Magnetic multilayer film device with three-dimensional chiral spin structure and preparation method and application thereof

Abstract

The invention discloses a magnetic multilayer film device with a three-dimensional chiral spin structure and a preparation method and application thereof, and relates to the technical field of spintronics. The magnetic multilayer film device is sequentially constructed by adopting a layered structure and comprises a substrate, a smooth layer, a first magnetic layer, a spacing layer, a second magnetic layer and a protective layer. Wherein the first magnetic layer and the second magnetic layer are thin films made of ferromagnetic materials or ferromagnetic materials, and the spacing layer is made of non-magnetic materials, so that a bridge effect is achieved, and the long-range spin coupling effect between the adjacent magnetic layers is promoted. Based on an antisymmetric interlayer exchange coupling mechanism, a three-dimensional chiral spin structure penetrating through the whole magnetic multilayer film structure is successfully realized through the medium action of the spacing layer, and a key technology is provided for research, development and application of high-integration-density spintronics devices.

Description

Technical Field

[0001] The present invention relates to the technical field of spintronics, and more specifically, to a magnetic multilayer film device having a three-dimensional chiral spin structure, a preparation method thereof, and an application thereof. Background Art

[0002] A spintronic device is an electronic device that utilizes the spin property of electrons for information storage, transmission, and processing. Different from traditional electronic devices that rely on charge, spintronic devices achieve functions by manipulating the spin state of electrons, and have advantages such as low power consumption, high speed, and non-volatility. They are considered to be one of the most promising solutions for storage and logic devices in the post-Moore era.

[0003] In a magnetic thin film, due to the breaking of inversion symmetry at the interface or in the bulk, an in-plane DMI (Dyzaloshinskii-Moriya) interaction will be generated. Theoretically, DMI is an antisymmetric exchange coupling caused by a spin-orbit coupling effect due to the lack of inversion symmetry in the magnetic system. Different from the collinear spin arrangement generated by the traditional Heisenberg symmetric exchange interaction, a magnetic system with DMI tends to make adjacent spins in the material have a chiral perpendicular arrangement. The existence of in-plane DMI is crucial for the formation and stability of chiral spin structures in magnetic thin films, such as spin spirals, chiral magnetic domain walls, and skyrmions. In future spintronic devices, these chiral spin structures with micro-nano sizes have important application values in spin logic and storage devices. For example, the size of a skyrmion is between nanometers and micrometers. Based on skyrmions, a racetrack memory with extremely high storage density can be designed, and at the same time, its topological stability can be used to achieve long-term storage of information.

[0004] However, the above chiral spin structure generated based on the in-plane DMI effect belongs to the spin structure in a two-dimensional plane, with a low integration density and unable to meet the requirements of high integration for future spintronic devices. To increase the integration density, it is necessary to expand the spin structure and its interactions in the three-dimensional direction to achieve stacking perpendicular to the substrate film surface. Patent CN112652706A proposes a spin-orbit torque storage unit without an external magnetic field, including an antiferromagnetic insulating layer, a heavy metal layer located on the antiferromagnetic insulating layer, and a free layer. The heavy metal layer uses a heavy metal material with strong spin-orbit coupling. By applying a current to the heavy metal layer, a spin current perpendicular to the surface of the heavy metal layer can be generated. There is DMI between the free layer and the heavy metal layer, and the DMI between the free layer and the heavy metal layer is adjusted through the antiferromagnetic insulating layer, enabling the magnetic layer to achieve a directional flip of the magnetic moment induced by the spin-orbit torque without an external magnetic field, thereby realizing the magnetic moment flip of the free layer without the assistance of an external magnetic field. However, it is only a two-dimensional in-plane spin structure based on the in-plane DMI effect and fails to meet the requirements of a three-dimensional chiral spin structure. Summary of the Invention

[0005] The object of the present invention is to overcome the defects and deficiencies of the existing two-dimensional spin magnetic multilayer film structure, and provide a magnetic multilayer film device with a three-dimensional chiral spin structure, which has a chiral spin structure with a specific three-dimensional arrangement orientation, expands the distribution of the spin structure to the three-dimensional space throughout the magnetic thin film, and improves the integration density of spintronic devices.

[0006] Another object of the present invention is to provide a preparation method for a magnetic multilayer film device with a three-dimensional chiral spin structure.

[0007] Another object of the present invention is to provide the application of the above magnetic multilayer film device with a three-dimensional chiral spin structure in the preparation of a spin memory or a programmable logic device.

