Spin orbit moment effective field measurement method, device, equipment, medium and program product

Abstract

The invention discloses a method, a device, equipment, a medium and a program product for measuring an effective field of a spin orbit moment, and relates to the technical field of spin electronics, and the method comprises the steps: obtaining a target sample of an in-plane magnetic anisotropy film, applying a current to the target sample in a first direction parallel to the target sample, a scanning magnetic field is applied to the target sample in the second direction perpendicular to the first direction, the first direction is the current direction, and the second direction is the direction perpendicular to the current direction in the plane; in the process of applying the scanning magnetic field, detecting the voltage of the target sample in the scanning magnetic field to obtain a second-order magnetoresistance curve of the resistance corresponding to the voltage to the magnetic field; and determining the spin orbit moment effective field 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. According to the invention, high-precision and high-reliability measurement of the spin orbit moment effective field of the in-plane magnetic anisotropy film is realized without depending on a first-order curve form and avoiding temperature drift interference.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spin electronics, and in particular to a method for measuring spin-orbit torque effective field, a device for measuring spin-orbit torque effective field, an apparatus for measuring spin-orbit torque effective field, a storage medium and a computer program product. BACKGROUND

[0002] In the prior art, the measurement of the spin-orbit torque effective field of the in-plane magnetic anisotropy film mainly has the following limitations: the commonly used magnetoresistance (MR) curve shift method relies on the first-order MR curve having a sharp peak or mutation feature to accurately identify the magnetic field shift; however, for most actual samples, the first-order MR curve changes gently and significantly broadens, making it difficult to identify the characteristic points, thereby failing to accurately determine the spin-orbit torque (SOT) effective field. In addition, the MR curve shift method needs to use a permanent magnet to provide a bias magnetic field, and the magnetization intensity of the permanent magnet is easily affected by temperature drift, which further introduces measurement errors and affects the reliability and accuracy of the measurement.

[0003] Therefore, the existing method is difficult to achieve high-precision measurement of the spin-orbit torque effective field when dealing with in-plane magnetic anisotropy films with smooth or significantly broadened first-order MR curve signals. SUMMARY

[0004] The main purpose of the present application is to provide a method for measuring spin-orbit torque effective field, a device for measuring spin-orbit torque effective field, an apparatus for measuring spin-orbit torque effective field, a storage medium and a computer program product, aiming to solve the technical problem of low accuracy in measuring the spin-orbit torque effective field of the in-plane magnetic anisotropy film by the existing method.

[0005] To achieve the above-mentioned purpose, the present application provides a method for measuring spin-orbit torque effective field, which 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 the direction perpendicular to the current direction in the plane; 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 corresponding to the resistance of the target sample under the scanning magnetic field; Based on the offset of the magnetic field value corresponding to the characteristic point on the second-order magnetoresistance curve under different current conditions, the spin-orbit torque effective field of the target sample is determined.

[0006] In an embodiment, the current applied to the target sample along the first direction parallel to the target sample is a composite current of an alternating reading current superimposed with a direct bias current, and the step of detecting the voltage of the target sample under the scanning magnetic field to obtain a second-order magnetoresistance curve of the resistance versus the magnetic field corresponding to the voltage during the application of the scanning magnetic field comprises: performing the scanning magnetic field operation along the second direction under the direct bias current; detecting a first harmonic component and a second harmonic component of the longitudinal voltage signal generated by the target sample during each magnetic field scanning; converting the first harmonic component into a first-order magnetoresistance curve of the target sample and converting the second harmonic component into a second-order magnetoresistance curve of the target sample based on the amplitude of the alternating reading current.

[0007] In an embodiment, the step of determining the spin-orbit 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 comprises: obtaining the second-order magnetoresistance curve measured under the direct bias current with at least two different current values, and the magnetic field value corresponding to the feature point on each second-order magnetoresistance curve; calculating the spin-orbit effective field of the target sample based on the shift of the magnetic field value corresponding to the feature point with the direct bias current.

[0008] In an embodiment, the current applied to the target sample along the first direction parallel to the target sample is a composite current of an alternating reading current superimposed with a direct bias current, and the step of detecting the voltage of the target sample under the scanning magnetic field to obtain a second-order magnetoresistance curve of the resistance versus the magnetic field corresponding to the voltage during the application of the scanning magnetic field comprises: performing the scanning magnetic field operation along the second direction during each pulse of the pulse current; detecting and recording the longitudinal voltage generated by the target sample during each scanning magnetic field; calculating the difference value of the longitudinal voltage corresponding to the positive pulse and the negative pulse at the same magnetic field point, and generating the second-order magnetoresistance curve according to the difference value.

[0009] In an embodiment, the step of determining the spin-orbit 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 comprises: determining the magnetic field value corresponding to the feature point on each second-order magnetoresistance curve; Based on the offset of the magnetic field value corresponding to the feature point with the change of the pulse current amplitude, the spin-orbit effective field of the target sample is calculated.

[0010] In an embodiment, 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 includes a lead electrode along the current direction and at least two pairs of test electrodes for measuring voltage, wherein the voltage is longitudinal voltage; The Hall bar structure is subjected to wire bonding treatment to obtain a target sample for testing the in-plane magnetic anisotropy thin film.

[0011] In addition, in order to achieve the above-mentioned purpose, the present application also provides a spin-orbit effective field measurement device, which comprises: A power supply module is used to perform: 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 the direction perpendicular to the current direction in the plane; A detection module is used to perform: 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 corresponding to the magnetic field of the voltage; A display module is used to perform: based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistance curve under different current conditions, determining the spin-orbit effective field of the target sample.

