Method for enhancing magnetic performance of ferromagnetic thin film material regulated and controlled by surface acoustic waves

Abstract

The invention relates to the technical field of spintronics, in particular to a method for enhancing magnetic performance of a surface acoustic wave regulation and control ferromagnetic thin film material.The method comprises the steps that a Pt / CoxTb1-x / Si3N4 multilayer film is deposited on the surface of a lithium niobate substrate, then the obtained multilayer film is regulated and controlled through surface acoustic waves, and the value range of x is larger than 0 and smaller than 1. According to the method, the regulation and control effect of the surface acoustic wave on the magnetic performance of the ferromagnetic thin film material can be remarkably enhanced, the performance of a spinning electronic device is further improved, a promising method is provided for developing the high-performance and low-power-consumption spinning electronic device, and by researching regulation and control of the surface acoustic wave on the magnetic performance of the ferromagnetic thin film material, the magnetic performance of the ferromagnetic thin film material is improved. Particularly, the understanding of the acoustic surface wave induced modulation of the ferromagnetic film material near the compensation point is enhanced through the change of a coercive field and domain wall dynamics near the magnetic moment compensation point, and a new view angle and a new way are opened up for the design and development of a new generation of spinning electronic devices.

Description

Technical Field

[0001] This invention relates to the technical field of spintronics, and more specifically to a method for enhancing the magnetic properties of ferrimagnetic thin film materials by modulating surface acoustic waves. Background Technology

[0002] Surface acoustic waves (SAWs), which utilize dynamic stress generated by alternating voltage, to modulate the magnetism of materials offer advantages such as high efficiency, low power consumption, and long transmission distances. Some studies have shown that SAWs can locally weaken the coercive field of magnetic materials, thereby reducing the external magnetic field required for magnetization reversal. Furthermore, SAWs can influence the kinematics of magnetic domain walls and even drive complex magnetic structures such as skyrmions. Therefore, SAW-based magnetization manipulation technology holds immense potential for innovation in next-generation magnetic memories and spintronic devices.

[0003] Extensive research has demonstrated the potential of surface acoustic waves (SAWs) in modulating the magnetic properties of ferromagnetic thin films, but studies on their effects on subferromagnetic thin films remain lacking. Subferromagnetic thin films exhibit rapid domain wall velocities and ultrafast magnetization dynamics near the magnetic moment compensation point. Summary of the Invention

[0004] One objective of this invention is to provide a method for enhancing the magnetic properties of ferrimagnetic thin film materials by modulating surface acoustic waves. This method can effectively control the coercive field in ferrimagnetic thin film materials, which is beneficial for the development of high-performance, low-power spintronic devices.

[0005] One of the solutions adopted to achieve the objective of this invention is: a method for enhancing the magnetic properties of ferrimagnetic thin film materials by modulating surface acoustic waves, which first involves depositing Pt / Co on the surface of a lithium niobate substrate. x Tb 1-x A Si3N4 multilayer film is obtained, and then the obtained multilayer film is controlled by surface acoustic waves, where the value of x is in the range of 0 < x < 1.

[0006] Preferably, the specific steps of the regulation are as follows: measuring the hysteresis loop of the sample at room temperature using magneto-optical Kerr effect measurement technology and processing the data to obtain the coercive field and Co of the subferromagnetic thin film material. x Tb 1-x The relationship between the composition of the magnetic layer is shown in the figure. By adjusting the power and frequency of the surface acoustic wave (SAW) to control the coercive field and magnetic domain wall motion of the sample, the magnetic properties of the ferromagnetic thin film material can be controlled.

[0007] Preferably, Co x Tb 1-x The coercive field of the magnetic film decreases as the power of the surface acoustic wave increases.

[0008] Preferably, the surface acoustic wave is generated by an interdigital transducer excited by a radio frequency signal. When the frequency of the surface acoustic wave matches the intrinsic frequency of the interdigital transducer, the coercive field is reduced to the maximum.

