Magnetic thin film core structure, magnetic sensing unit and magnetic field measurement method

Abstract

This invention provides a magnetic thin film core structure, a magnetic sensing unit, and a magnetic field measurement method. The magnetic thin film core structure includes a buffer layer, a first magnetic layer, an insulating barrier layer, a second magnetic layer, a spin-orbit coupling layer, a bias layer, and a capping layer, grown layer by layer on a substrate. The first magnetic layer has a spontaneous magnetization vector parallel to the substrate plane; the second magnetic layer has a spontaneous magnetization vector perpendicular to the substrate plane; the coercivity of the second magnetic layer when its magnetization is perpendicular to the film surface is greater than the saturation field of the first magnetic layer; the insulating barrier layer, the second magnetic layer, and the spin-orbit coupling layer constitute a spin-orbit torque structure. Advantages of this invention: simple fabrication, improved device integration, reduced cost and power consumption, and improved device stability and lifespan.

Description

[Technical Field]

[0001] This invention relates to the field of magnetic sensor technology, and in particular to a magnetic thin film core structure, a magnetic sensing unit, and a magnetic field measurement method. [Background Technology]

[0002] The core magnetic sensing unit of existing two-dimensional magnetic sensors can be designed based on Hall effect devices, anisotropic magnetoresistive devices, giant magnetoresistive devices, or tunneling magnetoresistive devices.

[0003] To measure the two orthogonal components of a magnetic field in space using Hall effect devices, anisotropic magnetoresistive devices, or giant magnetoresistive devices, at least two orthogonally arranged core magnetoresistive units are typically required. However, using multiple magnetoresistive units reduces integration density, increases the difficulty of device packaging, and also increases cost.

[0004] If the measurement of two orthogonal components of a magnetic field in space is achieved based on a tunneling magnetoresistive (TMR) device, a single-barrier magnetic tunnel junction can be used as the core magnetosensitive sensing unit, employing two orthogonally arranged independent magnetosensitive sensing units. However, this increases the device size, reduces integration density, and is relatively expensive. Based on the TMR device, if a double-barrier magnetic tunnel junction is used in conjunction with voltage-controlled magnetic anisotropy, multiple orthogonal components of the magnetic field can be measured within a single core magnetosensitive sensing unit. However, the double-barrier magnetic tunnel junction suffers from stringent material preparation requirements, complex micro / nano fabrication processes, and high cost. Furthermore, to achieve voltage-controlled magnetic anisotropy, a large bias voltage needs to be applied to a barrier layer of the magnetic tunnel junction, which can easily break down the magnetic tunnel junction barrier, requiring high-precision bias voltage control. Therefore, existing magnetosensitive sensing units suffer from low integration density, high cost, and difficult fabrication. In view of these problems, the inventors of this case conducted in-depth research on this issue, resulting in this invention. [Summary of the Invention]

[0005] The technical problem to be solved by the present invention is to provide a magnetic thin film core structure, a magnetic sensing unit, and a magnetic field measurement method, thereby solving the problems of low integration, high cost, and high processing difficulty of existing magnetic sensing units.

[0006] This invention is implemented as follows:

[0007] In a first aspect, a magnetic thin film core structure includes a buffer layer, a first magnetic layer, an insulating barrier layer, a second magnetic layer, a spin-orbit coupling layer, a bias layer, and a capping layer grown layer by layer on a substrate.

[0008] The first magnetic layer has a magnetization vector that is spontaneously parallel to the substrate plane; the second magnetic layer has a magnetization vector that is spontaneously perpendicular to the substrate plane; the coercive force of the second magnetic layer when the magnetization intensity is perpendicular to the film plane is greater than the saturation field of the hard axis of the first magnetic layer; the insulating barrier layer, the second magnetic layer, and the spin-orbit coupling layer form a spin-orbit torque structure;

[0009] When there is no external magnetic field, the bias layer and the second magnetic layer have the same direction of spontaneous magnetization. At the same time, the coercive force of the bias layer in the direction of the spontaneous magnetization is greater than that of the second magnetic layer, and the saturation field of the hard axis of the bias layer is much greater than the saturation field of the hard axis of the second magnetic layer.

[0010] Furthermore, the buffer layer is a single-layer thin film composed of any one of Ta, Ru, Cu, Cr, Au, Ag, and Pt, or a multi-layer thin film composed of at least two of them; the thickness of the buffer layer is 5 nm - 50 nm;

[0011] The first magnetic layer is Co, Fe, Ni, or an alloy material containing any one of Co, Fe, Ni; the thickness of the first magnetic layer is 0.5 nm - 20 nm;

[0012] The insulating barrier layer uses an inorganic insulating material, and the inorganic insulating material is MgO, Mg 10 , 10 , n , n , 10 Zn j O, Mg j Al 2 / 3(1-j) O, AlO i , BaTiO3, Ta2O5, ZrO2, HfO2, TiO2, where 0 < i < 3 / 2, 0 < j < 1; the thickness of the insulating barrier layer is 0.5 nm - 5 nm;

[0013] The second magnetic layer is any one of CoFeB, GdFeCo, MnAl, MnGa; the thickness of the second magnetic layer is 0.2 nm - 20 nm;

[0014] The spin-orbit coupling layer uses a heavy metal with a strong magnetic spin-orbit coupling effect, and the heavy metal is any one of Pt, Pd, W, β-Ta; the thickness of the spin-orbit coupling layer is 0.5 nm - 20 nm;

[0015] The bias layer is L with spontaneous perpendicular magnetization 10 -FePt, L 10 -CoPt, L 10 -FePd, [Co / Pt] n , [Co / Pd] n , GdFeCo, MnAl, MnGa; the thickness of the bias layer is 0.2 nm - 20 nm;

[0016] The capping layer is a single-layer thin film composed of any one of Ta, Ru, Cu, Cr, Au, Ag and Pt, or a multilayer thin film composed of at least two of them; the thickness of the capping layer is 1nm-100nm.

[0017] In a second aspect, a magnetic sensing unit includes a substrate and the aforementioned magnetic thin film core structure, wherein the magnetic thin film core structure is fabricated on the substrate using a single-barrier magnetic tunnel junction micro-nano fabrication technology.