[0012] In addition, in order to achieve the above-mentioned purpose, the present application also provides a spin-orbit effective field measurement device, which comprises: at least one phase-locked 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 effective field measurement method as described above.

[0013] In addition, in order to achieve the above-mentioned purpose, the present application also provides a storage medium, which is a computer readable storage medium, and the storage medium stores a computer program, wherein the computer program is executed by a processor to implement the steps of the spin-orbit effective field measurement method as described above.

[0014] In addition, to achieve the above object, the present application also provides a computer program product, which comprises a computer program, and the computer program realizes the steps of the spin-orbit torque effective field measurement method when executed by a processor.

[0015] The one or more technical solutions provided by the present application have at least the following technical effects: The present application effectively solves the problem that the prior art cannot accurately measure flat or widened signal samples due to the dependence on the sharp features of the first-order magnetoresistance curve by using the technical means of applying orthogonal current and scanning magnetic field on the in-plane magnetic anisotropy thin film target sample, detecting the voltage signal of the target sample to obtain the second-order magnetoresistance curve of resistance versus magnetic field, and finally determining the spin-orbit torque effective field based on the shift of the characteristic point corresponding to the magnetic field value on the second-order magnetoresistance curve under different current conditions. Specifically, the present application enhances the signal sensitivity of the magnetization flipping critical point by using the second-order differential processing, so that the capture of the characteristic magnetic field shift becomes clear and reliable. At the same time, the present application uses electromagnetic scanning field instead of permanent magnet to provide the bias magnetic field, which eliminates the measurement error introduced by the temperature drift of the permanent magnet. It can be seen that, compared with the prior art, the present application realizes high-precision and high-reliability measurement of the spin-orbit torque effective field of the in-plane magnetic anisotropy thin film under the premise of not relying on the first-order curve form and avoiding temperature drift interference. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0018] Figure 1 The flowchart provided by the embodiment of the spin-orbit torque effective field measurement method of the present application; Figure 2 The measurement schematic diagram provided by the spin-orbit torque effective field measurement method of the present application; Figure 3 The schematic diagram of applying composite current provided by the spin-orbit torque effective field measurement method of the present application; Figure 4 The schematic diagram of applying pulse current provided by the spin-orbit torque effective field measurement method of the present application; Figure 5 The schematic diagram of the alternating harmonic method magnetoresistance curve provided by the spin-orbit torque effective field measurement method of the present application; Figure 6 The pulse method magnetoresistance curve diagram provided for the measurement method of the spin-orbit torque effective field of the application; Figure 7 The module structure diagram of the measurement device of the spin-orbit torque effective field of the application; Figure 8 The device structure diagram of the hardware running environment involved in the measurement method of the spin-orbit torque effective field of the application.

[0019] The purpose implementation, functional characteristics and advantages of the application will be further described with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the application and are not used to limit the application.

[0021] In order to better understand the technical solutions of the application, the following will be described in detail in combination with the drawings and specific embodiments of the specification.

[0022] In recent years, spintronic devices using spin-orbit torque SOT effect to write information have attracted widespread attention, which has the advantages of fast read-write speed, low power consumption and non-volatility. A typical SOT device uses a heavy metal / ferromagnetic (HM / FM) heterostructure as the basic functional structure for information writing, and its principle is to use the strong spin-orbit coupling of the heavy metal layer or the interface Rashba (a physical effect that can associate the electron spin with its momentum due to the asymmetry of the interface structure) spin-orbit coupling to cause the spin current to exert torque on the magnetization, thereby driving the magnetization of the adjacent ferromagnetic layer to flip.

[0023] In the study of spin-orbit torque SOT effect, it is extremely important to evaluate the size of SOT effective field and the magnetization flip induced by SOT. For a thin film with perpendicular magnetic anisotropy, its SOT effective field can be obtained by the mature second harmonic Hall voltage method: the harmonic signals of the field scanning along the current direction (longitudinal field scanning) and the harmonic signals of the field scanning perpendicular to the current (transverse field scanning) can determine two components of the SOT effective field, respectively. For the measurement of SOT effective field of a thin film with in-plane magnetic anisotropy, there are fewer related research works, which are still developing in recent years. The previous method proposed that the size of SOT effective field can be characterized by the shift of the magnetoresistance (MR) curve under the current.

[0024] The MR curve shift method helps to determine the size of the SOT effective field by applying a bias magnetic field, but the bias magnetic field is more dependent on the permanent magnet, and the magnetization of the permanent magnet changes significantly with temperature, which may cause the drift of the bias magnetic field, thereby affecting the accuracy of the measurement. And the MR shift method is suitable for the first-order MR curve with sharp peak or sudden jump, and the SOT effective field is determined by the shift of the magnetic field of the peak or jump. For most samples, the first-order MR curve changes gently or has obvious broadening, and the peak or jump is not obvious, so it is difficult to get the accurate change of the magnetic field.

[0025] The application provides an improved method for measuring the spin-orbit torque effective field of an in-plane magnetic anisotropy thin film. The spin-orbit torque effective field measurement method of the application enhances the measurement sensitivity and accuracy by using the second-order magnetoresistance curve.

[0026] It should be noted that the execution subject of the embodiment can be a spin-orbit torque effective field measurement device, or a computing service device with data processing, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or an electronic device or a processor capable of realizing the above functions. The following will take the spin-orbit torque effective field measurement device (hereinafter referred to as the measurement device) as an example to describe the embodiment and the following embodiments.

