阅读说明：本技术 一种应变控制的可重构自旋波通道及控制方法 (Strain-controlled reconfigurable spin wave channel and control method ) 是由 周浩淼 王凡 朱明敏 邱阳 郭荣迪 吴国华 郁国良 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种应变控制的可重构自旋波通道及控制方法,包括衬底层,所述衬底层上方设有磁性层,所述磁性层上方设有压电层,所述压电层上表面设有顶部电极,所述磁性层上设有激发区。方法包括：构建模拟自旋波通道获取自旋波色散曲线；根据自旋波色散曲线选取施加应变并获取激发频率；构建应用自旋波通道；激发区内采用交变磁场按照激发频率激发并施加应变；自旋波在通道内稳定激发并传播。上述技术方案通过构建可重构自旋波通道,在通道区域内施加应变影响内部有效场,导致自旋波色散曲线发生移动,通道可重构,自旋波传输过程中不会产生固有焦耳热,其外围电路由电压控制,避免了磁场或电流的使用。(The invention discloses a strain-controlled reconfigurable spin wave channel and a control method thereof. The method comprises the following steps: constructing a simulated spin wave channel to obtain a spin wave dispersion curve; selecting applied strain according to the spin wave dispersion curve and acquiring excitation frequency; constructing an application spin wave channel; exciting and applying strain in the excitation area by adopting an alternating magnetic field according to excitation frequency; the spin wave is stably excited and propagated in the channel. According to the technical scheme, the reconfigurable spin wave channel is constructed, the strain is applied in the channel region to influence the internal effective field, so that the spin wave dispersion curve moves, the channel is reconfigurable, the inherent joule heat cannot be generated in the spin wave transmission process, the peripheral circuit is controlled by voltage, and the use of a magnetic field or current is avoided.)

1. The utility model provides a restructural spin wave channel of strain control, its characterized in that, includes substrate layer (1), substrate layer (1) top is equipped with magnetic layer (2), magnetic layer (2) top is equipped with piezoelectric layer (3), piezoelectric layer (3) upper surface is equipped with top electrode (4), be equipped with excitation area (5) on magnetic layer (2).

2. The strain-controlled reconfigurable spin wave channel according to claim 1, wherein the length of the piezoelectric layer (3) in the y-axis direction is smaller than that of the magnetic layer (2), the length of the piezoelectric layer (3) in the x-axis direction is smaller than or equal to that of the magnetic layer (2), one end of the piezoelectric layer (3) in the y-axis direction is flush with the magnetic layer (2), and the piezoelectric layer (3) in the x-axis direction is located in the center of the magnetic layer (2).

3. The strain-controlled reconfigurable spin-wave channel according to claim 1, wherein the excitation region (5) is disposed below one end of the piezoelectric layer (3) that is not flush with the magnetic layer (2) in the y-axis direction, the excitation region (5) penetrates through the magnetic layer (2) in the x-axis direction, and an alternating magnetic field is disposed in the excitation region (5).

4. The strain-controlled reconfigurable spin-wave channel and the control method thereof according to claim 1, wherein the spin-wave channel surface is covered with a ferromagnetic ultrathin film, the ferromagnetic ultrathin film is made of cobalt-iron-boron material with saturation magnetization Ms of 1e6A/m, exchange stiffness A of 1.9e-11J/m, and first magneto-elastic coupling constant B1 of-6.9 e6J/m³Anisotropy constant k is 6.5e5J/m³。

5. The strain-controlled reconfigurable spin-wave channel and the control method thereof according to claim 1, wherein high damping is provided at both ends of the magnetic layer (2) in the y-axis direction.

6. A control method of a strain-controlled reconfigurable spin wave channel is characterized by comprising the following steps:

s1, constructing a simulated spin wave channel to obtain a spin wave dispersion curve;

s2 selecting applied strain according to the spin wave dispersion curve and obtaining the excitation frequency;

s3 constructing an application spin wave channel;

exciting and applying strain in an excitation area of S4 by using an alternating magnetic field according to excitation frequency;

the S5 spin wave is excited and propagated stably in the channel.

