Wireless transmission application based on novel antiferromagnetic spin Hall oscillator

Abstract

The invention relates to wireless transmission application based on a novel antiferromagnetic spin Hall oscillator. The invention provides a novel spin Hall nano oscillator (SHNO). The novel spin Hall nano oscillator comprises a first layer of non-collinear antiferromagnetic material and a second layer of strong spin orbit coupling material. To improve oscillator power, a series coupling technique is employed to connect a plurality of antiferromagnetic SHNOs to a rectification circuit to produce a high rectified voltage and a broadband frequency response. Besides, an n * n synchronous array is further designed, each row of oscillators is provided with an independent direct-current bias source, synchronous coupling of the oscillators in the rows is achieved by accurately adjusting bias current, interaction between the rows is allowed, and the output frequency of the whole array is flexibly regulated and controlled. The wireless communication system based on the antiferromagnetic SHNO synchronous array shows the potential in the aspects of small-scale communication, large-scale data return, short-distance high-speed transmission and the like, and opens up a new way for the development of a new generation of wireless communication technology.

Description

Technical Field

[0001] The present invention relates to the fields of spintronics and wireless communication, and in particular to wireless communication and transmission based on an antiferromagnetic spin Hall oscillator. Background Art

[0002] With the rapid development of mobile communication and the trend of high-frequency and broadband signal transmission, there are increasingly high requirements for the miniaturization and integration of circuits. As an emerging spintronic device, the spin Hall nano-oscillator (SHNO) has broad application prospects in the fields of information storage, processing, and communication. It has excellent characteristics such as nanoscale size, fast and ultra-wide microwave frequency tunability, and the ability to achieve large-scale mutual synchronization in chains and two-dimensional arrays. Compared with spin nano-oscillators, the structure of spin Hall oscillators is simpler, usually only containing a single magnetic free layer, which is convenient for micro-nano processing and space magneto-optical detection. The spin Hall oscillator utilizes the spin Hall effect (SHE). By applying a current to the spin-orbit coupling layer, the charge current is converted into a spin current. When the spin current passes through the adjacent ferromagnetic layer, it will drive the magnetic moment of the ferromagnetic layer into a precessional state.

[0003] However, traditional spin Hall nano-oscillators still have many drawbacks and conflicting requirements: for example, the non-magnetic layer that generates the spin current significantly increases the zero-current spin-wave damping of the ferromagnetic layer, and the current is shared between the driving layer and the magnetoresistive ferromagnetic layer, resulting in problems such as non-optimal threshold current, extended oscillation period, low output power, and unnecessary dissipation and heating. In addition, the characteristics of the ferromagnetic oscillation layer determine the following problems: (i) the oscillation frequency is limited to the GHz range of the ferromagnetic material's magnetic dynamics process, making it difficult to meet the requirements of higher-frequency transmission; (ii) the lower output power and narrower spectral linewidth result in a communication distance of only about 1 m for spin nano-oscillators in wireless communication systems; (iii) the ability to resist external magnetic field interference is poor, and the interference of the external magnetic field will affect the oscillation behavior; (iv) the size of the device cannot be further reduced. Due to the limitation of the stray field crosstalk between adjacent devices, it is difficult to achieve a high-density device design. Therefore, finding a suitable metal layer to replace the traditional ferromagnetic layer material has become the key to solving the above problems.

[0004] Research shows that when another major type of antiferromagnetic (AFM) material in magnetic materials is used as the medium of a storage device, it exhibits faster speed, lower energy consumption, and ultra-high storage density compared to traditional ferromagnetic materials. In the field of spin nano-oscillators, the ultrafast dynamic process of AFM materials in the terahertz range is particularly important. When AFM materials are designed into nano-sized oscillators, high-frequency oscillations in the THz range can be achieved, which can be further applied to the field of neural network computing. In addition, antiferromagnetic materials also have good robustness to magnetic field perturbations, greatly enhancing the ability of the oscillator to resist external magnetic field interference. At the same time, it has no stray field, and the interference between adjacent devices at small sizes can be minimized, which is conducive to the miniaturization of devices. Therefore, antiferromagnetic spin devices are expected to become the next generation of efficient and fast spintronic devices. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention aims to propose an array synchronization of a novel antiferromagnetic spin nano-oscillator structure and its application in a wireless communication system, which has many advantages such as simple process, anti-interference, and large output power.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] 1. A novel antiferromagnetic spin nano-oscillator structure: It is composed of a first layer of non-collinear antiferromagnetic material and a second layer of strong spin-orbit coupling material.

[0008] Further, the first layer is non-collinear antiferromagnetic, and the non-collinear antiferromagnetic materials include but are not limited to Mn 3 X, Mn 2 X (X = Ga, Ge, Sn, Ir, Rh, and Pt), etc.

