Spin current enhanced acoustic-magnetic coupling device of multilayer film structure

Abstract

The invention provides a spin current enhanced acoustic-magnetic coupling device of a multilayer film structure, and belongs to the technical field of acoustic-magnetic coupling film materials. The first interdigital transducer is arranged on one side of the end surface of the piezoelectric substrate and is used for exciting a surface acoustic wave; the second interdigital transducer is arranged on the other side of the end surface of the piezoelectric substrate, is arranged opposite to the first interdigital transducer, and is used for receiving the surface acoustic wave which is excited by the first interdigital transducer and is transmitted along the piezoelectric substrate; the multi-film layer structure is stacked on the piezoelectric substrate between the first interdigital transducer and the second interdigital transducer, and when a sound wave drives ferromagnetic resonance of the first ferromagnetic layer, spin current excited by the first ferromagnetic material layer acts on the second ferromagnetic material layer through the non-magnetic metal layer to drive magnetization precession of the second ferromagnetic material layer; and the magnetization precession of the second ferromagnetic material layer generates spin current, and the spin current reacts on the first ferromagnetic material layer through the non-magnetic metal layer, so that ferromagnetic resonance enhancement is realized.

Description

Technical Field

[0001] The invention relates to the technical field of acoustic-magnetic coupling thin film materials, and in particular to a spin-current enhanced acoustic-magnetic coupling device with a multi-layer film structure. Background Art

[0002] The interaction between spin torque and magnetic moment at the interface of ferromagnetic and nonmagnetic multilayer structures forms the basis of spintronic effects, which are at the core of modern magnetic technology. In recent years, acoustic waves have become a promising tool for controlling spintronic effects in multilayer systems composed of ferromagnetic and nonmagnetic materials. Acoustic waves can couple with magnetic layers through magnetoelastic interactions, and the magnetization dynamics driven by acoustic waves provide an energy-efficient and localized way to control magnetic materials, eliminating the need for large magnetic fields or large currents for traditional means. A typical example of acoustic magnetocoupling is acoustic-wave-induced ferromagnetic resonance, which can enhance spintronic effects in multilayer systems composed of ferromagnetic and nonmagnetic materials, and can then pump spin currents or realize nonreciprocal transmission of acoustic waves.

[0003] Traditional acoustomagnetic coupling devices only have a single ferromagnetic layer, and strong acoustomagnetic coupling can be achieved by using horizontal shear waves in an acoustic cavity with a frequency of up to 6 GHz. However, acoustic wave devices above 2 GHz often require more complex manufacturing processes, which makes it challenging to enhance acoustomagnetic coupling in practical applications. In view of this, it is very necessary to provide a spin current enhanced acoustomagnetic coupling device with a multilayer film structure, which adopts a traditional magnetron sputtering method, does not need to increase the frequency of the acoustic wave device, improves the strength of the acoustomagnetic coupling, and simplifies the preparation process of the multilayer film structure. Summary of the invention

[0004] In view of this, the present invention proposes a spin current enhanced acoustic magnetic coupling device that replaces the conventional single ferromagnetic layer with a composite multilayer film structure of ferromagnetic layer-nonmagnetic metal-ferromagnetic layer and improves the acoustic magnetic coupling strength through the action of spin current.

[0005] The technical solution of the present invention is achieved in this way:

[0006] The present invention provides a spin current enhanced acoustic magnetic coupling device of a multilayer film structure, comprising:

[0007] Piezoelectric substrate;

[0008] A first interdigital transducer, disposed on one side of the end surface of the piezoelectric substrate, for exciting a surface acoustic wave;

[0009] A second IDT is disposed on the other side of the end surface of the piezoelectric substrate and is disposed opposite to the first IDT, and is used to receive the surface acoustic wave excited by the first IDT and transmitted along the piezoelectric substrate;

[0010] A multi-film layer structure includes a first ferromagnetic material layer, a non-magnetic metal layer and a second ferromagnetic material layer, wherein the first ferromagnetic material layer is arranged on the end surface of the piezoelectric substrate between the first interdigital transducer and the second interdigital transducer, the non-magnetic metal layer is arranged on the end surface of the first ferromagnetic material layer away from the piezoelectric substrate, and the second ferromagnetic material layer is arranged on the end surface of the non-magnetic metal layer away from the first ferromagnetic material layer; the easy magnetization directions of the first ferromagnetic material layer and the second ferromagnetic material layer are in-plane, and the easy axis direction of the first ferromagnetic material layer and the easy axis direction of the second ferromagnetic material layer have an angle of 90°.