7. The method according to claim 6, wherein the step S1 is performed by exciting in an excitation region (5) with an alternating magnetic field, and the excitation function is H sinc (2 pi ft), where f is 20GHz to excite enough multi-frequency spin waves, and performing two-dimensional fourier transform on simulation data with no strain and with strain to obtain spin-wave dispersion relation curves.

8. The method for controlling a strain-controlled reconfigurable spin-wave channel according to claim 6, wherein the step S2 is a spin-wave dispersion curve analytical formula:

wherein A is exchange constant, Ms is saturation magnetization, and U₀For vacuum permeability, H is the total effective field except the strain field, H_εIn order to be a strain field, the strain field,ε_zzstrain applied in the z-axis direction, m_x＝m_y＝0,m_z＝1，B₁C is the magnetoelastic coupling constant and c is the magnetic layer thickness.

9. The method of claim 8, wherein the strain field is applied to the reconfigurable spin wave channel

Wherein m is_x＝m_y＝0,m_z＝1，B₁Is the magneto-elastic coupling constant, epsilon_xxIs the strain applied in the direction of the x-axis,. epsilon_yyIs strain applied in the y-axis direction, epsilon_zzIs the strain applied in the z-axis direction.

10. The method for controlling the strain-controlled reconfigurable spin-wave channel according to claim 8, wherein the strain epsilon applied in the z-axis direction_zzThe strain range of (A) is 0ppm to 8000 ppm.

Technical Field

The invention relates to the technical field of spin electronic devices, in particular to a strain-controlled reconfigurable spin wave channel and a control method thereof.

Background

As the development of Moore's law approaches the limit, the traditional semiconductor ecology will change dramatically. Transistor size and integrated circuit scale are quickly becoming unable to meet modern computing system requirements, and for the development of future high performance electronic devices, the industry has proposed the idea of developing programmable devices using the spin of particles such as electrons. The spin wave is expected to become an effective information carrier in future low-power consumption spin electronic devices. Unlike conventional microelectronic devices that rely on electrons to propagate information, spin waves are the collective precession of the electron spins in a magnetic material, and can carry information such as frequency, phase, etc. The spin wave transmission process does not depend on the movement of particles, so that joule heat does not exist, which is the advantage of designing the spin electronic device with ultra-low power consumption.

There are data showing that spintronics devices based on magnetic field or current control have been widely studied, but their peripheral circuits are complicated and the circuits inevitably bring joule heat. The method for applying the strain can effectively avoid the use of a magnetic field and current, does not need complex design, and has great benefit to the integration of devices.

Chinese patent document CN108767107B discloses a "two-dimensional spintronic device controlled by electric field" and a method for manufacturing the same. Electric field regulation involving the generation of spin current and polarizability was employed. The device structure comprises a sandwich structure of a first BN two-dimensional material/a III-VI family chalcogenide two-dimensional material doped with ferromagnetic metal/a second BN two-dimensional material, a transparent electrode connected with the first BN two-dimensional material and the second BN two-dimensional material, and a channel electrode connected with the III-VI family chalcogenide two-dimensional material. The ferromagnetic metal is doped in lattice substitutional positions or interstitial positions of the III-VI family chalcogenide two-dimensional material, so that the electrons of the III-VI family chalcogenide two-dimensional material have spin polarization; spin-polarized electrons generate spin current through a channel loop under the excitation of incident laser, and the magnetic structure of the III-VI family chalcogenide two-dimensional material doped with ferromagnetic metal is adjusted to be converted between ferromagnetic coupling and antiferromagnetic coupling through an external vertical electric field, so that the polarizability of the spin current can be regulated within the range of 0-100%, and the two-dimensional spin electronic device with the electrically controllable polarizability is formed. The technical scheme is based on current control spin electrons to generate joule heat, and is not beneficial to integration.

Disclosure of Invention

The invention mainly solves the technical problems that the prior technical scheme is not beneficial to integration because spin electrons are controlled to generate joule heat based on a magnetic field or current, and provides a reconfigurable spin wave channel controlled by strain and a control method.