[0018] In the magnetic sensing unit, the buffer layer and the first magnetic layer of the magnetic thin film core structure constitute the bottom elongated electrode, and the second magnetic layer, spin-orbit coupling layer, bias layer and cover layer of the magnetic thin film core structure constitute the top elongated electrode orthogonal to the bottom elongated electrode.

[0019] The top elongated electrode has at least a first terminal and a second terminal; the bottom elongated electrode has at least a third terminal.

[0020] Furthermore, during the growth of the first magnetic layer of the magnetic thin film core structure, an in-plane induced magnetic field with a constant direction is applied, and this constant direction is denoted as the x-axis direction.

[0021] Furthermore, in the magnetic sensing unit, the insulating barrier layer is grown using any one of the following methods: radio frequency magnetron sputtering, ion beam sputtering, electron beam evaporation, and chemical vapor deposition.

[0022] The buffer layer, first magnetic layer, second magnetic layer, spin-orbit coupling layer, bias layer, and capping layer are grown using any one of the following methods: DC magnetron sputtering, radio frequency magnetron sputtering, ion beam sputtering, electron beam evaporation, and thermal evaporation.

[0023] Furthermore, the magnetic sensing unit has an elliptical junction region; the major axis a of the ellipse of the elliptical junction region is parallel to the x-axis direction, and the minor axis b of the ellipse is perpendicular to the x-axis direction.

[0024] Furthermore, in the elliptical junction region, a / b > 3.

[0025] Furthermore, the substrate is an inorganic substrate or an organic substrate. The inorganic substrate is any one of glass substrate, Si substrate, Si / SiO2 substrate, and SiC substrate. The organic substrate is any one of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyimide, and polycarbonate.

[0026] Thirdly, a method for measuring the magnetic field of a magnetically sensitive sensing unit, the method comprising:

[0027] Step S1: Construct a rectangular coordinate system with the layer-by-layer growth direction of the magnetic thin film core structure as the positive z-axis and the selected positive x-axis direction parallel to the film surface;

[0028] Step S2: Measure the magnetic field component along the z-axis, specifically including:

[0029] Step S21: Before measuring the magnetic field component in the z-axis direction, apply a constant probe current I between the first and third terminals or between the second and third terminals. z And read the corresponding voltage V z The magnetoresistance R is calibrated by applying a series of magnetic fields along the z-axis. z (H z ) = V z (H z ) / I z The relationship between the magnetic field along the z-axis and the change in the magnetic field is used to obtain the first calibration data;

[0030] Step S22: When measuring the magnetic field component in the z-axis direction, a constant probe current I is applied between the first terminal and the third terminal. z Read the corresponding voltage V z Thus, the magnetoresistance R is obtained. z The obtained magnetoresistance R z By comparing the data with the first calibration data, the magnitude of the component of the magnetic field to be measured in the z-axis direction can be obtained.

[0031] Furthermore, the method also includes:

[0032] Step S3: Measure the two-dimensional yoz magnetic field, specifically including:

[0033] Step S31: Apply a modulation current I between the first terminal and the second terminal. t This induces a spin-orbit torque effect in the spin-orbit torque structure on the core structure of the magnetic thin film, generating a magnetic torque along the y-axis on the second magnetic layer. However, the stray magnetic field from the bias layer of the core structure and the anisotropy of the top elongated electrode cause the energy required for the magnetization vector of the second magnetic layer to flip to the positive z-axis direction under the spin-orbit torque effect to be higher than the energy required for the magnetization vector to stabilize in the y-axis direction. Therefore, it is necessary to determine a suitable modulation current I. t To stabilize the magnetization vector of the second magnetic layer in the negative y-axis direction;

[0034] Step S32: Determine the modulation current I that stabilizes the magnetization vector of the second magnetic layer in the negative y-axis direction. t Specifically, it includes:

[0035] Step S321: Given the magnetic field component H in the z-axis directionz First, a constant detection current I is applied between the first terminal and the third terminal. y0 Read the corresponding voltage V y0 Then gradually increase the detection current I t,Hz until the magnetoresistance R is reduced y0 (H z ) = V y0 (H z ) / I y0 This is an extreme value, at which point the magnetization vector of the second magnetic layer stabilizes in the negative y-axis direction. The given magnetic field component H is recorded. z and the detection current I at this time t,Hz The detection current I t,Hz That is, the modulation current I under a given magnetic field. t ;

[0036] Step S322: Change the magnetic field component H in the given z-axis direction. z Repeat step S321 to determine a series of magnetic field components H in the z-axis direction. zi The modulation current I that stabilizes the magnetization vector of the second magnetic layer in the negative y-axis direction. t,Hzi This means obtaining the second calibration data;

[0037] Step S33: In the above series of magnetic field components H zi Below, establish the magnetic field component H in the y-axis direction. yj,zi With magnetoresistance R yj,zi The relationship, where i and j are both natural numbers, specifically includes:

[0038] Step S331, under the given magnetic field component H zi Next, a modulation current I is applied from the first terminal to the second terminal. t,Hzi At the same time, a constant detection current I is applied between the first terminal and the third terminal. y Read the corresponding voltage V yj,zi By applying a series of magnetic fields H along the y-axis yj,zi Thus, the magnetoresistance R is calibrated. yj,zi (H yj,zi ) = V yj,zi (H yj,zi ) / I y With the y-axis magnetic field H yj,zi The changing relationship;

[0039] Step S332: Change the given magnetic field component H zi Repeat step S331 to determine a series of different magnetic field components H zi The y-axis magnetic field H below yj,zi With magnetoresistance Ryj,zi The relationship between the changes is obtained, thus acquiring the third calibration data; this completes the calibration of the two-dimensional yoz magnetic field.

[0040] Step 34: During measurement, first measure the magnitude H of the component of the two-dimensional yoz magnetic field in the z-axis direction as described in step S2. z Then, set the modulation current I based on the second calibration data. t,Hz A constant probe current I is applied between the first terminal and the third terminal. y Read the corresponding voltage V y,Hz Thus, the magnetoresistance R is obtained. y,Hz The obtained magnetoresistance R y,Hz By comparing the data with the third calibration data, the magnitude of the component of the two-dimensional yoz magnetic field to be measured in the y-axis direction can be obtained.

