A method, heterostructure device, and spintronic device for generating a controllable spin current using antiferromagnetic material

Abstract

The application discloses a method for generating controllable spin current by using anti-ferromagnetic material, a heterostructure device and a spintronics device. The method comprises the following steps: manipulating the anti-ferromagnetic moment of an anti-ferromagnetic spin source / ferromagnetic functional layer heterostructure device by using multiple fields, and regulating the spin polarization direction of the spin current and / or adjusting the spin current intensity by using the interaction between the anti-ferromagnetic moment and the spin; the anti-ferromagnetic spin source / ferromagnetic functional layer heterostructure device comprises a substrate layer, an anti-ferromagnetic layer and a ferromagnetic layer which are sequentially stacked from bottom to top and constitute the heterostructure; the material of the anti-ferromagnetic layer is a collinear anti-ferromagnetic material or a non-collinear anti-ferromagnetic material; and the ferromagnetic layer is a perpendicular magnetization ferromagnetic layer or an in-plane magnetization ferromagnetic layer. The heterostructure device can generate the spin current with controllable spin polarization direction, so as to realize the efficient magnetization flipping of the adjacent ferromagnetic layer and bring the advantage of low power consumption of the device, and the critical spin current density can be reduced by one order of magnitude compared with the traditional non-magnetic spin source.

Description

Technical Field

[0001] This invention relates to a method for generating controllable spin current using antiferromagnetic materials, heterostructure devices, and spintronic devices, belonging to the field of electronic information materials. Background Technology

[0002] Spintronic devices aim to achieve efficient and controllable electrical transport by manipulating the spin degree of freedom of electrons, thereby constructing high-speed, low-power information processing and storage devices (e.g., spin-wave transistors and magnetic random access memories), as well as high-response-frequency radio frequency transceivers (e.g., spin torque nanooscillators). Current-induced spin current is the core of spintronic devices, and its magnetization manipulation of magnetic materials is the mainstream approach for information writing and radio frequency excitation in spintronic devices. Traditional spin source materials mainly include heavy metals (e.g., Pt, ...). β -Τa, β Materials / interfaces such as -W, Rashba interfaces (e.g., LaAlO3 / SrTiO3), and topological insulators (e.g., Bi2Se3) can efficiently generate spin currents to achieve various functions of spintronic devices. However, traditional spin sources still have two problems: First, the polarization direction of the spin current is limited by symmetry, and only in-plane polarized spin currents can be generated, resulting in low efficiency in manipulating perpendicular magnetization layers; second, once traditional spin source materials are fabricated, their charge-spin polarization efficiency is fixed. If their efficiency could be controlled, it would open up new avenues for spin logic and multi-valued memory devices. To construct novel spintronic devices, spin source materials with controllable spin polarization directions and tunable spin current intensity are urgently needed. Due to the interaction between the antiferromagnetic moment and the spin, the spin generated in the antiferromagnetic source is modulated by the magnetic moment and thus has controllability. In addition, many antiferromagnetic materials have strong spin-orbit coupling and topological magnetic bands, which make them highly efficient at generating spin currents. Therefore, using antiferromagnetism to generate efficient and controllable spin currents is a highly desirable technology. Summary of the Invention

[0003] The purpose of this invention is to provide a method for generating controllable spin current using antiferromagnetic materials, a heterostructure device, and a spintronic device. This invention utilizes the interaction between the antiferromagnetic magnetic moment and the spin to manipulate the antiferromagnetic magnetic moment through multiple fields (magnetic field, electric field, stress field), thereby generating a multi-field controllable spin current (controllable spin polarization direction and / or adjustable spin current intensity).

[0004] This invention provides a method for generating controllable spin current using antiferromagnetic materials, comprising: By manipulating the antiferromagnetic moment of the antiferromagnetic spin source / ferromagnetic functional layer heterostructure device through multiple fields, the spin polarization direction of the spin current and / or the intensity of the spin current can be controlled by the interaction between the antiferromagnetic moment and the spin. The multiple fields can be any one of magnetic field, electric field and stress field; The antiferromagnetic spin source / ferromagnetic functional layer heterostructure device comprises a substrate layer, an antiferromagnetic layer and a ferromagnetic layer stacked sequentially from bottom to top to form a heterostructure. The antiferromagnetic layer is made of a collinear antiferromagnetic material or a non-collinear antiferromagnetic material; the collinear antiferromagnetic material is at least one of ruthenium oxide RuO2, Mn2Au, and iron-rhodium alloy FeRh; the non-collinear antiferromagnetic material is Mn3X or Mn3YN; wherein X = Ga, Ge, Sn, Ir, Pt, or Rh; Y = Ga, Ni, or Sn; The ferromagnetic layer is a vertically magnetized ferromagnetic layer or an in-plane magnetized ferromagnetic layer.