[0009] Preferably, Co x Tb 1-x The farther the magnetic film is from the magnetic moment compensation point, the more significant the surface acoustic wave modulation effect.

[0010] Preferably, the domain wall velocity increases with increasing surface acoustic power.

[0011] Preferably, Pt / Co is deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x / Si3N4 multilayer film, the Co x Tb 1-x It is a multi-component ferrimagnetic thin film with perpendicular magnetic anisotropy; the thickness of the sputtered Pt layer is 5-8 nm, and the Co layer is... x Tb 1-x The thickness of the magnetic layer is 6-10 nm, and the thickness of the Si3N4 protective layer is 2-3 nm.

[0012] Preferably, Co x Tb 1-x The magnetic film is composed of Co. 0.62 Tb 0.38 Co 0.65 Tb 0.35 Co 0.70 Tb 0.30 Co 0.74 Tb 0.26 Co 0.79 Tb 0.21 Co 0.81 Tb 0.19 or Co 0.82 Tb 0.18 .

[0013] Preferably, the surface acoustic wave is generated by an interdigital transducer excited by a radio frequency signal. Two interdigital transducers are set up to generate and receive the surface acoustic wave, respectively. The finger width and finger spacing of each interdigital transducer are 1.58 μm, the center frequency is 610 MHz, and the wavelength of the generated surface acoustic wave is 6.32 μm. Each interdigital transducer consists of 30 pairs of interdigits with a finger length of 158 μm and a spacing of 1264 μm between adjacent interdigital transducers. The surface acoustic wave is designed to propagate along the x-axis of the lithium niobate substrate.

[0014] The principle of this invention lies in the fact that surface acoustic waves (SAWs) can effectively modulate the coercive field and domain wall dynamics of ferrimagnetic thin film materials. On the one hand, when SAWs propagate in ferrimagnetic thin films, they reduce the potential barrier for magnetization reversal through magnetoelastic coupling, thereby leading to a decrease in the coercive field. On the other hand, due to magnetoelastic coupling, SAWs can periodically change the magnetic anisotropy of ferrimagnetic materials, thereby reducing the nucleation barrier of domain walls, increasing the nucleation probability, and thus accelerating the movement of domain walls.

[0015] The present invention has the following advantages and beneficial effects: This invention discloses a method for controlling the magnetic properties of ferrimagnetic thin film materials, which can significantly enhance the control effect of surface acoustic waves on the magnetic properties of ferrimagnetic thin film materials, further improve the performance of spintronic devices, and provide a promising method for developing high-performance, low-power spintronic devices.

[0016] The method of this invention enhances the understanding of surface acoustic wave-induced modulation of ferrimagnetic thin films near the compensation point by studying the modulation of magnetic properties by surface acoustic waves, especially the changes in coercive field and domain wall dynamics near the magnetic moment compensation point. This opens up new perspectives and approaches for the design and development of next-generation spintronic devices.