[0027] Based on this, the application provides a spin-orbit torque effective field measurement method, which is described in detail below with reference to Figure 1 , Figure 1 The flowchart of an embodiment of the spin-orbit torque effective field measurement method of the application is shown in the figure.

[0028] In the embodiment, the spin-orbit torque effective field measurement method comprises steps S10-S30: Step S10, 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 the direction perpendicular to the current direction in the plane; It should be noted that the target sample of the in-plane magnetic anisotropy thin film can be understood as a magnetic material whose magnetization direction is mainly in the plane of the thin film, and the spin-orbit torque effective field is an effective magnetic field induced by the spin-orbit coupling effect, which is crucial for the performance evaluation of spintronic devices.

[0029] A current is applied along a first direction parallel to the target sample, and a scanning magnetic field is applied in a second direction perpendicular to the first direction. In an embodiment, the first direction can be the current injection direction of the target sample in the x-y plane (for example Figure 2The x-axis shown) for generating spin-orbit torque, and the second direction is the scanning direction of the magnetic field in the x-y plane (for example Figure 2 The y-axis shown) to change the magnetization state inside the sample to ensure that the magnetic field is perpendicular to the current direction, so as to effectively excite the spin-orbit torque effect.

[0030] Exemplarily, the target sample, for example, a Zr / Ni (zirconium-nickel) thin film with a thickness in nanometers, can be prepared into a Hallbar (Hall bar) structure with a line width ranging from 3 to 30 microns and multiple pairs of electrodes for facilitating the detection of electrical signals. In specific embodiments, the current can be an alternating current reading current combined with a direct current bias current, and the current can also be a pulse current, and the scanning magnetic field is adjusted by an electromagnet to cover the required magnetic field range. Step S10 adjusts the resistance or voltage of the target sample by applying the current and scanning the magnetic field.

[0031] In one possible embodiment, step S10 includes steps S11-S13: Step S11, preparing a metal thin film with in-plane magnetic anisotropy; It should be noted that a metal thin film with in-plane magnetic anisotropy needs to be prepared. It can be understood that in-plane magnetic anisotropy refers to the characteristic that the magnetization direction of a magnetic material is preferentially located in the plane of the thin film.

[0032] In an embodiment, such a thin film can be prepared by a magnetron sputtering method, for example, using a multi-layer material system such as Zr / Ni, by precisely controlling sputtering parameters such as working gas pressure, sputtering power and substrate temperature to induce the formation of in-plane anisotropy. Exemplarily, the thickness of the thin film is usually regulated in nanometers to ensure that it has uniform magnetic properties and good electrical conductivity characteristics.

[0033] In specific embodiments, the preparation process further includes an annealing process after deposition to further optimize the crystal structure and magnetic anisotropy of the thin film.

[0034] Step S12, patterning the metal thin film into a Hallbar structure, wherein the Hallbar structure includes a lead electrode along the current direction and at least two pairs of test electrodes for measuring voltage, wherein the voltage is a longitudinal voltage; It should be noted that the prepared metal thin film is patterned into a Hall bar structure, which is a micro-nano scale device pattern specially used for electrical transport measurement. It can be understood that the Hall bar structure includes lead electrodes along the current direction and at least two pairs of test electrodes for measuring longitudinal voltage, which is the voltage drop along the current direction, used to characterize the magnetoresistance behavior of the material. In an embodiment, the patterning process can be realized by exposure and etching process, for example, the Hall bar pattern is first transferred to the photoresist layer by photolithography technology, and then the ion etching or wet etching is used to selectively remove the excess thin film material to form a strip structure with a line width of 3 to 30 microns.

[0035] Exemplarily, 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.

[0036] In step S13, the lead bonding process is performed on the Hall bar structure to obtain a target sample for testing the in-plane magnetic anisotropy thin film.

[0037] It should be noted that the lead bonding process is performed on the patterned Hall bar structure to obtain a target sample for testing the in-plane magnetic anisotropy thin film. Lead bonding is a micro-assembly technology that connects the Hall bar electrodes with external circuits through metal wires to realize the input and output of electrical signals. In an embodiment, thermal ultrasonic bonding or wedge bonding can be used to form reliable electrical connections on the electrode pads using gold or aluminum wires to ensure low contact resistance and mechanical stability. Exemplarily, the lead bonding process needs to be carefully operated under a microscope to avoid damage to the fragile thin film or introduce stress.

[0038] In a specific embodiment, after the bonding is completed, the target sample is fixed on a special chip carrier or probe station for easy integration into an electrical transport measurement system. It can be understood that this step completes the final preparation of the target sample, enabling the Hall bar structure to be efficiently interfaced with the measurement device for subsequent quantitative measurement of the spin-orbit torque effective field.

[0039] In this embodiment, the longitudinal voltage (i.e. the voltage drop along the current direction) is measured instead of the Hall voltage (i.e. the transverse voltage perpendicular to the current direction), because the magnetization vector of the in-plane magnetic anisotropy thin film is confined in the film plane. Therefore, the conventional and mature second harmonic method cannot be used in this application, and the SOT effective field is extracted by fixing the relative direction of current and magnetic field (current along x-axis and scanning magnetic field along y-axis) and observing the nonlinear change of longitudinal resistance with perpendicular magnetic field. In view of the measurement blind spot of the prior art for in-plane anisotropy thin film, this application realizes high-precision and reliable measurement of the SOT effective field, effectively overcoming the inapplicability of traditional methods for such materials.