[0005] In the above method for generating controllable spin current using antiferromagnetic materials, the spin polarization direction includes in-plane spin polarization and out-of-plane spin polarization; The in-plane spin polarization direction includes in-plane... x Direction and in-plane y direction.

[0006] For example, in one embodiment of the present invention, the spin polarization direction is controlled by magnetic field annealing. The magnetic field annealing may include: holding the antiferromagnetic spin source / ferromagnetic functional layer heterostructure device at 200ºC and an external magnetic field of 0.8 T for 1 hour, and then cooling it to room temperature at a rate of 1 K / min. Specifically, the principle is to manipulate the Nell vector of the antiferromagnetic layer through magnetic field annealing, thereby controlling the spin polarization direction.

[0007] For example, in another embodiment of the invention, the spin polarization direction is modulated using an electric field or a stress field. Specifically, by applying a current direction parallel to the Nell vector of the antiferromagnetic layer, the in-plane spin precesses to an out-of-plane direction.

[0008] In the above method for generating controllable spin current using antiferromagnetic materials, the polarization direction of the spin current generated by the antiferromagnetic layer is controlled to be out-of-plane spin polarization, thereby inducing the ferromagnetic layer, especially the vertically magnetized ferromagnetic layer, to achieve flipping without an external auxiliary magnetic field, so as to adjust the intensity of the spin current.

[0009] Preferably, the antiferromagnetic layer uses a non-collinear antiferromagnetic material (such as Mn3Pt) as a spin source. Non-collinear antiferromagnetic materials have the characteristic of high spin flow generation efficiency due to their topological band structure.

[0010] In the above method for generating controllable spin current using antiferromagnetic materials, the substrate layer is made of at least one of ferroelectric substrate PMN-PT, magnesium oxide MgO, aluminum oxide Al2O3, and titanium oxide TiO2. The chemical formula of the ferroelectric substrate PMN-PT is Pb(Mg)1 / 3 Nb 2 / 3 ) 0.7 Ti 0.3 O3.

[0011] In the above method for generating controllable spin current using antiferromagnetic materials, the thickness of the antiferromagnetic layer can be 3~50nm, specifically 12nm.

[0012] As an example, the non-collinear antiferromagnetic material is Mn3Ir, Mn3Pt, or Mn3SnN.

[0013] In the above method for generating controllable spin current using antiferromagnetic materials, the material of the vertically magnetized ferromagnetic layer is at least one of cobalt-iron-boron alloy CoFeB, cobalt-nickel [Co / Ni] multilayer film, cobalt-palladium [Co / Pd] multilayer film, and cobalt-platinum [Co / Pt] multilayer film; The thickness of the vertically magnetized ferromagnetic layer can be 0.3~10nm, specifically 3.6nm.

[0014] As an example, the material of the vertically magnetized ferromagnetic layer is a Co (0.4 nm) / Pd (0.8 nm) / Co (0.4 nm) / Pd (2 nm) multilayer film.

[0015] In the above method for generating controllable spin current using antiferromagnetic materials, the material of the in-plane magnetized ferromagnetic layer is at least one of iron, cobalt, nickel, cobalt-iron alloy CoFe, nickel-iron alloy NiFe, and cobalt-iron-boron alloy CoFeB. The thickness of the in-plane magnetized ferromagnetic layer can be 0.3~50nm, specifically 8nm or 16nm.

[0016] The present invention further provides an antiferromagnetic spin source / ferromagnetic functional layer heterostructure device in any of the methods for generating controllable spin current using antiferromagnetic materials.

[0017] The present invention also provides a spintronic device, including the aforementioned antiferromagnetic spin source / ferromagnetic functional layer heterostructure device.

[0018] Specifically, the spintronic device may be any one of a magnetic memory, a spin-wave transistor, and a spin torque nano-oscillator.

