] In some embodiments, the antiferromagnetic insulating layer is an antiferromagnetic insulating oxide such as nickel oxide (NiO), cobalt oxide (CoO), or chromium sesquioxide (Cr2O3). Taking nickel oxide and pulsed laser deposition as an example, during the deposition process, a pulsed laser is used to strike the nickel oxide target according to the preset deposition parameters to generate high-energy plasma, and the materials in the nickel oxide target evaporate and deposit on the substrate to form a thin film, obtaining the antiferromagnetic insulating layer.

[0058] The thickness of the thin film (antiferromagnetic insulating layer) is precisely controlled by setting the number of pulses of the pulsed laser. Specifically: for a relatively thin antiferromagnetic insulating layer (thickness less than the preset critical thickness), due to the stress effect of the substrate, its Néel vector (spin direction) will be perpendicular to the substrate surface; while for a relatively thick antiferromagnetic insulating layer (thickness not less than the preset critical thickness), due to the stress relaxation phenomenon, its Néel vector tends to be parallel to the substrate surface.

[0059] In step S102, the deposited antiferromagnetic insulating layer is transferred into the cavity of the second deposition system, and a ferromagnetic metal / heavy metal heterojunction of the preset material is deposited based on the second preset deposition method.

[0060] In some embodiments, in step S101, the pulsed laser deposition method is used. After the laser strike is completed, the transfer is carried out after the temperature in the pulsed laser deposition system cavity naturally cools to room temperature to ensure the stability of the deposited thin film.

[0061] In some embodiments, for the ferromagnetic metal layer, the preset material can be a magnetic metal material such as cobalt (Co), cobalt iron boron alloy (CoFeB), cobalt iron alloy (CoFe), or nickel iron alloy (NiFe); for the heavy metal layer, the preset material can be a heavy metal material such as platinum (Pt), tantalum (Ta), palladium (Pd), gold platinum alloy (AuPt), or palladium platinum alloy (PdPt).

[0062] In some embodiments, the second preset deposition method includes at least the pulsed laser deposition method, the magnetron sputtering method, the molecular beam epitaxy method, etc. When using the magnetron sputtering method, its deposition conditions include: pumping the cavity of the second deposition system (magnetron sputtering coating) to a vacuum state. Preferably, the vacuum degree is 2.0×10 -5 Pa, the deposition temperature is room temperature, and the deposition conditions are controlled by adjusting the atmosphere of the sputtering system. For example, argon (Ar) is used as the atmosphere, and the argon gas pressure is controlled to be 0.4~1.2 Pa.

[0063] In some embodiments, the thickness of the deposited ferromagnetic metal layer is 0.6~6.5 nm, and the thickness of the heavy metal layer is 1~10 nm.

[0064] After the deposition is completed, a multilayer film structure composed of an antiferromagnetic insulating layer, a ferromagnetic metal layer, and a heavy metal layer in sequence from bottom to top is obtained. Taking the antiferromagnetic insulating layer using nickel oxide (NiO) material, the ferromagnetic metal layer using cobalt (Co) material, and the heavy metal layer using platinum (Pt) material as an example, a NiO / Co (ferromagnetic) / Pt (heavy metal) multilayer film heterojunction can be obtained.

[0065] In step S103, by regulating the direction of the Néel vector of the antiferromagnetic insulating layer, the reflection and absorption of the spin current of the ferromagnetic / heavy metal heterojunction are regulated to change the magnitude and sign of the spin Hall magnetoresistance.

[0066] For the sake of easy understanding, the principle of the method of the present invention is further described.

[0067] As Figure 2 shown, the multi-layer film structure proposed by the present invention is, from bottom to top, an antiferromagnetic insulating layer (AFMI), a ferromagnetic metal layer (FMM), and a heavy metal layer (HM). Among them, in Figures (a) and (b), the Néel vector of the antiferromagnetic insulating layer is perpendicular to the film plane; in Figures (c) and (d), the Néel vector of the antiferromagnetic insulating layer is parallel to the film plane.

[0068] When the Néel vector of the antiferromagnetic insulating layer is in the out-of-plane direction, the spin current absorbed at the interface between the ferromagnetic metal layer and the antiferromagnetic insulating layer when the normalized magnetization vector of the ferromagnetic metal layer is parallel to the z-axis is less than the spin current absorbed at the interface between the ferromagnetic metal layer and the antiferromagnetic insulating layer when the magnetization vector is parallel to the y-axis. Thus, the total reflected spin current satisfies Equation (2):

[0069] (2)

[0071] Wherein, represents the spin current reflected at the interface between the heavy metal layer and the ferromagnetic metal layer ; represents the spin current reflected at the interface between the ferromagnetic metal layer and the antiferromagnetic insulating layer ; represents the normalized magnetization vector of the ferromagnetic metal layer; and are respectively the axis and axis of the rectangular coordinate system; represents parallel.