[0008] The above objects of the present invention are achieved through the following technical solutions:

[0009] The present invention protects a magnetic multilayer film device with a three-dimensional chiral spin structure, including:

[0010] A substrate;

[0011] A smoothing layer grown on the substrate;

[0012] A first magnetic layer grown on the smoothing layer, made of ferromagnetic metal and / or ferrimagnetic metal;

[0013] An interlayer grown on the in-plane easy magnetization layer, made of non-magnetic metal;

[0014] A second magnetic layer, grown on the spacer layer, made of ferromagnetic metal and / or ferrimagnetic metal; used to generate an interlayer DMI effect with the first magnetic layer through the spacer layer as a medium, and induce a chiral exchange bias field.

[0015] A protective layer, grown on the perpendicularly magnetized layer.

[0016] The magnetic multi-layer film device of the present invention includes a first magnetic layer, a spacer layer, and a second magnetic layer connected in sequence. The spacer layer acts as a bridge to promote the long-range spin coupling between adjacent magnetic layers. Based on the anti-symmetric interlayer exchange coupling mechanism, through the mediation of the spacer layer, a three-dimensional chiral spin structure throughout the magnetic multi-layer film structure is realized, providing guidance for the research and development of high-integration-density spintronic devices.

[0017] In some embodiments, the magnetic anisotropies between the first magnetic layer and the second magnetic layer are perpendicular to each other. In a magnetic multi-layer film, the interlayer DMI tends to make the magnetic moments of the magnetic layers oriented perpendicular to each other. When the initial magnetic anisotropies of the two magnetic layers are perpendicular to each other, that is, the angle between the magnetic moments is close to 90 degrees, this initial perpendicular arrangement of the magnetic moments effectively promotes the formation of the interlayer DMI and maximizes the interlayer DMI intensity.

[0018] Optionally, the first magnetic layer has perpendicular magnetic anisotropy, and the second magnetic layer has in-plane anisotropy.

[0019] Optionally, the first magnetic layer has in-plane anisotropy, and the second magnetic layer has perpendicular magnetic anisotropy.

[0020] It should be noted that ferromagnetic metal refers to the general term for metal materials with ferromagnetism, including but not limited to iron, nickel, cobalt, gadolinium metals and their alloy materials. Similarly, ferrimagnetic metal refers to the general term for metals with ferrimagnetism and their oxide or compound materials.

[0021] In some embodiments, the materials of the first magnetic layer and the second magnetic layer are independently selected from at least one of Fe, CoFe, Co, Co2MnAl, Co2MnSi, CoFeB, L10-MnGa, CoFeB, D0 22 -Mn3Ga, FePt, CoTb or CoGd.

[0022] In some embodiments, the thicknesses of the first magnetic layer and the second magnetic layer are respectively 0.5 - 6 nm.

[0023] In some embodiments, the material of the spacer layer is selected from at least one of Pt, Ta, Ru, W, Ag and Pd. Preferably Pt.

[0024] In some of these embodiments, the thickness of the spacer layer is 0.5 - 8 nm.

[0025] In some of these embodiments, the material of the smoothing layer is selected from at least one of GaAs, Si, MgO, Cr, InAs, InGaAs, AlGaAs, Al, Ta, or CoGa.

[0026] In some of these embodiments, the material of the protective layer is selected from at least one of Al, Cu, MgO, or Pt.

[0027] The present invention protects a method for preparing a magnetic multilayer film device having a three-dimensional chiral spin structure. A smoothing layer, a first magnetic layer, a spacer layer, a second magnetic layer, and a protective layer are sequentially grown on a substrate, and thus the magnetic multilayer film device having a three-dimensional chiral spin structure is obtained.

[0028] In some of these embodiments, after depositing and growing the magnetic multilayer film device having a three-dimensional chiral spin structure, a magnetic field annealing treatment is further included under vacuum.

[0029] In some of these embodiments, the method includes the following steps:

[0030] S1. Place the substrate in an MBE preparation chamber. The substrate temperature is 190 - 210 °C. Deposit and grow the smoothing layer with a growth rate of 8 - 12 nm / min and a growth thickness of 20 - 100 nm, and then raise the temperature to 275 - 285 °C and hold for 8 - 12 min.

[0031] S2. Lower the temperature of the substrate to 180 - 250 °C. Grow an in-plane easy magnetization layer on the smoothing layer with a growth thickness of 1.5 - 2.5 nm, and then raise the temperature to 295 - 305 °C and hold for 8 - 12 min.