[0041] By adopting the technical solution of the present invention, at least the following beneficial effects are achieved:

[0042] 1. A magnetic thin film core structure can be fabricated on a substrate using single-barrier magnetic tunnel junction micro / nano fabrication technology to obtain a magnetic sensing unit. The magnetic thin film core structure itself has a spin-orbit torque effect (SOT). By combining the single-barrier magnetic tunnel junction and the SOT, it is possible to measure the two orthogonal components of a two-dimensional magnetic field using a single single-barrier magnetic tunnel junction without relying on voltage-controlled magnetic anisotropy. This avoids the use of two orthogonally arranged magnetic tunnel junction devices and also avoids the use of double-barrier magnetic tunnel junction devices based on voltage-controlled magnetic anisotropy. Therefore, it can effectively improve the device integration and reduce the manufacturing cost. At the same time, an integrated two-dimensional magnetic sensing unit can be obtained with only one micro / nano patterning process, which simplifies the fabrication process.

[0043] 2. Because it does not rely on voltage to regulate magnetic anisotropy, it avoids applying a large bias voltage to the insulation barrier. Therefore, the magnetic tunnel junction is not easily broken down, has better stability, and can thus ensure the stability of the device in use.

[0044] 3. Electronic devices based on spin-orbit torque do not require current to flow through the device, resulting in low power consumption and long device life. [Attached Image Description]

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] Figure 1 This is a schematic diagram of the layer structure of the magnetic thin film core structure of the present invention;

[0047] Figure 2 This is a schematic diagram of the magnetic moment orientation of each magnetic layer and electrode connection when using the magnetic thin film core structure to measure the z-axis magnetic field in this invention;

[0048] Figure 3 This is a schematic diagram of the magnetic moment orientation and electrode connection of each magnetic layer when determining the modulation current that stabilizes the magnetization vector of the second magnetic layer in the negative y-axis direction according to the present invention.

[0049] Figure 4 This is a schematic diagram of the spin-orbit torque effect generated by the spin-orbit torque structure when the magnetic thin film core structure is used to measure the two-dimensional yoz magnetic field.

Detailed Implementation Methods

[0050] This invention provides a magnetic thin film core structure, a magnetic sensing unit, and a magnetic field measurement method, which solves the technical problems of low integration, high cost, and difficult processing of existing magnetic sensing units. It achieves the technical effects of simple processing, improved device integration, reduced cost, and improved device stability.

[0051] The technical solution in this invention is to solve the above problems. The overall idea is as follows: The core structure of the magnetic thin film is designed to include a buffer layer, a first magnetic layer, an insulating barrier layer, a second magnetic layer, a spin-orbit coupling layer, a bias layer, and a capping layer grown layer by layer on the substrate. Combined with a single-barrier magnetic tunnel junction and the spin-orbit torque effect (SOT), it is possible to measure the two orthogonal components of a two-dimensional magnetic field using a single single-barrier magnetic tunnel junction without relying on voltage to control the magnetic anisotropy.

[0052] To better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Example 1

[0054] Please see Figure 1 As shown, the present invention discloses a magnetic thin film core structure, which includes a buffer layer BL, a first magnetic layer M1, an insulating barrier layer I, a second magnetic layer M2, a spin-orbit coupling layer SOCL, a bias layer PL, and a capping layer CL, which are grown layer by layer on a substrate (not shown).

[0055] The first magnetic layer M1 has a magnetization vector that is spontaneously parallel to the substrate plane; the second magnetic layer M2 has a magnetization vector that is spontaneously perpendicular to the substrate plane (i.e., perpendicular magnetic anisotropy).

[0056] The coercivity H of the second magnetic layer M2 when its magnetization is perpendicular to the film surface (i.e., perpendicular to the substrate plane) c2⊥ The saturation field H on the hard axis is greater than that of the first magnetic layer M1. s1⊥(The magnetization intensity of the second magnetic layer M2 is rotated from in-plane to the direction perpendicular to the film surface; the insulating barrier layer I, the second magnetic layer M2 and the spin-orbit coupling layer SOCL constitute a spin-orbit torque structure, so that the spin-orbit torque effect SOT is generated through the spin-orbit torque structure.

[0057] In the absence of an external magnetic field, the bias layer PL and the second magnetic layer M2 have the same spontaneous magnetization direction, i.e., a direction perpendicular to the substrate plane; simultaneously, the coercivity of the bias layer PL in this spontaneous magnetization direction... Greater than the coercivity of the second magnetic layer M2 in the direction of spontaneous magnetization. Furthermore, the hard-axis saturation field of the bias layer PL is much larger than the hard-axis saturation field of the second magnetic layer M2.

[0058] Since the bias layer PL and the second magnetic layer M2 are located on the upper and lower sides of the spin-orbit coupling layer SOCL respectively in the core structure of the magnetic thin film of the present invention, under the action of the spin-orbit coupling layer SOCL, the bias layer PL and the second magnetic layer M2 have no static magnetic coupling except for the stray magnetic field interaction between them.

[0059] By employing the magnetic thin film core structure described above in this invention, at least the following beneficial effects are achieved:

[0060] 1. A magnetic thin film core structure can be fabricated on a substrate using single-barrier magnetic tunnel junction micro / nano fabrication technology to obtain a magnetic sensing unit. The magnetic thin film core structure itself has a spin-orbit torque effect. By combining the single-barrier magnetic tunnel junction and the spin-orbit torque effect, it is possible to measure the two orthogonal components of a two-dimensional magnetic field using a single single-barrier magnetic tunnel junction without relying on voltage-controlled magnetic anisotropy. This avoids the use of two orthogonally arranged magnetic tunnel junction devices and also avoids the use of double-barrier magnetic tunnel junction devices based on voltage-controlled magnetic anisotropy. Therefore, it can effectively improve the device integration and reduce the manufacturing cost. At the same time, an integrated two-dimensional magnetic sensing unit can be obtained with only one micro / nano patterning process, which simplifies the fabrication process.

