Artificial antiferromagnetic coupling regulation and control method and device

Abstract

The invention discloses an artificial antiferromagnetic coupling regulation and control method and device, and the method comprises the steps: growing a diamagnetic thin film on a photovoltaic substrate, and enabling the diamagnetic thin film to be of a sandwich type structure; visible natural light irradiation is carried out on the sandwich type structure, the photovoltaic substrate absorbs natural light to generate photo-induced electrons, the photo-induced electrons are migrated to the antiferromagnetic layer, and the antiferromagnetic thin film is adjusted. Through on / off of visible light, complete reversible magnetic switching of an antiferromagnetic state (AFM) and a ferromagnetic state (FM) can be achieved, and a highly flexible and controllable magnetic state transition mode is provided for application of magnetic materials in the fields of storage and the like. Visible light control of a 180-degree deterministic magnetization switch with a tiny bias magnetic field is achieved, the determinacy is crucial to accurate information storage and processing, accurate switching of magnetic states can be ensured, and the reliability of storage and processing is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of antiferromagnetic thin film regulation, and particularly relates to a method and device for regulating artificial antiferromagnetic coupling. Background Art

[0002] Spintronics uses the spin rather than the charge to store information. Since electrons moving from one position to another consume more energy than rotating their spin directions, its regulation consumes less energy than traditional physical electronics.

[0003] Generally, spin-polarized currents are widely applied in various heterostructures to reorient the spin directions between ferromagnetic and antiferromagnetic states, while increasing the spin current conversion rate and reducing the external magnetic bias. However, due to the large driving current density (104 - 106 A·cm-2) required for current-driven spintronic devices, it limits their data storage density and operating speed, and there are relatively large energy dissipation and local heating problems.

[0004] Voltage control of interface magnetism through strain / stress, exchange coupling, interface charge, ion doping, etc. can reduce energy dissipation due to its near-zero driving current. However, the manufacturing challenges of ferromagnetic / ferroelectric heterostructures and the problem of strain instability limit their application in integrated circuits. Adjusting the interlayer coupling through charge accumulation inevitably brings the problem of interface chemical corrosion.

[0005] In addition, magnetic control is performed through femtosecond circularly polarized laser pulses using the magneto-optical Faraday effect or the thermal excitation of the coupling between spin and photons. At the same time, the magnetization reversal can also be manipulated by the light helicity. However, the heating problem caused by the laser leads to excessive energy consumption, triggers unstable neighboring magnetic domains, and inhibits the storage density and stability. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and device for regulating artificial antiferromagnetic coupling to solve the above problems.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] An artificial antiferromagnetic coupling regulation method includes:

[0009] Growing an antiferromagnetic thin film on a photovoltaic substrate, and the antiferromagnetic thin film has a sandwich structure;

[0010] Irradiating the sandwich structure with visible natural light, and the photovoltaic substrate absorbs the natural light to generate photoinduced electron migration to the antiferromagnetic layer to regulate the antiferromagnetic thin film.

[0011] Further, growing the antiferromagnetic thin film on the photovoltaic substrate includes:

[0012] The deposition of the antiferromagnetic film was started using the DC magnetron sputtering method when the vacuum reached 9.0x10 -8 Torr. During the deposition process, a quartz crystal microbalance was used to control the film thickness.

[0013] Furthermore, the sandwich structure is a first magnetic layer, a metal layer, and a second magnetic layer; the thicknesses of the first magnetic layer and the second magnetic layer are greater than 1.4 nm, and the thickness of the metal layer is 4.5 nm - 7 nm.

[0014] Furthermore, the first magnetic layer and the second magnetic layer are the same and are CoFe or CoFeB.

[0015] Furthermore, the metal layer is Cu, Mo, or Ru.

[0016] Furthermore, the photovoltaic substrate is a PN Si wafer with a resistivity of 0.02 Ω·cm, where the n-type layer has a thickness of 10 μm and a resistivity less than 0.025 Ω·cm; the p-type layer has a thickness of 525 μm and a resistivity of 4 - 5 Ω·cm.

[0017] Furthermore, the visible natural light irradiation on the sandwich structure includes: simulating the light irradiation under a xenon lamp solar simulator, passing through an AM 1.5G filter and then applying it to the sandwich structure, and the light intensity is 100 mW cm -2 .

[0018] Furthermore, the sample was placed in an environment without light except for the light source of the xenon lamp solar simulator to receive the light irradiation.

[0019] Furthermore, during the test, the repeatability test of the antiferromagnetic film regulation was realized by repeatedly removing and applying the light irradiation.

[0020] An artificial antiferromagnetic coupling regulation device is prepared according to the described artificial antiferromagnetic coupling regulation method.