The technical problem of the invention is mainly solved by the following technical scheme:

the utility model provides a strain control's restructural spin wave passageway, includes the substrate layer, the substrate layer top is equipped with the magnetic layer, the magnetic layer top is equipped with the piezoelectric layer, the piezoelectric layer upper surface is equipped with the top electrode, be equipped with the excitation area on the magnetic layer. The magnetic layer is used for moving the spin electrons, the piezoelectric layer realizes the control of the spin electrons, and the excitation area applies an alternating magnetic field to excite the electrons.

Preferably, the length of the piezoelectric layer in the y-axis direction is less than that of the magnetic layer, the length of the piezoelectric layer in the x-axis direction is less than or equal to that of the magnetic layer, one end of the piezoelectric layer in the y-axis direction is flush with the magnetic layer, and the piezoelectric layer in the x-axis direction is located in the center of the magnetic layer.

Preferably, the excitation area is arranged below one end of the piezoelectric layer, which is not flush with the magnetic layer in the y-axis direction, the excitation area penetrates through the magnetic layer in the x-axis direction, and an alternating magnetic field is arranged in the excitation area.

Preferably, the spin wave channel surface is covered with a ferromagnetic ultrathin film, the ferromagnetic ultrathin film is made of cobalt-iron-boron material with saturation magnetization Ms of 1e6A/m, exchange stiffness A of 1.9e-11J/m, and first magnetoelastic coupling constant B1 of-6.9 e6J/m³Anisotropy constant k is 6.5e5J/m³. The applied strain in the channel region can affect the internal effective field, so that the spin wave dispersion curve moves, and the spin wave dispersion curve can reflect the relationship between the spin wave frequency and the wave vector.

Preferably, high damping is provided at both ends of the magnetic layer in the y-axis direction. Higher damping is arranged in specific areas away from the left end and the right end of the film so as to reduce reflection generated when the spin wave is transmitted to the edge as much as possible.

A control method of a strain-controlled reconfigurable spin wave channel comprises the following steps:

s1, constructing a simulated spin wave channel to obtain a spin wave dispersion curve; the transmission of spin waves in the constructed channel was simulated using a finite element method. By comparing spin wave dispersion curves under the condition of not applying strain, a spin wave excitation frequency range can be obtained, in the excitation frequency range, spin waves in a channel can be sequentially excited, and the excitation condition of the spin waves outside the channel can not be met, so that the spin waves can be only constrained in the constructed channel to be transmitted.

S2 selecting applied strain according to the spin wave dispersion curve and obtaining the excitation frequency;

s3 constructing an application spin wave channel;

exciting and applying strain in an excitation area of S4 by using an alternating magnetic field according to excitation frequency;

the S5 spin wave is excited and propagated stably in the channel.

Preferably, in step S1, the excitation region is excited by an alternating magnetic field, the excitation function is H-sinc (2 pi ft), where f is 20GHz to excite enough multi-frequency spin waves, and two-dimensional fourier transform is performed on the simulation data without strain and with strain to obtain the spin-wave dispersion relation curve.

Preferably, the spin wave dispersion curve analysis formula of step S2 is:

wherein A is exchange constant, Ms is saturation magnetization, and U₀For vacuum permeability, H is the total effective field except the strain field, H_εIn order to be a strain field, the strain field,ε_zzstrain applied in the z-axis direction, m_x＝m_y＝0,m_z＝1，B₁C is the magnetoelastic coupling constant and c is the magnetic layer thickness.

Preferably, the strain field

Wherein m is_x＝m_y＝0,m_z＝1，B₁Is the magneto-elastic coupling constant, epsilon_xxIs the strain applied in the direction of the x-axis,. epsilon_yyIs strain applied in the y-axis direction, epsilon_zzIs the strain applied in the z-axis direction. The strain direction relationship is xx ═ yy ═ -zz ═ 4000 ppm.

Preferably, the strain ε is applied in the z-axis direction_zzThe strain range of (A) is 0ppm to 8000 ppm. By strain epsilon imposed in the z-axis direction_zzThe dispersion curve produced a significant downward shift at 4000ppm strain.

The invention has the beneficial effects that:

1. the spin wave transmission process of the invention can not generate intrinsic joule heat, and the peripheral circuit is controlled by voltage, thus avoiding the use of magnetic field or current, therefore, the invention provides a design idea for future miniaturized and low-power consumption spin electronic devices.