[0061] 2. Because it does not rely on voltage to regulate magnetic anisotropy, it avoids applying a large bias voltage to the insulation barrier. Therefore, the magnetic tunnel junction is not easily broken down, has better stability, and can thus ensure the stability of the device in use.

[0062] 3. Electronic devices based on spin-orbit torque do not require current to flow through the device, resulting in low power consumption and long device life.

[0063] In embodiments of the present invention, the buffer layer BL needs to be a conductive metal material with high resistance and close contact with the substrate. Preferably, the buffer layer BL is a single-layer thin film composed of any one of Ta, Ru, Cu, Cr, Au, Ag, and Pt, or a multilayer thin film composed of at least two of them; for example, in specific implementations, the buffer layer BL can be a single-layer thin film grown from Cu, or a single-layer thin film grown from Au, etc.; as another example, the buffer layer BL can be a double-layer thin film composed of Ru and Cu grown layer by layer, or a double-layer thin film composed of Ag and Pt grown layer by layer, etc.; as yet another example, the buffer layer BL can be a triple-layer thin film composed of Ru, Cu, and Cr grown layer by layer, or a triple-layer thin film composed of Ta, Au, and Ag grown layer by layer, etc.; of course, more layers of thin films can be grown from the above materials according to actual needs.

[0064] Preferably, the thickness of the buffer layer BL is 5nm-50nm; for example, in a specific implementation, the thickness of the buffer layer BL when it is Ta can be selected from any one of 10nm, 30nm, and 50nm. Of course, other materials and thicknesses can also be selected according to actual needs.

[0065] In embodiments of the present invention, the first magnetic layer M1 needs to have in-plane magnetic anisotropy (i.e., its easy magnetization axis is parallel to the substrate plane) and be able to conduct electricity. Preferably, the first magnetic layer M1 is Co, Fe, Ni, or an alloy material containing any one of Co, Fe, and Ni; for example, in specific implementations, the first magnetic layer M1 can be grown using CoFeB or FeNi; or, for example, the first magnetic layer M1 can be grown using any one of the alloy materials CoFe, CoFeBSi, NiFeCr, NiFeCrSi, CoFeAl, CoMnAl, CoMnGe, and CoMnGa.

[0066] Preferably, the thickness of the first magnetic layer M1 is 0.5nm-20nm; for example, in a specific implementation, when the first magnetic layer M1 is CoFeB, the thickness is preferably one of 2.5nm, 5nm, and 20nm. Of course, other materials and thicknesses can be selected according to actual needs.

[0067] In an embodiment of the present invention, the insulating barrier layer I is used to insulate and isolate the first magnetic layer M1 and the second magnetic layer M2 to obtain two electrodes. Preferably, the insulating barrier layer I is made of an inorganic insulating material, and the inorganic insulating material is MgO or Mg 1-j Zn j O, Mg j Al 2 / 3(1-j) O, AlO i, any one of BaTiO3, Ta2O5, ZrO2, HfO2, TiO2, where 0 < i < 3 / 2 and 0 < j < 1; for example, in specific implementation, the insulating barrier layer I can be grown using MgO or Ta2O5, etc.

[0068] Preferably, the thickness of the insulating barrier layer I is 0.5 nm - 5 nm; for example, in specific implementation, when the insulating barrier layer I is MgO, the thickness is preferably any one of 1 nm, 1.5 nm, 2 nm, 2.5 nm. Of course, other materials and thicknesses can also be selected according to actual needs.

[0069] In an embodiment of the present invention, the second magnetic layer M2 has perpendicular magnetic anisotropy (i.e., its easy magnetization axis is perpendicular to the substrate) and is conductive. Preferably, the second magnetic layer M2 is any one of Fe, Co, CoFeB, GdFeCo, MnAl, MnGa; for example, in specific implementation, the second magnetic layer M2 can be grown using CoFeB or Co, etc.

[0070] Preferably, according to its magnetic anisotropy requirements, the thickness of the second magnetic layer M2 is 0.2 nm - 20 nm; for example, in specific implementation, when the second magnetic layer M2 is CoFeB, the thickness is preferably any one of 0.8 nm, 1 nm, 1.2 nm. Of course, other materials and thicknesses can also be selected according to actual needs.

[0071] In an embodiment of the present invention, the spin - orbit coupling layer SOCL is used not only to form a spin - orbit torque structure with the insulating barrier layer I and the second magnetic layer M2, but also to weaken the direct magnetostatic coupling (including RKKY exchange coupling, magnetostatic rigidity coupling, and magnetostatic spring exchange coupling) between the second magnetic layer M2 and the bias layer PL. Preferably, the spin - orbit coupling layer SOCL is made of a heavy metal with a strong magnetic spin - orbit coupling effect, and the heavy metal is any one of Pt, Pd, W, β - Ta; for example, in specific implementation, the spin - orbit coupling layer SOCL can be grown using Pd or β - Ta.

[0072] Preferably, the thickness of the spin - orbit coupling layer SOCL is 0.5 nm - 20 nm; for example, in specific implementation, when the spin - orbit coupling layer SOCL is Pt, the thickness is preferably any one of 1 nm, 1.8 nm, 3 nm, 5 nm. Of course, other materials and thicknesses can also be selected according to actual needs.

[0073] In embodiments of the present invention, the bias layer PL can utilize its own stray magnetic field and high coercivity in the easy-axis direction to bias the magnetization direction of the second magnetic layer M2. Preferably, the bias layer PL is a spontaneously perpendicularly magnetized L... 10 -FePt, L 10 -CoPt, L 10 -FePd, [Co / Pt] n [Co / Pd] n Any one of GdFeCo, MnAl, and MnGa; for example, in a specific implementation, the bias layer PL can be L 10 It can be obtained by growing -CoPt, or by growing GdFeCo, etc.;

[0074] Preferably, depending on the magnetic anisotropy requirements, the thickness of the bias layer PL is 0.2 nm to 20 nm; for example, in a specific implementation, the thickness of the bias layer PL is L. 10 The thickness of FePt is preferably any one of 1nm, 3nm, 5nm, and 10nm. Of course, other materials and thicknesses can be selected according to actual needs.