[0072] The calculation formula for the net spin current in the heavy metal layer is as shown in Equation (3), and it satisfies that the net spin current when the magnetization vector is parallel to the z-axis ( ) is less than the net spin current when the magnetization vector is parallel to the y-axis ( ), as shown in Equation (4):

[0073] ; (3)

[0074] ; (4)

[0075] Wherein, represents the net spin current in the heavy metal layer; represents the total spin current; and The annotation refers to Equation (2).

[0076] According to the inverse spin Hall effect (ISHE), a current opposite to the applied current is generated in the heavy metal layer, resulting in a negative spin Hall magnetoresistance, as shown in Equation (5):

[0077] ; (5)

[0078] where represents the spin Hall magnetoresistance when the magnetization vector is parallel to the z-axis; represents the spin Hall magnetoresistance when the magnetization vector is parallel to the y-axis.

[0079] Conversely, when the Néel vector of the antiferromagnetic insulating layer is in the plane, the total reflected spin current satisfies Equation (6):

[0080] (6)

[0082] The net spin current in the heavy metal layer satisfies Equation (7):

[0083] ; (7)

[0084] resulting in a positive spin Hall magnetoresistance, as shown in Equation (8):

[0085] ; (8)

[0086] Specific embodiments are listed below to further illustrate the present invention.

[0087] As Figure 3 shown, for the angular magnetoresistance of the Co / Pt heterojunction formed on the NiO thin film under temperature measurements from 5K to 400K, where the thickness of the NiO thin film (antiferromagnetic insulating layer) is 20nm, which is a relatively thin thickness, the thickness of Co (ferromagnetic metal layer) is 1.2nm, and the thickness of Pt (heavy metal layer) is 3nm.

[0088] As Figure 3 shown, the NiO / Co / Pt multilayer heterojunction exhibits a negative spin Hall magnetoresistance at low temperatures, and as the temperature increases, the spin Hall magnetoresistance changes from negative to positive.

[0089] As Figure 4As shown, it is the angular magnetoresistance of the Co / Pt heterojunction formed on the NiO thin film under temperature measurements from 5K to 400K. Among them, the thickness of the NiO thin film (antiferromagnetic insulating layer) is 78nm, which is a relatively thick thickness. The thickness of Co (ferromagnetic metal layer) is 1.2nm, and the thickness of Pt (heavy metal layer) is 3nm.

[0090] As Figure 4 shown, the spin Hall magnetoresistance of the NiO / Co / Pt multilayer heterojunction always remains positive; as the temperature increases, the spin Hall magnetoresistance gradually tends to saturate and stabilizes near room temperature; when the temperature is further increased to 400K, the spin Hall magnetoresistance decreases.

[0091] It can be seen from this that at low temperatures, the sign of the spin Hall magnetoresistance is mainly regulated by the Néel vector of the antiferromagnetic insulating layer NiO. For the antiferromagnetic insulating layer NiO with the Néel vector perpendicular to the thin film, the reflection of the spin current at the NiO / Co interface is significantly enhanced. As the temperature increases, the modulation effect of the spin orientation of NiO on the spin Hall magnetoresistance of the Co / Pt heterojunction gradually weakens. Therefore, at room temperature, the spin Hall magnetoresistance of the NiO / Co / Pt heterojunction is mainly determined by the reflection of the spin current at the Co / Pt interface.

[0092] As Figure 5 shown, for the Co(1.2 nm) / Pt(3 nm) heterojunction with zero NiO thickness, its spin Hall magnetoresistance gradually tends to saturate and always remains positive as the temperature increases.

[0093] The above results show that by regulating the direction of the Néel vector of NiO, effective regulation of the spin current transport in the Co / Pt heterojunction can be achieved, thereby changing the sign and magnitude of the spin Hall magnetoresistance.

[0094] It should be clear that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, the detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order between the steps after understanding the spirit of the present invention.