2. The channel of the reconfigurable spin wave channel can be selected at will in the magnetic ultrathin film area, and spin waves can be transmitted in the bent irregular channel. The reconfigurable spin wave channel is simple in design and can provide guidance for the design of a future high-integration spin electronic device.

Drawings

FIG. 1 is a hierarchy chart for obtaining spin-wave dispersion curves according to the present invention.

FIG. 2 is a spin-wave dispersion curve calculated for two strains according to the present invention.

FIG. 3 is a constructed spin wave channel hierarchy diagram of the present invention.

FIG. 4 is a diagram of the results of a micro-magnetic simulation for constructing spin wave channels according to the present invention.

FIG. 5 is a two-dimensional block diagram of a constructed "Y" channel spin wave transmission of the present invention.

FIG. 6 is a diagram of the results of a "Y" shaped channel spin wave transmission micromagnetic simulation constructed in accordance with the present invention.

In the figure 1 substrate layer, 2 magnetic layer, 3 piezoelectric layer, 4 top electrode, 5 excitation area.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.

Example (b): the reconfigurable spin wave channel and the control method of strain control of the embodiment are shown in fig. 3 and comprise a substrate layer (1), a magnetic layer (2) is arranged above the substrate layer (1), a piezoelectric layer (3) is arranged above the magnetic layer (2), a top electrode (4) is arranged on the upper surface of the piezoelectric layer (3), the length of the y axis direction of the piezoelectric layer (3) is smaller than that of the magnetic layer (2), the length of the x axis direction of the piezoelectric layer (3) is smaller than or equal to that of the magnetic layer (2), one end of the piezoelectric layer (3) in the y axis direction is flush with the magnetic layer (2), and the center of the magnetic layer (2) is positioned in the x axis direction of the piezoelectric layer (3). Be equipped with excitation area (5) on magnetic layer (2), excitation area (5) are located piezoelectric layer (3) y axle direction and are not in the one end below that flushes with magnetic layer (2), excitation area (5) run through magnetic layer (2) in the x axle direction, be equipped with alternating magnetic field in excitation area (5). High damping is arranged at two ends of the magnetic layer (2) in the y-axis direction.

The surface of the spin wave channel is covered with a ferromagnetic ultrathin film, the ferromagnetic ultrathin film is made of cobalt-iron-boron material with saturation magnetization Ms being 1e6A/m, and exchange is carried outRigidity A is 1.9e-11J/m, and first magnetoelastic coupling constant B1 is-6.9 e6J/m³Anisotropy constant k is 6.5e5J/m³。

A control method of a strain-controlled reconfigurable spin wave channel comprises the following steps:

s1, constructing a simulated spin wave channel to obtain a spin wave dispersion curve; and (3) exciting by adopting an alternating magnetic field in the excitation area (5), wherein the excitation function is H-sinc (2 pi ft), wherein f-20 GHz is used for exciting spin waves with multiple enough frequencies, and two-dimensional Fourier transform is respectively carried out on simulation data without strain and simulation data with strain to obtain a spin-wave dispersion relation curve.

S2 selecting applied strain according to the spin wave dispersion curve and obtaining the excitation frequency; spin wave dispersion curve analytic formula:

wherein A is exchange constant, Ms is saturation magnetization, and U₀For vacuum permeability, H is the total effective field except the strain field, H_εIn order to be a strain field, the strain field,ε_zzstrain applied in the z-axis direction, m_x＝m_y＝0,m_z＝1，B₁C is the magnetoelastic coupling constant and c is the magnetic layer thickness.

Strain field

Wherein m is_x＝m_y＝0,m_z＝1，B₁Is the magneto-elastic coupling constant, epsilon_xxIs the strain applied in the direction of the x-axis,. epsilon_yyIs strain applied in the y-axis direction, epsilon_zzStrain applied in the z-axis direction, strain epsilon applied in the z-axis direction_zzThe strain range of (A) is 0ppm to 8000 ppm. The strain direction relationship is xx ═ yy ═ -zz ═ 4000 ppm.

S3 constructing an application spin wave channel;

exciting and applying strain in an excitation area of S4 by using an alternating magnetic field according to excitation frequency;

the S5 spin wave is excited and propagated stably in the channel. The spin wave is changed by randomly selecting the magnitude and direction of the applied strain in the magnetic ultrathin film area without changing the channel, so that the reconstruction of the spin wave channel is realized.

