Magnetic sensor element, magnetic sensor device, magnetic sensor system, and method for manufacturing magnetic sensor element

Abstract

A magnetic sensor element (100) for determining a magnetic field includes a substrate (10), a heavy metal layer (12) laminated on the substrate (10), an antiferromagnetic layer (14) laminated on the heavy metal layer (12) and composed of a first antiferromagnetic (e.g., Mn3Sn) having an antiferromagnetic magnetic structure in which time reversal symmetry has been macroscopically broken, and a cap layer (16) laminated on the antiferromagnetic layer (14). In the heavy metal layer (12), when an electric current (I) flows in an in-plane direction, a spin current is generated in a direction perpendicular to the plane, and a spin orbit moment generated by the spin current acts on a magnetic sequence of a first antiferromagnetic body of the antiferromagnetic layer (14), thereby controlling the magnetic sequence. The read signal of the first antiferromagnetic body of the antiferromagnetic layer (14) is linearly responsive to the magnetic field within a predetermined magnetic field range including a zero magnetic field.

Description

Technical Field

[0001] This invention relates to magnetic sensor elements, magnetic sensor devices, magnetic sensor systems, and methods for manufacturing magnetic sensor elements. Background Technology

[0002] Hall sensors, as a type of magnetic sensor, utilize the Hall effect to measure magnetic fields. The Hall effect is the phenomenon where a voltage (Hall voltage) is generated in a direction orthogonal to both the current and the magnetic field when a magnetic field is applied perpendicular to a current. This Hall voltage is proportional to the strength and direction of the magnetic field, thus Hall sensors are effective for measuring magnetic fields (see, for example, Patent Document 1). Additionally, tunneling magnetoresistive (TMR) sensors are also well-known, utilizing the TMR effect where resistance changes according to the magnetic field (see, for example, Patent Document 2). Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-13891 Patent Document 2: International Publication No. 2020 / 208907 Summary of the Invention The problem that the invention aims to solve

[0004] In recent years, there has been a demand for magnetic sensors with high sensitivity and excellent response characteristics in various applications such as portable devices, automobiles, and medical equipment.

[0005] The purpose of this invention is to provide a magnetic sensor element, magnetic sensor device, magnetic sensor system, and a method for manufacturing the magnetic sensor element, which uses an antiferromagnet with negligible leakage magnetic field and has excellent response characteristics. Methods for solving problems

[0006] The magnetic sensor element of the present invention is a magnetic sensor element for measuring magnetic fields, wherein it includes an antiferromagnetic layer, the antiferromagnetic layer is composed of a first antiferromagnetic body having an antiferromagnetic magnetic structure with macroscopically broken time reversal symmetry, and the read signal of the antiferromagnetic layer has a linear response to the magnetic field within a predetermined magnetic field range including zero magnetic field.

[0007] The magnetic sensor device of the present invention includes the above-described magnetic sensor element, a current supply unit for supplying power to the magnetic sensor element, and a processor for processing readout signals from the antiferromagnetic layer of the magnetic sensor element.

[0008] The magnetic sensor system of the present invention is a magnetic sensor system in which a plurality of magnetic sensor elements are arranged, each of the plurality of magnetic sensor elements being defined as the magnetic sensor element described above.

[0009] In the method for manufacturing the magnetic sensor element of the present invention, a multilayer film is formed, the multilayer film including at least a substrate made of an insulator, a capping layer made of an oxide, and an antiferromagnetic layer disposed between the substrate and the capping layer. After the multilayer film is formed, the multilayer film is annealed. The effects of the invention

[0010] According to the present invention, by using an antiferromagnetic layer composed of a first antiferromagnetic material having a macroscopically broken time-reversal symmetry, the readout signal responds linearly to the magnetic field within a predetermined magnetic field range including zero magnetic field, thereby providing a magnetic sensor element with excellent response characteristics. Attached Figure Description