[0017] The method of this invention can effectively control the coercive field in ferrimagnetic thin film materials, accelerate the motion of magnetic domain walls, and has a more significant surface acoustic wave control effect on ferrimagnetic thin film samples far from the magnetic moment compensation point, which is beneficial to the development of high-performance, low-power spintronic devices. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method for enhancing the magnetic properties of subferromagnetic thin film materials by surface acoustic waves according to the present invention. Figure 2 Examples of the surface acoustic wave device and the prepared ferrimagnetic thin film material used in this invention are shown in the figure. Figure 3 The coercivity and Co of the ferrimagnetic thin film material obtained by the method of enhancing surface acoustic waves to modulate the magnetic properties of the ferrimagnetic thin film material in Embodiment 1 of the present invention are shown. x Tb 1-x A graph showing the relationship between the composition of the magnetic layer; Figure 4 The percentage reduction in coercivity of the ferrimagnetic thin film material obtained by the method of enhancing surface acoustic waves to modulate the magnetic properties of the ferrimagnetic thin film material in Embodiment 1 of the present invention is related to Co. x Tb 1-x A graph showing the relationship between the composition of the magnetic layer; Figure 5 The ferrimagnetic Co obtained in Embodiment 2 of this invention is obtained by using the method of enhancing surface acoustic waves to modulate the magnetic properties of ferrimagnetic thin film materials. 0.79 Tb0.21 Magnetic property test diagram of thin film material; where a is the preferrimagnetic Co. 0.79 Tb 0.21 The graph shows the relationship between the percentage reduction in coercivity of the thin film material and the surface acoustic wave power (dBm), where b represents the coercive field of the hypoferromagnetic Co. 0.79 Tb 0.21 A graph showing the relationship between the percentage reduction in coercivity of thin film materials and the variation of surface acoustic wave transmission spectrum with surface acoustic wave frequency (MHz); Figure 6 The ferrimagnetic Co obtained in Embodiment 3 of this invention is obtained by using the method of enhancing surface acoustic waves to modulate the magnetic properties of ferrimagnetic thin film materials. 0.70 Tb 0.30 Magnetic property test diagram of thin film material; where a is the preferrimagnetic Co. 0.70 Tb 0.30 The graph shows the relationship between the percentage reduction in coercivity of the thin film material and the surface acoustic wave power (dBm), where b represents the coercive field of the hypoferromagnetic Co. 0.70 Tb 0.30 A graph showing the relationship between the percentage reduction in coercivity of thin film materials and the variation of surface acoustic wave transmission spectrum with surface acoustic wave frequency (MHz); Figure 7 In Embodiment 4 of the present invention, surface acoustic waves are used to modulate the Co-ferrimagnetic magnet. 0.62 Tb 0.38 The magnetic property test pattern of the ferrimagnetic thin film material obtained by the method of magnetic property analysis of thin film materials; where a is the ferrimagnetic Co. 0.62 Tb 0.38 The graph showing the relationship between the domain wall velocity of the thin film material and the surface acoustic wave frequency (MHz); b represents the subferromagnetic Co... 0.62 Tb 0.38 The relationship between the magnetic domain wall movement distance and the linear fitting time (s) of thin film materials, with an inset showing the relationship between the magnetic domain wall velocity and the surface acoustic wave power (dBm). Figure 8 In Embodiment 5 of the present invention, surface acoustic waves are used to modulate the co-ferrimagnetic Co. 0.74 Tb 0.26 Co 0.79 Tb 0.21 and Co 0.82 Tb 0.18 The magnetic property test pattern of the ferrimagnetic thin film material obtained by the method of magnetic property analysis of thin film materials; where a is the ferrimagnetic Co. 0.74 Tb 0.26 The graph shows the relationship between the displacement of the magnetic domain walls of the thin film material and time under the influence of surface acoustic waves; b represents the subferromagnetic Co. 0.74 Tb 0.26 Co 0.79 Tb 0.21 and Co0.82 Tb 0.18 A graph showing the relationship between the domain wall velocity of the thin film material and the surface acoustic wave power (dBm); c represents the subferromagnetic Co. 0.74 Tb 0.26 Co 0.79 Tb 0.21 and Co 0.82 Tb 0.18 The relationship between the magnetic domain wall velocity of thin film materials and the surface acoustic wave power (mW). Detailed Implementation

[0019] To better understand the present invention, the following embodiments are further illustrations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0020] Example 1

[0021] This embodiment relates to a method for enhancing the magnetic properties of ferrimagnetic thin film materials by modulating surface acoustic waves. First, Pt / Co is deposited on the surface of a lithium niobate substrate. x Tb 1-x A Si3N4 multilayer film is obtained, and then the obtained multilayer film is controlled by surface acoustic waves, where the value of x is in the range of 0 < x < 1.

[0022] The specific steps of the regulation are as follows: at room temperature, the hysteresis loop of the sample is measured using magneto-optical Kerr effect measurement technology, and the data is processed to obtain the coercivity of the subferromagnetic thin film material and the Co... x Tb 1-x The relationship between the composition of the magnetic layer is shown in the figure. By adjusting the power and frequency of the surface acoustic wave (SAW) to control the coercive field and magnetic domain wall motion of the sample, the magnetic properties of the ferromagnetic thin film material can be controlled.