[0011] On the basis of the above technical solution, preferably, the thickness of the first ferromagnetic material layer and the second ferromagnetic material layer are consistent and do not exceed 100 nm.

[0012] Preferably, the first ferromagnetic material layer and the second ferromagnetic material layer are made of Co or NiFe.

[0013] Preferably, the non-magnetic metal layer is made of Cu, and its thickness does not exceed 10 nm; the thickness of the non-magnetic metal layer does not exceed the spin diffusion length of the selected material.

[0014] Preferably, an anti-oxidation layer is provided on the end surface of the second ferromagnetic material layer away from the non-magnetic metal layer.

[0015] More preferably, the material of the anti-oxidation layer is Pt, and the thickness of the anti-oxidation layer is 5 nm.

[0016] Preferably, the first interdigital transducer includes a plurality of first metal electrodes, a plurality of second metal electrodes, a first bus bar and a second bus bar; the first bus bar and the second bus bar are both arranged on the end surface of the piezoelectric substrate, and the first bus bar and the second bus bar are arranged in parallel and at intervals, one end of the plurality of first metal electrodes is electrically connected to the first bus bar, and the other end of the plurality of first metal electrodes extends in the direction of the second bus bar; one end of the plurality of second metal electrodes is electrically connected to the second bus bar, and the other end of the plurality of second metal electrodes extends in the direction of the first bus bar; the plurality of first metal electrodes and the plurality of second metal electrodes are arranged in an alternating manner; the plurality of first metal electrodes serve as signal input ports, and the plurality of second metal electrodes are grounded through the second bus bar.

[0017] Further preferably, the second interdigital transducer includes a plurality of third metal electrodes, a plurality of fourth metal electrodes, a third bus bar and a fourth bus bar; the third bus bar and the fourth bus bar are both arranged on the end surface of the piezoelectric substrate, and the third bus bar and the first bus bar are correspondingly arranged on both sides of the multi-film layer structure, and the fourth bus bar and the second bus bar are correspondingly arranged on both sides of the multi-film layer structure; the third bus bar and the fourth bus bar are parallel and spaced apart, one end of a plurality of third metal electrodes is electrically connected to the third bus bar, and the other end of a plurality of third metal electrodes extends toward the fourth bus bar; one end of a plurality of fourth metal electrodes is electrically connected to the fourth bus bar, and the other end of a plurality of fourth metal electrodes extends toward the third bus bar; a plurality of third metal electrodes and a plurality of fourth metal electrodes are staggered and spaced apart; a plurality of third metal electrodes serve as signal output ports, and a plurality of fourth metal electrodes are grounded through the fourth bus bar.

[0018] More preferably, the width of the first metal electrode or the second metal electrode in the extension direction is equal to the spacing between adjacent first metal electrodes and second metal electrodes; the width of the third metal electrode or the fourth metal electrode in the extension direction is equal to the spacing between adjacent third metal electrodes and fourth metal electrodes.

[0019] On the basis of the above technical solution, preferably, the material of the piezoelectric substrate is a composite of 128°YX-LiNbO3 or 42°YX-LiTaO3, SiO2 and Si.

[0020] The invention provides a multi-layer film structured spin current enhanced acoustic magnetic coupling device, which has the following beneficial effects compared with the prior art:

[0021] (1) In the multi-film layer structure adopted on the substrate of the present invention, the easy axis directions of the first and second ferromagnetic material layers are at an angle of ninety degrees. When the sound wave drives the ferromagnetic resonance of the first ferromagnetic layer below, the spin current excited by the first ferromagnetic material layer acts on the second ferromagnetic material layer above through the non-magnetic metal layer, driving the magnetization precession of the second ferromagnetic material layer; the magnetization precession of the second ferromagnetic material layer above generates a spin current, which reacts on the first ferromagnetic material layer below through the non-magnetic metal layer, thereby enhancing the ferromagnetic resonance of the first ferromagnetic material layer; this enhancement is reflected in that the intensity of the acoustic-magnetic coupling is enhanced after the sound wave passes through the multi-layer film; this special combined film layer structure enhances the intensity of the acoustic-magnetic coupling through the spin current transmission between the two ferromagnetic material layers, and the implementation method is simple. In the traditional method, there is only a single ferromagnetic layer, and horizontal shear waves are used to achieve strong acoustic-magnetic coupling, but the preparation process is complicated;