[0095] In the present invention, the features described and / or illustrated for one embodiment can be used in the same way or in a similar way in one or more other embodiments, and / or combined with the features of other embodiments or replace the features of other embodiments.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for controlling spin Hall magnetoresistance of a ferromagnetic / heavy metal heterojunction, characterized in that: The method comprises the following steps: The pretreated substrate is placed in a first deposition system chamber, and based on a first preset deposition method, a thin film is deposited on the substrate to form an antiferromagnetic insulating layer, wherein the antiferromagnetic insulating layer is made of an antiferromagnetic insulating oxide material; the thickness of the antiferromagnetic insulating layer is controlled by setting deposition parameters, and when the thickness of the antiferromagnetic insulating layer is less than a preset critical thickness, its Né'er vector is perpendicular to the substrate surface, and when the thickness of the antiferromagnetic insulating layer is not less than the preset critical thickness, its Né'er vector is parallel to the substrate surface; The deposited antiferromagnetic insulating layer is transferred to the second deposition system chamber, and based on the second preset deposition method, the epitaxially grown antiferromagnetic insulating layer is used as the bottom layer, and a ferromagnetic metal / heavy metal heterojunction of a preset material is deposited to obtain a multilayer film structure of the antiferromagnetic insulating layer, the ferromagnetic metal layer and the heavy metal layer from bottom to top; By regulating the direction of the Née vector of the antiferromagnetic insulating layer, the reflection and absorption of the ferromagnetic / heavy metal heterojunction spin current are regulated to change the size and sign of the spin Hall magnetoresistance.

2. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: The antiferromagnetic insulating layer is made of antiferromagnetic insulating oxide material, and the antiferromagnetic insulating oxide material includes at least nickel oxide, cobalt oxide, and chromium oxide; the ferromagnetic metal layer is made of magnetic metal material, and the magnetic metal material includes at least cobalt, cobalt-iron-boron alloy, cobalt-iron alloy, and nickel-iron alloy; the heavy metal layer is made of heavy metal material, and the heavy metal material includes at least platinum, tantalum, palladium, gold-platinum alloy, and palladium-platinum alloy.

3. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: The substrate is a magnesium oxide single crystal with a 001 orientation, and the substrate is cleaned to remove possible organic pollution and particles.

4. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: The first preset deposition method at least includes a pulsed laser deposition method, a magnetron sputtering method, and a molecular beam epitaxy method; When the pulsed laser deposition method is used, the method further comprises: The pretreated substrate is placed in the first deposition system chamber, and a pulsed laser is used to strike a target material, and the target material is deposited on the substrate to form a thin film as an antiferromagnetic insulating layer; the thickness of the antiferromagnetic insulating layer is controlled by setting the number of pulses of the pulsed laser; The deposition conditions include evacuating the first deposition system chamber to a vacuum state, the repetition frequency of the pulsed laser is 1-5 Hz, the pulse energy is 300-350 mJ, the average power is 280-400 mW, and the voltage is 18-24 kV.

5. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 4, characterized in that: Before transferring the deposited antiferromagnetic insulating layer to the second deposition system chamber, the method further includes: After the laser striking is completed, the transfer is performed after the temperature in the first deposition system chamber cools down naturally to room temperature to ensure the stability of the deposited film.

6. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: The second preset deposition method at least includes pulsed laser deposition, magnetron sputtering, and molecular beam epitaxy; When the magnetron sputtering method is used, the deposition conditions include: The second deposition system chamber was evacuated to a vacuum state with a vacuum degree of 2.0×10 -5 Pa, the deposition temperature is room temperature, argon gas is introduced, and the argon pressure is maintained at 0.4~1.2Pa.

7. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: A multilayer film structure is obtained, which comprises, from bottom to top, the antiferromagnetic insulating layer, the ferromagnetic metal layer and the heavy metal layer, including: The thickness of the ferromagnetic metal layer is 0.6-6.5 nm, and the thickness of the heavy metal layer is 1-10 nm.

8. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: After obtaining a multilayer film structure including the antiferromagnetic insulating layer, the ferromagnetic metal layer and the heavy metal layer from bottom to top: The multilayer film results are characterized by using one or more methods of X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy to verify the film, including at least the structure, thickness, and lattice arrangement of the film.

9. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: When the multilayer film structure is obtained, and the thickness of the antiferromagnetic insulating layer of the multilayer film structure is less than a preset critical thickness: The multilayer film structure is measured at a temperature of 5K to 400K, and exhibits negative spin Hall magnetoresistance at low temperatures; As the temperature increases, the spin Hall magnetoresistance changes from negative to positive.

10. The ferromagnetic / heavy metal heterojunction spin Hall magnetoresistance control method according to claim 1, characterized in that: When the multilayer film structure is obtained, and the thickness of the antiferromagnetic insulating layer of the multilayer film structure is not less than the preset critical thickness: The multilayer film structure is measured at a temperature of 5K~400K, and the spin Hall magnetoresistance always remains positive; as the temperature increases, the spin Hall magnetoresistance gradually approaches saturation and tends to be stable when approaching room temperature; when the temperature is further increased to 400K, the spin Hall magnetoresistance decreases.

Images