[0040] As shown in the figure, Figure 2 , Figure 2 is a schematic diagram of measuring spin-orbit torque effective field, from Figure 2 it can be seen that the label 200 represents the target sample of the in-plane anisotropic film, and the label 100 represents the longitudinal voltage V of the target sample measured by the electrode, from Figure 2 it can be seen that it is along the x-axis direction; the label 300 represents the current I applied to the target sample, from Figure 2 it can be seen that it is along the x-axis direction; the label 400 represents the scanning magnetic field H applied to the target sample, from Figure 3 it can be seen that it is along the y-axis direction.

[0041] Step S20, in the process of applying the scanning magnetic field, detecting the voltage of the target sample under the scanning magnetic field, obtaining the second-order magnetoresistance curve of the resistance corresponding to the magnetic field; It should be noted that in the process of applying 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 corresponding to the magnetic field is obtained. It can be understood that the second-order magnetoresistance curve refers to the second derivative or the second harmonic response of the resistance with respect to the magnetic field, which can more sensitively reflect the subtle changes in the magnetization reversal process than the first-order curve. In an embodiment, the second-order signal can be extracted by detecting the first harmonic voltage and the second harmonic voltage under the alternating current reading current through a lock-in amplifier, or by measuring the differential resistance under the pulse current through a precision voltmeter.

[0042] Exemplarily, when using the alternating current harmonic method, the fixed frequency alternating current reading current and the adjustable direct current bias current act together, the lock-in amplifier synchronously captures the harmonic voltage, and then the second-order curve is obtained by scanning the field; if the pulse method is used, the resistance change is induced by the positive and negative pulse current, and the second-order curve is formed by directly calculating the differential signal. It can be understood that step S20 captures the critical point of the magnetization behavior through the high-order signal, which overcomes the measurement uncertainty caused by the smoothing or widening of the first-order curve.

[0043] Step S30, 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 curves under different current conditions.

[0044] It should be noted that a plurality of second-order magnetoresistance curves are obtained under different current conditions (for example, different direct current bias currents or positive and negative pulse currents are applied), and the magnetic field values corresponding to the characteristic points on each second-order curve are identified. It can be understood that due to the spin-orbit torque effect, an equivalent effective field is generated, which is superimposed with the external scanning magnetic field, thereby changing the actual magnetic field required for magnetization reversal, which is manifested as the offset of the characteristic point magnetic field value.

[0045] In an embodiment, the characteristic point can be any point on the second-order magnetoresistance curve, preferably, the characteristic point can be a peak value, a valley value or an inflection point, and the magnetic field value corresponding to the characteristic point will shift due to the change of the current polarity and size, that is, the critical magnetic field when the magnetization of the characteristic point is reversed; the shift amount of the magnetic field value corresponding to the characteristic point reflects the strength of the spin-orbit torque effective field.

[0046] Exemplarily, by comparing the magnetic field difference of the characteristic point under the positive and negative bias currents or pulse currents, and combining the known current parameters, the size of the effective field can be quantitatively calculated. In a specific embodiment, if the second-order curve shows left or right shift under positive and negative currents respectively, the value of the SOT effective field can be quantitatively calculated according to the linear relationship between the shift amount and the current. It can be understood that the application significantly improves the detection ability of the weak SOT effect in the in-plane magnetic anisotropy film by using the high sensitivity of the second-order signal, thereby realizing more accurate effective field measurement.

[0047] The embodiment provides a measurement method of a spin-orbit torque effective field. The application obtains the second-order magnetoresistance curve of the resistance to the magnetic field by applying the orthogonal current and the scanning magnetic field on the in-plane magnetic anisotropy film target sample and detecting the voltage signal of the target sample. Finally, the spin-orbit torque effective field is determined based on the shift of the magnetic field value corresponding to the characteristic point on the second-order magnetoresistance curve under different current conditions. The technical means effectively solves the problem that the prior art cannot accurately measure the flat or widened signal sample due to the dependence on the sharp characteristics of the first-order magnetoresistance curve. Specifically, the application enhances the signal sensitivity of the magnetization reversal critical point by using the second-order differential processing, so that the capture of the characteristic magnetic field shift amount becomes clear and reliable. At the same time, the application uses the electromagnetic scanning field instead of the permanent magnet to provide the bias magnetic field, which eliminates the measurement error introduced by the temperature drift of the permanent magnet. It can be known that, compared with the prior art, the application realizes the high-precision and high-reliability measurement of the spin-orbit torque effective field of the in-plane magnetic anisotropy film under the premise of not depending on the first-order curve form and avoiding temperature drift interference.

[0048] Based on the above-mentioned embodiments of the application, in another embodiment of the application, the same or similar contents as the above-mentioned embodiments can be referred to the above introduction, and will not be described in detail. The current applied to the target sample along the first direction parallel to the target sample is a composite current superimposed by the alternating reading current and the direct bias current, and step S20 further includes steps S21-S23: Step S21, under the action of the direct bias current, a scanning magnetic field operation is performed along the second direction; It is noted that the current applied along the first direction parallel to the target sample is not a single direct current or alternating current, but a composite current formed by superimposing the alternating read current and the direct bias current. It is appreciated that the composite current aims to achieve two functions simultaneously: the alternating read current is used to detect the electrical response of the target sample with high sensitivity, while the direct bias current is used to inject a bias field sufficient to induce the spin-orbit torque effect. In an embodiment, the amplitude of the alternating read current is usually small (e.g. 1 nA to 10 mA) and the frequency is fixed (e.g. 133.33 Hz) to avoid disturbance to the magnetic state of the target sample; the direct bias current is used to provide a stable spin polarization drive. Exemplarily, the two currents can be combined by a current source and then injected into the current channel of the Hall bar structure.