[0011] Figure 1A This is a cross-sectional view of a magnetic sensor element according to a first embodiment of the present invention. Figure 1B This is a cross-sectional view of a magnetic sensor element according to a variation of the first embodiment. Figure 2 This is a diagram showing the X-ray diffraction pattern of a MgO substrate / W / Mn3Sn / MgO sample. Figure 3 This is a schematic diagram used to illustrate the current-induced magnetic rotation (chiral spin rotation) of Mn3Sn. Figure 4 This is a schematic diagram illustrating the structure of a magnetic sensor element with a Hall bar structure. Figure 5 This is a block diagram of a magnetic sensor device that includes a magnetic sensor element. Figure 6A This is a graph showing the surface-vertical magnetic field dependence of the Hall resistivity of Mn3Sn at 300K for the magnetic sensor element of the first embodiment. Figure 6B This is a graph showing the surface-perpendicular magnetic field dependence of the Hall resistivity of Mn3Sn at 300K when a current exceeding the threshold current for current-induced magnetic rotation (chiral spin rotation) flows through the heavy metal layer in the magnetic sensor element of the first embodiment. Figure 7 This is a schematic diagram used to illustrate the hysteresis curve based on current-controlled permeability. Figure 8A This is a cross-sectional view of a magnetic sensor element according to a second embodiment of the present invention. Figure 8B This is a cross-sectional view of a magnetic sensor element according to a modified example of the second embodiment. Figure 9AThis is a graph showing the surface-vertical magnetic field dependence of the Hall resistivity of Mn3Sn in the magnetic sensor element of the second embodiment at 300K. Figure 9B This is a graph characterizing the surface-perpendicular magnetic field dependence of the Hall resistivity of Mn3Sn at 300K when the antiferromagnetic order of Mn3Sn reverses in the magnetic sensor element of the second embodiment. Figure 10 This is a timing diagram showing the timing relationship between the current applied to the magnetic sensor element and the read signal from the magnetic sensor element. Figure 11A From Figure 8A A cross-sectional view of a magnetic sensor element obtained by removing the heavy metal layer from the magnetic sensor element. Figure 11B From Figure 8B A cross-sectional view of a magnetic sensor element obtained by removing the heavy metal layer from the magnetic sensor element. Figure 12 This is a cross-sectional view of a magnetic sensor element when the antiferromagnetic layer is granular. Figure 13 This is a cross-sectional view of a magnetic sensor element when the antiferromagnetic layer is a single crystal film or an epitaxial film. Figure 14 This is a cross-sectional view of a magnetic sensor element according to a third embodiment of the present invention. Figure 15 This is a graph showing the dependence of the surface perpendicular magnetic field on the Hall resistivity of Mn3Sn at 300K in the magnetic sensor element of the third embodiment. Figure 16 This is a schematic diagram showing the structure of a magnetic sensor system that includes multiple magnetic sensor elements. Detailed Implementation

[0012] Embodiments of the present invention will now be described with reference to the accompanying drawings. In the following embodiments, the same or similar parts are given the same reference numerals throughout the drawings. The drawings are schematic, and the relationships between planar dimensions and thicknesses, as well as the ratios of the thicknesses of various parts, differ from actual measurements. Furthermore, the drawings naturally include portions with different dimensional relationships and ratios.

[0013] In the following embodiments, the multilayer film is sometimes labeled according to the materials of each layer constituting the multilayer film. For example, if a layer of material b and a layer of material c are sequentially stacked on a layer of material a, the multilayer film is labeled as "material a / material b / material c". In addition, the thickness (nm) of each layer is sometimes recorded in parentheses after the material name. For example, a layer with a thickness of ti (nm) composed of material j is recorded as "material j (ti)".

[0014] <First Implementation> Reference Figures 1A to 7 The first embodiment of the present invention will now be described. The magnetic sensor element in the first embodiment is an element whose coercivity or permeability is controlled by current.

[0015] like Figure 1A As shown, the magnetic sensor element 100 of the first embodiment includes a substrate 10, a heavy metal layer 12 stacked on the substrate 10, an antiferromagnetic layer 14 stacked on the heavy metal layer 12 as a magnetic sensing layer, and a capping layer 16 stacked on the antiferromagnetic layer 14. Alternatively, as... Figure 1B As shown, a magnetic sensor element 102 (substrate / antiferromagnetic layer / heavy metal layer / capping layer) can also be obtained by stacking a heavy metal layer 12 on the antiferromagnetic layer 14.