[0075] In embodiments of the present invention, the capping layer CL is used to protect the structure from oxidation and corrosion, and therefore requires a metal that is not easily oxidized or corroded and has poor electrical conductivity. Preferably, the capping layer CL is a single-layer film composed of any one of Ta, Ru, Cu, Cr, Au, Ag, and Pt, or a multilayer film composed of at least two of them; for example, in specific implementations, the capping layer CL can be a single-layer film grown from Au, or a single-layer film grown from Ta, etc.; or, for example, the capping layer CL can be a double-layer film composed of Ru and Pt grown layer by layer, or a double-layer film composed of Ta and Cr grown layer by layer, etc.; or, for example, the capping layer CL can be a triple-layer film composed of Ru, Cu, and Ag grown layer by layer, or a triple-layer film composed of Ta, Cr, and Ag grown layer by layer, etc.; of course, more layers of films can be grown from the above materials according to actual needs.

[0076] Preferably, the thickness of the cover layer CL is 1nm-100nm; for example, in a specific implementation, when the cover layer CL is Ru, the thickness is preferably any one of 1nm, 3nm, 5nm, and 10nm. Of course, other materials and thicknesses can be selected according to actual needs.

[0077] Example 2

[0078] Please refer to Figures 1 to 3As shown, this invention discloses a magnetic sensing unit, which includes a substrate and a magnetic thin film core structure. The specific structure of the magnetic thin film core structure is detailed in Embodiment 1 and will not be repeated here. The magnetic thin film core structure is fabricated on the substrate using a single-barrier magnetic tunnel junction micro / nano fabrication technology. That is, a single magnetic sensing unit can be obtained by fabricating a magnetic thin film core structure on the substrate using this technology. The single-barrier magnetic tunnel junction micro / nano fabrication technology is a mature and conventional technology in the prior art and will not be described in detail here.

[0079] In the magnetic sensing unit, the buffer layer BL and the first magnetic layer M1 of the magnetic thin film core structure constitute the bottom elongated electrode BE, and the second magnetic layer M2, the spin-orbit coupling layer SOCL, the bias layer PL and the cover layer CL of the magnetic thin film core structure constitute the top elongated electrode TE orthogonal to the bottom elongated electrode BE.

[0080] The top elongated electrode TE has at least a first terminal P1 and a second terminal P2, and the bottom elongated electrode BE has at least a third terminal P3, so that an external probe current can be applied when performing magnetic field measurements.

[0081] The magnetic sensing unit of this invention combines a single-barrier magnetic tunnel junction and a spin-orbit torque effect (SOT), enabling the measurement of two orthogonal components of a two-dimensional magnetic field using a single single-barrier magnetic tunnel junction without relying on voltage-controlled magnetic anisotropy. Therefore, it effectively improves device integration, reduces manufacturing costs, and only requires a single micro-nano patterning process to obtain the integrated two-dimensional magnetic sensing unit, simplifying the fabrication process. Furthermore, because it does not rely on voltage-controlled magnetic anisotropy, it avoids applying a large bias voltage to the insulating barrier, making the magnetic tunnel junction less prone to breakdown and exhibiting good stability.

[0082] To facilitate the selection of the direction during magnetic field measurement, in one embodiment of the present invention, the first magnetic layer M1 of the magnetic thin film core structure is subjected to an in-plane induced magnetic field with a constant direction during its growth, and this constant direction is denoted as the x-axis direction. In another embodiment of the present invention, after the first magnetic layer M1 has been grown without an induced magnetic field, an in-plane induced magnetic field in the x-axis direction can be applied for annealing.

[0083] In embodiments of the present invention, in the magnetic sensing unit, the insulating barrier layer I is grown using any one of the following methods: radio frequency magnetron sputtering, ion beam sputtering, electron beam evaporation, and chemical vapor deposition. For example, in specific implementations, radio frequency magnetron sputtering technology can be used to grow the insulating barrier layer I, or electron beam evaporation technology can be used to grow the insulating barrier layer I, etc.

[0084] The buffer layer BL, the first magnetic layer M1, the second magnetic layer M2, the spin-orbit coupling layer SOCL, the bias layer PL, and the capping layer CL are grown using any one of the following methods: DC magnetron sputtering, radio frequency magnetron sputtering, ion beam sputtering, electron beam evaporation, and thermal evaporation. For example, in a specific implementation, DC magnetron sputtering technology can be used to grow the buffer layer BL, radio frequency magnetron sputtering technology can be used to grow the second magnetic layer M2, and radio frequency magnetron sputtering technology can be used to grow the spin-orbit coupling layer SOCL, etc.

[0085] In an embodiment of the present invention, the magnetic sensing unit has an elliptical junction region, wherein the insulating barrier layer I and the first magnetic layer M1 can form an elliptical junction region, and the second magnetic layer M2 and the insulating barrier layer I can also form an elliptical junction region; the major axis a of the ellipse of the elliptical junction region is parallel to the x-axis direction, and the minor axis b of the ellipse is perpendicular to the x-axis direction.

[0086] Preferably, in order to ensure better device performance, a / b > 3 in the elliptical junction region.

[0087] In embodiments of the present invention, the substrate is an inorganic substrate or an organic substrate; the inorganic substrate is any one of a glass substrate, a Si substrate, a Si / SiO2 substrate, or a SiC substrate; for example, in specific implementations, when an inorganic substrate is used, the substrate can be a glass substrate or a SiC substrate, etc.

[0088] The organic substrate is any one of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyimide, and polycarbonate; for example, in a specific implementation, when an organic substrate is used, the substrate can be polypropylene or polycarbonate, etc.