[0019] The present invention has the following beneficial effects: The method provided by this invention utilizes multi-field manipulation of antiferromagnetic magnetic moments and the charge-spin conversion process related to magnetic moments to apply antiferromagnetic spin source / ferromagnetic functional layer heterostructure devices to spintronic devices such as magnetic memories, spin-wave transistors, and spin torque nano-oscillators. It offers the following advantages: antiferromagnetic materials can generate spin currents with controllable spin polarization directions, enabling efficient magnetization reversal of adjacent ferromagnetic layers and resulting in low power consumption. The critical spin current density is an order of magnitude lower than that of traditional non-magnetic spin sources. Controllable spin currents lead to controllable magnetization dynamics and potential multi-valued storage and programmable spin logic behavior. Specifically, non-collinear antiferromagnets exhibit high spin current generation efficiency due to their topological band structure; the critical current density for reversing adjacent perpendicular magnetization layers using non-collinear antiferromagnets is only 1 / 5 that of collinear antiferromagnetic Mn2Au. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the heterostructure thin film of the antiferromagnetic spin source / ferromagnetic functional layer of the present invention and the antiferromagnetic spin current generation. The markings in the figure are as follows: 1-substrate layer; 2-antiferromagnetic layer; 3-ferromagnetic layer; 4-magnetic field (perpendicular to the thin film plane, i.e., z direction); 5-electric field (perpendicular to the thin film plane, i.e., z direction); 6-stress field (along the thin film plane, x or y direction).

[0021] Figure 2 This is Example 1 of the present invention. The experimental results of investigating the spin current generated by Mn3Ir using spin torque ferromagnetic resonance in non-collinear antiferromagnetic Mn3Ir (12 nm) / NiFe (16 nm) samples are shown. Both in-plane and out-of-plane spin polarization are present.

[0022] Figure 3 This is Example 2 of the present invention. The experimental results of investigating the spin current generated by Mn3SnN using spin torque ferromagnetic resonance in non-collinear antiferromagnetic Mn3SnN (12 nm) / NiFe (16 nm) samples are shown. Both in-plane and out-of-plane spin polarization are present.

[0023] Figure 4 Example 3 of this invention shows the experimental results of exploring the spin current generated by RuO2 in collinear antiferromagnetic RuO2 (12 nm) / NiFe (8 nm) samples using spin torque ferromagnetic resonance. Both in-plane and out-of-plane spin polarization are present.

[0024] Figure 5 In Embodiment 4 of this invention, the magnetization direction of antiferromagnetic RuO2 (12 nm) / NiFe (8 nm) samples was controlled by magnetic field annealing, thereby regulating the direction of spin polarization and achieving the switching behavior of in-plane spin polarization in the x-direction.

[0025] Figure 6Example 5 of this invention shows the experimental results of electrically manipulating the spin generation in Mn2Au in collinear antiferromagnetic Mn2Au (12 nm) / NiFe (16 nm) samples, demonstrating the switching behavior of out-of-plane spin polarization achieved using an electric field.

[0026] Figure 7 Example 6 of this invention presents experimental results of the Hall resistance change caused by current-induced magnetization reversal in a non-collinear antiferromagnetic Mn3Pt (12 nm) / Co (0.4 nm) / Pd (0.8 nm) / Co (0.4 nm) / Pd (2 nm) sample without an auxiliary magnetic field. The critical spin current density for the reversal is ~5 × 10⁻⁶. 5 Acm -2 Compared to traditional non-magnetic spin source materials (such as Pt), the current density is an order of magnitude lower, demonstrating the advantages of controllable spin current and out-of-plane spin polarization in antiferromagnetic spin sources, resulting in highly efficient magnetization reversal; the critical current density for reversal is ~9×10⁻⁶. 6 Acm -2 It is 1 / 5 of the collinear antiferromagnetic Mn2Au, which reflects the efficient spin generation capability brought about by the topological band in non-collinear antiferromagnets.