[0016] The substrate 10 is composed of insulators such as MgO and SiO2 / Si. The heavy metal layer 12 is composed of non-magnetic heavy metals such as tantalum (Ta), tungsten (W), and platinum (Pt).

[0017] The antiferromagnetic layer 14 is composed of an antiferromagnet (first antiferromagnet), wherein the antiferromagnet (first antiferromagnet) has an antiferromagnetic magnetic structure with macroscopically broken time-reversal symmetry. This first antiferromagnet includes non-collinear antiferromagnets or alternating magnets. The first antiferromagnet of the antiferromagnetic layer 14, based on a macroscopically broken time-reversal symmetry antiferromagnetic magnetic structure, is capable of expressing the anomalous Hall effect. Furthermore, the first antiferromagnet includes manganese (Mn)-containing antiferromagnetic metals, or collinear antiferromagnets with a rutile crystal structure. Examples of the former include: Mn3X (where X is selected from one or more of the group consisting of tin (Sn), germanium (Ge), gallium (Ga), rhodium (Rh), platinum (Pt), and iridium (Ir)) and Mn3XN (where X is selected from one or more of the group consisting of gallium (Ga), tin (Sn), and nickel (Ni)). Examples of the latter include RuO2, Mn5Si3, or CrSb. Compounds with non-stoichiometric compositional deviations or those mixed with impurities are permissible, provided that the macroscopically broken antiferromagnetic structure due to time-reversal symmetry is compensated. By adjusting the compositional ratio of the compound, the temperature range or sensitivity of the magnetic field measurement can be adjusted.

[0018] The capping layer 16 is designed to prevent oxidation and is composed of MgO and AlO. x It is composed of oxides. Even without the capping layer 16, the magnetic sensor element 100 can be used as a magnetic sensor. The same applies to the second and third embodiments described below.

[0019] When an in-plane current I flows through the heavy metal layer 12, a spin current is generated in the direction perpendicular to the plane due to the spin Hall effect. The spin orbital moment (SOT) generated by the spin current acts on the magnetic sequence of the antiferromagnetic layer 14 in contact with the heavy metal layer 12, thereby controlling the magnetic sequence.

[0020] Next, an example of the fabrication method of the magnetic sensor element 100 will be described. Below, an example of forming a W (10 nm) / Mn3Sn (15 nm) / MgO (5 nm) multilayer film on a MgO (110) substrate is given. Furthermore, the thickness (nm) of each layer of the magnetic sensor element 100 is merely an example and is not intended to be limiting.

[0021] First, the MgO substrate was annealed at 800°C for 10 minutes in an ultra-high vacuum chamber. The W (10 nm) / Mn3Sn (15 nm) / MgO (5 nm) multilayer film was prepared with a base pressure of 2 × 10⁻⁶. -8 Under ultra-high vacuum of Pa, the Mn3Sn (110) layer was fabricated on a MgO (110) substrate by molecular beam epitaxy (MBE). A W (10 nm) layer was deposited at 300 °C at a rate of 0.1 Å / s and then annealed at 800 °C for 10 min. A Mn3Sn (15 nm) layer was fabricated by co-evaporation of Mn and Sn at a rate of 0.25 Å / s. First, a Mn3Sn (5 nm) layer was deposited at room temperature and then annealed at 400 °C. Next, an additional Mn3Sn (10 nm) layer was deposited at approximately 260 °C.

[0022] Subsequently, a MgO layer (5 nm) was fabricated at room temperature at a rate of 0.1 Å / s. Finally, the MgO (110) substrate / W ​​(10 nm) / Mn3Sn (15 nm) / MgO (5 nm) multilayer film was annealed at 700 °C for 30 min.

[0023] Thus, by annealing the multilayer film after stacking the MgO layer as the capping layer 16 (cap anneal), the coercivity of the Mn3Sn layer can be reduced compared to magnetic sensor elements fabricated by annealing without the capping layer 16.