[0022] (2) In order to reduce the attenuation of the spin current in the non-magnetic layer, the spin diffusion length of the non-magnetic layer needs to be no less than 1 nm. The selected Cu spin diffusion length is in the order of 10 nm, which meets the requirement. When the damping coefficient of the second ferromagnetic layer is less than 0.01, it is helpful to stimulate a sufficiently strong ferromagnetic resonance in the second ferromagnetic layer. The selected NiFe damping coefficient is in the order of 0.001, which meets the requirement. The anti-oxidation layer needs to be selected from inert metals, or metals that can be oxidized to form a dense oxide film, which can protect the underlying ferromagnetic layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic structural diagram of a spin current enhanced acoustic magnetic coupling device of a multi-layer film structure according to the present invention;

[0025] Figure 2 Magnetic hysteresis loops of the first ferromagnetic material layer and the second ferromagnetic material layer of Embodiment 1 of a spin current enhanced acoustic magnetic coupling device with a multi-layer film structure of the present invention;

[0026] Figure 3 A schematic diagram of the absorption of acoustic wave energy by a multi-film structure of a spin current enhanced acoustic magnetic coupling device of a multi-film structure in Example 1 of the present invention;

[0027] Figure 4 Magnetic hysteresis loops of the first ferromagnetic material layer and the second ferromagnetic material layer of Example 2 of a spin current enhanced acoustic magnetic coupling device with a multi-layer film structure of the present invention;

[0028] Figure 5 A schematic diagram of the absorption of acoustic wave energy by a multi-film structure of a spin current enhanced acoustic magnetic coupling device of a multi-film structure according to Example 2 of the present invention;

[0029] Figure 6 This is a schematic diagram of the absorption of acoustic wave energy by the multi-film layer structure of Example 3 of a spin-current enhanced acoustic-magnetic coupling device with a multi-film structure of the present invention.

[0030] Figure numerals: 01, piezoelectric substrate; 100, first interdigital transducer; 200, second interdigital transducer; 300, multi-film layer structure; 10, first ferromagnetic material layer; 11, non-magnetic metal layer; 12, second ferromagnetic material layer; 02, first metal electrode; 03, second metal electrode; 04, first bus bar; 05, second bus bar; 06, third metal electrode; 07, fourth metal electrode; 08, third bus bar; 09 fourth bus bar. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 1 As shown, the present invention provides a spin current enhanced acoustic magnetic coupling device of a multilayer film structure, comprising:

[0033] The piezoelectric substrate 01 is used to transmit surface acoustic waves and is made of a composite material of 128°YX-LiNbO3 or 42°YX-LiTaO3, SiO2 and Si.

[0034] The first interdigital transducer 100 is disposed on one side of the end surface of the piezoelectric substrate 01 and is used to excite surface acoustic waves;

[0035] The second IDT 200 is disposed on the other side of the end surface of the piezoelectric substrate 01 and is directly opposite to the first IDT 100 , and is used to receive the surface acoustic wave excited by the first IDT 100 and transmitted along the piezoelectric substrate 01 .

[0036] The multi-layer structure 300 includes a first ferromagnetic material layer 10, a non-magnetic metal layer 11 and a second ferromagnetic material layer 12. The first ferromagnetic material layer 10 is arranged on the end face of the piezoelectric substrate 01 between the first interdigital transducer 100 and the second interdigital transducer 200. The non-magnetic metal layer 11 is arranged on the end face of the first ferromagnetic material layer 10 away from the piezoelectric substrate 01, and the second ferromagnetic material layer 12 is arranged on the end face of the non-magnetic metal layer 12 away from the first ferromagnetic material layer 10; the easy magnetization direction of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 is in-plane, and the easy axis direction of the first ferromagnetic material layer 10 and the easy axis direction of the second ferromagnetic material layer 12 have an angle of 90°. The direction of the spin current is perpendicular to the magnetization plane of the two ferromagnetic material layers. In the present application, the spin current propagates vertically between the two ferromagnetic material layers, so the magnetization direction of the ferromagnetic material layer needs to be in-plane.