[0027] Figure 8 Example 6 of this invention presents the experimental results of Hall resistance changes caused by current-induced magnetization reversal in a conventional heavy metal Pt (2 nm) / Co (0.4 nm) / Pd (0.8 nm) / Co (0.4 nm) / Pd (2 nm) sample under an in-plane magnetic field of 0.1 T in the x-direction. The critical spin current density for the reversal is approximately 9 × 10⁻⁶. 6 Acm -2 The experimental results of Hall resistance changes caused by current-induced magnetization reversal in collinear antiferromagnetic Mn2Au (9 nm) / Co (0.4 nm) / Pd (0.8 nm) / Co (0.4 nm) / Pd (2 nm) samples without an auxiliary magnetic field are shown in the figure. The critical current density for reversal is approximately 5.5 × 10⁻⁶. 7 Acm -2 . Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] As described in the background art, to address the shortcomings of existing technologies where traditional spin source materials cannot control spin polarization and adjust spin current intensity, this invention provides a method for generating controllable spin current using antiferromagnetic materials. The method includes: manipulating the antiferromagnetic moment of an antiferromagnetic spin source / ferromagnetic functional layer heterostructure device through multiple fields; controlling the spin polarization direction and / or adjusting the spin current intensity by utilizing the interaction between the antiferromagnetic moment and the spin; the multiple fields are any one of magnetic field, electric field, and stress field; the antiferromagnetic spin source / ferromagnetic functional layer heterostructure device... The heterogeneous structure device comprises a substrate layer 1, an antiferromagnetic layer 2, and a ferromagnetic layer 3, stacked sequentially from bottom to top to form a heterogeneous structure. The antiferromagnetic layer 2 is made of either a collinear or non-collinear antiferromagnetic material. The collinear antiferromagnetic material is at least one of ruthenium oxide (RuO2), iron-rhodium alloy (FeRh), and Mn2Au. The non-collinear antiferromagnetic material is Mn3X or Mn3YN. Wherein, X = Ga, Ge, Sn, Ir, Pt, or Rh; Y = Ga, Ni, or Sn. The ferromagnetic layer 3 is a perpendicularly magnetized ferromagnetic layer or an in-plane magnetized ferromagnetic layer. This invention also provides the aforementioned antiferromagnetic spin source / ferromagnetic functional layer heterogeneous structure device.

[0030] like Figure 1 As shown, in some embodiments of the present invention, antiferromagnetic magnetization can be manipulated through magnetic fields, electric fields, and stress fields, thereby achieving controllable spin polarization direction and spin current intensity. Specific physical mechanisms include spin precession induced by the antiferromagnetic magnetic moment and spin splitting effects related to the antiferromagnetic sublattice bands. Specifically, magnetic field 4 can manipulate the magnetic moment of the antiferromagnetic layer (RuO2)2 in the RuO2 / NiFe sample. In this sample, using magnetic field annealing technology, at temperatures above the RuO2 Nell temperature, the ferromagnetic layer (NiFe)3 can align the Nell vector of the antiferromagnetic layer (RuO2)2 with the magnetic field direction through magnetic exchange interactions. Electric and stress fields can manipulate the magnetic moment of the antiferromagnetic layer (Mn2Au)2 in the PMN-PT / / Mn2Au / NiFe sample. In this sample, an electric field 5 along the normal of the thin film can induce electrostriction in the substrate layer (piezoelectric substrate PMN-PT) 1, and the resulting stress field 6 will change the magnetic anisotropy of the antiferromagnetic Mn2Au, thereby aligning the Nell vector of the antiferromagnetic layer (Mn2Au) 2 in the direction of compressive strain.

[0031] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; and the materials and reagents used are commercially available unless otherwise specified.

[0033] Example 1: Preparation of MgO / / Mn3Ir (12 nm) / NiFe (16 nm) heterojunction samples for spin torque ferromagnetic resonance experiments.

[0034] Mn3Ir(12 nm) / NiFe(16 nm) heterojunction samples were deposited on MgO(110) substrates by magnetron sputtering.

[0035] Mn3Ir was epitaxially deposited by magnetron sputtering at 600ºC, with a base vacuum of 1×10⁻⁶ before cavity sputtering. -8 Torr, DC sputtering power of 30 W. After Mn3Ir deposition was completed, the chamber cooled to room temperature for NiFe deposition. The base vacuum before sputtering was 1 × 10⁻⁶. -8 Torr, DC sputtering power is 20 W.