[0024] Based on the compositional analysis results from SEM-EDX, the composition of the Mn3Sn layer is Mn 3.05 Sn 0.95 . Figure 2 The X-ray diffraction pattern of the fabricated MgO(110) substrate / W(10 nm) / Mn3Sn(15 nm) / MgO(5 nm) sample is shown. Figure 2As shown, the W layer has a (211) orientation, and the Mn3Sn layer is an epitaxial film with a (01-10) orientation.

[0025] Furthermore, the resistivity of the bilayer W (10 nm) / Mn3Sn (15 nm) was measured to be 136 μΩ·cm using the four-terminal method. Based on the measurement results of the single-layer film, the resistivity of W is 40 μΩ·cm, therefore the resistivity of Mn3Sn can be calculated to be 200 μΩ·cm.

[0026] like Figure 3 As shown, Mn3Sn is an antiferromagnetic material with a crystal structure called a kagome lattice based on triangles, and the kagome lattice is stacked along the

[0001] direction. The Mn at the vertices of the kagome lattice exhibits a non-collinear magnetic structure with magnetic moments (directions of local spin) tilted 120 degrees to each other at temperatures below 420 K due to geometric frustration. The three types of six spin units arranged on the double-layered kagome lattice form a spin order represented by hexagons, known as cluster octodeps. This antiferromagnetic structure macroscopically breaks time-reversal symmetry.

[0027] The Mn3Sn layer of the magnetic sensor element fabricated as described above is a single-crystal film or an epitaxial film, oriented in a (2-1-10) or (01-10) pattern with the clasp plane perpendicular to the film surface. If a predetermined in-plane current I flows through the heavy metal layer 12, a spin current is generated in the plane-perpendicular direction (z-direction). The SOT generated by this spin current causes the antiferromagnetic order of Mn3Sn to rotate. By utilizing this current-induced magnetic rotation (chiral spin rotation), the coercivity of the Mn3Sn layer can be suppressed. The suppression of coercivity using current-induced magnetic rotation will be described later (see [reference]). Figure 6A and Figure 6B ).

[0028] Figure 4 The diagram illustrates a Hall strip structure when the magnetic sensor element 100 is used as a Hall sensor element (Hall element). In the Hall strip structure of the magnetic sensor element 100, electrodes 17a and 17b made of Au / Ti are arranged at both ends in the length direction (x-direction), and electrodes 18a and 18b made of Au / Ti are arranged in the width direction (y-direction). Furthermore, in... Figure 4 In the middle, the cap layer 16 is omitted.

[0029] A write current I flows between electrodes 17a and 17b. write Or read the current I read The Hall voltage V is detected between electrodes 18a and 18b. H .

[0030] When the write current I write When a heavy metal layer 12 (e.g., pulse current, alternating current, etc.) flows along the length direction (x direction), a spin current is generated in the direction perpendicular to the surface (z direction) due to the spin Hall effect. The SOT generated by the spin current acts on the magnetic order of the antiferromagnetic layer 14, thereby controlling the magnetic order.

[0031] When measuring the magnetic field, the current I is read. read (DC) current flows along the x-direction through the antiferromagnetic layer 14. Consequently, due to the anomalous Hall effect, a Hall voltage V corresponding to the magnitude of the magnetic field is generated. H .

[0032] Figure 5 The structure of a magnetic sensor device 1000, including a magnetic sensor element 100, is shown. The magnetic sensor device 1000 includes a magnetic sensor element 100, a current supply unit 1002, a processor 1004, a memory 1006, and a voltage detection unit 1008. The current supply unit 1002 supplies current (IC) to the magnetic sensor element 100 according to control from the processor 1004. write I read The voltage detection unit 1008 detects the read signal (Hall voltage V) from the antiferromagnetic layer 14 of the magnetic sensor element 100. H The processor 1004 has a central processing unit (CPU) and controls the current supply unit 1002 to supply current to the magnetic sensor element 100, or processes the read signal (Hall voltage V) detected by the voltage detection unit 1008. H The memory 1006 stores the data or read signals required by the processor 1004 to perform various processes.

[0033] in addition, Figure 4 Hall bar structure and Figure 5 The magnetic sensor device 1000 is not only suitable for Figure 1A The magnetic sensor element 100 can also be used in Figure 1B The magnetic sensor element 102, and the magnetic sensor elements of the second and third embodiments described later.