[0009] Further, the second layer is a strong spin-orbit coupling material, and the strong spin-orbit coupling materials include but are not limited to heavy metal materials such as Pt, W, Ta, and topological quantum materials such as MnBi 2 Te, Bi 2 Se 3 、Bi 2 Te 3 、Sb 2 Te 3 、(Bi 1-x Sbx) 2 Te 3 、etc.

[0010] The antiferromagnetic spin Hall nano-oscillator structure includes but is not limited to nano-gap type, "bow-tie" type, nano-wire type, and vertical nano-point contact type structures of the "pair of triangles" structure.

[0011] Furthermore, the "opposite triangle" structure of the nanogap simplifies the micro-nano processing procedure of the device and reduces the difficulty of processing and optical testing. However, only at low temperatures (after the magnon scattering caused by thermal fluctuations is effectively suppressed) can it exhibit a center single-mode excitation with good coherence and have a narrow microwave linewidth.

[0012] The "bowtie" type spin Hall oscillator can suppress high-frequency spin wave modes under limited geometric structures. The potential well induced by its local boundary dipole field can increase the energy difference between the local mode and the continuous spin wave spectrum, thereby enhancing the thermal stability of the device. However, due to size limitations, the propagation type spin wave mode cannot be realized.

[0013] For the one-dimensional "nanowire" type spin Hall oscillator, due to the relatively large effective magnetic moment oscillation region and the small energy (or frequency) interval of the spin wave dynamic modes in this magnetic system, multiple spin wave coexistence, coupling and other multi-mode behaviors are often observed, which greatly affects the coherence of the oscillator and is not conducive to its application in the fields of microwave and spin wave electronics.

[0014] The "point contact" type spin Hall nano-oscillator has a simple structure and is easy to fabricate. It also eliminates the excitation of high-frequency boundary modes caused by the above-mentioned planar "opposite triangle" geometry. This type of oscillator provides a feasible solution for realizing current-excited coherent single-mode spin waves or microwave signals with narrow linewidths at room temperature.

[0015] According to the described materials, select appropriate materials and device geometric structures to suppress the phase noise caused by the jump between different oscillation modes and thermal fluctuations, so as to improve the coherence of the spin Hall nano-oscillator.

[0016] Furthermore, prepare the thin film by magnetron sputtering method, and after completion, use electron beam lithography or ultraviolet lithography, and dry etching process to prepare the spin Hall nano-oscillator.

[0017] 2. The series coupling of antiferromagnetic spin nano-oscillators is applied to the terahertz electromagnetic wave detection system.

[0018] Furthermore, connect 3, 4, 5,... n (n≥3) spin Hall oscillators in series, apply a DC bias current to the series-connected multiple spin Hall oscillators to induce a polarization current, thereby causing the precession of the magnetic moment of the free antiferromagnetic layer, and adjust the input DC current to make the whole row achieve a synchronous coupling state.

[0019] Furthermore, utilize the advantage of being connected in series in the rectifier circuit to achieve a broadband frequency response with a high rectification voltage. Use an antenna as the emission source to perform wireless energy harvesting and transmission in the terahertz frequency band, and rectify it by the SHNOs series array. The rectified voltage is stored in the capacitor over time to provide a stable voltage input for the DC-DC boost converter (V C)。

[0020] Furthermore, the external high-frequency electromagnetic wave microwave signals include but are not limited to ubiquitous terahertz signals, WiFi signals, high-frequency radiation waves, etc.

[0021] 3. The antiferromagnetic spin Hall oscillator synchronization array is used in a wireless communication system.

[0022] Furthermore, the amplitudes and frequencies of 2, 3,... n (n≥2) series-coupled oscillator rows are modulated. Since the size of the integrated device array is small, the spacing between rows is very small, and the signals between adjacent rows can affect each other. By adjusting the magnitude of the bias current and selecting a suitable modulation method, the output of the coupled signals of multiple spin Hall oscillator array rows can be achieved.

[0023] Furthermore, the modulation methods include but are not limited to orthogonal frequency division multiplexing (OFDM), orthogonal time-frequency space modulation (OTFS), etc.

[0024] Furthermore, the wireless communication system consists of a transmitter and a receiver. The transmitter mainly includes but is not limited to an antiferromagnetic spin Hall oscillator synchronization array, a bias tee, a terahertz amplifier, and a transmitting antenna. The receiver mainly includes but is not limited to a receiving antenna, a terahertz amplifier, a detector, and an oscilloscope.

[0025] Furthermore, low-noise amplifiers and band-pass filters and other signal processing procedures can be added to the transmitter and receiver according to the quality requirements of the transmitted signal.

[0026] Furthermore, the signal detection method is envelope detection or synchronous detection.