[0032] S3. Lower the substrate temperature to 40 - 80 °C. Turn on the electron beam evaporation power supply with an acceleration voltage of 5.5 - 6.5 KV and an emission current of 80 - 130 mA. Grow the spacer layer on the in-plane easy magnetization layer with a growth thickness of 2 - 3 nm, and then raise the substrate temperature to 315 - 325 °C and hold for 8 - 12 min.

[0033] S4. Lower the substrate temperature to 150 - 250 °C. Grow a perpendicular easy magnetization layer on the spacer layer with a growth thickness of 1.5 - 2.5 nm, and then raise the substrate temperature to 275 - 285 °C and hold for 15 - 25 min.

[0034] S5. Lower the substrate temperature to 0 - 100 °C. Grow the protective layer on the perpendicular easy magnetization layer with a deposition thickness of 1.5 - 2.5 nm, and then raise the substrate temperature to 195 - 205 °C and hold for 8 - 12 min.

[0035] The present invention protects the application of a magnetic multi-layer film device with a three-dimensional chiral spin structure in the preparation of a spin memory or a programmable logic device.

[0036] Optionally, the magnetic multi-layer film device with a three-dimensional chiral spin structure of the present invention is applied to a magnetic tunnel junction memory device.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The present invention provides a magnetic multi-layer film device with a three-dimensional chiral spin structure. Through the interlayer DMI effect between the first magnetic layer and the second magnetic layer with a spacer layer as a medium, a chiral spin structure with a specific three-dimensional arrangement orientation is generated, inducing a chiral exchange bias field, and realizing a chiral spin structure with an orderly distribution on a three-dimensional scale. It also has the following advantages:

[0039] (1) Compared with the two-dimensional spin structure in traditional spintronics, the magnetic multi-layer film device with a three-dimensional chiral spin structure extends the distribution of the spin structure to the three-dimensional space throughout the magnetic thin film, improving the integration density of spintronic devices.

[0040] (2) Based on the interlayer DMI effect, the spin structure in the layer can be indirectly and non-contact regulated, greatly expanding the functionality of spintronic devices.

[0041] (3) The exchange bias field generated by field cooling in a traditional ferromagnetic / antiferromagnetic bilayer film cannot be changed in direction after growth, while the chiral exchange bias effect induced by the interlayer DMI interaction can be regulated after growth to change the direction of the bias field, and is expected to be applied to spin memory devices. Description of the Drawings

[0042] Figure 1 It is a schematic diagram of the thin film structure of the magnetic multi-layer film device with a three-dimensional chiral spin structure according to Embodiment 1 of the present invention.

[0043] Figure 2 It is a magnetic hysteresis loop diagram in the vertical direction of the magnetic multi-layer film device with a three-dimensional chiral spin structure according to Embodiment 1 of the present invention.

[0044] Figure 3 It is a chiral exchange bias diagram of the magnetic multi-layer film device with a three-dimensional chiral spin structure according to Embodiment 1 of the present invention.

[0045] Figure 4 It is a schematic diagram of the magnetic moment tendency of the magnetic multi-layer film device with a three-dimensional chiral spin structure according to Embodiment 1 of the present invention.

[0046] Figure 5Schematic diagram of the three-dimensional spin arrangement of the magnetic multilayer device with a three-dimensional chiral spin structure in Embodiment 1 of the present invention under different magnetic moment arrangements. Detailed implementation manners

[0047] The present invention will be further described below in conjunction with the detailed implementation manners, but the embodiments do not impose any form of limitation on the present invention.

[0048] It should be noted that in the description of the specification, similar or identical parts use the same figure numbers. The implementation manners not depicted or described in the drawings are in forms known to those of ordinary skill in the art. Additionally, although this document may provide examples containing specific values of parameters, it should be understood that the parameters do not necessarily exactly equal the corresponding values, but may approximate the corresponding values within an acceptable error tolerance or design constraint. Furthermore, the directional terms mentioned in the following embodiments, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., are only with reference to the directions in the drawings. Therefore, the directional terms used are for illustration and not for limiting the solutions of the present invention.

[0049] Embodiment 1

[0050] A magnetic multilayer device with a three-dimensional chiral spin structure includes a substrate 1, a smoothing layer 2, a first magnetic layer 3, a spacer layer 4, a second magnetic layer 5, and a protective layer 6. Specifically, as Figure 1 shown,

[0051] The substrate 1 is a GaAs(001) substrate.

[0052] The material of the smoothing layer is CoGa, and the thickness is 50 nm.

[0053] The material of the first magnetic layer 3 is Co, and the thickness is 2.0 nm.

[0054] The material of the spacer layer 4 is Pt, and the thickness is 2.5 nm.