[0049] In a specific embodiment, the process of obtaining the second-order magnetoresistance curve is always performed under the action of the direct bias current, and the scanning magnetic field is performed along the direction perpendicular to the current direction. It is appreciated that the scanning magnetic field changes the magnetization state of the target sample, and the fixed direct bias current is equivalent to a stable drive for exciting and maintaining the spin-orbit torque. In an embodiment, the magnetic field scanning covers a symmetric range in a continuous or step-by-step manner to ensure that the magnetization flipping process is completely captured. Exemplarily, each magnetic field scanning is equivalent to recording the complete trajectory of the resistance of the target sample with respect to the external magnetic field under the condition of a fixed bias.

[0050] In step S22, the first harmonic component and the second harmonic component of the longitudinal voltage signal generated by the target sample are detected during each magnetic field scanning process. It is noted that the first harmonic component and the second harmonic component of the longitudinal voltage signal generated by the target sample are detected by the lock-in amplifier synchronously during each continuous magnetic field scanning process. It is appreciated that the first harmonic component refers to the voltage response with the same frequency as the alternating read current, which reflects the resistance value of the sample, i.e. the first-order magnetoresistance signal; and the second harmonic component refers to the voltage response with a frequency twice that of the alternating read current, which is more sensitive to the change of the magnetization vector direction and can highlight the nonlinear behavior near the critical point of the magnetization flipping.

[0051] In an embodiment, the lock-in amplifier is tuned to the base frequency and the second harmonic frequency, so that the first harmonic component and the second harmonic component can be extracted from the complex voltage signal with high precision. Exemplarily, the frequency domain separation detection technology in the lock-in amplifier can effectively suppress noise and significantly improve the signal-to-noise ratio of the signal measurement.

[0052] In step S23, 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 based on the amplitude of the alternating read current.

[0053] 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.

[0054] 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.

[0055] 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. ), wherein the second harmonic component is derived from the nonlinear response of the resistance R(H) to the magnetic field H, and the amplitude thereof is proportional to the derivative dR / dH of the first-order magnetoresistance curve R(H) to the magnetic field H; the first harmonic component reflects the instantaneous size of the resistance R(H) itself, and the amplitude thereof is proportional to R(H). According to the first harmonic component, the first-order magnetoresistance curve R(H) of the sample can be reconstructed, i.e., the direct change relationship of the resistance to the magnetic field; and according to the second harmonic component, the second-order magnetoresistance curve dR / dH can be reconstructed, i.e., the curve of the resistance change rate. It can be understood that the second harmonic component is generated by the nonlinear change of the resistance R(H) dependent on the first harmonic.

[0056] In the embodiment, the composite current is not a simple superposition of the two currents, but creates a synergistic measurement environment: the direct current bias current is responsible for injecting a spin-polarized current of sufficient strength in the target sample to effectively excite the spin-orbit torque; at the same time, the alternating current reading current with extremely small amplitude and fixed frequency has a nearly zero disturbance to the magnetic state of the target sample to perceive the resistance change caused by SOT, so that the weak second harmonic component can be extracted and converted into the second-order magnetoresistance curve. The magnetic field value corresponding to the feature point on the second-order magnetoresistance curve is very sensitive to the strength and direction of the direct current bias current, so the SOT effective field can be calculated based on the offset of the feature point. Therefore, by combining the composite current with the harmonic detection, the embodiment solves the SOT effective field measurement problem of the in-plane magnetic anisotropy film caused by the gentle change of the first-order magnetoresistance curve, converts the originally ambiguous magnetic field shift into a clear and quantifiable electrical signal difference, and finally realizes high-precision and reliable measurement of the SOT effective field.

[0057] Exemplarily, as shown in Figure 3 , Figure 3 is a schematic diagram of the composite current applied to the present application, i.e., a schematic diagram of the alternating harmonic method, Figure 3 , wherein the abscissa t represents time, and the ordinate represents the instantaneous value of the size of the current changing with time, represents the alternating current reading current, represents the direct current bias current; it can be seen from Figure 2 that the composite current applied is a group of currents with equal size and opposite direction. It can be understood that the composite current is emitted by a current source and can act on the target sample through the label 300 in Figure 5 .

[0058] In a feasible implementation, based on the offset of the magnetic field value corresponding to the feature point on the second-order magnetoresistance curve under different current conditions, the step of determining the spin-orbit torque effective field of the target sample includes steps S24-S25: Step S24, obtaining the second-order magnetoresistance curves measured at the at least two different direct current bias currents, and the magnetic field values corresponding to the feature points on each second-order magnetoresistance curve; It should be noted that after obtaining the second-order magnetoresistance curves representing the rate of resistance change, the spin-orbit torque effective field is quantitatively extracted. In an embodiment, at least two different direct current bias current values of different sizes or polarities can be set, for example, +2 mA, 0 mA and -2 mA, and a complete transverse magnetic field scan is performed under each constant direct current bias current, so as to record each corresponding second-order magnetoresistance curve respectively. Exemplarily, different direct current bias currents introduce spin-orbit torques of different strengths and directions in the sample, which is equivalent to applying different perturbations to the magnetic state of the target sample.

