All-optical magnetic turnover magnetic film and preparation method and application thereof

Abstract

The invention discloses an all-optomagnetic turnover magnetic film as well as a preparation method and application thereof. The all-optical magnetic turnover magnetic film comprises a Ta layer, a first Pt layer, a Co layer, a Ru layer, a Gd layer and a second Pt layer which are sequentially stacked on the surface of a substrate, wherein the thickness of the Ru layer is 0.8 nm, 1.3 nm or 1.5 nm. The preparation method of the all-optical magnetic flipping magnetic film comprises the following steps: sequentially depositing a Ta layer, a first Pt layer, a Co layer, a Ru layer, a Gd layer and a second Pt layer on the surface of a substrate by adopting ultrahigh vacuum direct current magnetron sputtering to obtain the all-optical magnetic flipping magnetic film. The all-optical magnetic flipping magnetic film has the advantages of high switching efficiency, low switching energy, wide energy window, easiness in regulation and control, stability in repeated writing and the like, can be applied to the fields of high-density ultrafast magnetic storage, information processing and the like, and is suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of spintronics technology, specifically to an all-optical magnetic reversal magnetic thin film, its preparation method, and its application. Background Technology

[0002] Single-pulse all-optical magnetic reversal (SP-AOS) technology is a technique that uses a single femtosecond laser pulse to directly control the magnetization direction of magnetic materials. It does not require an external magnetic field or external current, has an ultra-fast response speed (sub-picosecond level) and extremely low energy consumption, and has broad application prospects in high-density ultrafast magnetic storage and information processing.

[0003] Research has found that although many material systems possess antiferromagnetically coupled sublattices and have different demagnetization times, only a few material systems can exhibit the SP-AOS effect. Currently, the material systems capable of achieving SP-AOS mainly include the following: 1) Ferromagnetic alloys or multilayer films containing rare earth elements, such as GdFeCo alloys and Gd / Co multilayer films. Their SP-AOS mechanism originates from the different ultrafast demagnetization dynamics between transition metal (TM) and rare earth (RE) sublattices. The femtosecond laser pulse first causes the TM sublattice to undergo rapid demagnetization, and then it is magnetized parallel to the RE magnetic rectangle into a transient ferromagnetic state, thereby driving magnetization reversal; 2) Heusler-type ferromagnets, such as Mn2Ru. x Ga magnets; 3) Spin valve structure, for example: Pt / Co / Cu / Co / Pt multilayer film.

[0004] However, the aforementioned material systems capable of achieving SP-AOS still have the following problems:

[0005] 1) Unstable switching efficiency: The SP-AOS switching ratio of existing material systems is usually low and uncontrollable. For example, in the Pt / Co / Gd multilayer film structure, when the thickness of the Co layer exceeds 1.4 nm, the single-pulse AOS effect almost disappears completely, which seriously limits the design flexibility of the device. 2) Narrow energy window: In existing material systems, SP-AOS is only effective within a very narrow laser energy range. If the energy is slightly lower, it cannot be switched, and if the energy is slightly higher, it will lead to the formation of multiple domains, making it difficult to achieve reliable and stable repeated writing. 3) Lack of controllability: In GdFeCo alloys or Mn2Ru x In conventional AOS materials such as Ga magnets, the coupling strength between transition metals and rare earth elements is chemically fixed and cannot be continuously adjusted through structural design, making it difficult to optimize SP-AOS performance. 4) High energy consumption: Existing material systems typically require high-energy laser pulses to achieve magnetic reversal, which severely limits their application in low-power devices.

[0006] Therefore, it is of great significance to develop an all-optical magnetic reversal magnetic thin film with high switching efficiency, wide energy window, easy control, low energy consumption, and stable rewrite. Summary of the Invention

[0007] The purpose of this invention is to provide a fully optically magnetically reversible magnetic thin film, its preparation method, and its application.