[0023] Specifically, as shown in Figure 1, the method for enhancing the magnetic properties of subferromagnetic thin film materials by surface acoustic wave modulation includes the following steps: S1. Pt / Co were deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x / Si3N4 multilayer film, the vacuum level of the sputtering chamber is maintained at 3.2×10. -6 Pa, the working pressure of argon is 0.4 Pa; the Co x Tb 1-x It is a multi-component ferrimagnetic thin film with perpendicular magnetic anisotropy (PMA), prepared by co-sputtering technology. The sputtering power of Tb was set to 20 W, and the sputtering power of Co was set to 35 W, 40 W, 50 W, 60 W, 80 W, 90 W and 100 W, respectively. The resulting Co x Tb 1-xThe magnetic film is composed of Co. 0.62 Tb 0.38 Co 0.65 Tb 0.35 Co 0.70 Tb 0.30 Co 0.74 Tb 0.26 Co 0.79 Tb 0.21 Co 0.81 Tb 0.19 and Co 0.82 Tb 0.18 The sputtered Pt layer has a thickness of 8 nm, and the Co layer... x Tb 1-x The thickness of the magnetic layer is 7 nm, and the thickness of the Si3N4 protective layer is 2 nm.

[0024] S2. Surface acoustic wave (SAW) modulation is applied to the multilayer film structure obtained in step S1. The SAW is generated by applying a radio frequency (RF) signal to an interdigital transducer (IDT). The IDT has two parts: one for generating SAW and the other for receiving it. Each IDT has a finger width and a finger spacing of 1.58 μm, a center frequency of 610 MHz, and generates a SAW wavelength of 6.32 μm. Each IDT consists of 30 pairs of interdigits, with an interdigit length of 158 μm, and a spacing of 1264 μm between adjacent IDTs. The SAW is designed to propagate along the x-axis of the LiNbO3 substrate.

[0025] S3. The surface acoustic wave described in step S2 propagates along the x-axis, passes through the magnetic thin film layer, reaches the interdigital transducer at the other end of the LiNbO3 substrate, and is converted back into an electrical signal through the piezoelectric effect. To analyze the changes in the magnetic properties of the subferromagnetic thin film material under surface acoustic wave modulation, the magneto-optical Kerr effect (MOKE) measurement technique is used to analyze the hysteresis loop and monitor the motion of the magnetic domain walls.

[0026] In step S1, Pt / Co is deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x The specific operating parameters for the Si3N4 multilayer film are as follows: the vacuum level of the sputtering chamber is maintained at 3.2 × 10⁻⁶. -6 Pa, the working pressure of argon gas is 0.4 Pa; the thickness of the sputtered Pt layer is 8 nm, Co x Tb 1-x The thickness of the magnetic layer is 7 nm, and the thickness of the Si3N4 protective layer is 2 nm.

[0027] The Co x Tb 1-xThis is a multi-component ferrimagnetic thin film with perpendicular magnetic anisotropy (PMA), prepared using co-sputtering technology. The sputtering power of Tb was set to 20W, and the sputtering power of Co was set to 35W, 40W, 50W, 60W, 80W, 90W, and 100W respectively. Considering the anomalous magnetic properties exhibited by the ferrimagnetic thin film material at its magnetic moment compensation point, but the range of its magnetic moment compensation point needs to be confirmed, Co should be selected. x Tb 1-x The magnetic film is composed of Co. 0.62 Tb 0.38 Co 0.65 Tb 0.35 Co 0.70 Tb 0.30 Co 0.74 Tb 0.26 Co 0.79 Tb 0.21 Co 0.81 Tb 0.19 and Co 0.82 Tb 0.18 .