[0036] Subsequently, the Mn3Ir / NiFe heterojunction sample was processed into a 20×50 μm shape using ultraviolet exposure and argon ion etching. 2 The sample strip is then connected to the GSG waveguide using overlay, electron beam evaporation, and stripping processes to form a standard spin torque ferromagnetic resonance device. A wire is led out from each of the three ports of the GSG waveguide for high-frequency electrical transport testing.

[0037] Figure 2 Mid-temperature room-temperature magnetic field angle-dependent spin torque ferromagnetic resonance experimental results indicate that out-of-plane (FOB) torque experienced in NiFe is... V A ) and in-plane ( V S The angle dependence of the torque has two terms: ~sin2 φ cos φ and ~sin2 φ The former is from the inside of the surface y Spin polarization contribution in the direction of alternating current (AC current direction is) x Direction, outward direction of the thin film is z (direction), the latter from out-of-plane z The spin polarization contribution in the direction of rotation. Compared to traditional non-magnetic spin source materials, which can only generate in-plane spin polarization... y Spin polarization in the direction of the antiferromagnetic material, the out-of-plane spin polarization generated in the antiferromagnetic material can achieve electrical reversal of perpendicular magnetization without the assistance of an external magnetic field, and the reversal efficiency of out-of-plane spin polarization is higher than that of in-plane spin polarization.

[0038] The mechanism of out-of-plane spin polarization in non-collinear antiferromagnetic Mn3X and Mn3YN (X = Sn, Ga, Ge, Pt, Ir, Rh; Y = Ga, Ni, Sn) is as follows: The non-collinear antiferromagnetic magnetic octupole configuration equates the local magnetic moment to the magnetic octupole moment. Due to the magnetic exchange interaction, the current can induce charge carriers with polarization directions parallel to the magnetic octupole moment direction. Under the action of the spin-orbit coupling field perpendicular to the magnetic octupole moment direction, the polarization direction of the charge carriers precesses to the out-of-plane z-direction, thus generating out-of-plane spin polarization.

[0039] Example 2: Preparation of MgO / / Mn3SnN(12 nm) / NiFe(16 nm) heterojunction samples for spin torque ferromagnetic resonance experiments.

[0040] Mn3SnN(12 nm) / NiFe(16 nm) heterojunction samples were deposited on MgO(110) substrates by magnetron sputtering.

[0041] Mn3SnN was epitaxially deposited by magnetron sputtering at 400ºC, with a base vacuum of 1×10⁻⁶ before cavity sputtering. -7 Torr, sputtering gas pressure Ar:N2 = 20:3. DC sputtering power was 30 W. After Mn3SnN deposition was completed, the chamber was cooled to room temperature for NiFe deposition. The base vacuum before sputtering was 1 × 10⁻⁶. -7 Torr, DC sputtering power is 20 W.

[0042] Subsequently, the Mn3SnN / NiFe heterojunction sample was processed into a 20×50 μm shape using ultraviolet exposure and argon ion etching. 2 The sample strip is then connected to the GSG waveguide using overlay, electron beam evaporation, and stripping processes to form a standard spin torque ferromagnetic resonance device. A wire is led out from each of the three ports of the GSG waveguide for high-frequency electrical transport testing.

[0043] Figure 3 Mid-temperature room-temperature magnetic field angle-dependent spin torque ferromagnetic resonance experimental results indicate that out-of-plane (FOB) torque experienced in NiFe is... V A ) and in-plane ( V S The angle dependence of the torque has two terms: ~sin2 φ cos φ and ~sin2 φ The former is from the inside of the surface y Spin polarization contribution in the direction of alternating current (AC current direction is) x Direction, outward direction of the thin film is z (direction), the latter from out-of-plane z The spin polarization contribution of the direction. Experimental results show that out-of-plane spin polarization can be generated in non-collinear antiferromagnetic Mn3SnN, making it a potential spin source material for efficiently flipping the perpendicular magnetization layer without the assistance of an external magnetic field.

[0044] Example 3: Preparation of TiO2 / / RuO2 (12 nm) / NiFe (8 nm) heterojunction samples for spin torque ferromagnetic resonance experiments.

[0045] RuO2 (12 nm) / NiFe (8 nm) heterojunction samples were deposited on TiO2 (011) substrates by magnetron sputtering.