[0008] The technical solution adopted in this invention is: A fully optical magnetic reversal magnetic thin film comprises a Ta layer, a first Pt layer, a Co layer, a Ru layer, a Gd layer, and a second Pt layer sequentially stacked on the surface of a substrate.

[0009] Preferably, the substrate is one of a silicon dioxide substrate, an aluminum oxide substrate, a silicon substrate, or a tantalum nitride substrate.

[0010] Preferably, the thickness of the Ta layer is 4.0 nm to 6.0 nm.

[0011] Preferably, the thickness of the first Pt layer is 3.0 nm to 5.0 nm.

[0012] Preferably, the thickness of the Co layer is 0.6 nm to 1.6 nm.

[0013] Preferably, the thickness of the Ru layer is 0.8 nm, 1.3 nm, or 1.5 nm.

[0014] More preferably, the thickness of the Ru layer is 0.8 nm.

[0015] Preferably, the thickness of the Gd layer is 1.0 nm to 3.0 nm.

[0016] Preferably, the thickness of the second Pt layer is 1.0 nm to 2.0 nm.

[0017] Note: Ta is tantalum, Pt is platinum, Co is cobalt, Ru is ruthenium, and Gd is gadolinium.

[0018] A method for preparing a fully optically magnetically reversible thin film as described above includes the following steps: A Ta layer, a first Pt layer, a Co layer, a Ru layer, a Gd layer, and a second Pt layer were sequentially deposited on the substrate surface using ultra-high vacuum DC magnetron sputtering to obtain an all-optical-magnetic reversal magnetic thin film.

[0019] Preferably, the process parameters for the ultra-high vacuum DC magnetron sputtering include: substrate pressure <5×10⁻⁶. -8Torr, the ignition pressure is 6mTorr~8mTorr, the growth pressure is 6mTorr~8mTorr, and the growth power is 5W~25W.

[0020] A spin memory comprising the aforementioned all-optical-magnetic reversible magnetic thin film.

[0021] The principle of this invention: The all-optical magnetic reversal magnetic thin film of this invention, by setting a Ru layer of a specific thickness, enables strong AFM coupling between magnetic material thin films (the material system enters a low-dissipation exchange-mediated angular momentum transfer channel, rather than a dissipative SOC-mediated channel of a traditional ferromagnetic material system). The angular momentum transfer speed between Co and Gd sublattices is fast, and the Co magnetic moment can be reversed to form a transient ferromagnetic state within about 2 ps, thereby achieving efficient SP-AOS.

[0022] The beneficial effects of the present invention are: the all-optical magnetic reversal magnetic thin film of the present invention has the advantages of high switching efficiency, low switching energy, wide energy window, easy control, and stable repeated writing, and can be used in fields such as high-density ultrafast magnetic storage and information processing, and is suitable for large-scale applications.

[0023] Specifically: 1) Ultra-high switching efficiency: The all-optical magnetic reversal magnetic thin film of the present invention can achieve a single-pulse all-optical magnetic reversal switching ratio of nearly 100% at the optimal Ru thickness (0.8nm). The switching ratio is much higher than that of traditional GdFeCo alloy materials (switching ratio is usually <90%) and direct Co-Gd contact structure (switching ratio is about 92%), which solves the problem of incomplete switching in existing material systems. 2) Ultra-low switching energy: The all-optical magnetic reversal magnetic thin film of this invention has an energy of only 7.5 nJ (1.66 mJ / cm). 2 It can achieve effective switching under low-energy laser pulses, reducing energy demand by about 30% to 50% compared with existing material systems, and greatly improving energy efficiency; 3) Wide energy window: The all-optical magnetic reversal magnetic thin film of the present invention can maintain efficient single-domain switching in the energy range of 7.5nJ to 15.5nJ. The energy window width is 2 to 3 times that of existing material systems, which significantly improves the fault tolerance and reliability of operation. 4) Stable rewrite performance: The all-optical magnetic reversal magnetic film of the present invention can exhibit excellent rewrite performance under multiple pulse irradiation and will not form a multi-domain state, thus solving the problem of unstable rewrite in existing material systems. 5) Breakthrough in material limitations: This invention can successfully achieve efficient SP-AOS in a structure with a Co thickness of 1.5nm (exceeding the traditional limit of 1.4nm), which greatly expands the range of material choices and provides more possibilities for device integration; 6) High-density storage compatibility: The all-optical magnetic reversal magnetic film of the present invention is suitable for ultra-high-density data storage, with a write speed reaching the sub-picosecond level, which is more than 1,000 times faster than traditional magnetic storage technology. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the Pt / Co / Ru / Gd / Pt multilayer film structure in the all-optical magnetic reversal magnetic thin film of the present invention.