[0028] In step S2, the surface acoustic wave (SAW) of the multilayer film structure obtained in step S1 is modulated. The SAW is generated by applying a radio frequency (RF) signal to an interdigital transducer (IDT). The IDT has two parts, one for generating and the other for receiving SAW. Each IDT has a finger width and a finger spacing of 1.58 μm, a center frequency of 610 MHz, and generates a SAW wavelength of 6.32 μm. Each IDT consists of 30 pairs of interdigits, with an interdigit length of 158 μm, and a spacing of 1264 μm between adjacent IDTs. The SAW is designed to propagate along the x-axis of the LiNbO3 substrate.

[0029] The interdigital transducer is also located on the LiNbO3 substrate and is designed to allow surface acoustic waves to propagate along the x-axis of the LiNbO3 substrate. Therefore, the surface acoustic waves generated by the IDT through the inverse piezoelectric effect can be used to modulate the magnetic properties of the ferrimagnetic thin film material using magnetoelastic coupling.

[0030] The specific parameters of the interdigital transducers in step S2 are as follows: the finger width and finger spacing of each interdigital transducer (IDT) are both 1.58 μm, the center frequency is 610 MHz, and the wavelength of the generated surface acoustic wave is 6.32 μm. Each IDT consists of 30 pairs of interdigits, the interdigit length is 158 μm, and the spacing between adjacent IDTs is 1264 μm.

[0031] In step S3, the magneto-optical Kerr effect (MOKE) measurement technique can be used to accurately map the hysteresis loop of the subferrimagnetic thin film material and record the magnetic domain reversal. Analyzing and processing these data can yield changes in the coercive field and domain wall velocity of the subferrimagnetic thin film material.

[0032] Furthermore, this invention provides examples of the surface acoustic wave (SAW) device used and the prepared subferromagnetic thin film material, as shown in Figure 2. In the figure, connecting the interdigital electrodes to the SAW device with aluminum wire allows for the application of radio frequency signals to the interdigital transducer.

[0033] like Figure 3 As shown, the present invention prepares Co with different components. x Tb 1-x The role of the ferrimagnetic thin film material is specifically explained, and the preparation conditions of the ferrimagnetic thin film material are as follows: Pt / Co was deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x / Si3N4 multilayer film, wherein the Co x Tb 1-x The material was prepared using co-sputtering technology. The sputtering power of Tb was set to 20 W, and the sputtering power of Co was set to 35 W, 40 W, 50 W, 60 W, 80 W, 90 W, and 100 W, respectively. The resulting Co... x Tb 1-x The magnetic film is composed of Co. 0.62 Tb 0.38 Co 0.65 Tb 0.35 Co 0.70 Tb 0.30 Co 0.74 Tb 0.26 Co 0.79 Tb 0.21 Co 0.81 Tb 0.19 and Co 0.82 Tb 0.18 .

[0034] The vacuum level in the sputtering chamber is maintained at 3.2 × 10⁻⁶. -6 Pa, the working pressure of argon gas is 0.4 Pa; the thickness of the sputtered Pt layer is 8 nm, Co x Tb 1-x The thickness of the magnetic layer is 7 nm, and the thickness of the Si3N4 protective layer is 2 nm.

[0035] After preparation, the hysteresis loop of the sample was measured at room temperature using magneto-optical Kerr effect (MOKE) measurement technology, and the data was processed to obtain the coercivity and Co of the subferromagnetic thin film material. x Tb 1-x Figure 3 shows the relationship between the composition of the magnetic layer. It confirms that the subferromagnetic thin film material has anomalous magnetic properties near the magnetic moment compensation point, which is manifested by the larger the coercive field as it gets closer to the magnetic moment compensation point.

[0036] like Figure 4 As shown, by adjusting the composition of the magnetic layer, images of the percentage reduction in the coercive field of subferromagnetic thin film materials with different compositions under surface acoustic wave modulation can be obtained. From Figure 4 It can be seen that the magnetic film exhibits a very small percentage reduction in coercivity field under the action of surface acoustic waves when it is close to the magnetic moment compensation point, while the percentage reduction in coercivity field is greater for the subferromagnetic thin film material far from the magnetic moment compensation point. This indicates that the subferromagnetic thin film sample far from the magnetic moment compensation point has a more significant surface acoustic wave modulation effect, where the frequency and power of the surface acoustic waves are 610 MHz and 30 dBm, respectively.