[0059] Subsequently, the magnetic field values corresponding to the specific feature points need to be identified and read from each second-order magnetoresistance curve. It can be understood that the feature points can refer to the extreme points on the second-order magnetoresistance curve, such as the peak value or the valley value, the feature points correspond to the position where the slope of the first-order magnetoresistance curve is the largest, that is, the critical point of the most intense magnetization reversal, and the feature point magnetic field coordinate is sensitive to the change of the small effective field.

[0060] Step S25, based on the offset of the magnetic field value corresponding to the feature point with the change of the direct current bias current, the spin-orbit torque effective field of the target sample is calculated.

[0061] It should be noted that the spin-orbit torque is equivalent to an effective magnetic field with magnetization intensity, and when positive and negative direct current bias currents are applied, the direction of the spin-orbit torque effective field will be reversed, thereby causing the critical condition of magnetization reversal to change, which is specifically embodied as the offset of the feature point magnetic field value on the second-order magnetoresistance curve.

[0062] Specifically, the method for calculating the spin-orbit torque effective field comprises: for a given direct current bias current , there are two reversal fields on the second-order magnetoresistance curve, that is, the magnetic field values corresponding to the two feature points and The average value ΔH of the two reversal fields ( + ) / 2, that is, the offset of the second-order magnetoresistance curve relative to the 0 magnetic field (i.e. the magnetic field value is 0), is the spin-orbit effective field, as indicated by the arrow of the b(1) subgraph in Figure 4 . For positive and negative direct current bias currents (such as and ), the sign of the offset ΔH (i.e. the spin-orbit effective field) is also opposite, that is, the positive and negative bias currents make the second-order magnetoresistance curve offset to the negative magnetic field and the positive magnetic field respectively.

[0063] In the specific embodiment, based on the differential calculation method of magnetic field offset under symmetric current, the influence of factors such as thermal drift, DC offset voltage caused by Joule heat can be effectively eliminated, so as to realize high-precision and reliable measurement of the SOT effective field.

[0064] In the embodiment, the strength of the SOT effect is modulated by setting DC bias currents of different sizes or polarities, and the magnetic field values corresponding to the characteristic points on each second-order curve are recorded respectively. By calculating the magnetic field offset of the same characteristic point under positive and negative bias currents, and converting the ratio of the offset to the bias current in combination with the parameters of the target sample, the quantitative value of the SOT effective field can be directly calculated. Not only does it overcome the measurement uncertainty caused by the flatness of the first-order magnetoresistance curve, but also it realizes reliable and high-sensitivity measurement of the SOT effective field by improving the signal-to-noise ratio.

[0065] Based on the above embodiments of the application, in another embodiment of the application, the same or similar contents as the above embodiments can be referred to the above introduction, and will not be described in detail. The step S20 of applying a current along the first direction parallel to the target sample to the target sample as a group of positive and negative pulse currents with equal amplitude and opposite direction further includes steps S31-S33: Step S31, during the duration of each pulse in the pulse current, a scanning magnetic field operation is performed along the second direction; It should be noted that the current applied along the first direction parallel to the target sample is a group of positive and negative pulse currents with equal amplitude but alternatingly reversed direction It can be understood that the positive and negative pulse current waveform consists of a positive pulse and a negative pulse in one period, the amplitude of the pulse is exemplarily in the range of 10 nA to 10 mA, and the pulse width is in the range of 50 μs to 10 ms. Exemplarily, the opposite direction pulse is applied to induce opposite direction spin-orbit moment in the target sample. In an embodiment, the positive and negative pulse current can effectively reduce the continuous heating effect of the current Joule heat on the target sample, and avoid the influence of temperature drift on the measurement accuracy.

[0066] In the specific embodiment, the measurement process needs to be synchronized with the pulse sequence, that is, during the duration of each pulse in the pulse current sequence, whether the current direction is positive or negative, a scanning magnetic field operation is performed along the second direction perpendicular to the current. Exemplarily, the scanning magnetic field process is slow and continuous, while the pulse current is repeatedly applied, so as to ensure that the voltage data corresponding to the same magnetic field point under positive and negative current can be collected.

[0067] Step S32, during each scanning magnetic field process, detecting and recording the longitudinal voltage generated by the target sample; 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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 2It can be seen that the applied pulse current is a set of pulse currents with equal amplitude and opposite direction. Understandably, the pulse current is emitted by a current source, which can pass through Figure 6 the label 300 in FIG. 10 acts on the target sample.

[0072] In a feasible implementation, based on the shift of the magnetic field values corresponding to the characteristic points on the second-order magnetoresistance curves under different current conditions, the step of determining the spin-orbit effective field of the target sample includes steps S34-S35: Step S34, determining the magnetic field values corresponding to the characteristic points on each second-order magnetoresistance curve; It should be noted that the magnetic field values corresponding to the characteristic points on each second-order magnetoresistance curve measured under a specific pulse current amplitude are determined, wherein the magnetic field values corresponding to the characteristic points correspond to the region with the maximum slope of the first-order magnetoresistance curve, that is, the critical point of the most drastic magnetization reversal.

[0073] Step S35, based on the shift of the magnetic field values corresponding to the characteristic points with the change of the pulse current amplitude, the spin-orbit effective field of the target sample is calculated.

[0074] It should be noted that the spin-orbit torque is proportional to the applied pulse current. When measurements are made using pulse currents with different amplitudes (for example, +2 mA and -2 mA), the equivalent SOT effective field intensity also changes linearly, resulting in a change in the critical condition of magnetization reversal, which is specifically embodied as the shift of the magnetic field values of the characteristic points on the second-order magnetoresistance curve. According to the shift, the shift amount is obtained, and the spin-orbit effective field of the target sample is calculated.