[0025] Figure 2 The graph shows the Gd magnetic moment and magnetization reversal rate of the all-optical magnetic reversal magnetic films of Examples 1-3 and the magnetic films of Comparative Examples 1-15, as well as the magnetization reversal test results under laser pulses of different energies. Detailed Implementation

[0026] The present invention will be further explained and described below with reference to specific embodiments.

[0027] Example 1: A fully optically-magnetically reversible magnetic thin film, the preparation method of which is as follows: The glass slide was cleaned with alcohol and deionized water, dried, and then subjected to ultra-high vacuum DC magnetron sputtering. The following layers were deposited sequentially on a single surface of the glass slide: a 5 nm thick Ta layer, a 4 nm thick first Pt layer, a 1.5 nm thick Co layer, a 0.8 nm thick Ru layer, a 3 nm thick Gd layer, and a 2 nm thick second Pt layer (no heating was applied to the glass slide during the growth process to minimize interdiffusion at the Ru / Gd interface). The ultra-high vacuum DC magnetron sputtering process parameters were as follows: substrate pressure < 5 × 10⁻⁵. -8 The ignition pressure was 6 mTorr, the growth pressure was 6 mTorr, the growth power of Ta was 25 W, and the deposition rate of Ta was 0.33 Å / s; the growth power of Pt was 5 W, and the deposition rate of Pt was 0.13 Å / s; the growth power of Co was 5 W, and the deposition rate of Co was 0.08 Å / s; the growth power of Ru was 5 W, and the deposition rate of Ru was 0.17 Å / s; the growth power of Gd was 5 W, and the deposition rate of Gd was 0.24 Å / s. This yielded a fully optically magnetically reversible magnetic thin film (the schematic diagram of the Pt / Co / Ru / Gd / Pt multilayer structure is shown in Figure 1). Figure 1 (As shown).

[0028] Example 2: A fully optical magnetic reversing magnetic thin film is identical to the fully optical magnetic reversing magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.3nm".

[0029] Example 3: A fully optical magnetic reversing magnetic thin film is identical to the fully optical magnetic reversing magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.5nm".

[0030] Comparative Example 1: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0nm (i.e., no Ru layer)".

[0031] Comparative Example 2: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0.2nm".

[0032] Comparative Example 3: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0.3nm".

[0033] Comparative Example 4: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0.4nm".

[0034] Comparative Example 5: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0.5nm".

[0035] Comparative Example 6: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0.6nm".

[0036] Comparative Example 7: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0.7nm".

[0037] Comparative Example 8: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "0.9nm".

[0038] Comparative Example 9: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.0nm".

[0039] Comparative Example 10: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.1nm".

[0040] Comparative Example 11: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.2nm".

[0041] Comparative Example 12: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.4nm".

[0042] Comparative Example 13: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.6nm".

[0043] Comparative Example 14: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.7nm".

[0044] Comparative Example 15: A magnetic thin film is identical to the all-optical magnetic reversal magnetic thin film of Example 1, except that the thickness of the Ru layer is adjusted from "0.8nm" to "1.8nm".

