Methods, apparatus, equipment, media, and procedures for measuring the effective field of spin orbital moments.

Abstract

This application discloses a method, apparatus, device, medium, and program product for measuring the effective field of spin orbital moments, relating to the field of spintronics technology. The method includes: acquiring a target sample of an in-plane magnetically anisotropic thin film; applying a current to the target sample along a first direction parallel to the target sample; and applying a scanning magnetic field to the target sample in a second direction perpendicular to the first direction, wherein the first direction is the current direction and the second direction is a direction perpendicular to the current direction within the plane; during the application of the scanning magnetic field, detecting the voltage of the target sample under the scanning magnetic field, and obtaining a second-order magnetoresistance curve of the resistance to the magnetic field corresponding to the voltage; and determining the effective field of the spin orbital moments of the target sample based on the offset of the magnetic field values ​​corresponding to characteristic points on the second-order magnetoresistance curve under different current conditions. This application achieves high-precision and high-reliability measurement of the effective field of the spin orbital moments of an in-plane magnetically anisotropic thin film without relying on the first-order curve morphology and avoiding temperature drift interference.

Description

Technical Field

[0001] This application relates to the field of spintronics technology, and in particular to methods, devices, equipment, storage media, and computer program products for measuring the effective field of spin orbital moments. Background Technology

[0002] In existing technologies, the measurement of the effective field of spin orbit torque (SOT) in in-plane magnetically anisotropic thin films has the following limitations: The commonly used magnetoresistance (MR) curve offset method relies on the sharp peaks or abrupt changes in the first-order MR curve to accurately identify the magnetic field offset; however, for most practical samples, the first-order MR curve changes gradually and broadens significantly, making it difficult to identify characteristic points and thus impossible to accurately measure the effective field of spin orbit torque (SOT). Furthermore, the MR curve offset method requires a permanent magnet to provide a bias magnetic field, but the magnetization of permanent magnets is easily affected by temperature fluctuations, which further introduces measurement errors and affects the reliability and accuracy of the measurement.

[0003] Therefore, existing methods struggle to achieve high-precision measurements of the effective field of spin orbit moments when dealing with in-plane magnetically anisotropic thin films whose first-order MR curve signals are smooth or significantly broadened. Summary of the Invention

[0004] The main objective of this application is to provide a method, apparatus, device, storage medium, and computer program product for measuring the effective field of spin orbital moments, aiming to solve the technical problem of low accuracy in measuring the effective field of spin orbital moments of in-plane magnetically anisotropic thin films using existing methods.

[0005] To achieve the above objectives, this application proposes a method for measuring the effective field of spin orbital moments, the method comprising:

[0006] A target sample of an in-plane magnetically anisotropic thin film is obtained. A current is applied to the target sample along a first direction parallel to the target sample, and a scanning magnetic field is applied to the target sample in a second direction perpendicular to the first direction. The first direction is the current direction, and the second direction is a direction in the plane perpendicular to the current direction.

[0007] During the application of the scanning magnetic field, the voltage of the target sample under the scanning magnetic field is detected, and the second-order magnetoresistance curve of the resistance to the magnetic field corresponding to the voltage is obtained.

[0008] The effective field of the spin orbit moment of the target sample is determined based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistance curve under different current conditions.

[0009] In one embodiment, the step of applying a current to the target sample along a first direction parallel to the target sample is a composite current consisting of an AC readout current and a DC bias current. The step of detecting the voltage of the target sample under the scanning magnetic field during the application of the scanning magnetic field, and obtaining the second-order magnetoresistance curve of the resistance to the magnetic field corresponding to the voltage, includes:

[0010] Under the action of DC bias current, the operation of scanning magnetic field is performed along the second direction;

[0011] During each magnetic field scan, the first and second harmonic components of the longitudinal voltage signal generated by the target sample are detected.

[0012] Based on the amplitude of the AC reading current, the first harmonic component is converted into the first-order magnetoresistance curve of the target sample, and the second harmonic component is converted into the second-order magnetoresistance curve of the target sample.

[0013] In one embodiment, the step of determining the effective field of the spin orbital moment of the target sample based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistance curve under different current conditions includes:

[0014] Obtain second-order magnetoresistive curves measured under at least two different DC bias currents, and the magnetic field values ​​corresponding to feature points on each second-order magnetoresistive curve.

[0015] Based on the offset of the magnetic field value corresponding to the feature point as a function of the DC bias current, the effective field of the spin orbit moment of the target sample is calculated.

[0016] In one embodiment, the step of applying a current to the target sample along a first direction parallel to the target sample is a set of positive and negative pulse currents with equal amplitude and opposite direction. The step of detecting the voltage of the target sample under the scanning magnetic field during the application of the scanning magnetic field, and obtaining the second-order magnetoresistance curve of the resistance to the magnetic field corresponding to the voltage, includes:

[0017] During the duration of each pulse in the pulsed current, the operation of scanning the magnetic field is performed along the second direction;

[0018] During each scanning of the magnetic field, the longitudinal voltage generated by the target sample is detected and recorded;

[0019] Calculate the difference in longitudinal voltage between the positive and negative pulses at the same magnetic field point, and generate the second-order magnetoresistive curve based on the difference.

[0020] In one embodiment, the step of determining the effective field of the spin orbital moment of the target sample based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistance curve under different current conditions includes:

[0021] Determine the magnetic field value corresponding to the characteristic point on each of the second-order magnetoresistance curves;

[0022] Based on the offset of the magnetic field value corresponding to the feature point as a function of the pulse current amplitude, the effective field of the spin orbit moment of the target sample is calculated.

[0023] In one embodiment, the step of obtaining the target sample of the in-plane magnetic anisotropic thin film includes:

[0024] Fabrication of metallic thin films with in-plane magnetic anisotropy;

[0025] The metal thin film is patterned into a Hall strip structure, wherein the Hall strip structure includes lead electrodes along the current direction and at least two pairs of test electrodes for measuring voltage, wherein the voltage is a longitudinal voltage;

[0026] The Hall strip structure is wire bonded to obtain a target sample for testing in-plane magnetic anisotropic thin films.

[0027] Furthermore, to achieve the above objectives, this application also proposes a measuring device for the effective field of spin orbital moments, the measuring device comprising:

[0028] The power module is used to perform the following actions: acquiring a target sample of an in-plane magnetic anisotropic thin film, applying a current to the target sample along a first direction parallel to the target sample, and applying a scanning magnetic field to the target sample in a second direction perpendicular to the first direction, wherein the first direction is the current direction and the second direction is a direction in the plane perpendicular to the current direction;

[0029] The detection module is used to perform the following: during the application of the scanning magnetic field, detect the voltage of the target sample under the scanning magnetic field, and obtain the second-order magnetoresistance curve of the resistance to the magnetic field corresponding to the voltage;

[0030] The display module is used to perform the following: determining the effective field of the spin orbit moment of the target sample based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistive curve under different current conditions.

[0031] Furthermore, to achieve the above objectives, this application also proposes a measuring device for the effective field of spin orbit moment, the device comprising: at least one lock-in amplifier, a current source for applying current to a sample, an electromagnet and a gaussmeter for applying a magnetic field to the sample, and a processor that executes the steps of the method for measuring the effective field of spin orbit moment as described above.

[0032] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the method for measuring the effective field of spin orbit moment as described above.

[0033] In addition, to achieve the above objectives, this application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the method for measuring the effective field of spin orbit moment as described above.