[0037] As a preferred embodiment, in the present invention, the thickness of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are consistent and do not exceed 100 nm. The first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are made of Co or NiFe.

[0038] The material of the non-magnetic metal layer 11 is Cu, and the thickness does not exceed 10nm. The thickness of the non-magnetic metal layer 11 does not exceed the spin diffusion length of the selected material; it is used to increase the energy change of the surface acoustic wave and enhance the intensity of the acoustic magnetic coupling. When the thickness of the non-magnetic metal layer 11 exceeds the spin diffusion length, the spin current cannot pass through the non-magnetic metal layer, that is, it cannot be transmitted from one ferromagnetic layer to another ferromagnetic layer. When there is no spin current between the two ferromagnetic layers, the effect of enhancing the acoustic magnetic coupling described in this patent cannot be achieved.

[0039] As a further improvement of this solution, in order to prevent the second ferromagnetic material layer 12 from being oxidized, an anti-oxidation layer is provided on the end surface of the second ferromagnetic material layer 12 away from the non-magnetic metal layer 11. The material of the anti-oxidation layer is Pt, and the thickness of the anti-oxidation layer is 5 nm.

[0040] If the magnetoelastic coefficient of the first ferromagnetic material layer is above 1T, the spin current can be injected into the non-magnetic metal layer through the ferromagnetic resonance effect stimulated by acoustic waves. When the spin current propagates in the non-magnetic metal layer, it will gradually decay. After the spin current enters the second ferromagnetic layer through the non-magnetic metal layer, the ferromagnetic resonance can be excited in the second ferromagnetic material layer with a low damping coefficient, and the ferromagnetic resonance intensity of the second ferromagnetic material layer is sufficient to inject the spin current into the non-magnetic metal layer and act on the first ferromagnetic material layer to enhance the acoustic magnetic coupling intensity. According to the above description, the first ferromagnetic material layer requires a magnetoelastic coefficient of more than 1T, and the selected Co magnetoelastic coefficient is about 10T, which meets the requirements. In order to reduce the attenuation of the spin current in the non-magnetic layer, the spin diffusion length of the non-magnetic metal layer needs to be no less than 1nm, and the selected Cu spin diffusion length is in the order of 10nm, which meets the requirements. When the damping coefficient of the second ferromagnetic material layer is lower than 0.01, it is helpful to excite a sufficiently strong ferromagnetic resonance effect in the second ferromagnetic material layer, and the selected NiFe damping coefficient is in the order of 0.001, which meets the requirements. The anti-oxidation layer needs to be made of an inert metal, or a metal that can be oxidized to form a dense oxide film, which can protect the ferromagnetic material layer below. The selected Pt is an inert metal that meets the requirements.

[0041] When the thickness of the ferromagnetic material layer is as low as 1nm, the ferromagnetic layer is usually a vertical film. The present invention requires an in-plane film, that is, the easy magnetization direction is in-plane, and the thickness of the ferromagnetic material layer needs to be above 10nm. When the thickness of the ferromagnetic material layer exceeds 100nm, the consistency along the thickness direction is difficult to ensure. Therefore, the thickness of the first ferromagnetic material layer and the second ferromagnetic material layer are both between 10nm and 100nm. As a transmission channel for the spin current, the non-magnetic metal layer needs to ensure that the spin current can pass through the non-magnetic metal layer, so the thickness cannot exceed the spin diffusion length of the selected material. When the selected non-magnetic metal layer is Cu, the thickness of Cu does not exceed 10nm. The thickness of the anti-oxidation layer is sufficient to allow the selected material to form a dense protective layer on the surface of the ferromagnetic material layer, and the thickness is usually above 1nm.