[0075] In addition, it should be noted that for the pulse current method, the method of calculating the spin-orbit effective field based on the shift of the magnetic field values corresponding to the characteristic points with the change of the pulse current amplitude is similar to the principle of the above-mentioned AC harmonic method, that is, for a given positive and negative pulse current (for example, and ), there are two reversal fields on the second-order magnetoresistance curve, that is, the magnetic field values and corresponding to the two characteristic points. The average value ΔH of the two reversal fields ( + ) / 2, that is, the shift of the second-order magnetoresistance curve relative to the 0 magnetic field (that is, the magnetic field value is 0), is the spin-orbit effective field, as indicated by the arrow of the b(4) subgraph in FIG. 10. Figure 5 ​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.

[0076] 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: 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.

[0077] 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.

[0078] 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 5As can be seen from a (1), a (2), a (3) of FIG. 6, the first-order magnetoresistance curve peak is relatively smooth and wide, and the accurate magnetic field value cannot be directly read, so that the accurate SOT effective field cannot be obtained.

[0079] Figure 5 The curve shown in b (1), b (2), b (3) of FIG. 7 is a second-order magnetoresistance curve obtained according to the second harmonic component value under a specific direct current bias current. For example, taking 2 mA as an example, that is, Figure 5 b (1) of FIG. 7, two curves are shown, curve 3 represents that the target sample is applied with a magnetic field from -50 Oe to +50 Oe under a direct current bias current of 2 mA, and then a second-order magnetoresistance curve is obtained according to the second harmonic component value corresponding to each magnetic field value; curve 4 represents that the target sample is applied with a magnetic field from +50 Oe to -50 Oe under a direct current bias current of 2 mA, and then a second-order magnetoresistance curve is obtained according to the second harmonic component value corresponding to each magnetic field value.

[0080] In Figure 6 b (1), b (2), b (3) of FIG. 7, each second-order magnetoresistance curve represents a second-order magnetoresistance signal under a specific direct current bias current, and the characteristic points on the curve correspond to the critical points of magnetization reversal. For each direct current bias current, the second-order magnetoresistance curve contains two characteristic points, which correspond to the reversal of different magnetization directions, respectively.

[0081] For example, in Figure 6 b (1) of FIG. 7, the dashed line with a magnetic field value of -2.5 (Oe), that is, a magnetic field of -2.5, is offset to the left relative to the dashed line with a magnetic field value of 0 (Oe), that is, a magnetic field of 0, and is represented by a left arrow; in Figure 6 b (3) of FIG. 7, the dashed line with a magnetic field value of 2.5 (Oe), that is, a magnetic field of +2.5, is offset to the right relative to the dashed line with a magnetic field value of 0 (Oe), that is, a magnetic field of 0, and is represented by a right arrow. Exemplarily, a horizontal line is drawn through the center of the intersection point of the dashed line with a magnetic field of -2.5 and curves 3 and 4, that is, Figure 6 the horizontal dashed line b (1) of FIG. 7, and the two intersection points of the horizontal line and curves 3 and 4, that is, the characteristic point 1 and the characteristic point 2. Then the magnetic field values corresponding to the characteristic point 1 and the characteristic point 2 are read, respectively, and finally the SOT effective field is obtained according to ΔH=( + ) / 2.

[0082] Please refer to Figure 6 , Figure 6 provides a magnetic resistance curve schematic diagram of a spin orbit torque effective field pulse method under different current sizes, and specifically: 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).

[0083] 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.

[0084] Figure 7 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 8 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.

[0085] exist Figure 8 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.

[0086] For example, in Figure 8In 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 ​ 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. ​ 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.

[0087] 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.

[0088] This application also provides a measuring device for the effective field of spin orbital moment, please refer to... ​ The measuring device for the effective field of the spin orbital moment includes: 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; 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; 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.

[0089] Optionally, the power module 10 is also used to perform: fabrication of a metal thin film having in-plane magnetic anisotropy; 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; The Hall bar structure is subjected to a wire bonding process to obtain a target sample for testing an in-plane magnetic anisotropy film.

[0090] Optionally, the detection module 20 is further configured to perform: under the action of the direct current bias current, performing the operation of scanning the magnetic field along the second direction; In each magnetic field scanning process, detecting a first harmonic component and a second harmonic component of a longitudinal voltage signal generated by the target sample; 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.

[0091] Optionally, the display module 30 is further configured to perform: obtaining a second-order magnetoresistance curve measured under the direct current bias current at at least two different current values, and a magnetic field value corresponding to a feature point on each second-order magnetoresistance curve; Based on the offset of the magnetic field value corresponding to the feature point with respect to the direct current bias current, the spin-orbit effective field of the target sample is calculated.

[0092] Optionally, the detection module 20 is further configured to perform: during each pulse duration in the pulse current, performing the operation of scanning the magnetic field along the second direction; In each magnetic field scanning process, detecting and recording a longitudinal voltage generated by the target sample; Calculating a difference value of the longitudinal voltages corresponding to the positive pulse and the negative pulse at the same magnetic field point, and generating the second-order magnetoresistance curve according to the difference value.

[0093] Optionally, the display module 30 is further configured to perform: determining a magnetic field value corresponding to a feature point on each second-order magnetoresistance curve; Based on the offset of the magnetic field value corresponding to the feature point with respect to the pulse current amplitude, the spin-orbit effective field of the target sample is calculated.