[0034] One or more technical solutions proposed in this application have at least the following technical effects:

[0035] This application employs a technique that involves applying orthogonal currents and scanning magnetic fields to an in-plane magnetically anisotropic thin-film target sample, and detecting the voltage signal of the target sample to obtain a second-order magnetoresistance curve (MRC) of resistance versus magnetic field. Finally, it determines the effective field of the spin orbital moment based on the shift in magnetic field values ​​corresponding to characteristic points on the MRC under different current conditions. This effectively solves the problem in existing technologies that rely on the sharp characteristics of the first-order magnetoresistance curve, making it impossible to accurately measure samples with smooth or broad signals. Specifically, this application enhances the signal sensitivity of the magnetization reversal critical point by utilizing second-order differential processing, making the capture of characteristic magnetic field shifts clear and reliable. Simultaneously, this application uses an electromagnetic scanning field instead of a permanent magnet to provide the bias magnetic field, eliminating measurement errors introduced by the temperature drift of the permanent magnet. Therefore, compared with existing technologies, this application achieves high-precision and high-reliability measurement of the effective field of the spin orbital moment of an in-plane magnetically anisotropic thin film without relying on the shape of the first-order curve and avoiding temperature drift interference. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic flowchart illustrating an embodiment of the method for measuring the effective field of spin orbital moment according to this application;

[0039] Figure 2 A measurement schematic diagram provided for the measurement method of the effective field of spin orbit moment in this application;

[0040] Figure 3 A schematic diagram of applying a composite current for the method of measuring the effective field of spin orbit moment provided in this application;

[0041] Figure 4 A schematic diagram of the applied pulsed current provided for the method of measuring the effective field of spin orbit moment in this application;

[0042] Figure 5 A schematic diagram of the magnetoresistance curve provided for the measurement method of the effective field of spin orbit moment in this application using the AC harmonic method;

[0043] Figure 6 A schematic diagram of the magnetoresistive curve of the pulse method provided for the measurement method of the effective field of spin orbit moment in this application;

[0044] Figure 7 This is a schematic diagram of the module structure of the measuring device for the effective field of spin orbit moment in this application;

[0045] Figure 8 This is a schematic diagram of the equipment structure of the hardware operating environment involved in the measurement method of the effective field of spin orbit moment in this application.

[0046] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0047] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of this application and are not intended to limit this application.

[0048] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0049] In recent years, spintronic devices that utilize the spin-orbit moment (SOT) effect to write information have attracted widespread attention due to their superior characteristics such as fast read / write speeds, low power consumption, and non-volatility. Typical SOT devices employ a heavy metal / ferromagnetic (HM / FM) heterostructure as the basic functional structure for information writing. The principle involves utilizing the strong spin-orbit coupling of the heavy metal layer or the spin-orbit coupling at the interface (a physical effect caused by interface asymmetry that correlates electron spin with its momentum) to apply a torque to the magnetization, thereby driving the magnetization reversal of adjacent ferromagnetic layers.

[0050] In studying the spin orbital moment (SOT) effect, evaluating the magnitude of the effective SOT field and the SOT-induced magnetization reversal is extremely important. For thin films with perpendicular magnetic anisotropy, the effective SOT field can be obtained using the well-established second-harmonic Hall voltage method: the harmonic signals swept along the current direction (longitudinal sweep) and the harmonic signals swept perpendicular to the current (transverse sweep) can respectively determine the two components of the effective SOT field. However, for the measurement of the effective SOT field of thin films with in-plane magnetic anisotropy, related research is relatively limited and is still under development in recent years. Previous researchers proposed characterizing the magnitude of the effective SOT field by the shift of the magnetoresistance (MR) curve under current.

[0051] The MR curve shift method uses a bias magnetic field to help determine the magnitude of the effective field of the SOT (Surface-Oriented Trap). However, the bias magnetic field is highly dependent on the permanent magnet, and the magnetization of the permanent magnet changes significantly with temperature, which may cause the bias magnetic field to drift, thus affecting the measurement accuracy. Furthermore, the MR shift method is suitable for first-order MR curves with sharp peaks or abrupt jumps, where the effective field of the SOT is determined by the shift of the magnetic field at the peak or jump. For most samples, the first-order MR curve changes relatively smoothly or has obvious broadening, with indistinct peaks or jumps, making it difficult to obtain accurate changes in the magnetic field.

[0052] This application provides an improved method for measuring the effective field of spin orbit moment in in-plane magnetically anisotropic thin films. The method for measuring the effective field of spin orbit moment in this application enhances the measurement sensitivity and accuracy by utilizing second-order magnetoresistance curves.

[0053] It should be noted that the execution subject of this embodiment can be a measuring device for the effective field of spin orbital moments, or a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device or processor capable of performing the above functions. The following description uses a measuring device for the effective field of spin orbital moments (hereinafter referred to as the measuring device) as an example to illustrate this embodiment and the following embodiments.

[0054] Based on this, embodiments of this application provide a method for measuring the effective field of spin orbital moments, referring to... Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the method for measuring the effective field of spin orbital moment according to this application.

[0055] In this embodiment, the method for measuring the effective field of the spin orbital moment includes steps S10 to S30:

[0056] Step S10: Obtain the target sample of the in-plane magnetic anisotropic thin film, apply a current to the target sample along a first direction parallel to the target sample, and apply a scanning magnetic field to the target sample in a second direction perpendicular to the first direction, wherein the first direction is the current direction and the second direction is the direction in the plane perpendicular to the current direction.

[0057] It should be noted that the target sample for obtaining in-plane magnetic anisotropic thin films can be understood as a magnetic material whose magnetization direction is mainly located in the plane of the thin film, while the spin-orbit moment effective field is the effective magnetic field induced by the spin-orbit coupling effect, which is crucial for the performance evaluation of spintronic devices.

[0058] A current is applied along a first direction parallel to the target sample, while a scanning magnetic field is applied in a second direction perpendicular to the first direction. In one embodiment, the first direction may be the current injection direction of the target sample in the xy plane (e.g., Figure 2 The x-axis (as shown) is used to generate the spin orbital moment, and the second direction is the scanning direction of the magnetic field in the xy plane (e.g., Figure 2 The y-axis (as shown) is used to change the magnetization state inside the sample to ensure that the magnetic field is perpendicular to the current direction, thereby effectively exciting the spin orbital moment effect.

[0059] For example, the target sample, such as a Zr / Ni (zirconium nickel) thin film with a thickness in the nanometer range, can be fabricated as a Hall bar structure with a linewidth ranging from 3 to 30 micrometers and multiple pairs of electrodes to facilitate the detection of electrical signals. In a specific embodiment, the current can be an AC readout current combined with a DC bias current, or it can be a pulsed current. The scanning magnetic field is adjusted by an electromagnet to cover the required magnetic field range. Step S10, by applying the current and the scanning magnetic field, modulates the resistance or voltage of the target sample using the magnetic field.

[0060] In one feasible implementation, step S10 includes steps S11 to S13:

[0061] Step S11: Prepare a metal thin film with in-plane magnetic anisotropy;

[0062] It should be noted that a metallic thin film with in-plane magnetic anisotropy needs to be prepared. In-plane magnetic anisotropy, as understood, refers to the characteristic that the magnetization direction of a magnetic material preferentially lies within the plane of the thin film.

[0063] In one embodiment, such a thin film can be prepared by magnetron sputtering, for example using a multilayer material system such as Zr / Ni. Magnetron sputtering precisely controls sputtering parameters such as working pressure, sputtering power, and substrate temperature to induce in-plane anisotropy. Exemplarily, the film thickness is typically controlled in the nanometer range to ensure uniform magnetic properties and good electrical conductivity.

[0064] In a specific embodiment, the preparation process also includes post-deposition annealing to further optimize the crystal structure and magnetic anisotropy of the thin film.