[0046] RuO2 was epitaxially deposited by magnetron sputtering at 500ºC, with a base vacuum of 1×10⁻⁶ before chamber sputtering. -8 Torr was used, with an Ar:O2 sputtering gas ratio of 5:1 and a DC sputtering power of 20 W. After RuO2 deposition was complete, the chamber was cooled to room temperature for NiFe deposition. The initial vacuum before sputtering was 1 × 10⁻⁶ W. -8 Torr, DC sputtering power is 20 W.

[0047] Subsequently, the RuO2 / NiFe heterojunction sample was processed into a 20×50 μm shape using ultraviolet exposure and argon ion etching. 2 The sample strip is then connected to the GSG waveguide using overlay, electron beam evaporation, and stripping processes to form a standard spin torque ferromagnetic resonance device. A wire is led out from each of the three ports of the GSG waveguide for high-frequency electrical transport testing. Figure 4 The results show that out-of-plane (FOB) sensing in NiFe V A ) and in-plane ( V S The angle dependence of the torque has two terms: ~sin2 φ cos φ and ~sin2 φ The former is from the inside of the surface y The spin polarization contribution of the direction, the latter being determined by out-of-plane... z The spin polarization contribution of the direction. Experimental results show that unconventional out-of-plane spin polarization can be generated in collinear antiferromagnetic RuO2.

[0048] The mechanism of out-of-plane spin polarization in collinear antiferromagnetic RuO2 is as follows: The anisotropic spin-splitting magnetic energy bands in RuO2 enable the generation of spins parallel to the antiferromagnetic Nell vector, with the spin flow flowing in the opposite direction along the RuO2. <100> Crystal orientation. Therefore, in RuO2 (101) thin films, the current applied along the RuO2

[010] crystal orientation can induce the generation of out-of-plane spin polarization.

[0049] Example 4: Preparation of YSZ / / RuO2 (12 nm) / NiFe (8 nm) heterojunction samples for spin torque ferromagnetic resonance experiments.

[0050] RuO2 (12 nm) / NiFe (8 nm) heterojunction samples were deposited on a YSZ (100) substrate by magnetron sputtering.

[0051] RuO2 was epitaxially deposited by magnetron sputtering at 500ºC, with a base vacuum of 1×10⁻⁶ before chamber sputtering. -8 Torr was used, with an Ar:O2 sputtering gas ratio of 5:1 and a DC sputtering power of 20 W. After RuO2 deposition was complete, the chamber was cooled to room temperature for NiFe deposition. The initial vacuum before sputtering was 1 × 10⁻⁶ W. -8 Torr, DC sputtering power is 20 W.

[0052] Subsequently, a magnetic field annealing experiment was performed on the RuO2 (12 nm) / NiFe (8 nm) heterojunction sample. The sample was held at 200ºC and an external magnetic field of 0.8T for 1 h, and then slowly cooled to room temperature at a cooling rate of 1 K / min. The magnetic field annealing process can align the Nell vector of the antiferromagnetic RuO2 in a direction parallel to the annealing magnetic field.

[0053] The RuO2 / NiFe heterojunction sample annealed under magnetic field was processed into a 20×50 μm shape using ultraviolet exposure and argon ion etching. 2 The sample strip is then connected to the GSG waveguide using overlay, electron beam evaporation, and stripping processes to form a standard spin torque ferromagnetic resonance device. A wire is led out from each of the three ports of the GSG waveguide for high-frequency electrical transport testing.

[0054] Figure 5 The middle figure shows the results of spin-torque ferromagnetic resonance experiments under two configurations. The left figure shows the results when the annealing magnetic field (Nell vector) is perpendicular to the microwave current; the linear separation results indicate that the in-plane ( V S The angle dependence of the torque satisfies ~sin2. φ cos φ This refers to the in-plane spin in the y-direction. The right figure shows the result when the annealing magnetic field (Nell vector) is parallel to the microwave current. The linear separation results indicate that the in-plane spin experienced in NiFe is... V S The angle dependence of the torque has two terms: ~sin2 φ cos φ and ~sin2 φ sin φ The former is from the inside of the surface y The spin polarization contribution of the direction, the latter being determined by the in-plane spin polarization contribution. xThe spin polarization contribution of the direction. Experimental results show that spin parallel to the Nell vector direction can be generated in antiferromagnetic RuO2. The Nell vector of RuO2 can be manipulated by magnetic field annealing, thereby controlling the spin polarization direction.