[0027] In the said wireless communication system, since the main component of the transmitter is an antiferromagnetic spin Hall oscillator synchronization array, the communication distance between the transceiver will not be limited to within 1m.

[0028] The wireless applications based on the novel antiferromagnetic spin Hall oscillator involved in the present invention mainly have the following advantages:

[0029] The spin Hall oscillator uses an antiferromagnetic layer instead of a ferromagnetic layer, exploring a new material field, having ultrafast dynamics in the terahertz range, wide-band low-power transmission, and no stray field at the same time. The interference between adjacent devices can be minimized in small sizes;

[0030] The antiferromagnetic spin Hall oscillator can be prepared by magnetron sputtering method, having the advantages of simple preparation method and industrialization;

[0031] The electromagnetic wave signal system applying an antiferromagnetic spin Hall oscillator is expected to realize the detection of terahertz signals ubiquitous in life. In our daily life, terahertz waves exist everywhere. If they can be utilized, their highly concentrated energy is expected to become an alternative energy source.

[0032] The wireless communication system applying an antiferromagnetic spin Hall oscillator synchronization array is expected to realize functions such as small-scale communication, wide-band low-power consumption transmission, ultra-large-capacity data backhaul, and short-distance ultra-high-speed transmission. Brief Description of the Drawings

[0033] Figure 1 Schematic diagrams of different device structures of the novel antiferromagnetic spin Hall oscillator;

[0034] Figure 2 Test diagram of the structure of a single spin Hall oscillation device and its external circuit;

[0035] Figure 3 Schematic diagram of the application of a series of spin Hall oscillators in a wireless electromagnetic wave detection system;

[0036] Figure 4 Schematic diagram of the application of an antiferromagnetic spin Hall oscillator array in a wireless communication system. Detailed Implementation Modes

[0037] Based on our analysis of the prepared antiferromagnetic spin Hall oscillator and its applications in the present invention, the best implementation mode will be described in detail below:

[0038] Prepare W / Mn 3 Sn heterojunction

[0039] (1) Use a magnetron sputtering device and install Mn 3 Sn and W targets on the sputtering target head;

[0040] (2) Place a suitable substrate (such as a c-Al 2 O 3 substrate) at the sample holder position and adjust the necessary process parameters to achieve the growth of the heterojunction. The reaction parameters include: substrate temperature, sputtering atmosphere, sputtering power, etc.

[0041] (3) For the grown sample, select a suitable process for micro-nano processing to process it into a "butterfly-shaped" structured micro-scale or nano-scale device. The process parameters include: spin coating speed and time, pre-baking temperature, exposure time, development time, etching time, etc.

[0042] Build an external circuit diagram for applying a single antiferromagnetic spin Hall oscillator. Such as Figure 2 Test diagram of the structure of a single spin Hall oscillation device and its external circuit:

[0043] A DC bias current is applied to the antiferromagnetic spin Hall oscillator, inducing a polarized current in the antiferromagnetic layer, which causes the magnetic moment of the free magnetic layer to precess.

[0044] According to Figure 2 The circuit structure can measure parameters such as the oscillation frequency, power, and signal bandwidth of a single oscillation signal.

[0045] Build a terahertz electromagnetic wave detection system using a series-coupled antiferromagnetic spin Hall oscillator. As Figure 3 shown in the system structure diagram:

[0046] Use a microwave patch antenna as the transmitter, perform wireless energy transfer in the terahertz frequency band, and rectify it by a series-coupled array of antiferromagnetic spin Hall oscillators. The rectified voltage is stored in a capacitor over time to provide a stable voltage input for a DC-DC boost converter. The output voltage can directly drive the backend electrical appliance (LED lamp) to work.

[0047] Build a wireless communication system using a synchronous array of antiferromagnetic spin Hall oscillators. As Figure 4 shown in the system structure diagram:

[0048] (1) For every three spin Hall oscillators connected in series in each row, synchronous coupling of the three oscillators is achieved by changing the magnitude of the input DC current.

[0049] (2) After synchronous coupling is achieved for each row of series-connected oscillators, the entire 3*3 array is synchronized by applying AC currents of different frequencies, i.e., orthogonal frequency division multiplexing (OFDM) modulation.

[0050] The transmitting end of the wireless communication system mainly consists of a signal generator, a spin Hall oscillator array, a bias tee, a two-stage cascaded RF amplifier, and a radiation array antenna. The transmitting end first frames the bit information, modulates it into symbols, and outputs an analog intermediate frequency signal after pre-equalization, pulse shaping, etc. The analog intermediate frequency signal is mixed with the terahertz signal generated by the spin Hall oscillator array, amplified, and then transmitted by the radiation array antenna.