[0065] Step S12: Pattern the metal thin film into a Hall strip structure, wherein the Hall strip structure includes lead electrodes along the current direction and at least two pairs of test electrodes for measuring voltage, wherein the voltage is a longitudinal voltage.

[0066] It should be noted that the prepared metal thin film is patterned into a Hall strip structure, where the Hall strip structure is a micro-nano scale device pattern specifically designed for electrical transport measurements. Understandably, the Hall strip structure includes lead electrodes along the current direction and at least two pairs of test electrodes for measuring the longitudinal voltage, which refers to the voltage drop generated along the current direction and is used to characterize the magnetoresistance behavior of the material. In one embodiment, the patterning process can be achieved through exposure and etching processes. For example, the Hall strip pattern can be transferred to a photoresist layer using photolithography, followed by selective removal of excess thin film material using ion etching or wet etching to form a strip structure with a linewidth of 3 to 30 micrometers.

[0067] For example, the test electrodes are symmetrically arranged on both sides of the Hall bar to ensure the accuracy and repeatability of voltage detection. In a specific embodiment, this arrangement can focus the current path and enhance the signal-to-noise ratio of the magnetic signal.

[0068] Step S13: Perform wire bonding on the Hall strip structure to obtain the target sample for testing in-plane magnetic anisotropic thin films.

[0069] It should be noted that the patterned Hall strip structure undergoes wire bonding to obtain the target sample for testing in-plane magnetic anisotropic thin films. Wire bonding is a micro-assembly technique that connects the Hall strip electrodes to external circuits via fine metal wires to achieve electrical signal input and output. In one embodiment, thermo-ultrasonic bonding or wedge bonding can be used, employing gold or aluminum wires to form a reliable electrical connection on the electrode pads, ensuring low contact resistance and mechanical stability. Exemplarily, the wire bonding process must be performed precisely under a microscope to avoid damaging the fragile thin film or introducing stress.

[0070] In a specific implementation, after bonding, the target sample is fixed on a dedicated chip carrier or probe stage, facilitating integration into the electrical transport measurement system. This step completes the final preparation of the target sample, enabling the Hall strip structure to efficiently interface with the measurement equipment for subsequent quantitative measurement of the effective field of the spin-orbit moment.

[0071] In this embodiment, the longitudinal voltage (i.e., the voltage drop along the current direction) is measured, rather than the Hall voltage (i.e., the transverse voltage perpendicular to the current direction), because the magnetization vector of the in-plane magnetically anisotropic thin film is confined within the film plane. Therefore, this application cannot use the conventional and mature angle-shifting second harmonic method. Instead, this application extracts the effective field of SOT by fixing the relative directions of the current and magnetic field (current along the x-axis, scanning magnetic field along the y-axis) and observing the nonlinear change of the longitudinal resistance with the vertical magnetic field. This addresses the measurement blind spots of existing technologies when measuring in-plane anisotropic thin films, achieving high-precision and reliable measurement of the effective field of SOT, effectively overcoming the inapplicability of traditional methods to such materials.

[0072] For example, such as Figure 2 As shown, Figure 2 This is a schematic diagram of the measurement of the effective field of a spin orbital moment. Figure 2 As can be seen from the diagram, reference numeral 200 indicates the target sample of the in-plane anisotropic thin film, and reference numeral 100 indicates the longitudinal voltage V of the target sample measured by electrodes. Figure 2 It can be seen from this that it is along the x-axis direction; the label 300 indicates that a current I is applied to the target sample, from Figure 2 As can be seen, it is along the x-axis direction; the label 400 indicates that a scanning magnetic field H is applied to the target sample, from... Figure 2 As can be seen from this, it is along the y-axis.

[0073] Step S20: During the application of the scanning magnetic field, the voltage of the target sample under the scanning magnetic field is detected, and the second-order magnetoresistance curve of the resistance to the magnetic field corresponding to the voltage is obtained.

[0074] It should be noted that during the application of the scanning magnetic field, the voltage signal of the target sample under the scanning magnetic field is detected, and the second-order magnetoresistance curve of the resistance versus the magnetic field is obtained. It can be understood that the second-order magnetoresistance curve refers to the second derivative or second harmonic response of the resistance as a function of the magnetic field; it is more sensitive than the first-order curve in reflecting subtle changes during the magnetization reversal process. In one embodiment, the second-order signal can be extracted by detecting the first and second harmonic voltages under AC readout current using a lock-in amplifier, or by measuring the differential resistance under pulsed current using a precision voltmeter.

[0075] For example, when using the AC harmonic method, the fixed-frequency AC readout current and the adjustable DC bias current work together to synchronously capture the harmonic voltage using a lock-in amplifier, thereby obtaining a second-order curve through field sweeping. If the pulse method is used, the resistance change is induced by positive and negative pulse currents, and the differential signal is directly calculated to form a second-order curve. It can be understood that step S20 captures the critical point of magnetization behavior through a higher-order signal, overcoming the measurement uncertainty caused by the smoothing or broadening of the first-order curve.

[0076] Step S30: Based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistance curve under different current conditions, determine the effective field of the spin orbit moment of the target sample.

[0077] It should be noted that multiple second-order magnetoresistive curves were obtained under different current conditions (e.g., applying different DC bias currents or positive and negative pulse currents), and the magnetic field value corresponding to the characteristic point on each second-order curve was identified. It is understandable that the spin-orbit moment effect generates an equivalent effective field, which superimposes with the external scanning magnetic field, thereby changing the actual magnetic field required for magnetization reversal, manifested as a shift in the magnetic field value at the characteristic point.

[0078] In one embodiment, the feature point can be any point on the second-order magnetoresistance curve. Preferably, the feature point can be a peak, valley, or inflection point. The magnetic field value corresponding to the feature point will shift due to changes in the polarity and magnitude of the current, i.e., the critical magnetic field at the magnetization reversal corresponding to the feature point. The shift in the magnetic field value corresponding to the feature point reflects the strength of the effective field of the spin orbit moment.

[0079] For example, by comparing the magnetic field difference at characteristic points under positive and negative bias currents or pulsed currents, and combining this with known current parameters, the magnitude of the effective field can be quantitatively calculated. In a specific embodiment, if the second-order curve shows a leftward or rightward shift under positive and negative currents, respectively, the value of the SOT effective field can be quantitatively calculated based on the linear relationship between the shift and the current. It is understood that this application utilizes the high sensitivity of the second-order signal to significantly improve the detection capability of weak SOT effects in anisotropic thin films with inward magnetic properties, thereby achieving more accurate effective field measurements.

[0080] This embodiment provides a method for measuring the effective field of spin orbit moments. This application employs an orthogonal current and scanning magnetic field applied to an in-plane magnetically anisotropic thin film target sample, and detects the voltage signal of the target sample to obtain a second-order magnetoresistance curve (MRC) of resistance versus magnetic field. Finally, the effective field of the spin orbit moment is determined based on the shift in magnetic field values ​​corresponding to characteristic points on the second-order MRC under different current conditions. This effectively solves the problem in existing technologies where the sharp characteristics of the first-order MRC curve prevent accurate measurement of samples with smooth or broad signals. Specifically, this application enhances the signal sensitivity of the magnetization reversal critical point by utilizing second-order differential processing, making the capture of characteristic magnetic field shifts clear and reliable. Simultaneously, this application uses an electromagnetic scanning field instead of a permanent magnet to provide the bias magnetic field, eliminating measurement errors introduced by the temperature drift of the permanent magnet. Therefore, compared with existing technologies, this application achieves high-precision and high-reliability measurement of the effective field of spin orbit moments in in-plane magnetically anisotropic thin films without relying on the shape of the first-order curve and avoiding temperature drift interference.