[0055] Example 5: Preparation of PMN-PT / / Mn2Au (12 nm) / NiFe (16 nm) heterojunction samples for spin torque ferromagnetic resonance experiments Mn2Au (12 nm) / NiFe (16 nm) heterojunction samples were deposited on a PMN-PT(011) substrate by magnetron sputtering.

[0056] Mn2Au was epitaxially deposited by magnetron sputtering at 300ºC, with a base vacuum of 1×10⁻⁶ before cavity sputtering. -7 Torr, DC sputtering power of 30 W. After Mn2Au deposition, the chamber cooled to room temperature for NiFe deposition. The base vacuum before sputtering was 1×10⁻⁶. -7 Torr, DC sputtering power is 10 W.

[0057] Subsequently, the Mn2Au / NiFe heterojunction sample was processed into a 20×50 μm shape using ultraviolet exposure and argon ion etching. 2 The sample strips are then connected to the GSG waveguide using overlay, electron beam evaporation, and stripping processes to form a standard spin-torque ferromagnetic resonance device. A wire is led out from each of the three ports of the GSG waveguide for high-frequency electrical transport testing. Silver paste is coated on the back of the substrate, and a wire is led out to apply a voltage, thereby creating an electric field effect in the PMN-PT substrate.

[0058] Figure 6 Mid-temperature room-temperature magnetic field angle-dependent spin torque ferromagnetic resonance experiments show that the current in naturally grown Mn2Au / NiFe samples can only induce in-plane... y Spin polarization of direction (~sin2) φ cos φ When a voltage of +200 V (+4 kV / cm) is applied to the upper and lower electrodes of the device, the current can induce out-of-plane spin polarization (~sin2). φThe reason is that the electric field acting on the piezoelectric substrate PMN-PT causes electrostriction, and the resulting stress field alters the magnetic anisotropy of the antiferromagnetic Mn2Au, inducing a 90º flip in its Nell vector. When the applied current is parallel to the Nell vector of Mn2Au, the spin-orbit coupling field caused by the breaking of sublattice symmetry in Mn2Au causes in-plane spin precession to the out-of-plane direction. However, when the applied current is perpendicular to the Nell vector of Mn2Au, the spin-orbit coupling field does not affect the in-plane spin. The experimental results show that electric and stress fields can realize the switching behavior of out-of-plane spin polarization in antiferromagnetic Mn2Au.

[0059] Example 6: Preparation of MgO / / Mn3Pt(12 nm) / Co(0.4 nm) / Pd(0.8 nm) / Co(0.4 nm) / Pd(2 nm) multilayer film samples for current-induced vertical magnetization reversal.

[0060] A multilayer film of Mn3Pt(12 nm) / Co(0.4 nm) / Pd(0.8 nm) / Co(0.4 nm) / Pd(2 nm) was deposited on a MgO(111) substrate by magnetron sputtering.

[0061] Mn3Pt was epitaxially deposited by magnetron sputtering at 600ºC, with a base vacuum of 1×10⁻⁶ before cavity sputtering. -8 Torr, DC sputtering power of 30 W. After Mn3Pt deposition, the chamber was cooled to room temperature for further deposition of a Co (0.4 nm) / Pd (0.8 nm) / Co (0.4 nm) / Pd (2 nm) ferromagnetic multilayer film. The base vacuum before sputtering was 1 × 10⁻⁶. -8 Torr, DC sputtering power is 20 W.

[0062] Subsequently, the multilayer film sample was processed into a core size of 5×5 μm using ultraviolet exposure and argon ion etching. 2 A cross-shaped device is used, with one wire leading from each of the four ports for DC current transmission testing. A current is applied to one channel of the cross, and the Hall voltage signal of the channel perpendicular to it is recorded using a nanovoltmeter. The ratio of the Hall voltage to the applied current is the Hall resistance signal of the sample.