[0042] like Figure 1 As shown, the first interdigital transducer 100 includes a plurality of first metal electrodes 02, a plurality of second metal electrodes 03, a first bus bar 04 and a second bus bar 05; the first bus bar 04 and the second bus bar 05 are both arranged on the end surface of the piezoelectric substrate 01, and the first bus bar 04 and the second bus bar 05 are arranged in parallel and at intervals, one end of the plurality of first metal electrodes 02 is electrically connected to the first bus bar 04, and the other end of the plurality of first metal electrodes 02 extends toward the direction of the second bus bar 05; one end of the plurality of second metal electrodes 03 is electrically connected to the second bus bar 05, and the other end of the plurality of second metal electrodes 03 extends toward the direction of the first bus bar 04; the plurality of first metal electrodes 02 and the plurality of second metal electrodes 03 are arranged in a staggered manner; the plurality of first metal electrodes 02 serve as signal input ports, and the plurality of second metal electrodes 03 are grounded through the second bus bar 05.

[0043] Likewise Figure 1 As shown, the second interdigital transducer 200 includes a plurality of third metal electrodes 06, a plurality of fourth metal electrodes 07, a third bus bar 08 and a fourth bus bar 09; the third bus bar 08 and the fourth bus bar 09 are both arranged on the end surface of the piezoelectric substrate 01, and the third bus bar 08 and the first bus bar 04 are arranged on both sides of the multi-film layer structure 300, and the fourth bus bar 09 and the second bus bar 05 are arranged on both sides of the multi-film layer structure 300; the third bus bar 08 and the fourth bus bar 09 are arranged in parallel and at intervals, and the plurality of One end of the third metal electrode 06 is electrically connected to the third bus bar 08, and the other ends of the third metal electrodes 06 extend toward the fourth bus bar 09; one end of the fourth metal electrodes 07 is electrically connected to the fourth bus bar 09, and the other ends of the fourth metal electrodes 07 extend toward the third bus bar 08; the third metal electrodes 06 and the fourth metal electrodes 07 are arranged alternately; the third metal electrodes 06 serve as signal output ports, and the fourth metal electrodes 07 are grounded through the fourth bus bar 09. Figure 1As shown, the multi-layer structure 300 located at the first IDT 100 and the second IDT 200 adjusts specific signal energy through acoustic and magnetic coupling.

[0044] The width of the first metal electrode 02 or the second metal electrode 03 in the extension direction is equal to the spacing between adjacent first metal electrodes 02 and second metal electrodes 03 ; the width of the third metal electrode 06 or the fourth metal electrode 07 in the extension direction is equal to the spacing between adjacent third metal electrodes 06 and fourth metal electrodes 07 .

[0045] The technical solution of the present invention is described below by way of embodiments in combination with the accompanying drawings:

[0046] Embodiment 1:

[0047] Experimental acoustic-magnetic coupling device: A first interdigital transducer 100 and a second interdigital transducer 200 are respectively prepared on the surface of a piezoelectric substrate 01 made of 128°YX-LiNbO3, the widths of the first metal electrode 02, the second metal electrode 03, the third metal electrode 06 and the fourth metal electrode 07 are all 600nm, the spacing between adjacent first metal electrodes 02 and second metal electrodes 03 is 600nm, the spacing between adjacent third metal electrodes 06 and fourth metal electrodes 07 is 600nm, and the frequency of the acoustic waves excited in the piezoelectric substrate 01 is 1.6GHz. A multi-layer structure 300 is configured on the piezoelectric substrate 01 between the first interdigital transducer 100 and the second interdigital transducer 200: the first ferromagnetic material layer 10 is made of Co with a thickness of 20 nm, the non-magnetic metal layer 11 is made of Cu with a thickness of 8 nm, the second ferromagnetic material layer 12 is made of NiFe with a thickness of 20 nm, and the end surface of the second ferromagnetic material layer 12 away from the non-magnetic metal layer 11 is covered with 5 nm of Pt to prevent the second ferromagnetic material layer 12 from being oxidized.

[0048] In addition, a control group is set up. The difference between the structure of the experimental acoustic-magnetic coupling device of the present embodiment is that the non-magnetic metal layer 11 is removed, and the other structures are exactly the same.