[0081] Based on the above embodiments of this application, in another embodiment of this application, the same or similar content as the above embodiments can be referred to the above description, and will not be repeated hereafter. Applying a composite current of AC reading current and DC bias current to the target sample along a first direction parallel to the target sample, step S20 further includes steps S21~S23:

[0082] Step S21: Under the action of DC bias current, perform the operation of scanning the magnetic field along the second direction;

[0083] It should be noted that the current applied along the first direction parallel to the target sample is not a single DC or AC current, but a composite current formed by superimposing an AC readout current and a DC bias current. Understandably, the composite current aims to simultaneously achieve two functions: the AC readout current is used to sensitively detect the electrical response of the target sample, while the DC bias current is used to inject a bias field sufficient to induce a spin-orbit moment effect. In one embodiment, the amplitude of the AC readout current is typically small (e.g., 1 nA to 10 mA) and the frequency is fixed (e.g., 133.33 Hz) to avoid perturbing the magnetic state of the target sample; the DC bias current is used to provide stable spin polarization drive. Exemplarily, the two currents can be synthesized from current sources and jointly injected into the current channel of the Hall bar structure.

[0084] In a specific implementation, the process of acquiring the second-order magnetoresistance curve is always performed under a DC bias current, with the scanning magnetic field being executed perpendicular to the current direction. It can be understood that the scanning magnetic field changes the magnetization state of the target sample, while the fixed DC bias current acts as a stable drive to excite and maintain the spin orbital moment. In one implementation, the magnetic field scan covers a symmetrical range continuously or in steps to ensure complete capture of the magnetization reversal process. Exemplarily, each magnetic field scan is equivalent to recording the complete trajectory of the target sample's resistance changing with the external magnetic field under fixed bias conditions.

[0085] Step S22: During each magnetic field scan, detect the first harmonic component and the second harmonic component of the longitudinal voltage signal generated by the target sample.

[0086] It should be noted that during each continuous magnetic field scan, the first and second harmonic components of the longitudinal voltage signal generated by the target sample are simultaneously detected by a lock-in amplifier. The first harmonic component refers to the voltage response with the same frequency as the AC readout current, reflecting the sample's resistance value, i.e., the first-order magnetoresistance signal; while the second harmonic component refers to the voltage response with a frequency twice that of the AC readout current, which is more sensitive to changes in the magnetization vector direction and can highlight the nonlinear behavior near the magnetization reversal critical point.

[0087] In one embodiment, the lock-in amplifier is tuned to the fundamental frequency and the second harmonic frequency, thereby enabling high-precision extraction of the first and second harmonic components from complex voltage signals. Exemplarily, frequency-domain separation detection techniques in the lock-in amplifier can effectively suppress noise and significantly improve the signal-to-noise ratio of signal measurements.

[0088] Step S23: Based on the amplitude of the AC reading current, the first harmonic component is converted into the first-order magnetoresistance curve of the target sample, and the second harmonic component is converted into the second-order magnetoresistance curve of the target sample.

[0089] It should be noted that, based on the known amplitude of the AC reading current, the detected first harmonic voltage component is converted into a first-order magnetoresistive curve of the target sample, and the second harmonic voltage component is converted into a second-order magnetoresistive curve. It can be understood that the essence of the conversion is, according to Ohm's law (V = I*R, where V is voltage, I is current, and R is resistance), dividing the measured first harmonic voltage component by the amplitude of the AC reading current to obtain the resistance value. In one embodiment, the first-order magnetoresistive curve represents the direct relationship between resistance and magnetic field, while the second-order magnetoresistive curve is the first derivative of this first-order magnetoresistive curve with respect to the magnetic field, amplifying the characteristics of the steeply changing regions in the first-order curve. For example, when the first-order magnetoresistive curve exhibits a gentle peak shape due to the characteristics of the target sample, its corresponding second-order magnetoresistive curve will show clear extreme points. The magnetic field position corresponding to the extreme points is extremely sensitive to the offset caused by the spin orbital moment, thus providing a reliable basis for accurately calculating the effective field.

[0090] Understandably, applying a scanning magnetic field (H) is intended to change the magnetization state of the target sample, causing its resistance R to change with the magnetic field H, i.e., generating a magnetoresistance (MR) effect. In this case, the resistance R(H) is a function of the magnetic field H. However, because the applied AC readout current is very small and has a high frequency, the disturbance to the magnetic state under test is minimal. Therefore, at each specific magnetic field point H, the resistance value R(H) can be considered an instantaneous constant at that point. Although R(H) changes with the scanning of H, the circuit still satisfies instantaneous Ohm's law within each micro-cycle of the AC current. Therefore, the amplitude of the first harmonic component of the generated voltage signal is proportional to the instantaneous resistance value R(H) at that point. By accurately measuring the amplitude of the first harmonic voltage using a lock-in amplifier and dividing it by the known AC current amplitude, the first-order magnetoresistance curve R(H) as a function of the magnetic field H can be directly obtained. Correspondingly, the second-order magnetoresistance curve is obtained by taking the first derivative (dR / dH) of the first-order magnetoresistance curve R(H) with respect to the magnetic field H. It is understandable that the second-order magnetoresistance curve is essentially the rate of change of resistance with respect to the magnetic field.

[0091] In one specific implementation, an AC readout current with an amplitude of 1 nA-10 mA and a frequency of 133.33 Hz is provided by a current source. ) and DC bias current ( In this process, the AC reading current and DC bias current are along the x-axis, the scanning magnetic field is along the y-axis, and the harmonic longitudinal voltage is connected along the x-axis. Then, a lock-in amplifier is used to detect the first harmonic longitudinal voltage. That is, the first harmonic component and the second harmonic longitudinal voltage, i.e., the second harmonic component. The second harmonic component originates from the nonlinear response of the resistance R(H) to the magnetic field H, and its amplitude is proportional to the derivative of the first-order magnetoresistance curve R(H) with respect to the magnetic field H, dR / dH. The first harmonic component reflects the instantaneous magnitude of the resistance R(H), and its amplitude is proportional to R(H). The first-order magnetoresistance curve R(H), representing the direct relationship between resistance and magnetic field, can be reconstructed from the first harmonic component. Conversely, the second-order magnetoresistance curve dR / dH, representing the rate of change of resistance, can be reconstructed from the second harmonic component. It can be understood that the second harmonic component is generated by the nonlinear change in resistance R(H), upon which the first harmonic component depends.

[0092] In this embodiment, the composite current is not a simple superposition of two currents, but rather creates a synergistic measurement environment: the DC bias current injects a sufficiently strong spin-polarized current into the target sample to effectively excite the spin orbital moment; simultaneously, the AC readout current with extremely small amplitude and fixed frequency provides a near-zero disturbance to the magnetic state of the target sample, sensing the resistance change caused by the SOT (Spin-Orbital) field. This allows the extraction of weak second harmonic components, which are then converted into a second-order magnetoresistive curve. The magnetic field values ​​corresponding to feature points on the second-order magnetoresistive curve are highly sensitive to the strength and direction of the DC bias current; therefore, the effective SOT field can be calculated based on the offset of these feature points. Thus, this embodiment, by combining composite current with harmonic detection, solves the problem of measuring the effective SOT field of in-plane magnetically anisotropic thin films due to the smooth change of the first-order magnetoresistive curve. It transforms the originally ambiguous magnetic field offset into a clear and quantifiable electrical signal difference, ultimately achieving high-precision and reliable measurement of the effective SOT field.