[0055] The material of the second magnetic layer 5 is L10-MnGa, and the thickness is 2.0 nm.

[0056] The material of the protective layer 6 is Al, and the thickness is 2.0 nm.

[0057] The preparation method of the magnetic multilayer device with a three-dimensional chiral spin structure includes the following steps:

[0058] S1, grow the CoGa smoothing layer 2; specifically: place the GaAs(001) substrate 1 into the molecular beam epitaxy preparation chamber, and the chamber vacuum degree is higher than 2×10 -7Pa. After degassing and deoxidation, raise the substrate temperature to 200 °C, deposit a smooth GaAs layer with a growth rate of 10 nm / min and a thickness of 50 nm, then raise the temperature to 280 °C and hold for 10 min.

[0059] S2. Grow the first magnetic layer 3 on the CoGa smooth layer 2; specifically: lower the substrate temperature to 200 °C, grow a Co layer with a thickness of 2.0 nm and a growth rate of 0.2 nm / min, then raise the temperature to 300 °C and hold for 10 min.

[0060] S3. Grow a Pt spacer layer 4 on the first magnetic layer 3; specifically: lower the substrate temperature to 60 °C, turn on the electron beam evaporation power supply, with an acceleration voltage of 6 KV and an emission current of 80 - 130 mA, grow a Pt layer with a deposited thickness of 2.5 nm, then raise the substrate temperature to 320 °C and hold for 10 min.

[0061] S4. Grow the second magnetic layer 5 on the Pt spacer layer 4. Specifically: lower the substrate temperature to 200 °C, deposit and grow an L10 - MnGa layer with a growth rate of 1 nm / min and a thickness of 2.0 nm, then raise the substrate temperature to 280 °C and hold for 20 min;

[0062] S5. Grow an Al protective layer 6 on the second magnetic layer 5. Specifically: lower the substrate temperature to 0 - 100 °C, deposit and grow an Al layer with a thin film deposited thickness of 2.0 nm, then raise the substrate temperature to 200 °C and hold for 10 min;

[0063] Finally, a GaAs / CoGa / Co / Pt / L10 - MnGa / Al magnetic multilayer film structure is obtained, and magnetic field annealing treatment is carried out under vacuum.

[0064] Example 2

[0065] A magnetic multilayer film device with a three - dimensional chiral spin structure, which is different from Example 1 in that the thickness of Pt in the spacer layer 4 is 2.0 nm.

[0066] The magnetic multilayer film device with a three - dimensional chiral spin structure in this example also exhibits the chiral exchange bias phenomenon; compared with Example 1, due to the thinner thickness, the interlayer DMI effective field becomes stronger, and the chiral exchange bias field of the hysteresis loop is enhanced.

[0067] Example 3

[0068] A magnetic multilayer film device with a three - dimensional chiral spin structure, which is different from Example 1 in that the material of the spacer layer is Pd.

[0069] The magnetic multilayer device with a three-dimensional chiral spin structure in this embodiment also exhibits the chiral exchange bias phenomenon; compared with Embodiment 1, due to the relatively weak spin-orbit coupling effect of the spacer layer Pd, the interlayer DMI effective field becomes weaker, and the chiral exchange bias field of the hysteresis loop becomes smaller.

[0070] Performance Test

[0071] 1. Hysteresis Loop Experiment

[0072] Take the GaAs / CoGa / Co / Pt / L10-MnGa / Al magnetic multilayer obtained in Embodiment 1 for testing. Use a superconducting quantum interference device (SQUID) to measure the hysteresis loops of the magnetic multilayer in the out-of-plane and in-plane directions respectively. The measurement magnetic field range is -50 kOe to +50 kOe, and the measurement temperature T = 280 K. The results are as Figure 2 shown.

[0073] The results show that the magnetic signal of the magnetic multilayer structure is jointly composed of the first magnetic layer and the second magnetic layer. Among them, the second magnetic layer (L10-MnGa) exhibits good perpendicular magnetic anisotropy, while the first magnetic layer (Co) has good in-plane anisotropy.

[0074] 2. Chiral Exchange Bias Measurement

[0075] Take the GaAs / CoGa / Co / Pt / L10-MnGa / Al magnetic multilayer obtained in Embodiment 1, and pre-magnetize the magnetization vector M of the second magnetic layer (L10-MnGa) z in the +z direction or -z direction respectively. Use a magneto-optical Kerr system to measure the hysteresis loop of the magnetic layer 1 (Co).