FIG. 1 is a typical structural design diagram for obtaining dispersion curves in the reconfigurable spin wave channel. Three-directional (X, Y, Z) strains are applied in the channel region by the inverse piezoelectric effect of the piezoelectric material. The strain affects the internal effective field to construct a spin wave channel. The left end region is provided with an excitation region, and spin waves can be continuously excited in the magnetic film by applying an alternating magnetic field with a certain frequency in the excitation region. Higher damping is arranged in specific areas away from the left end and the right end of the film so as to reduce reflection generated when the spin wave is transmitted to the edge as much as possible.

FIG. 2 is a diagram of a structure diagram of a film with a specific size under the condition of applying strain of 0ppm and 4000ppm and a result diagram of spin wave dispersion relation calculation, wherein a dispersion curve in FIG. 2 is obtained by Fourier transform of finite element data and is not directly drawn by a formula, only the Fourier transform result and the formula can be fitted, and the result correctness can be explained. The dimensions of the magnetic thin film of FIG. 1 are 2000 nm long by 150 nm wide by 1 nm thick. High damping is provided in the 25 nm region at the left and right ends. An excitation area with the length of 50 nanometers is arranged 125 nanometers away from the left end, and an alternating magnetic field is adopted in the excitation area for excitation. The excitation function is H-sinc (2 pi ft), where f-20 GHz to excite spin waves of sufficient multifrequency. The spin-wave dispersion relation curve shown in fig. 2 was obtained by performing two-dimensional fourier transform on simulation data with no strain applied and with strain applied, respectively. The results show that the dispersion curve produced a significant downward shift when 4000ppm strain was applied. This phenomenon enables the application of strain to construct a reconfigurable spin wave channel according to the present invention.

Fig. 3 is a schematic diagram of a method for constructing a linear spin wave channel according to the present invention, and fig. 4 is a diagram of a result of a micromagnetic simulation for constructing a spin wave channel, but the present invention is not limited thereto. The film dimensions of the design of fig. 3 were 2000 nm long by 500 nm wide by 1 nm thick, and a 1875 nm long by 150 nm wide strain application region was designed in the middle region as a spin wave propagation channel. According to the spin wave dispersion relation shown in FIG. 2, 4000ppm strain is applied, the spin wave is excited in the excitation area by adopting single-frequency magnetic fields of 3.6GHz and 4.2GHz respectively, and the two frequencies can stably excite the spin wave under the action of the 4000ppm strain but cannot form stable excitation of the spin wave in the non-strain area.

FIG. 4 is a graph of the results of a micromagnetic simulation with 3.6GHz and 4.2GHz frequency excitations applied under 4000ppm strain, respectively, and the spin waves form stable excitation and propagation in the channel. The 4.2GHz frequency excitation forms spin waves of shorter wavelength.

FIG. 5 is a diagram of a "Y" spin wave channel and a diagram of the result of the micromagnetic simulation according to the present invention, but the present invention is not limited thereto. The dimensions of the film designed in fig. 5 were 2000 nm long, 750 nm wide, 1 nm thick, and a "Y-shaped channel" with a width of 150 nm was designed in the region of the film. Spin wave channels are constructed by applying 4000ppm strain in the channel region, and a single-frequency magnetic field of 3.6GHz acts on the excitation region. The Y-shaped spin wave channel is adopted to have two application modes, the first application mode is that the excitation area 5 is arranged on the left side of the Y-shaped channel as shown in figure 5, and spin waves with double outlets in different directions are realized by applying different strains in double channels on the right side of the Y-shaped channel; the second application mode is that excitation areas are respectively arranged at the right ends of two channels on the right side of the Y-shaped channel, and the change of spin waves in the two channels is realized by measuring different excitation areas of the two channels and corresponding strain, so that the spin waves in the two channels are converged into the channel on the left side, and the output of a unified channel is realized.

The graph of the result of the micromagnetic simulation shown in fig. 6 can show that the spin wave is stably excited and propagated in the Y-shaped channel.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Although terms such as, etc. are used more herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.