[0093] For example, such as Figure 3 As shown, Figure 3 This is a schematic diagram of the composite current of the superposition of AC read current and DC bias current applied to this application, i.e., a schematic diagram of the AC harmonic method. Figure 3 In the graph, the horizontal axis t represents time, and the vertical axis represents the instantaneous value of the current magnitude as a function of time. Indicates AC current reading. Indicates DC bias current; from Figure 3 It can be seen that the applied composite current is a set of currents of equal magnitude but opposite direction. Understandably, this composite current originates from a current source and can pass through... Figure 2 The label 300 is applied to the target sample.

[0094] In one feasible implementation, the step of determining the effective field of the spin orbital moment of the target sample based on the offset of the magnetic field value corresponding to the characteristic point on the second-order magnetoresistance curve under different current conditions includes steps S24-S25:

[0095] Step S24: Obtain the second-order magnetoresistive curves measured under the DC bias current at at least two different current values, and the magnetic field value corresponding to the feature point on each second-order magnetoresistive curve.

[0096] It should be noted that after obtaining the second-order magnetoresistance curve characterizing the rate of change of resistance, the effective field of the spin orbital moment is quantitatively extracted. In one embodiment, at least two DC bias current values ​​of different magnitudes or polarities can be set, such as +2 mA, 0 mA, and -2 mA, and a complete transverse magnetic field scan is performed under each constant DC bias current, thereby recording each corresponding second-order magnetoresistance curve. Exemplarily, different DC bias currents introduce spin orbital moments of different intensities and directions into the sample, which is equivalent to applying different perturbations to the magnetic state of the target sample.

[0097] Subsequently, it is necessary to identify and read the magnetic field value corresponding to a specific feature point from each second-order magnetoresistive curve. It can be understood that the feature point can refer to the extreme point on the second-order magnetoresistive curve, such as the peak or valley value. The feature point corresponds to the position where the slope of the first-order magnetoresistive curve is the largest, that is, the critical point where the magnetization reversal is the most violent. The magnetic field coordinates of the feature point are very sensitive to small changes in the effective field.

[0098] Step S25: Based on the offset of the magnetic field value corresponding to the feature point as a function of the DC bias current, the effective field of the spin orbit moment of the target sample is calculated.

[0099] It should be noted that the spin orbit moment is equivalent to an effective magnetic field with magnetization intensity. When a positive or negative DC bias current is applied, the direction of the effective field of the spin orbit moment will be reversed, thereby changing the critical condition for magnetization reversal. Specifically, this is manifested as the shift of the magnetic field value at the characteristic point on the second-order magnetoresistance curve.

[0100] Specifically, the method for calculating the effective field of the spin orbital moment includes: for a given DC bias current The second-order magnetoresistance curve has two flipped fields, which are the magnetic field values ​​corresponding to two characteristic points. and The average value of these two flipping fields is ΔH = ( + The offset of the second-order magnetoresistance curve relative to a zero magnetic field (i.e., a magnetic field value of 0) / 2 is the effective field of the spin orbit, such as... Figure 5 The arrows in sub-diagram b(1) are shown. For positive and negative DC bias currents (such as + and- The sign of the offset ΔH (i.e., the effective field of the spin orbit) is also opposite, meaning that the positive and negative bias currents cause the second-order magnetoresistance curve to shift towards the negative and positive magnetic fields, respectively.

[0101] In a specific implementation, the differential calculation method based on the magnetic field offset under symmetrical current can effectively eliminate the influence of factors such as thermal drift caused by Joule heating and DC offset voltage, thereby achieving high-precision and reliable measurement of the effective field of SOT.

[0102] In this embodiment, the intensity of the SOT effect is modulated by setting DC bias currents of different magnitudes or polarities, and the magnetic field values ​​corresponding to characteristic points on each second-order curve are recorded. By calculating the magnetic field offset of the same characteristic point under positive and negative bias currents, and combining the ratio of the offset to the bias current with the parameters of the target sample, the quantitative value of the effective SOT field can be directly calculated. This not only overcomes the measurement uncertainty caused by the flatness of the first-order magnetoresistance curve, but also improves the signal-to-noise ratio, achieving reliable and highly sensitive measurement of the effective SOT field.

[0103] Based on the above embodiments of this application, in another embodiment of this application, the same or similar content as the above embodiments can be referred to the above description, and will not be repeated hereafter. Step S20, which applies a set of positive and negative pulse currents of equal amplitude and opposite direction to the target sample along a first direction parallel to the target sample, further includes steps S31~S33:

[0104] Step S31: During the duration of each pulse in the pulsed current, perform the operation of scanning the magnetic field along the second direction;

[0105] It should be noted that the current applied along the first direction parallel to the target sample is a set of positive and negative pulse currents with equal amplitude but alternating reverse directions. It is understood that the positive and negative pulse current waveforms consist of a positive pulse and a negative pulse forming one cycle, with the pulse amplitude typically ranging from 10 nA to 10 mA and the pulse width from 50 μs to 10 ms. Exemplarily, applying pulses in opposite directions induces opposite spin orbital moments in the target sample. In one embodiment, the positive and negative pulse currents can effectively reduce the continuous heating effect of Joule heating on the target sample, avoiding the impact of temperature drift on measurement accuracy.

[0106] In a specific implementation, the measurement process needs to be synchronized with the pulse sequence. That is, during the duration of each pulse in the pulse current sequence, regardless of whether the current direction is positive or negative, a scanning operation of the magnetic field must be performed once in a second direction perpendicular to the current. For example, the scanning process of the magnetic field is slow and continuous, while the pulse current is repeatedly applied, thereby ensuring that voltage data corresponding to the same magnetic field point under both positive and negative currents can be acquired.

[0107] Step S32: During each scanning magnetic field process, detect and record the longitudinal voltage generated by the target sample;

[0108] It should be noted that during each magnetic field scan, a precision voltmeter can be used to detect and record the longitudinal voltage generated by the target sample in real time. The longitudinal voltage refers to the voltage drop measured along the current direction (i.e., the x-axis). According to Ohm's law, this voltage drop reflects the resistance state of the target sample under the instantaneous magnetic field and instantaneous current.

[0109] Step S33: Calculate the difference in longitudinal voltage between the positive and negative pulses at the same magnetic field point, and generate a second-order magnetoresistive curve based on the difference.

[0110] It should be noted that the difference calculation is performed by calculating the difference between the longitudinal voltages corresponding to the positive and negative pulses at the same magnetic field point. That is, for each magnetic field point H, the voltage measured under the positive pulse is used. Subtract the voltage measured under the negative pulse The differential voltage ΔV(H) is obtained as follows: - For example, plotting the differential voltage signal ΔV(H) as a function of the magnetic field H is equivalent to obtaining an approximation of the second-order magnetoresistance curve (dR / dH-H curve) of the resistance to the magnetic field. In specific implementations, this differential method eliminates symmetry signals (e.g., thermal effects) that are independent of the current direction, thereby highlighting the asymmetric response caused by the SOT effect with high sensitivity.

[0111] In this embodiment, a method is proposed to measure the effective field of an in-plane magnetically anisotropic thin film (SOT) by employing a set of positive and negative pulse currents with equal amplitude and opposite direction, combined with synchronous magnetic field scanning. By alternately applying short-duration pulses of opposite polarity, the pulse current effectively excites the SOT effect while suppressing Joule heat accumulation caused by continuous current, thus avoiding the negative impact of thermal drift on measurement stability. By calculating the difference between the longitudinal voltages corresponding to the positive and negative pulses at the same magnetic field point, the resulting differential voltage-magnetic field curve is directly equivalent to a second-order magnetoresistive curve. Therefore, this embodiment eliminates the need for complex harmonic detection circuits or lock-in amplifier detectors; it directly extracts the second-order magnetoresistive curve for calculating the effective field of the SOT through pulse control and differential operations in the time domain. This not only simplifies the equipment configuration for measurement but also enhances anti-interference capabilities and measurement reliability, ultimately achieving high-precision quantization of the effective field of the SOT.