[0063] Figure 7 The DC transport test results at room temperature show that, with zero external magnetic field, as the current pulse increases from 15 mA (spin current density...) J S 5×10 5 A cm -2 Charge current density J C 1×10 7A cm -2 -15 mA (spin flux density) J S -5×10 5 A cm -2 Charge current density J C -1×10 7 A cm -2 Then to 15 mA (spin flux density) J S 5×10 5 A cm -2 Charge current density J C 1×10 7 A cm -2 The Hall resistance change obtained by the test is in a high resistance state. J S = 5×10 5 A cm -2 , J C = 1×10 7 A cm -2 ) Low resistance state ( J S -5×10 5 A cm -2 , J C = -1×10 7 A cm -2 ) High resistance state ( J S = 5×10 5 A cm -2 , J C = 1×10 7 A cm -2 The phenomenon occurs because the current induces out-of-plane spin polarization in Mn3Pt, and the resulting spin current drives the magnetization reversal of the Co / Pd multilayer film, causing a change in the Hall resistance. The spin current generated by the antiferromagnetism has out-of-plane spin polarization (see Examples 2-4), and its induction of vertical magnetization reversal has two main advantages: (1) the magnetization reversal does not require an external auxiliary magnetic field (as a contrast, the traditional non-magnetic heavy metal Pt requires an external auxiliary magnetic field to induce vertical magnetization reversal, see Examples 2-4). Figure 8 (2) Out-of-plane spin polarization is more efficient for vertical magnetization reversal than in-plane spin polarization, thus the critical spin current density for reversal in the Mn3Pt system (5×10⁻⁶) is higher. 5 A cm -2Compared to traditional non-magnetic spin sources ( J S,Pt = 9×10 6 A cm -2 ,See Figure 8 The current density is an order of magnitude lower. Furthermore, non-collinear antiferromagnets, due to their topological band structure, have a higher spin current generation efficiency, meaning they produce a higher spin current density for the same current density. Therefore, without an external auxiliary magnetic field, the critical current density at which Mn3Pt induces perpendicular magnetization reversal is ( J C = 9×10 6 A cm -2 Only for Mn2Au system ( J C = 5.5 × 10 7 A cm -2 1 / 5 of ). Therefore, non-collinear antiferromagnetic oscillators are a class of potentially efficient and controllable spin source materials, and are expected to be applied to magnetic memories, spin-wave transistors and spin torque nano-oscillators.

[0064] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for generating controllable spin current using antiferromagnetic materials, characterized in that, include: By manipulating the antiferromagnetic moment of the antiferromagnetic spin source / ferromagnetic functional layer heterostructure device with an electric field, the spin polarization direction and intensity of the spin current can be controlled by the interaction between the antiferromagnetic moment and the spin. The antiferromagnetic spin source / ferromagnetic functional layer heterostructure device includes a substrate layer, an antiferromagnetic layer and a ferromagnetic layer stacked sequentially from bottom to top to form a heterostructure. The antiferromagnetic layer is made of non-collinear antiferromagnetic material Mn3Pt, and the thickness of the antiferromagnetic layer is 12nm. The ferromagnetic layer is a vertically magnetized ferromagnetic layer, and the material of the vertically magnetized ferromagnetic layer is a cobalt-palladium multilayer film. The cobalt-palladium multilayer film includes a first cobalt layer, a first palladium layer, a second cobalt layer, and a second palladium layer. The thickness of the first cobalt layer is 0.4 nm, the thickness of the first palladium layer is 0.8 nm, the thickness of the second cobalt layer is 0.4 nm, and the thickness of the second palladium layer is 2 nm. The spin polarization direction includes in-plane spin polarization and out-of-plane spin polarization. The non-collinear antiferromagnetic magnetic octupole configuration equates the local magnetic moment to the magnetic octupole moment. Due to the magnetic exchange interaction, the current can induce charge carriers with polarization directions parallel to the magnetic octupole moment direction. Under the action of the spin-orbit coupling field perpendicular to the magnetic octupole moment direction, the polarization direction of the charge carriers precesses to the out-of-plane z-direction, generating out-of-plane spin polarization. The polarization direction of the spin current generated by the antiferromagnetic layer is controlled to be out-of-plane spin polarization, thereby inducing the ferromagnetic layer to achieve flipping without an external auxiliary magnetic field, so as to adjust the intensity of the spin current.

2. The method for generating controllable spin current using antiferromagnetic materials according to claim 1, characterized in that: The substrate is made of at least one of the following materials: ferroelectric substrate PMN-PT, magnesium oxide MgO, aluminum oxide Al2O3, and titanium oxide TiO2.

Images