[0049] The hysteresis loops of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are as follows: Figure 2 As shown, 0° indicates that the direction of the applied external magnetic field is parallel to the direction of sound wave propagation, and 90° indicates that the direction of the applied external magnetic field is perpendicular to the direction of sound wave propagation. At this time, the easy axis direction of the first ferromagnetic material layer 10 is 0°, and the easy axis direction of the second ferromagnetic material layer 12 is 90°. There is a 90° angle between the two easy axis directions. The Landau-Lifshith-Gilbert equation of the first ferromagnetic material layer 10 is expressed as:

[0050] Wherein m is the magnetization vector of the first ferromagnetic material layer 10; H eff is the external magnetic field; m′ is the magnetization vector of the second ferromagnetic material layer 12; γ is the gyromagnetic ratio; α is the damping coefficient; c represents the intensity of the spin current of the second ferromagnetic material layer on the first ferromagnetic material layer 10, which does not exist in the conventional single-layer ferromagnetic layer structure.

[0051] When the direction of the external magnetic field is 90°, the magnetization directions of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are perpendicular, and the two ferromagnetic material layers generate a spin current transmission effect through the non-magnetic metal layer 11. The spin current will enhance the intensity of the acoustic-magnetic coupling, and this enhancement is reflected by the energy change of the acoustic wave, such as Figure 3 As shown, compared with the control group structure without the non-magnetic metal layer 11 in the multi-layer structure 300, the acoustic wave energy change ΔS caused by the multi-layer structure 300 with the 8nm non-magnetic metal layer 11 21 There is a significant improvement.

[0052] Embodiment 2:

[0053] Experimental acoustic-magnetic coupling device: A first interdigital transducer 100 and a second interdigital transducer 200 are respectively prepared on the surface of a piezoelectric substrate 01 made of 128°YX-LiNbO3, the widths of the first metal electrode 02, the second metal electrode 03, the third metal electrode 06 and the fourth metal electrode 07 are all 600nm, the spacing between adjacent first metal electrodes 02 and second metal electrodes 03 is 600nm, the spacing between adjacent third metal electrodes 06 and fourth metal electrodes 07 is 600nm, and the frequency of the acoustic waves excited in the piezoelectric substrate 01 is 1.6GHz. A multi-layer structure 300 is configured on the piezoelectric substrate 01 between the first interdigital transducer 100 and the second interdigital transducer 200: the material selected for the first ferromagnetic material layer 10 is Co with a thickness of 20nm, the material selected for the non-magnetic metal layer 11 is Cu with a thickness of 8nm, the material selected for the second ferromagnetic material layer 12 is NiFe with a thickness of 20nm, and the end surface of the second ferromagnetic material layer 12 away from the non-magnetic metal layer 11 is covered with 5nm of Pt to prevent the second ferromagnetic material layer 12 from being oxidized. That is, the experimental acoustic magnetic coupling device of this embodiment is different from the experimental acoustic magnetic coupling device of Example 1 in that the thickness and material of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are the same.

[0054] In addition, a control group is set up. The difference between the structure of the experimental acoustic-magnetic coupling device of the present embodiment is that the structure other than the second ferromagnetic material layer 12 is removed, and the other structures are exactly the same.

[0055] The hysteresis loops of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are as follows: Figure 4As shown, 0° indicates that the direction of the applied external magnetic field is parallel to the direction of sound wave propagation, and 90° indicates that the direction of the applied external magnetic field is perpendicular to the direction of sound wave propagation. At this time, the easy axis direction of the first ferromagnetic material layer 10 is 0°, and the easy axis direction of the second ferromagnetic material layer 12 is 90°, and there is a 90° angle between the two easy axis directions.

[0056] When the direction of the external magnetic field is 90°, the magnetization directions of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are perpendicular, and the two ferromagnetic material layers generate a spin current transmission effect through the non-magnetic metal layer 11. The spin current will enhance the intensity of the acoustic-magnetic coupling, and this enhancement is reflected by the energy change of the acoustic wave, such as Figure 5 As shown, compared with the control group structure without the second ferromagnetic material layer 12, the multilayer film structure 300 with the second ferromagnetic material layer 12 causes the acoustic wave energy change ΔS 21 There is a significant improvement.