[0089] Example 3

[0090] Please refer to Figures 1 to 4 As shown, this invention provides a magnetic field measurement method using a magnetic sensing unit. The specific structure of the magnetic sensing unit is detailed in Embodiment 2 and will not be repeated here. The method includes:

[0091] Step S1: Construct a rectangular coordinate system with the layer-by-layer growth direction of the magnetic thin film core structure as the positive z-axis and the selected positive x-axis direction parallel to the film surface;

[0092] Step S2: Measure the magnetic field component along the z-axis, specifically including:

[0093] Step S21: Before measuring the magnetic field component in the z-axis direction, apply a constant probe current I between the first terminal P1 and the third terminal P3, or between the second terminal P2 and the third terminal P3. zAnd read the corresponding voltage V z The magnetoresistance R is calibrated by applying a series of magnetic fields (the magnitude of which is known) along the z-axis. z (H z ) = V z (H z ) / I z The relationship between the magnetic field and the z-axis is used to obtain the first calibration data; because the applied probe current I z It is constant. By applying a series of magnetic fields of known magnitude along the z-axis, the magnetoresistance R corresponding to each applied magnetic field of known magnitude can be obtained. z (H z This way, during measurement, only a constant probe current I needs to be applied. z Read the corresponding voltage V z Then the magnetoresistance R can be obtained. z Furthermore, because the first calibration data already contains the magnetoresistance R corresponding to each known magnetic field size, z (H z To calibrate, it is only necessary to obtain the magnetoresistance R. z By comparing it with the first calibration data, the magnetoresistive value R can be obtained. z The magnitude of the corresponding magnetic field;

[0094] Step S22: When measuring the magnetic field component in the z-axis direction, a constant probe current I is applied between the first terminal P1 and the third terminal P3. z Read the corresponding voltage V z Thus, the magnetoresistance R is obtained. z The obtained magnetoresistance R z By comparing the data with the first calibration data, the magnitude of the component of the magnetic field to be measured in the z-axis direction can be obtained.

[0095] In the technical solution of this invention, the maximum measurable component of the magnetic field along the z-axis is H. z,max <H c2⊥ (H c2⊥ (This refers to the coercivity when the magnetization of the second magnetic layer M2 is perpendicular to the film surface).

[0096] In an embodiment of the present invention, the method further includes:

[0097] Step S3: Measure the two-dimensional yoz magnetic field, specifically including:

[0098] Step S31: Apply a modulation current I between the first terminal P1 and the second terminal P2. tThis causes the spin-orbit torque structure on the core structure of the magnetic thin film to generate a spin-orbit torque effect (SOT), which in turn generates a magnetic torque along the y-axis on the second magnetic layer M2 on the core structure of the magnetic thin film. The direction of this magnetic torque is related to the direction of the current flow. If the modulation current I... t If the current flows from the first terminal P1 to the second terminal P2, the magnetic torque acting on the second magnetic layer M2 is along the negative half-axis of the y-axis; conversely, if the modulation current I... t The modulation current I flows from the second terminal P2 to the first terminal P1. t The magnetic torque is along the positive half-axis of the y-axis;

[0099] The stray magnetic field from the bias layer PL of the magnetic thin film core structure and the anisotropy of the top elongated electrode TE cause the magnetization vector of the second magnetic layer M2 to flip to the positive z-axis direction under the spin-orbit torque effect SOT, resulting in a higher energy level for the magnetization vector to stabilize in the y-axis direction than the energy level for the magnetization vector to stabilize in the z-axis direction. Therefore, it is necessary to determine a suitable modulation current I. t To stabilize the magnetization vector of the second magnetic layer M2 in the negative y-axis direction; such as Figure 4 As shown, when there is a current in the spin-orbit coupling layer SOCL of the spin-orbit torque structure flowing from the first terminal P1 to the second terminal P2, there will be a spin current J. s The spin current J diffuses into the second magnetic layer M2. s The generated magnetic torque direction causes the magnetization vector of the second magnetic layer M2 to rotate in the negative half-axis direction of the y-axis, and finally stabilizes in the negative half-axis direction of the y-axis under the action of the stray field of the bias layer PL.

[0100] Step S32: Determine the modulation current I that stabilizes the magnetization vector of the second magnetic layer M2 in the negative y-axis direction. t Specifically, it includes:

[0101] Step S321: Given the magnetic field component H in the z-axis direction z (the magnetic field component H) z Size known), such as Figure 4 As shown, a constant detection current I is first applied between the first terminal P1 and the third terminal P3. y0 Read the corresponding voltage V y0 Then gradually increase the detection current I t,Hz until the magnetoresistance R is reduced y0 (H z ) = V y0 (H z ) / I y0 For extreme values ​​(in specific implementation, if the magnetic field component H in the z-axis direction is given) z To ensure the probe current I is along the positive z-axis, it should be gradually increased. t,Hz Until the magnetoresistance R y0(H z ) = V y0 (H z ) / I y0 It is a local minimum; if the magnetic field component H in the z-axis direction is given. z To detect the direction along the negative z-axis, the detection current I should be gradually increased. t,Hz Until the magnetoresistance R y0 (H z ) = V y0 (H z ) / I y0 (At its maximum value), the magnetization vector of the second magnetic layer M2 stabilizes in the negative y-axis direction. Record the given magnetic field component H. z and the detection current I at this time t,Hz The detection current I t,Hz That is, the modulation current I under a given magnetic field. t ;

[0102] Step S322: Change the magnetic field component H in the given z-axis direction. z Repeat step S321 to determine a series of magnetic field components H in the z-axis direction. zi The modulation current I that stabilizes the magnetization vector of the second magnetic layer M2 in the negative y-axis direction. t,Hzi This means obtaining the second calibration data;

[0103] Because this invention provides a series of magnetic field components H in the z-axis direction zi And for each given magnetic field component H zi Both are achieved by increasing the detection current I t,Hz Until the magnetoresistance R y0 (H z ) = V y0 (H z ) / I y0 The extreme value is that for each given magnetic field component H, the extreme value is... zi Each magnetic field component H is pre-calibrated. zi Modulation current I under t Thus, during measurement, the magnitude H of the magnetic field component in the z-axis direction is measured. z Then, the magnitude H of the component in the z-axis direction can be used as a basis. z Obtain the modulation current I that needs to be set from the second calibration data. t ;

[0104] Step S33: Continue with further calibration, based on the above series of magnetic field components H zi Below, establish the magnetic field component H in the y-axis direction. yj,zi With magnetoresistance R yj,zi The relationship, where i and j are both natural numbers, specifically includes:

[0105] Step S331, under the given magnetic field component H zi Next, a modulation current I is applied from the first terminal P1 to the second terminal P2. t,Hzi At the same time, a constant detection current I is applied between the first terminal P1 and the third terminal P3. y Read the corresponding voltage V yj,zi By applying a series of magnetic fields H along the y-axis yj,zi Thus, the magnetoresistance R is calibrated. yj,zi (H yj,zi ) = V yj,zi (H yj,zi ) / I y With the y-axis magnetic field H yj,zi The changing relationship;

[0106] Step S332: Change the given magnetic field component H zi Repeat step S331 to determine a series of different magnetic field components H zi The y-axis magnetic field H below yj,zi With magnetoresistance R yj,zi The relationship between the changes, that is, to obtain the third calibration data; by adjusting the given magnetic field component H zi In addition to applying modulation current I t,Hzi and constant probe current I y In addition, a series of magnetic fields H along the y-axis are applied to them. yj,zi Thus, the magnetic field component H in each z-axis direction can be obtained. zi Magnetic field H in each y-axis direction below yj,zi With magnetoresistance R yj,zi The relationship is such that, during measurement, when the magnetic field component H in the z-axis direction is known... zi The modulation current I can then be set. t,Hzi And thus obtain the magnetic field component H zi and modulation current I t,Hzi The magnetoresistance R below yj,zi According to magnetoresistance R yj,zi The corresponding y-axis magnetic field H can also be obtained from the third calibration data. yj,zi This enables the measurement of the y-axis component.

[0107] This completes the calibration of the two-dimensional yoz magnetic field, including the magnetic field component H along the z-axis. zi With modulation current I t,Hzi The relationship between different magnetic field components H zi Apply modulation current I t,Hzi Rear magnetoresistance R yj,zi With the y-axis magnetic field H yj,zi Relationship;

[0108] Step 34: During measurement, first measure the magnitude H of the component of the two-dimensional yoz magnetic field in the z-axis direction as described in step S2. z Then, set the modulation current I based on the second calibration data. t，Hz (That is, based on the magnitude H of the component in the z-axis direction) z The corresponding modulation current I can be obtained from the second calibration data. t，Hz (And configure), apply a constant detection current I between the first terminal P1 and the third terminal P3. y Read the corresponding voltage V y,Hz Thus, the magnetoresistance R is obtained. y,Hz The obtained magnetoresistance R y,Hz By comparing the data with the third calibration data, the magnitude of the component of the two-dimensional yoz magnetic field to be measured in the y-axis direction can be obtained.

[0109] By adopting the technical solution of this invention, it is possible to effectively measure the magnetic field component in the z-axis direction and the two orthogonal components of the two-dimensional yoz magnetic field, thereby well meeting the actual measurement needs.

[0110] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A magnetic thin film core structure, characterized in that: It includes a buffer layer, a first magnetic layer, an insulating barrier layer, a second magnetic layer, a spin-orbit coupling layer, a bias layer, and a capping layer, which are grown layer by layer on the substrate. The first magnetic layer has a magnetization vector that is spontaneously parallel to the substrate plane; the second magnetic layer has a magnetization vector that is spontaneously perpendicular to the substrate plane; the coercivity of the second magnetic layer when its magnetization intensity is perpendicular to the film surface is greater than the saturation field of the first magnetic layer; the insulating barrier layer, the second magnetic layer and the spin-orbit coupling layer constitute a spin-orbit torque structure; In the absence of an external magnetic field, the bias layer and the second magnetic layer have the same spontaneous magnetization direction. At the same time, the coercivity of the bias layer in this spontaneous magnetization direction is greater than that of the second magnetic layer, and the hard axis saturation field of the bias layer is much greater than that of the hard axis saturation field of the second magnetic layer.

2. The magnetic thin film core structure as described in claim 1, characterized in that: The buffer layer is a single-layer thin film composed of any one of Ta, Ru, Cu, Cr, Au, Ag and Pt or a multilayer thin film composed of at least two of them; the thickness of the buffer layer is 5 nm-50 nm. The first magnetic layer is made of Co, Fe, Ni, or an alloy material containing any one of Co, Fe, and Ni; the thickness of the first magnetic layer is 0.5 nm to 20 nm. The insulating barrier layer is made of an inorganic insulating material, and the inorganic insulating material is any one of MgO, Mg 1-j Zn j O, Mg j Al 2 / 3（1-j） O, AlO i , BaTiO3, Ta2O5, ZrO2, HfO2, TiO2, where 0 < i < 3 / 2 and 0 < j < 1; the thickness of the insulating barrier layer is 0.5 nm - 5 nm; The second magnetic layer is any one of CoFeB, GdFeCo, MnAl, and MnGa; the thickness of the second magnetic layer is 0.2 nm to 20 nm. The spin-orbit coupling layer is made of a heavy metal with a strong magnetic spin-orbit coupling effect, and the heavy metal is any one of Pt, Pd, W, and β-Ta; the thickness of the spin-orbit coupling layer is 0.5 nm-20 nm. The bias layer is a spontaneously vertically magnetized L... 10 -FePt, L 10 -CoPt, L 10 -FePd, [Co / Pt] n [Co / Pd] n The bias layer is selected from any one of GdFeCo, MnAl, and MnGa; the thickness of the bias layer is 0.2 nm to 20 nm. The capping layer is a single-layer thin film composed of any one of Ta, Ru, Cu, Cr, Au, Ag and Pt, or a multilayer thin film composed of at least two of them; the thickness of the capping layer is 1 nm to 100 nm.

3. A magnetic sensing unit, characterized in that: The magnetic sensing unit includes a substrate and a magnetic thin film core structure as described in any one of claims 1-2, wherein the magnetic thin film core structure is fabricated on the substrate using a single-barrier magnetic tunnel junction micro-nano fabrication technology. In the magnetic sensing unit, the buffer layer and the first magnetic layer of the magnetic thin film core structure constitute the bottom elongated electrode, and the second magnetic layer, spin-orbit coupling layer, bias layer and cover layer of the magnetic thin film core structure constitute the top elongated electrode orthogonal to the bottom elongated electrode. The top elongated electrode has at least a first terminal and a second terminal; the bottom elongated electrode has at least a third terminal.