[0112] For example, such as Figure 4 As shown, Figure 4 This is a schematic diagram illustrating the application of a pulsed current, i.e., a schematic diagram of the pulsed method. Figure 4 In the graph, the horizontal axis t represents time, and the vertical axis represents the instantaneous value of the current magnitude as a function of time. Indicates pulse current; from Figure 4It can be seen that the applied pulse current is a set of pulse currents with equal amplitude and opposite direction. Understandably, this pulse current is emitted through a current source and can pass through... Figure 2 The label 300 is applied to the target sample.

[0113] In one feasible implementation, the step of determining the effective field of the spin orbital moment of the target sample based on the offset of the magnetic field value corresponding to the characteristic point on the second-order magnetoresistance curve under different current conditions includes steps S34-S35:

[0114] Step S34: Determine the magnetic field value corresponding to the characteristic point on each second-order magnetoresistance curve;

[0115] It should be noted that the magnetic field value corresponding to the characteristic point on each second-order magnetoresistive curve measured at a specific pulse current amplitude is determined. The magnetic field value corresponding to the characteristic point corresponds to the region with the largest slope of the first-order magnetoresistive curve, which is the critical point where the magnetization reverses most violently.

[0116] Step S35: Based on the offset of the magnetic field value corresponding to the feature point as a function of the pulse current amplitude, the effective field of the spin orbit moment of the target sample is calculated.

[0117] It should be noted that the magnitude of the spin orbital moment is proportional to the applied pulse current. When measurements are performed using pulse currents of different amplitudes (e.g., +2 mA and -2 mA), the equivalent SOT effective field strength also changes linearly, leading to a change in the critical condition for magnetization reversal. Specifically, this is manifested as a shift in the magnetic field value at a characteristic point on the second-order magnetoresistance curve. Based on this shift, the offset is obtained, and the effective field of the spin orbital moment of the target sample can be calculated.

[0118] Additionally, it should be noted that for the pulsed current method, the method for calculating the effective field of the spin orbital moment based on the offset of the magnetic field value corresponding to the feature point as a function of the pulsed current amplitude is similar in principle to the AC harmonic method described above. That is, for a given positive or negative pulsed current (e.g., + and- The second-order magnetoresistance curve has two flipped fields, i.e., the magnetic field values ​​corresponding to two characteristic points. and The average value of these two flipping fields is ΔH = ( + The offset of the second-order magnetoresistance curve relative to a zero magnetic field (i.e., a magnetic field value of 0) / 2 is the effective field of the spin orbit, such as... Figure 6 The arrow in subgraph b(4) is shown.

[0119] In this embodiment, the symmetry characteristics of the SOT effect under pulsed current driving are utilized to obtain the second-order magnetoresistance curve. The magnetic field positions of characteristic points on the second-order magnetoresistance curve are then determined, and the linear shift of these positions with the pulsed current amplitude is used as a direct observation. The effective field of the spin orbital moment of the target sample is then calculated, achieving a high signal-to-noise ratio and high reliability measurement of the effective field of the SOT in an inwardly magnetically anisotropic thin film.

[0120] For example, to help understand the implementation flow of the method for measuring the effective field of spin orbital moment obtained by combining the above embodiments, please refer to... Figure 5 , Figure 5 A schematic diagram of magnetoresistance curves for different current magnitudes is provided using an AC harmonic method for the effective field of spin orbital moments. Specifically:

[0121] Figure 5 Is The DC bias current is +2 mA, 0 mA, or -2 mA. The first-order magnetoresistance curve was obtained at an AC reading current of 1 mA (e.g.) Figure 5 a(1), a(2), a(3)) and second-order magnetoresistance curves (e.g. Figure 5 b(1), b(2), b(3) in the text.

[0122] Figure 5 The horizontal axis represents the magnetic field value, with the unit being Oe (Oersted). Figure 5 The ordinates of a(1), a(2), and a(3) in the equation This represents the value of the first harmonic component, in units of . (ohm); Figure 5 The ordinates of b(1), b(2), and b(3) in the equation This represents the value of the second harmonic component, in units of . (Ohm). As can be seen from the above embodiments, although the longitudinal voltage value is measured, according to Ohm's law, the measured longitudinal voltage value can be equivalent to the resistance value, therefore... Figure 5 The vertical axis represents the resistance value.

[0123] Figure 5 The curves shown in a(1), a(2), and a(3) are: the resistance change with the magnetic field obtained by scanning the magnetic field under a specific DC bias current, i.e., the first-order magnetoresistance curve. For example, taking 2mA as an example, i.e. Figure 5 In diagram a(1), two curves are shown—curve 1 represents the result obtained by applying a magnetic field from -50Oe to +50Oe to the target sample under a DC bias current of 2mA; curve 2 represents the result obtained by applying a magnetic field from +50Oe to -50Oe to the target sample under a DC bias current of 2mA. From Figure 5From a(1), a(2), and a(3), it can be seen that the peak of the first-order magnetoresistance curve is relatively smooth and has a wide broadening, making it impossible to directly read the precise magnetic field value, thus making it impossible to obtain the accurate SOT effective field.

[0124] Figure 5 The curves shown in b(1), b(2), and b(3) are: second-order magnetoresistance curves obtained based on the second harmonic component values ​​under a specific DC bias current. For example, taking 2mA as an example, that is... Figure 5 In b(1), the two curves shown are: Curve 3 represents the second-order magnetoresistance curve obtained by applying a magnetic field from -50Oe to +50Oe to the target sample under a DC bias current of 2mA, and then obtaining the second-order magnetoresistance curve based on the second harmonic component value corresponding to each magnetic field value; Curve 4 represents the second-order magnetoresistance curve obtained by applying a magnetic field from +50Oe to -50Oe to the target sample under a DC bias current of 2mA, and then obtaining the second-order magnetoresistance curve based on the second harmonic component value corresponding to each magnetic field value.

[0125] exist Figure 5 In b(1), b(2), and b(3), each second-order magnetoresistive curve represents the second-order magnetoresistive signal under a specific DC bias current, and the feature points on the curves correspond to the critical points of magnetization reversal. For each DC bias current, the second-order magnetoresistive curve contains two feature points, which correspond to the reversal of different magnetization directions.

[0126] For example, in Figure 5 In line b(1), the magnetic field value is -2.5 (Oe), i.e., the magnetic field = -2.5 is represented by a dashed line. The center of this dashed line is shifted to the left relative to the dashed line with a magnetic field value of 0 (Oe), i.e., the magnetic field = 0, indicated by a left-pointing arrow. Figure 5 In line b(3), the dashed line represents a magnetic field value of 2.5 (Oe), i.e., magnetic field = +2.5. The center of this dashed line is offset to the right relative to the dashed line representing a magnetic field value of 0 (Oe), i.e., magnetic field = 0, indicated by a right-pointing arrow. For example, a horizontal line is drawn at the center of the intersection of the dashed line representing magnetic field = -2.5 and curves 3 and 4. Figure 5 The horizontal dashed line in b(1) intersects curves 3 and 4 at two points, which are feature points 1 and 2. Then, the magnetic field values ​​corresponding to feature points 1 and 2 are read respectively. Finally, based on ΔH=( + ) / 2, to obtain the effective field of SOT.