[0051] The receiving end of the wireless communication system mainly consists of a receiving antenna, a low-noise amplifier, an RF amplifier, a band-pass filter, an envelope detector, and an oscilloscope. It receives the terahertz signal from the analog front end, processes it into a digital signal through a digital-to-analog signal conversion board, and then performs noise processing and signal demodulation and decoding. After the receiving antenna receives the signal, the signal is relatively weak. At this time, the low-noise amplifier reduces the noise of the amplifier itself to reduce interference with the transmitted signal and improve the signal-to-noise ratio of the output signal. Finally, the transmission of the terahertz signal in the wireless communication system is realized.

Claims

1. Wireless communication and transmission applications based on a novel antiferromagnetic spin Hall oscillator, Characterized in that: The novel antiferromagnetic spin Hall nano-oscillator (SHNO) includes a first layer of non-collinear antiferromagnetic material and a second layer of strong spin-orbit coupling material.

2. The novel antiferromagnetic spin Hall nano-oscillator structure according to claim 1, wherein the first layer is a non-collinear antiferromagnetic material, and the non-collinear antiferromagnetic material includes but is not limited to Mn 3 X, Mn 2 X (where X = Ga, Ge, Sn, Ir, Rh, and Pt, etc.).

3. The novel antiferromagnetic spin Hall nano-oscillator structure according to claim 1, wherein the second layer is a strong spin-orbit coupling material, and the strong spin-orbit coupling material includes but is not limited to heavy metal materials such as Pt, W, Ta, and MnBi 2 Te, Bi 2 Se 3 , Bi 2 Te 3 , Sb 2 Te 3 , (Bi 1-x Sbx) 2 Te 3 and other topological quantum materials.

4. The novel antiferromagnetic spin Hall nano-oscillator structure according to claim 1: The antiferromagnetic spin Hall nano-oscillator structure includes, but is not limited to, nanostructure types such as "pair of triangles" with nanogaps, "bowtie", nanowire, and vertical nanodot contact types, etc. According to the materials and device structures, appropriate materials and device geometries are selected to suppress the phase noise caused by the jumps between different oscillation modes and thermal fluctuations, so as to improve the coherence of the spin Hall nano-oscillator.

5. The structure based on the novel antiferromagnetic spin Hall oscillator according to claim 1, Characterized in that: Thin films are prepared by magnetron sputtering, and antispin Hall nano-oscillator devices are prepared by electron beam lithography and dry etching processes.

6. The structure based on the novel antiferromagnetic spin Hall oscillator according to claim 1, Characterized in that: By applying a DC bias current to a single spin Hall oscillator to induce a polarized current in the strong spin-orbit coupling layer, thereby causing the precession of the magnetic moment of the antiferromagnetic layer, and then generating terahertz signal oscillations.

7. The application circuit based on a single novel antiferromagnetic spin Hall oscillator according to claim 6, Characterized in that: Three, four, five,... n (n≥3) spin Hall oscillators are connected in series, and the overall signal output is synchronously coupled by adjusting the DC bias current.

8. The application circuit based on the series-connected antiferromagnetic spin Hall oscillator according to claim 7, Characterized in that: The series-connected spin Hall oscillators are applied to a terahertz electromagnetic wave measurement system.

9. The terahertz electromagnetic wave detection system according to claim 8, Characterized in that: Taking advantage of the series connection in the rectifier circuit, a broadband frequency response with a high rectification voltage is achieved. External electromagnetic wave signals include, but are not limited to, ubiquitous terahertz signals, WiFi signals, high-frequency radiation waves, etc. An antenna array is used as the emission source for wireless energy transmission in the terahertz frequency band, and the series array of antiferromagnetic spin Hall oscillators is used for rectification. The rectified voltage is stored in a capacitor over time to provide a stable voltage input for a DC-DC boost converter.

10. The application circuit based on the series-connected antiferromagnetic spin Hall oscillator according to claim 7, Characterized in that: The amplitudes and frequencies of two, three,... n (n≥2) series-coupled oscillators are modulated. Since the rows can interact with each other, by adjusting the magnitude of the bias current and selecting an appropriate modulation method, the output of different signal frequencies or the same signal frequency of the n spin Hall oscillator arrays can be achieved.

11. The synchronous array of antiferromagnetic spin Hall oscillators according to claim 10, Characterized in that: The synchronous array of n*n spin Hall oscillators is used in a wireless communication system.

12. The wireless communication system according to claim 11, Characterized in that: The wireless communication system consists of a transmitting end and a receiving end. The transmitting end includes but is not limited to a spin Hall oscillator synchronization array, a bias tee, a terahertz amplifier, and a transmitting antenna. The receiving end includes but is not limited to a receiving antenna, a terahertz amplifier, a detector, and an oscilloscope.

13. The wireless communication system according to claim 11, characterized in that: in the wireless communication system, since the transmitting end mainly consists of a spin Hall oscillator synchronization array, the communication distance between the transceiver will not be limited to only a few meters.

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