[0021] Compared with the prior art, the present invention has the following technical effects:

[0022] By turning the visible light on / off, the present invention can achieve a completely reversible magnetic switching between the antiferromagnetic state (AFM) and the ferromagnetic state (FM), which provides a highly flexible and controllable magnetic state transition method for the application of magnetic materials in storage and other fields.

[0023] The visible light control of a 180° deterministic magnetization switch with a small bias magnetic field is realized. This determinacy is crucial for precise information storage and processing, can ensure the accurate switching of the magnetic state, and improve the reliability of storage and processing.

[0024] The results using the magneto - optical Kerr effect reveal the magnetic domain switching path between antiferromagnetic domains and ferromagnetic domains, which helps to deeply understand the microscopic mechanism of magnetic materials under optical regulation and provides a theoretical basis for further optimizing material properties and device design.

[0025] The change in the giant magnetoresistance ratio reflects the significant change in resistance when the device undergoes a magnetic state transition. This property makes the prototype device have potential application value in the fields of magnetic storage, magnetic sensors, etc., and can achieve sensitive detection of magnetic field or magnetic state changes.

[0026] During the regulation process, there is no need to apply voltage or current, which avoids the power consumption problem caused by large currents, reduces energy consumption, and also avoids the chemical corrosion problem caused by charge accumulation, improves the stability and service life of the device, and conforms to the development concept of green conservation.

[0027] Due to the above - mentioned many advantages, this technology and device have broad application prospects. It has great potential in the field of fast, compact, and energy - saving solar - driven memories, is expected to promote the development of storage technology, and meet the demand for high - performance and low - power storage devices. In addition, it may also have important application value in the fields of magnetic sensors, spintronic devices, etc., providing new ideas and methods for technological innovation in related fields. Description of the Drawings

[0028] Figure 1 Schematic diagram of the PN Si / CoFe(1.87nm) / Cu(4.5nm) / CoFe(1.87nm) antiferromagnetic heterostructure.

[0029] Figure 2 Schematic diagram of the hysteresis loops of the antiferromagnetic heterostructure with and without light illumination.

[0030] Figure 3 MOKE images of magnetic domain evolution under visible light. a is the schematic diagram of the MOKE test device principle, and b is the magnetic domain change after applying visible light under a magnetic field from - 80 to + 80 Oe. Detailed Implementation Modes

[0031] The present invention will be further described below in conjunction with the drawings:

[0032] Example 1, a method for regulating the magnetism of a metal thin film using natural light, the method comprising the following steps:

[0033] S1. Preparation of the thin film: Grow a suitable antiferromagnetic thin film on a specific photovoltaic substrate;

[0034] S2. Regulating the magnetism of the antiferromagnetic thin film: Under normal indoor conditions, adjust the antiferromagnetic thin film by changing the light - receiving situation of the antiferromagnetic thin film.

[0035] In step S1, the substrate is: photovoltaic PN silicon.

[0036] In step S1, the thin film structure from top to bottom is: PN Si / CoFe(1.87nm) / Cu(4.5nm) / CoFe(1.87nm).

[0037] In step S2, the samples and devices used are simulated under illumination by a xenon lamp solar simulator.

[0038] In step S2, the applied illumination is applied to the samples and devices after passing through an AM 1.5G filter.

[0039] In step S2, the standard natural light illumination intensity applied is 100mW cm -2 , which is equivalent to the standard intensity of one sun.

[0040] In step S2, no external conditions such as additional voltage or current are required.

[0041] In step S2, when the illumination is stably irradiated on the sample, the magnetic test is carried out to confirm the regulation effect.

[0042] In step S2, the repeatability test of the antiferromagnetic thin film regulation is realized by repeatedly removing and applying the illumination.

[0043] The thickness of CoFe is greater than 1.4nm. In addition to CoFe, it can also be CoFeB.

[0044] The thickness of Cu is between 4.5nm and 7nm. In addition to Cu, it can also be Mo, Ru.

[0045] The antiferromagnetic heterostructure with adjustable natural light includes a photovoltaic layer PN Si and an antiferromagnetic layer with a "sandwich" structure composed of two layers of CoFe alloy and one layer of Cu. They jointly form a CoFeB / Cu / CoFeB / PN Si structure. When visible natural light is irradiated on this structure, the photovoltaic layer absorbs the natural light and generates photo-generated electrons that migrate to the antiferromagnetic layer, and it can achieve an obvious transformation of the heterojunction from antiferromagnetism to ferromagnetism when the light irradiates the photovoltaic layer.