[0037] Example 2

[0038] like Figure 5 As shown, the preparation conditions for the subferromagnetic thin film in this embodiment are as follows: Pt / Co was deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x / Si3N4 multilayer film, the vacuum level of the sputtering chamber is maintained at 3.2×10. -6 Pa, the working pressure of argon is 0.4 Pa; the Co x Tb 1-x The magnetic film was prepared using co-sputtering technology, with the sputtering power of Tb set to 20 W and the sputtering power of Co set to 80 W. The resulting Co... x Tb 1-x The magnetic film is composed of Co. 0.79 Tb 0.21 The sputtered Pt layer has a thickness of 8 nm, and the Co layer... 0.79 Tb 0.21 The thickness of the magnetic layer is 7 nm, and the thickness of the Si3N4 protective layer is 2 nm.

[0039] Then, at room temperature, the hysteresis loop of the sample under surface acoustic wave (SAW) modulation at different powers and frequencies was measured using magneto-optical Kerr effect (MOKE) measurement technology. After synthesizing the data, a graph showing the relationship between the percentage reduction in coercivity of the sample and the changes in SAW power (dBm) and SAW frequency (MHz) can be obtained, as shown below. Figure 5As shown in Figure a, it can be seen that increasing the power of surface acoustic waves leads to Co0. 79 Tb0. 21 The reduction in coercivity of the magnetic film is even greater. This is because higher surface acoustic wave power intensifies the strain within the ferrimagnetic thin film material, thereby reducing Co0. 79 Tb0. 21 The potential barrier for magnetization reversal in the thin film leads to a significant reduction in the coercive field. As can be seen from the red curve in b, the reduction in coercive field is greatest when the surface acoustic wave (SAW) frequency is 610 MHz, coinciding with the intrinsic frequency of the interdigital electrode. This indicates that the SAW frequency has the most significant impact on the coercive field when it matches the intrinsic frequency of the interdigital electrode.

[0040] in addition, Figure 5 The black curve in b is the normalized curve of the surface acoustic wave transmission spectrum at the corresponding frequency. The similar trend of the red and black curves confirms that the reduction of the coercive field is caused by surface acoustic waves rather than radio frequency microwaves.

[0041] Example 3

[0042] To verify the effect of surface acoustic waves on the ferrimagnetic Co of different compositions. x Tb 1-x To determine whether the thin film exhibits a modulating effect, Pt / Co was deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x / Si3N4 multilayer film, the vacuum level of the sputtering chamber is maintained at 3.2×10. -6 Pa, the working pressure of argon is 0.4 Pa; the Co x Tb 1-x The magnetic film was prepared using co-sputtering technology, with the sputtering power of Tb set to 20 W and the sputtering power of Co set to 50 W. The resulting Co... x Tb 1-x The magnetic film is composed of Co. 0.79 Tb 0.21 The sputtered Pt layer has a thickness of 8 nm, and the Co layer... 0.70 Tb 0.30 The thickness of the magnetic layer is 7 nm, and the thickness of the Si3N4 protective layer is 2 nm.

[0043] Then, at room temperature, the hysteresis loop of the sample under surface acoustic wave (SAW) modulation at different powers and frequencies was measured using magneto-optical Kerr effect (MOKE) measurement technology. After synthesizing the data, a graph showing the relationship between the percentage reduction in coercivity of the sample and the changes in SAW power (dBm) and SAW frequency (MHz) was obtained, as shown below. Figure 6As shown in Figure a, it can be seen that increasing the power of surface acoustic waves leads to Co0. 70 Tb0. 30 The reduction in coercive field is even greater for the magnetic film. As can be seen from the red curve in section b, the reduction in coercive field is greatest when the surface acoustic wave (SAW) frequency is 610 MHz, coinciding with the intrinsic frequency of the interdigital electrodes. This indicates that the influence of SAW on the coercive field is most significant when the SAW frequency matches the intrinsic frequency of the interdigital electrodes.