[0094] The spin-orbit effective field measurement device provided in the present application adopts the spin-orbit effective field measurement method in the above embodiments, which can solve the technical problem of low precision in measuring the spin-orbit effective field of the in-plane magnetic anisotropy film by the existing method. Compared with the prior art, the spin-orbit effective field measurement device provided in the present application has the same beneficial effects as the spin-orbit effective field measurement method provided in the above embodiments, and other technical features in the spin-orbit effective field measurement device are the same as the features disclosed in the above embodiments, which will not be repeated here.

[0095] The present application provides a spin-orbit torque effective field measurement device, the spin-orbit torque effective field measurement device comprising: at least one lock-in amplifier, a current source for applying a current to a sample, an electromagnet and a gauss meter for applying a magnetic field to the sample, and a processor capable of performing the steps of the spin-orbit torque effective field measurement method.

[0096] Reference is made below ​ , which shows a structural diagram of a spin-orbit torque effective field measurement device suitable for implementing embodiments of the present application. The spin-orbit torque effective field measurement device in embodiments of the present application can include, but is not limited to, mobile terminals such as notebook computers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), and the like, as well as fixed terminals such as digital TVs, desktop computers, and the like, and buses, lock-in amplifiers, current sources, excitation power supplies, electromagnets, gauss meters, and the like. ​ The spin-orbit torque effective field measurement device shown is merely an example and should not impose any limitation on the functions and use range of embodiments of the present application.

[0097] As shown in ​ , the spin-orbit torque effective field measurement device can include input devices (such as a mouse, a keyboard, etc.), which can adjust test conditions in time according to different test requirements and transmit them to the program of the computer (central processor), and then process different operation instructions. In the central processor, various programs and data required for the operation of the spin-orbit torque effective field measurement device are also stored. Generally, the following devices can be connected to the central processor through a bus: devices including lock-in amplifiers, current sources, excitation power supplies, electromagnets, gauss meters, etc.; the central processor is used to collect and process data, and communicates wirelessly or by wire with output devices to realize the output of data. Although the spin-orbit torque effective field measurement device with various systems is shown in the figure, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be alternatively implemented or provided.

[0098] In particular, according to embodiments disclosed in the present application, the processes described above with reference to the flowcharts can be implemented as a computer software program. For example, embodiments disclosed in the present application include a computer program product comprising a computer program carried on a computer readable medium, the computer program containing program codes for executing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network through a communication device to perform the above-mentioned functions defined in the methods of the embodiments disclosed in the present application.

[0099] The spin-orbit torque effective field measuring device provided by the application adopts the spin-orbit torque effective field measuring method in the above embodiment, and can solve the technical problem of low precision in measuring the spin-orbit torque effective field of an in-plane magnetic anisotropy film by the existing method. Compared with the prior art, the spin-orbit torque effective field measuring device provided by the application has the same beneficial effects as the spin-orbit torque effective field measuring method provided by the above embodiment, and other technical features in the spin-orbit torque effective field measuring device are the same as the features disclosed in the above embodiment, which will not be repeated here.

[0100] It should be understood that parts of the present application can be realized by 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 one or more embodiments or examples in a suitable manner.

[0101] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0102] The present application provides a computer readable storage medium having computer readable program instructions (i.e. computer programs) stored thereon, the computer readable program instructions being used to execute the spin-orbit torque effective field measuring method in the above embodiment.

[0103] The computer readable storage medium provided by the present application may, for example, be a U disk, but is not limited to an electric, magnetic, optical, electromagnetic, infrared, or semiconductor system or device, or any combination of the above. More specific examples of the computer readable storage medium can include, but are not limited to, an electric connection with one or more conductive wires, a portable computer disk, a hard disk, a random access memory (RAM), a read only memory (ROM), an erasable programmable read only memory (EPROM or flash memory), an optical fiber, a portable compact disk read only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present embodiment, the computer readable storage medium can 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 can be transmitted in any suitable medium, including but not limited to an electric wire, an optical cable, an RF (Radio Frequency), and the like, or any suitable combination of the above.

[0104] The above computer readable storage medium can be contained in the spin-orbit torque effective field measuring device, or can exist separately without being assembled into the spin-orbit torque effective field measuring device.

[0105] Computer program code for carrying out operations of the present application can be written in one or more programming languages or combinations of languages including object oriented programming languages such as Java, Smalltalk, C++ or conventional procedural programming languages such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0106] The flow and block diagrams in the drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flow and block diagrams can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations thereof, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or combinations of hardware and software.

[0107] The modules described in the embodiments of the present application can be implemented in the form of software, or can be implemented in the form of hardware. In some cases, the name of the module does not constitute a limitation on the unit itself.

[0108] The readable storage medium provided by the present application is a computer readable storage medium, which stores computer readable program instructions (i.e. computer programs) for executing the above-mentioned spin-orbit torque effective field measurement method, and can solve the technical problem of low precision in measuring the spin-orbit torque effective field of an in-plane magnetic anisotropy film by the existing method. Compared with the prior art, the computer readable storage medium provided by the present application has the same beneficial effects as the spin-orbit torque effective field measurement method provided by the above-mentioned embodiments, and will not be described here.

[0109] The present application also provides a computer program product comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned spin-orbit torque effective field measurement method.

[0110] The computer program product provided by the present application can solve the technical problem of low precision in measuring the spin-orbit torque effective field of an in-plane magnetic anisotropy film by the existing method. Compared with the prior art, the computer program product provided by the present application has the same beneficial effects as the spin-orbit torque effective field measurement method provided by the above-mentioned embodiments, and will not be described here.

[0111] The above only describes some embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made by using the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present 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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