[0046] In the example disclosed in this patent, the method steps for the visible light to achieve magnetization reversal are: preparing an antiferromagnetic heterostructure on the photovoltaic top layer, applying a natural light source, and performing a ferromagnetic test.

[0047] This application uses standard sunlight illumination as the condition for magnetic regulation and the only condition, which is convenient and environmentally friendly. Since natural light resources are abundant and easy to use, it has broad application prospects. Moreover, the regulation condition is simple. Since no voltage or current needs to be applied, it also avoids power consumption caused by large current or chemical corrosion caused by charge accumulation, which is green and energy-saving.

[0048] Example 2 will be further described below in conjunction with the drawings and examples.

[0049] The following process steps are carried out:

[0050] (1) Preparation of metal thin film: When the vacuum degree reaches 9.0x10-8 Torr, CoFe, Fe, and CoFe are sequentially deposited at a certain power using DC magnetron sputtering. A PN Si / CoFe(1.87nm) / Cu(4.5nm) / CoFe(1.87nm) structure is obtained. During the film coating process, the thickness of the thin film is controlled by a quartz crystal microbalance integrated in the magnetron sputtering system to ensure the accuracy of the growth parameters of each layer. Among them, the silicon wafer with a p-n junction as the light absorption medium is purchased from China Shunsheng Electronic Technology Co., Ltd. The epitaxial n-type layer is prepared on a p-type Si substrate to form a PN Si wafer with a resistivity of 0.02 Ωcm. The thickness of the n-type layer is 10 μm and the resistance is less than 0.025 Ωcm; the thickness of the p-type layer is 525 μm and the resistance is 4-5 Ωcm.

[0051] (2) Preparation for light control: Use a PL-XQ500W xenon lamp solar simulator to illuminate under AM 1.5G (100mW cm -2 ), and the standard visible light intensity is 100mWcm -2 (1 sun). Place the sample in an environment without light except for the above light source to receive illumination.

[0052] (3) In-situ measurement of magnetism: The in-situ correction of magnetic anisotropy was measured in a VSM (Lakeshore 7404), and the MOKE image was tested and recorded using an EM-KERR-HIGHRES MOKE microscope.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for regulating artificial antiferromagnetic coupling, characterized in that, Comprising: Growing an antiferromagnetic thin film on a photovoltaic substrate, the antiferromagnetic thin film having a sandwich structure; Irradiating the sandwich structure with visible natural light, the photovoltaic substrate absorbing the natural light to generate photo-generated electrons that migrate to the antiferromagnetic layer to adjust the antiferromagnetic thin film.

2. The artificial antiferromagnetic coupling regulation method according to claim 1, wherein The growing of the antiferromagnetic thin film on the photovoltaic substrate includes: The diamagnetic film was deposited by DC magnetron sputtering method when the vacuum degree reached 9.0x10 -8 Torr. During the deposition process, the thickness of the film was controlled by a quartz crystal microbalance.

3. The artificial antiferromagnetic coupling regulation method according to claim 2, wherein The sandwich structure is a first magnetic layer, a metal layer, and a second magnetic layer; the thicknesses of the first magnetic layer and the second magnetic layer are greater than 1.4 nm, and the thickness of the metal layer is 4.5 nm - 7 nm.

4. The artificial antiferromagnetic coupling regulation method according to claim 3, characterized in that The first magnetic layer and the second magnetic layer are the same and are CoFe or CoFeB.

5. The artificial antiferromagnetic coupling regulation method according to claim 3, wherein The metal layer is Cu, Mo, or Ru.

6. The artificial antiferromagnetic coupling regulation method according to claim 1, wherein The photovoltaic substrate is a PN Si wafer with a resistivity of 0.02 Ωcm, where the n-type layer has a thickness of 10 μm and a resistivity less than 0.025 Ωcm; the p-type layer has a thickness of 525 μm and a resistivity of 4 - 5 Ωcm.

7. The artificial antiferromagnetic coupling regulation method according to claim 1, wherein The sandwich structure is irradiated with visible natural light, including: simulating light irradiation under a xenon lamp solar simulator, applying it to the sandwich structure after passing through an AM 1.5G filter, and the light intensity is 100 mW cm -2 .

8. A method for regulating artificial antiferromagnetic coupling according to claim 7, characterized in that, Placing the sample in an environment without light except for the light source of a xenon lamp solar simulator for illumination.

9. A method for regulating artificial antiferromagnetic coupling according to claim 1, characterized in that, During testing, the repeatability test of the antiferromagnetic thin film regulation is achieved by repeatedly removing and applying light illumination.

10. An artificial antiferromagnetic coupling regulation device, characterized in that, Prepared by an artificial antiferromagnetic coupling regulation method according to any one of claims 1 to 9.

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