4. The magnetic sensing unit as described in claim 3, characterized in that: The first magnetic layer of the magnetic thin film core structure is subjected to an in-plane induced magnetic field with a constant direction during the growth process, and this constant direction is denoted as the x-axis direction.

5. The magnetic sensing unit as described in claim 3, characterized in that: In the magnetic sensing unit, the insulating barrier layer is grown using any one of the following methods: radio frequency magnetron sputtering, ion beam sputtering, electron beam evaporation, and chemical vapor deposition. The buffer layer, first magnetic layer, second magnetic layer, spin-orbit coupling layer, bias layer, and capping layer are grown using any one of the following methods: DC magnetron sputtering, radio frequency magnetron sputtering, ion beam sputtering, electron beam evaporation, and thermal evaporation.

6. The magnetic sensing unit as described in claim 4, characterized in that: The magnetic sensing unit has an elliptical junction region; the major axis a of the ellipse of the ellipse junction region is parallel to the x-axis direction, and the minor axis b of the ellipse is perpendicular to the x-axis direction.

7. The magnetic sensing unit as described in claim 6, characterized in that: In the elliptical junction region, a / b > 3.

8. The magnetic sensing unit as described in claim 3, characterized in that: The substrate is an inorganic substrate or an organic substrate. The inorganic substrate is any one of glass substrate, Si substrate, Si / SiO2 substrate, and SiC substrate. The organic substrate is any one of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyimide, and polycarbonate.

9. A method for measuring a magnetic field based on the magnetic sensing unit according to any one of claims 3-8, characterized in that: The method includes: Step S1: Construct a rectangular coordinate system with the layer-by-layer growth direction of the magnetic thin film core structure as the positive z-axis and the selected positive x-axis direction parallel to the film surface; Step S2: Measure the magnetic field component along the z-axis, specifically including: Step S21: Before measuring the magnetic field component in the z-axis direction, apply a constant probe current I between the first and third terminals or between the second and third terminals. z And read the corresponding voltage V z Given the magnetic field component H along the z-axis. z The magnetoresistance R is calibrated by applying a series of magnetic fields along the z-axis. z (H z )= V z (H z ) / I z The relationship between the magnetic field along the z-axis and the change in the magnetic field is used to obtain the first calibration data; Step S22: When measuring the magnetic field component in the z-axis direction, a constant probe current I is applied between the first terminal and the third terminal. z Read the corresponding voltage V z Thus, the magnetoresistance R is obtained. z The obtained magnetoresistance R z By comparing the data with the first calibration data, the magnitude of the component of the magnetic field to be measured in the z-axis direction can be obtained.

10. The magnetic field measurement method as described in claim 9, characterized in that: The method further includes: Step S3: Measure the two-dimensional yoz magnetic field, specifically including: Step S31: Apply a modulation current I between the first terminal and the second terminal. t This induces a spin-orbit torque effect in the spin-orbit torque structure on the core structure of the magnetic thin film, generating a magnetic torque along the y-axis on the second magnetic layer. The stray magnetic field from the bias layer of the core structure and the anisotropy of the top elongated electrode cause the magnetization vector of the second magnetic layer to flip to the positive z-axis direction under the spin-orbit torque effect, resulting in an energy level higher than the energy level at which the magnetization vector stabilizes in the y-axis direction. This determines the appropriate modulation current I. t To stabilize the magnetization vector of the second magnetic layer in the negative y-axis direction; Step S32: Determine the modulation current I that stabilizes the magnetization vector of the second magnetic layer in the negative y-axis direction. t Specifically, it includes: Step S321: Given the magnetic field component H in the z-axis direction z First, a constant detection current I is applied between the first terminal and the third terminal. y0 Read the corresponding voltage V y0 Then gradually increase the detection current I t,Hz until the magnetoresistance R is reduced y0 (H z )= V y0 (H z ) / I y0 This is an extreme value, at which point the magnetization vector of the second magnetic layer stabilizes in the negative y-axis direction. The given magnetic field component H is recorded. z and the detection current I at this time t,Hz The detection current I t,Hz That is, the modulation current I under a given magnetic field. t ; Step S322: Change the magnetic field component H in the given z-axis direction. z Repeat step S321 to determine a series of magnetic field components H in the z-axis direction. zi The modulation current I that stabilizes the magnetization vector of the second magnetic layer in the negative y-axis direction. t,Hzi This means obtaining the second calibration data; Step S33: In the above series of magnetic field components H zi Below, establish the magnetic field component H in the y-axis direction. yj,zi With magnetoresistance R yj,zi The relationship, where i and j are both natural numbers, specifically includes: Step S331, under the given magnetic field component H zi Next, a modulation current I is applied from the first terminal to the second terminal. t,Hzi At the same time, a constant detection current I is applied between the first terminal and the third terminal. y Read the corresponding voltage V yj,zi By applying a series of magnetic fields H along the y-axis yj,zi Thus, the magnetoresistance R is calibrated. yj,zi (H yj,zi )= V yj,zi (H yj,zi ) / I y With the y-axis magnetic field H yj,zi The changing relationship; Step S332: Change the given magnetic field component H zi Repeat step S331 to determine a series of different magnetic field components H zi The y-axis magnetic field H below yj,zi With magnetoresistance R yj,zi The relationship between the changes is obtained, thus acquiring the third calibration data; this completes the calibration of the two-dimensional yoz magnetic field. Step 34: During measurement, first measure the magnitude H of the component of the two-dimensional yoz magnetic field in the z-axis direction as described in step S2. z Then, set the modulation current I based on the second calibration data. t,Hz A constant probe current I is applied between the first terminal and the third terminal. y Read the corresponding voltage V y,Hz Thus, the magnetoresistance R is obtained. y,Hz The obtained magnetoresistance R y,Hz By comparing the data with the third calibration data, the magnitude of the component of the two-dimensional yoz magnetic field to be measured in the y-axis direction can be obtained.

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