[0057] Embodiment 3:

[0058] Experimental acoustic-magnetic coupling device: The first interdigital transducer 100 and the second interdigital transducer 200 are respectively prepared on the surface of a piezoelectric substrate 01 composed of 42°YX-LiTaO3, SiO2 and Si. The widths of the first metal electrode 02, the second metal electrode 03, the third metal electrode 06 and the fourth metal electrode 07 are all 600nm, the spacing between adjacent first metal electrodes 02 and second metal electrodes 03 is 600nm, the spacing between adjacent third metal electrodes 06 and fourth metal electrodes 07 is 600nm, and the frequency of the acoustic waves excited in the piezoelectric substrate 01 is 1.7GHz. A multi-layer structure 300 is configured on the piezoelectric substrate 01 between the first interdigital transducer 100 and the second interdigital transducer 200: the material selected for the first ferromagnetic material layer 10 is Co with a thickness of 20nm, the material selected for the non-magnetic metal layer 11 is Cu with a thickness of 8nm, the material selected for the second ferromagnetic material layer 12 is NiFe with a thickness of 20nm, and the end surface of the second ferromagnetic material layer 12 away from the non-magnetic metal layer 11 is covered with 5nm of Pt to prevent the second ferromagnetic material layer 12 from being oxidized. That is, the experimental acoustic-magnetic coupling device of this embodiment is different from the experimental acoustic-magnetic coupling device of embodiment 1 in that the material of the piezoelectric substrate 01 is different and the frequency of the excited acoustic wave is different.

[0059] In addition, a control group is set up. The difference between the structure of the experimental acoustic-magnetic coupling device of the present embodiment is that the non-magnetic metal layer 11 is removed, and the other structures are exactly the same.

[0060] Similar to the first embodiment, the hysteresis loops of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are as follows: Figure 2As shown, 0° indicates that the direction of the applied external magnetic field is parallel to the direction of sound wave propagation, and 90° indicates that the direction of the applied external magnetic field is perpendicular to the direction of sound wave propagation. At this time, the easy axis direction of the first ferromagnetic material layer 10 is 0°, and the easy axis direction of the second ferromagnetic material layer 12 is 90°, and there is a 90° angle between the two easy axis directions.

[0061] When the direction of the external magnetic field is 90°, the magnetization directions of the first ferromagnetic material layer 10 and the second ferromagnetic material layer 12 are perpendicular, and the two ferromagnetic material layers generate a spin current transmission effect through the non-magnetic metal layer 11. The spin current will enhance the intensity of the acoustic-magnetic coupling, and this enhancement is reflected by the energy change of the acoustic wave, such as Figure 6 As shown, compared with the control group structure without the non-magnetic metal layer 11 in the multi-layer structure 300, the acoustic wave energy change ΔS caused by the multi-layer structure 300 with the 8nm non-magnetic metal layer 11 21 There is a significant improvement.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A spin current enhanced acoustic magnetic coupling device with a multilayer film structure, characterized in that: include: Piezoelectric substrate (01); A first interdigital transducer (100), arranged on one side of the end surface of the piezoelectric substrate (01), for exciting surface acoustic waves; A second interdigital transducer (200) is arranged on the other side of the end surface of the piezoelectric substrate (01) and is arranged directly opposite to the first interdigital transducer (100), and is used to receive surface acoustic waves excited by the first interdigital transducer (100) and transmitted along the piezoelectric substrate (01); A multi-film layer structure (300) comprises a first ferromagnetic material layer (10), a non-magnetic metal layer (11) and a second ferromagnetic material layer (12); the first ferromagnetic material layer (10) is arranged on the end surface of a piezoelectric substrate (01) between a first interdigital transducer (100) and a second interdigital transducer (200); a non-magnetic metal layer (11) is arranged on the end surface of the first ferromagnetic material layer (10) away from the piezoelectric substrate (01); and a second ferromagnetic material layer (12) is arranged on the end surface of the non-magnetic metal layer (11) away from the first ferromagnetic material layer (10); the easy magnetization directions of the first ferromagnetic material layer (10) and the second ferromagnetic material layer (12) are in-plane, and the easy axis direction of the first ferromagnetic material layer (10) and the easy axis direction of the second ferromagnetic material layer (12) have an angle of 90°.

2. The spin current enhanced acoustic magnetic coupling device of a multilayer film structure according to claim 1, characterized in that: The thickness of the first ferromagnetic material layer (10) and the second ferromagnetic material layer (12) are consistent and do not exceed 100 nm.