[0127] Please refer to Figure 6 , Figure 6 A pulsed method for the effective field of spin orbital moment is provided, illustrating magnetoresistance curves under different current magnitudes. Specifically:

[0128] Figure 6 Is First-order magnetoresistance curves were obtained with pulse currents of +2 mA and -2 mA (e.g.) Figure 6 a(4) and a(5) in the figure) and the second-order magnetoresistance curve (as shown in the figure) Figure 6 (b(4) and b(5) in the text). Figure 6 The horizontal axis represents the magnetic field value, with the unit being Oe (Oersted). Figure 6 The ordinates of a(4) and a(5) in the equation This represents the value of the first harmonic component, in units of . (ohm); Figure 6 The ordinates of b(4) and b(5) in the equation This represents the value of the second harmonic component, in units of . (ohm).

[0129] Figure 6 The curves shown in a(4) and a(5) are: the change in resistance with magnetic field obtained by scanning the magnetic field under a specific pulse current, i.e., the first-order magnetoresistance curve. For example, taking 2mA as an example, i.e. Figure 6 In section a(4), two curves are shown—curve 5 represents the result obtained by applying a magnetic field from -50Oe to +50Oe to the target sample under a 2mA pulse current; curve 6 represents the result obtained by applying a magnetic field from +50Oe to -50Oe to the target sample under a 2mA pulse current. From Figure 6 In a(4) and a(5), it can be seen that the peak of the first-order magnetoresistance curve is relatively smooth and has a wide broadening, making it impossible to directly read the precise magnetic field value, thus making it impossible to obtain the accurate SOT effective field.

[0130] Figure 6 The curves shown in b(4) and b(5) are: second-order magnetoresistance curves obtained based on the second harmonic component values ​​under a specific pulse current. For example, taking 2mA as an example, that is... Figure 6 In b(4), the two curves shown are: Curve 7 represents the second-order magnetoresistance curve obtained by applying a magnetic field from -50Oe to +50Oe to the target sample under a 2mA pulse current and then using the second harmonic component value corresponding to each magnetic field value; Curve 8 represents the second-order magnetoresistance curve obtained by applying a magnetic field from +50Oe to -50Oe to the target sample under a 2mA pulse current and then using the second harmonic component value corresponding to each magnetic field value.

[0131] exist Figure 6 In b(4) and b(5), each second-order magnetoresistive curve represents the second-order magnetoresistive signal under a specific pulse current, and the feature points on the curve correspond to the critical points of magnetization reversal. For each pulse current, the second-order magnetoresistive curve contains two feature points, which correspond to the reversal of different magnetization directions.

[0132] For example, in Figure 6In line b(4), the magnetic field value is -2.5 (Oe), i.e., the magnetic field = -2.5 is represented by a dashed line. The center of this dashed line is shifted to the left relative to the dashed line with a magnetic field value of 0 (Oe), i.e., the magnetic field = 0, indicated by a left-pointing arrow. Correspondingly, in Figure 6 In line b(5), the dashed line represents a magnetic field value of 2.5 (Oe), i.e., magnetic field = +2.5. The center of this dashed line is offset to the right relative to the dashed line representing a magnetic field value of 0 (Oe), i.e., magnetic field = 0, indicated by a right-pointing arrow. For example, a horizontal line is drawn with the center of the intersection of the dashed line representing magnetic field = -2.5 and curves 7 and 8. Figure 6 The horizontal dashed line in b(4) intersects curves 7 and 8 at two points, which are feature points 3 and 4. Then, the magnetic field values ​​corresponding to feature points 3 and 4 are read respectively. Finally, based on ΔH=( + ) / 2, to obtain the effective field of SOT.

[0133] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the measurement method of the effective field of spin orbit moment of this application. Based on this technical concept, more simple transformations such as the interaction and combination of various embodiments are all within the protection scope of this application.

[0134] This application also provides a measuring device for the effective field of spin orbital moment, please refer to... Figure 7 The measuring device for the effective field of the spin orbital moment includes:

[0135] Power module 10 is used to perform: acquiring a target sample of an in-plane magnetic anisotropic thin film, applying a current to the target sample along a first direction parallel to the target sample, and applying a scanning magnetic field to the target sample in a second direction perpendicular to the first direction, wherein the first direction is the current direction and the second direction is a direction in the plane perpendicular to the current direction;

[0136] The detection module 20 is used to perform the following: during the application of the scanning magnetic field, detect the voltage of the target sample under the scanning magnetic field, and obtain the second-order magnetoresistance curve of the resistance to the magnetic field corresponding to the voltage;

[0137] Display module 30 is used to perform the following: determining the effective field of the spin orbit moment of the target sample based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistive curve under different current conditions.

[0138] Optionally, the power module 10 is also used to perform: fabrication of a metal thin film having in-plane magnetic anisotropy;

[0139] The metal thin film is patterned into a Hall strip structure, wherein the Hall strip structure includes lead electrodes along the current direction and at least two pairs of test electrodes for measuring voltage, wherein the voltage is a longitudinal voltage;

[0140] The Hall strip structure is wire bonded to obtain a target sample for testing in-plane magnetic anisotropic thin films.

[0141] Optionally, the detection module 20 is also configured to perform: scanning the magnetic field along the second direction under the action of a DC bias current;

[0142] During each magnetic field scan, the first and second harmonic components of the longitudinal voltage signal generated by the target sample are detected.

[0143] Based on the amplitude of the AC reading current, the first harmonic component is converted into the first-order magnetoresistance curve of the target sample, and the second harmonic component is converted into the second-order magnetoresistance curve of the target sample.

[0144] Optionally, the display module 30 is also configured to perform: acquiring second-order magnetoresistive curves measured under at least two different current values ​​of the DC bias current, and the magnetic field value corresponding to the feature point on each second-order magnetoresistive curve;

[0145] Based on the offset of the magnetic field value corresponding to the feature point as a function of the DC bias current, the effective field of the spin orbit moment of the target sample is calculated.

[0146] Optionally, the detection module 20 is further configured to perform the operation of scanning the magnetic field along the second direction during the duration of each pulse in the pulse current;

[0147] During each scanning of the magnetic field, the longitudinal voltage generated by the target sample is detected and recorded;

[0148] Calculate the difference in longitudinal voltage between the positive and negative pulses at the same magnetic field point, and generate the second-order magnetoresistive curve based on the difference.

[0149] Optionally, the display module 30 is also configured to perform: determining the magnetic field value corresponding to the feature point on each of the second-order magnetoresistive curves;

[0150] Based on the offset of the magnetic field value corresponding to the feature point as a function of the pulse current amplitude, the effective field of the spin orbit moment of the target sample is calculated.

[0151] The spin orbital moment effective field measurement device provided in this application, employing the spin orbital moment effective field measurement method described in the above embodiments, can solve the technical problem of low accuracy in measuring the spin orbital moment effective field of in-plane magnetically anisotropic thin films using existing methods. Compared with the prior art, the beneficial effects of the spin orbital moment effective field measurement device provided in this application are the same as those of the spin orbital moment effective field measurement method provided in the above embodiments, and other technical features in the spin orbital moment effective field measurement device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0152] This application provides a measuring device for the effective field of spin orbit moment. The measuring device includes: at least one lock-in amplifier, a current source for applying current to a sample, an electromagnet and a gaussmeter for applying a magnetic field to the sample, and a processor capable of executing the steps of the method for measuring the effective field of spin orbit moment.