[0045] Performance testing: The Gd magnetic moment and magnetization reversal rate of the all-optical magnetic reversal magnetic thin films of Examples 1-3 and the magnetic thin films of Comparative Examples 1-15, as well as the magnetization reversal test results under laser pulses of different energies, are as follows: Figure 2 (a is a graph showing the test results of Gd magnetic moment and magnetization reversal rate. The red / blue bars in the graph represent Gd magnetic moment, and the broken line represents magnetization reversal rate. Gd magnetic moment is positively correlated with antiferromagnetic coupling strength. b is a graph showing the test results of magnetization reversal under laser pulses of different energies. The blue area in the graph represents the area of ​​upward magnetization, and the red area represents the area of ​​downward magnetization. The larger the area of ​​the red area, the better the effect of all-optical magnetic reversal.)

[0046] Depend on Figure 2 It can be known that: 1) The antiferromagnetic coupling strength of the all-optical magnetic reversal magnetic films in Examples 1 to 3 is very high, and the magnetization reversal rate is higher than 70%. Among them, the all-optical magnetic reversal magnetic film in Example 1 has the best antiferromagnetic coupling strength and the magnetization reversal rate is close to 100%, showing excellent all-optical magnetic reversal performance. 2) The antiferromagnetic coupling effect of the magnetic films in Comparative Examples 1 to 15 is significantly weaker than that of the all-optical magnetic reversal magnetic films in Examples 1 to 3, and the magnetization reversal rate can only be maintained at about 50%. In summary, by precisely controlling the thickness of the Ru layer to 0.8 nm, 1.3 nm, and 1.5 nm, this invention can effectively enhance the antiferromagnetic coupling strength of the magnetic thin film, thereby significantly improving its magnetization reversal effect. The resulting all-optical magnetic reversal magnetic thin film is suitable for high-density ultrafast magnetic storage and information processing.

[0047] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A fully optically and magnetically reversible magnetic thin film, characterized in that, The composition includes a Ta layer, a first Pt layer, a Co layer, a Ru layer, a Gd layer, and a second Pt layer sequentially stacked on the substrate surface; the thickness of the Ru layer is 0.8 nm, 1.3 nm, or 1.5 nm.

2. The all-optical-magnetic reversible magnetic thin film according to claim 1, characterized in that: The Ru layer has a thickness of 0.8 nm.

3. The all-optical-magnetic reversible magnetic thin film according to claim 1 or 2, characterized in that: The substrate is one of the following: silicon dioxide substrate, aluminum oxide substrate, silicon substrate, and tantalum nitride substrate.

4. The all-optical-magnetic reversible magnetic thin film according to claim 1 or 2, characterized in that: The thickness of the Ta layer is 4.0 nm to 6.0 nm.

5. The all-optical-magnetic reversible magnetic thin film according to claim 1 or 2, characterized in that: The thickness of the first Pt layer is 3.0 nm to 5.0 nm.

6. The all-optical-magnetic reversible magnetic thin film according to claim 1 or 2, characterized in that: The thickness of the Co layer is 0.6 nm to 1.6 nm.

7. The all-optical-magnetic reversible magnetic thin film according to claim 1 or 2, characterized in that: The thickness of the Gd layer is 1.0 nm to 3.0 nm.

8. The all-optical-magnetic reversible magnetic thin film according to claim 1 or 2, characterized in that: The thickness of the second Pt layer is 1.0 nm to 2.0 nm.

9. A method for preparing a fully optically magnetically reversible thin film as described in any one of claims 1 to 8, characterized in that, Includes the following steps: A Ta layer, a first Pt layer, a Co layer, a Ru layer, a Gd layer, and a second Pt layer were sequentially deposited on the substrate surface using ultra-high vacuum DC magnetron sputtering to obtain an all-optical-magnetic reversal magnetic thin film.

10. A spin memory, characterized in that, It includes the all-optical magnetic reversal magnetic thin film according to any one of claims 1 to 8.

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