3. The spin current enhanced acoustic magnetic coupling device of a multilayer film structure according to claim 2, characterized in that: The first ferromagnetic material layer (10) and the second ferromagnetic material layer (12) are made of Co or NiFe.

4. The spin current enhanced acoustic magnetic coupling device of a multilayer film structure according to claim 2, characterized in that: The material of the non-magnetic metal layer (11) is Cu, and the thickness does not exceed 10 nm; the thickness of the non-magnetic metal layer (11) does not exceed the spin diffusion length of the selected material.

5. The spin current enhanced acoustic magnetic coupling device of a multilayer film structure according to claim 2, characterized in that: An anti-oxidation layer is provided on the end surface of the second ferromagnetic material layer (12) away from the non-magnetic metal layer (11).

6. The spin current enhanced acoustomagnetic coupling device of a multilayer film structure according to claim 5, characterized in that: The material of the anti-oxidation layer is Pt, and the thickness of the anti-oxidation layer is 5 nm.

7. The spin current enhanced acoustic magnetic coupling device of a multilayer film structure according to claim 2, characterized in that: The first interdigital transducer (100) comprises a plurality of first metal electrodes (02), a plurality of second metal electrodes (03), a first bus bar (04) and a second bus bar (05); the first bus bar (04) and the second bus bar (05) are both arranged on the end surface of the piezoelectric substrate (01), and the first bus bar (04) and the second bus bar (05) are arranged in parallel and at intervals; one end of the plurality of first metal electrodes (02) is electrically connected to the first bus bar (04), and the other end of the plurality of first metal electrodes (02) extends in the direction of the second bus bar (05); one end of the plurality of second metal electrodes (03) is electrically connected to the second bus bar (05), and the other end of the plurality of second metal electrodes (03) extends in the direction of the first bus bar (04); the plurality of first metal electrodes (02) and the plurality of second metal electrodes (03) are arranged in a staggered manner; the plurality of first metal electrodes (02) serve as signal input ports, and the plurality of second metal electrodes (03) are grounded through the second bus bar (05).

8. The spin current enhanced acoustomagnetic coupling device of a multilayer film structure according to claim 7, characterized in that: The second interdigital transducer (200) comprises a plurality of third metal electrodes (06), a plurality of fourth metal electrodes (07), a third bus bar (08) and a fourth bus bar (09); the third bus bar (08) and the fourth bus bar (09) are both arranged on the end surface of the piezoelectric substrate (01), and the third bus bar (08) and the first bus bar (04) are arranged on both sides of the multi-film layer structure (300) correspondingly, and the fourth bus bar (09) and the second bus bar (05) are arranged on both sides of the multi-film layer structure (300) correspondingly; the third bus bar (08) and the fourth bus bar (09) are arranged in parallel and at intervals. One end of a plurality of third metal electrodes (06) is electrically connected to a third bus bar (08), and the other end of a plurality of third metal electrodes (06) extends toward a fourth bus bar (09); one end of a plurality of fourth metal electrodes (07) is electrically connected to a fourth bus bar (09), and the other end of a plurality of fourth metal electrodes (07) extends toward the third bus bar (08); the plurality of third metal electrodes (06) and the plurality of fourth metal electrodes (07) are arranged in an alternating manner; the plurality of third metal electrodes (06) serve as signal output ports, and the plurality of fourth metal electrodes (07) are grounded through the fourth bus bar (09).

9. The spin current enhanced acoustomagnetic coupling device of a multilayer film structure according to claim 8, characterized in that: The width of the first metal electrode (02) or the second metal electrode (03) in the extension direction is equal to the spacing between the adjacent first metal electrode (02) and the second metal electrode (03); the width of the third metal electrode (06) or the fourth metal electrode (07) in the extension direction is equal to the spacing between the adjacent third metal electrode (06) and the fourth metal electrode (07).

10. The spin current enhanced acoustic magnetic coupling device of a multilayer film structure according to claim 1, characterized in that: The material of the piezoelectric substrate (01) is a composite of 128°YX-LiNbO3 or 42°YX-LiTaO3, SiO2 and Si.

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