[0153] The following is for reference. Figure 8 The diagram illustrates a structural schematic of a measurement device suitable for realizing the effective field of spin-orbit moment in the embodiments of this application. The measurement device for the effective field of spin-orbit moment in the embodiments of this application may include, but is not limited to, mobile terminals such as laptops, PDAs (Personal Digital Assistants), PADs (Portable Application Description), etc., and fixed terminals such as digital TVs, desktop computers, etc., as well as buses, lock-in amplifiers, current sources, excitation power supplies, electromagnets, gaussmeters, etc. Figure 8 The spin orbital moment effective field measurement device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0154] like Figure 8 As shown, the measurement device for the effective field of spin orbit moment may include input devices (such as a mouse, keyboard, etc.), which can adjust test conditions in a timely manner according to different test requirements and transmit the data to the computer (central processing unit) program for processing different operation instructions. The central processing unit also stores various programs and data required for the operation of the measurement device for the effective field of spin orbit moment. Typically, the following devices can be connected to the central processing unit via a bus: devices including lock-in amplifiers, current sources, excitation power supplies, electromagnets, gaussmeters, etc.; the central processing unit is used to acquire and process data, and to communicate wirelessly or wiredly with output devices to output data. Although the figure shows a measurement device for the effective field of spin orbit moment with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented alternatively.

[0155] In particular, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device to perform the functions defined in the methods of the embodiments disclosed in this application.

[0156] The spin orbital moment effective field measurement device provided in this application, employing the spin orbital moment effective field measurement method described in the above embodiments, can solve the technical problem of low accuracy in measuring the spin orbital moment effective field of in-plane magnetically anisotropic thin films using existing methods. Compared with the prior art, the beneficial effects of the spin orbital moment effective field measurement device provided in this application are the same as those of the spin orbital moment effective field measurement method provided in the above embodiments, and other technical features of this spin orbital moment effective field measurement device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0157] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0158] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0159] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to perform the method for measuring the effective field of spin orbit moment in the above embodiments.

[0160] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0161] The aforementioned computer-readable storage medium may be included in the measuring device for the effective field of spin orbit moment; or it may exist independently and not assembled into the measuring device for the effective field of spin orbit moment.

[0162] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0163] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0164] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0165] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described method for measuring the effective field of spin orbit moments. This solves the technical problem of low accuracy in measuring the effective field of spin orbit moments of in-plane magnetically anisotropic thin films using existing methods. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the effective field measurement method of spin orbit moments provided in the above embodiments, and will not be repeated here.

[0166] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method for measuring the effective field of spin orbit moment as described above.

[0167] The computer program product provided in this application can solve the technical problem of low accuracy in measuring the effective field of spin orbital moments of in-plane magnetically anisotropic thin films using existing methods. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the spin orbital moment effective field measurement method provided in the above embodiments, and will not be repeated here.

[0168] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method of measuring spin-orbit torque effective field, characterized by, The method for measuring the spin-orbit torque effective field comprises: Obtaining a target sample of an in-plane magnetic anisotropy film, applying a current to the target sample along a first direction parallel to the target sample, and applying a scanning magnetic field to the target sample in a second direction perpendicular to the first direction, wherein the first direction is the current direction, and the second direction is a direction in the plane perpendicular to the current direction; During the application of the scanning magnetic field, detecting the voltage of the target sample under the scanning magnetic field to obtain a second-order magnetoresistance curve of the resistance corresponding to the voltage with respect to the magnetic field; Based on the offset of the magnetic field values corresponding to the characteristic points on the second-order magnetoresistance curve under different current conditions, the spin-orbit torque effective field of the target sample is determined.

2. The method of claim 1, wherein, The current applied to the target sample along the first direction parallel to the target sample is a composite current superimposed by an alternating current reading current and a direct current bias current, and the step of detecting the voltage of the target sample under the scanning magnetic field during the application of the scanning magnetic field to obtain a second-order magnetoresistance curve of the resistance corresponding to the voltage with respect to the magnetic field comprises: Under the action of the direct current bias current, the scanning magnetic field is operated along the second direction; During each magnetic field scanning process, the first harmonic component and the second harmonic component of the longitudinal voltage signal generated by the target sample are detected; Based on the amplitude of the alternating current reading current, the first harmonic component is converted into a first-order magnetoresistance curve of the target sample, and the second harmonic component is converted into a second-order magnetoresistance curve of the target sample.

3. The method of claim 2, wherein, The step of determining the spin-orbit torque effective field of the target sample based on the offset of the magnetic field values corresponding to the characteristic points on the second-order magnetoresistance curve under different current conditions comprises: Obtaining the second-order magnetoresistance curves measured under at least two different current values of the direct current bias current, and the magnetic field values corresponding to the characteristic points on each second-order magnetoresistance curve; Based on the offset of the magnetic field values corresponding to the characteristic points with respect to the direct current bias current, the spin-orbit torque effective field of the target sample is calculated.

4. The method of claim 1, wherein, The current applied to the target sample along the first direction parallel to the target sample is a set of positive and negative pulse currents with equal amplitudes and opposite directions, and the step of detecting the voltage of the target sample under the scanning magnetic field during the application of the scanning magnetic field to obtain a second-order magnetoresistance curve of the resistance corresponding to the voltage with respect to the magnetic field comprises: During the duration of each pulse in the pulse current, the scanning magnetic field is operated along the second direction; During each scanning magnetic field process, the longitudinal voltage generated by the target sample is detected and recorded; The difference value of the longitudinal voltage corresponding to the positive pulse and the negative pulse at the same magnetic field point is calculated, and the second-order magnetoresistance curve is generated according to the difference value.

5. The method of claim 4, wherein, The step of determining the spin-orbit torque effective field of the target sample based on the offset of the magnetic field values corresponding to the characteristic points on the second-order magnetoresistance curve under different current conditions comprises: Determining the magnetic field values corresponding to the characteristic points on each second-order magnetoresistance curve; The spin-orbit torque effective field of the target sample is calculated based on a shift of a magnetic field value corresponding to the feature point with a change of the pulse current amplitude.

6. The method of claim 1, wherein, The step of obtaining the target sample of the in-plane magnetic anisotropy thin film comprises: Preparation of a metal thin film with in-plane magnetic anisotropy; The metal thin film is patterned into a Hall bar structure, wherein the Hall bar structure comprises a lead electrode along a current direction and at least two pairs of test electrodes for measuring voltage, wherein the voltage is a longitudinal voltage; The Hall bar structure is subjected to a wire bonding process to obtain a target sample for testing the in-plane magnetic anisotropy thin film.

7. A device for measuring spin-orbit torque effective field, characterized by, The spin-orbit torque effective field measurement device comprises: A power supply module for performing: obtaining a target sample of an in-plane magnetic anisotropy thin film, applying a current to the target sample along a first direction parallel to the target sample, and applying a scanning magnetic field to the target sample in a second direction perpendicular to the first direction, wherein the first direction is the current direction and the second direction is a direction perpendicular to the current direction in the plane; A detection module for performing: detecting the voltage of the target sample under the scanning magnetic field during the application of the scanning magnetic field to obtain a second-order magnetoresistance curve of the resistance corresponding to the magnetic field; A display module for performing: determining the spin-orbit torque effective field of the target sample based on the shift of the magnetic field value corresponding to the feature point on the second-order magnetoresistance curve under different current conditions.

8. A device for measuring spin-orbit torque effective field, characterized by, The device comprises at least one lock-in amplifier, a current source for applying a current to the sample, an electromagnet and a gauss meter for applying a magnetic field to the sample, and a processor, wherein the processor performs the steps of the spin-orbit torque effective field measurement method according to any one of claims 1 to 6.

9. A storage medium, characterized by The storage medium is a computer-readable storage medium, and the storage medium stores a computer program, wherein the computer program is executed by the processor to implement the steps of the spin-orbit torque effective field measurement method according to any one of claims 1 to 6.

10. A computer program product, characterised in that, The computer program product comprises a computer program, wherein the computer program is executed by the processor to implement the steps of the spin-orbit torque effective field measurement method according to any one of claims 1 to 6.

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