[0044] in addition, Figure 6 The black curve in Figure b is the normalized curve of the surface acoustic wave transmission spectrum at the corresponding frequency. The similar trend between the red and black curves confirms that the reduction in the coercive field is caused by surface acoustic waves rather than radio frequency microwaves, indicating that surface acoustic waves affect different components of Co. x Tb 1-x The coercive field of the thin film has a modulating effect.

[0045] Example 4

[0046] like Figure 7 As shown, the preparation conditions of the subferromagnetic thin film material in this embodiment are as follows: Pt / Co was deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x / Si3N4 multilayer film, the vacuum level of the sputtering chamber is maintained at 3.2×10. -6 Pa, the working pressure of argon is 0.4 Pa; the Co x Tb 1-x The magnetic film was prepared using co-sputtering technology, with the sputtering power of Tb set to 20 W and Co set to 35 W. The resulting Co... x Tb 1-x The magnetic film is composed of Co. 0.62 Tb 0.38 The sputtered Pt layer has a thickness of 8 nm, and the Co layer... x Tb 1-x The thickness of the magnetic layer is 7 nm, and the thickness of the Si3N4 protective layer is 2 nm.

[0047] Then, at room temperature, the motion of the magnetic domain walls was monitored and recorded using magneto-optical Kerr effect (MOKE) measurement technology, and the data was analyzed to obtain the relationship between the domain wall velocity and the surface acoustic wave frequency, as well as the linear fitting relationship between the domain wall advance distance and time under the presence and absence of surface acoustic wave modulation, such as... Figure 7As shown in Figure 7a, when the frequency of the surface acoustic wave (SAW) reaches 610 MHz, the domain wall velocity in the subferromagnetic thin film material is the highest, indicating a significant modulating effect of SAW on the domain wall motion. Figure 7b shows that the domain walls of the thin film sample modulated by SAW travel a greater distance within the same time frame. Furthermore, the inset in Figure 7b shows that the domain wall velocity increases with increasing SAW power.

[0048] Example 5

[0049] To verify the effect of surface acoustic waves on the ferrimagnetic Co of different compositions. x Tb 1-x Does the thin film have a modulating effect? ​​Pt / Co deposition on a 128° YX-LiNbO3 substrate. x Tb 1-x / Si3N4 multilayer film, the vacuum level of the sputtering chamber is maintained at 3.2×10. - 6 Pa, the working pressure of argon is 0.4 Pa; the Co x Tb 1-x The magnetic film was prepared using co-sputtering technology. The sputtering power of Tb was set to 20W, and the sputtering power of Co was set to 60W, 80W, and 100W. x Tb 1-x The magnetic film is composed of Co 0.74 Tb 0.26 Co 0.79 Tb 0.21 Co 0.82 Tb 0.18 The sputtered Pt layer has a thickness of 8 nm, and the Co layer... x Tb 1-x The thickness of the magnetic layer is 7 nm, and the thickness of the Si3N4 protective layer is 2 nm.

[0050] Then, at room temperature, the motion of the magnetic domain walls was monitored and recorded using magneto-optical Kerr effect (MOKE) measurement technology, and the data was analyzed to obtain the relationship between the domain wall velocity and the surface acoustic wave frequency, as well as the linear fitting relationship between the domain wall advance distance and time under the presence and absence of surface acoustic wave modulation, such as... Figure 8 As shown in Figure 8a, the magnetic domain wall advance distance of the thin film sample modulated by surface acoustic waves is greater in the same time period. Furthermore, Figures 8b and c show that different Co compositions... x Tb 1-x The magnetic domain wall velocity of the thin film increases with the increase of surface acoustic power.

[0051] In summary, from Figures 3 to 8It can be seen that the subferromagnetic thin film sample far from the magnetic moment compensation point has a more significant surface acoustic wave (SAW) modulation effect, manifested as a greater reduction in the coercive field. Furthermore, SAW can also increase the velocity of the magnetic domain walls.