[0076] As Figure 3 shown, when the magnetization orientation of the second magnetic layer (L10-MnGa) is towards +z, the hysteresis loop of the first magnetic layer (Co) is generally shifted to the right; when the magnetization orientation of the second magnetic layer is towards -z, the hysteresis loop of the first magnetic layer (Co) is generally shifted to the left. The direction of the exchange bias is related to the magnetization vector M of the second magnetic layer (L10-MnGa) z i.e., the chiral exchange bias phenomenon occurs.

[0077] 3. Chiral Three-Dimensional Spin Structure

[0078] As Figure 4As shown, when the magnetic moment of the second magnetic layer (L10-MnGa) is along +z, at this time, the magnetic moment of the first magnetic layer (Co) tends to be arranged along -x (the coercive force is smaller at this time). When the magnetic moment of the second magnetic layer (L10-MnGa) is along -z, at this time, the magnetic moment of the first magnetic layer (Co) tends to be arranged along +x (the coercive force is smaller at this time). It can be seen from this that when the magnetic moment orientation of the second magnetic layer (L10-MnGa) changes, the preferred orientation of the magnetic moment of the first magnetic layer (Co) changes simultaneously.

[0079] As Figure 5 shown in, in the two different magnetic moment arrangements of arrangement ① and arrangement ②, taking the magnetic moment orientation of the second magnetic layer (L10-MnGa) as the starting direction, the preferred orientation of the magnetic moment of the first magnetic layer (Co) can be obtained by counterclockwise rotation. Therefore, in the GaAs / CoGa / Co / Pt / L10-MnGa / Al magnetic multi-layer film in Example 1, there is a chiral three-dimensional spin arrangement and it has stability.

[0080] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A magnetic multilayer device with a three-dimensional chiral spin structure, characterized in that, Comprising: a substrate (1); a smoothing layer (2), grown on the substrate (1); a first magnetic layer (3), grown on the smoothing layer (2), the material being a ferromagnetic metal and / or a ferrimagnetic metal; a spacer layer (4), grown on the in-plane easy magnetization layer (3), the material being a non-magnetic metal; a second magnetic layer (5), grown on the spacer layer (4), the material being a ferromagnetic metal and / or a ferrimagnetic metal; used to generate an interlayer DMI effect with the first magnetic layer (3) through the spacer layer (4) as a medium, and induce a chiral exchange bias field; a protective layer (6), grown on the perpendicular easy magnetization layer (5).

2. The magnetic multilayer film device with a three-dimensional chiral spin structure according to claim 1, wherein The magnetic anisotropies between the first magnetic layer (3) and the second magnetic layer (5) are perpendicular to each other.

3. The magnetic multilayer film device with a three-dimensional chiral spin structure according to claim 1 or 2, characterized in that, The materials of the first magnetic layer (3) and the second magnetic layer (5) are independently selected from at least one of Fe, CoFe, Co, Co2MnAl, Co2MnSi, CoFeB, L10-MnGa, CoFeB, D0 22 -Mn3Ga, FePt, CoTb or CoGd.

4. The magnetic multilayer film device with a three-dimensional chiral spin structure according to claim 1, characterized in that, The material of the spacer layer (4) is selected from at least one of Pt, Ta, Ru, W, and Ag.

5. The magnetic multilayer film device with a three-dimensional chiral spin structure according to claim 1, wherein The material of the smoothing layer (2) is selected from at least one of GaAs, Si, MgO, Cr, InAs, InGaAs, AlGaAs, Al, Ta, or CoGa.

6. The magnetic multilayer film device with a three-dimensional chiral spin structure according to claim 1, characterized in that, The material of the protective layer (6) is selected from at least one of Al, Cu, MgO, or Pt.

7. The magnetic multilayer film device with a three-dimensional chiral spin structure according to claim 1, characterized in that, The thicknesses of the first magnetic layer (3) and the second magnetic layer (5) are respectively 0.5 - 6 nm.

8. The magnetic multilayer film device with a three-dimensional chiral spin structure according to claim 1, characterized in that, The thickness of the spacer layer (4) is 0.5 - 8 nm.

9. A method for preparing a magnetic multilayer film device having a three-dimensional chiral spin structure according to any one of claims 1-8, characterized in that, By sequentially growing a smoothing layer (2), a first magnetic layer (3), a spacer layer (4), a second magnetic layer (5), and a protective layer (6) on the substrate (1), the magnetic multi-layer film device with a three-dimensional chiral spin structure is obtained.

10. Use of the magnetic multi-layer film device with a three-dimensional chiral spin structure according to any one of claims 1 - 8 in the preparation of a spin memory or a programmable logic device.

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