[0052] Finally, it should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art will understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection of the present invention is defined by the scope of the claims.

Claims

1. A method for enhancing the magnetic properties of a ferrimagnetic thin film material by modulating surface acoustic waves, characterized in that: First, Pt / Co is deposited on the surface of a lithium niobate substrate. x Tb 1-x A Si3N4 multilayer film is obtained, and then the obtained multilayer film is controlled by surface acoustic waves, where the value of x is in the range of 0 < x < 1.

2. The method for enhancing the magnetic properties of a ferrimagnetic thin film material by surface acoustic wave modulation according to claim 1, characterized in that: The specific steps of the regulation are as follows: at room temperature, the hysteresis loop of the sample is measured using magneto-optical Kerr effect measurement technology, and the data is processed to obtain the coercivity of the subferromagnetic thin film material and the Co... x Tb 1-x The relationship between the composition of the magnetic layer is shown in the figure. By adjusting the power and frequency of the surface acoustic wave (SAW) to control the coercive field and magnetic domain wall motion of the sample, the magnetic properties of the ferromagnetic thin film material can be controlled.

3. The method for enhancing the magnetic properties of subferromagnetic thin film materials by surface acoustic wave modulation according to claim 2, characterized in that: Co x Tb 1-x The coercive field of the magnetic film decreases as the power of the surface acoustic wave increases.

4. The method for enhancing the magnetic properties of subferromagnetic thin film materials by surface acoustic wave modulation according to claim 2, characterized in that: The surface acoustic wave is generated by an interdigital transducer excited by a radio frequency signal. The coercive field decreases to its maximum when the frequency of the surface acoustic wave matches the intrinsic frequency of the interdigital transducer.

5. The method for enhancing the magnetic properties of subferromagnetic thin film materials by surface acoustic wave modulation according to claim 2, characterized in that: Co x Tb 1-x The farther the magnetic film is from the magnetic moment compensation point, the more significant the surface acoustic wave modulation effect.

6. The method for enhancing the magnetic properties of a ferrimagnetic thin film material by surface acoustic wave modulation according to claim 2, characterized in that: The domain wall velocity increases with increasing surface acoustic power.

7. The method for enhancing the magnetic properties of a ferrimagnetic thin film material by surface acoustic wave modulation according to claim 1, characterized in that: Pt / Co was deposited on a 128° YX-LiNbO3 substrate using magnetron sputtering. x Tb 1-x / Si3N4 multilayer film, wherein the Co x Tb 1-x It is a multi-component ferrimagnetic thin film with perpendicular magnetic anisotropy; the thickness of the sputtered Pt layer is 5-8 nm, and the Co layer is... x Tb 1-x The thickness of the magnetic layer is 6-10 nm, and the thickness of the Si3N4 protective layer is 2-3 nm.

8. The method for enhancing the magnetic properties of a ferrimagnetic thin film material by surface acoustic wave modulation according to claim 1, characterized in that: Co x Tb 1-x The magnetic film is composed of Co. 0.62 Tb 0.38 Co 0.65 Tb 0.35 Co 0.70 Tb 0.30 Co 0.74 Tb 0.26 Co 0.79 Tb 0.21 Co 0.81 Tb 0.19 or Co 0.82 Tb 0.18 .

9. The method for enhancing the magnetic properties of a ferrimagnetic thin film material by surface acoustic wave modulation according to claim 1, characterized in that: The surface acoustic wave (SAW) is generated by an interdigital transducer excited by a radio frequency (RF) signal. Two interdigital transducers are set up to generate and receive SAW respectively. The finger width and finger spacing of each interdigital transducer are 1.58 μm, the center frequency is 610 MHz, and the generated SAW wavelength is 6.32 μm. Each interdigital transducer consists of 30 pairs of interdigits with a finger length of 158 μm and a spacing of 1264 μm between adjacent interdigital transducers. The SAW is designed to propagate along the x-axis of the lithium niobate substrate.

Images