[0034] Next, the magnetic field measurement results of the magnetic sensor element 100, which serves as a Hall element, will be explained. The multilayer film of the magnetic sensor element 100 used for measurement is MgO (110) substrate / W ​​(10 nm) / Mn3Sn (15 nm) / MgO (5 nm), and Hall strips with a width of 2 μm and a length of 12 μm are fabricated by photolithography.

[0035] Figure 6A The diagram shows a current of 0.4 mA applied to the entire multilayer film (W layer, I layer). write=0.3 mA, current density J w =1.5 MA / cm 2 The surface vertical magnetic field dependence of the Hall resistivity of the Mn3Sn layer at 300K when reading the signal with a current of 0.4 mA. Figure 6B This illustrates the effect of applying a current of 4 mA (W layer, I layer) to the entire multilayer film. write =3mA, J w =15 MA / cm 2 Furthermore, when reading the signal with a current of 4mA, the surface vertical magnetic field dependence of the Hall resistivity of the Mn3Sn layer at 300K was determined.

[0036] Compare Figure 6A and Figure 6B It can be seen that, in Figure 6B In the graph, the hysteresis curve representing the response of the Mn3Sn layer almost disappears in the direction of the magnetic field. That is, Figure 6B This illustrates the effect of a current density of 1 MA / cm² exceeding the threshold current that induces magnetic rotation (chiral spin rotation) when flowing through it. 2 ~100 MA / cm 2 When writing a current on the order of magnitude of ρ and measuring the magnetic field, the read signal exhibits a linear response to the magnetic field within a predetermined magnetic field range, including zero magnetic field (refer to the dashed line). If the Hall resistivity is expressed as ρ... H If we denote the magnetic field as B, then according to Figure 6B Within the range of -100 mT to +100 mT, the slope dρ H / dB=-0.0057(μΩ·cm / mT). The absolute value of the slope |dρ H The higher the dB value, the higher the sensitivity. In addition, although the inherent noise frequency caused by current-induced magnetic rotation (chiral spin rotation) varies proportionally with the current density, it is robust to weak magnetic fields below 0.1T and remains approximately constant.

[0037] In this way, by employing a current exceeding the threshold current for current-induced magnetic rotation (chiral spin rotation), the coercivity of the Mn3Sn layer can be suppressed to almost zero, and a Hall voltage under zero magnetic field can be sensed. The phenomenon of a sharp change in Hall voltage as a function of magnetic field indicates that the magnetic sensor element 100 is useful as a magnetic field probe.

[0038] Next, the control of permeability based on current will be explained. Controlling the permeability helps to construct two states for the magnetic sensor: one with the magnetic field to be measured and the other without. Due to the difference in signal readings under the conditions of a magnetic field and no magnetic field, noise from 1 / f or other environmental sources is removed, and a high-precision signal can be obtained.

[0039] As an example of a magnetic sensor element 100 with controllable permeability, a multilayer film of MgO (110) substrate / W / Mn3Sn / MgO can be provided. In this film, the Mn3Sn layer is a polycrystalline film or an epitaxial film. When the Mn3Sn layer is an epitaxial film, the kumo facet, which serves as the current-sensing magnetic rotation surface, is oriented perpendicular to the substrate.

[0040] In this magnetic sensor element 100, maximum permeability is achieved when a magnetic field is applied in the direction perpendicular to the surface and a current exceeding the critical current density is provided. When an in-plane magnetic field is applied, a readout signal two orders of magnitude smaller than that obtained when magnetization is applied in the direction perpendicular to the surface is achieved. The critical current density is preferably 10 MA / cm². 2 100 MA / cm 2 The magnitude.

[0041] When the current is less than the critical current density, the domains of the antiferromagnetic layer 14 are oriented in random directions, and the coercivity is greater than 0.1T. Therefore, after the current is reduced to less than the critical current density, the permeability is 1 to 2 orders of magnitude smaller than the permeability measured at currents exceeding the critical current density. Figure 7 The dashed line shows the hysteresis curve, which represents the response to a magnetic field when no current is supplied and the coercivity is greater than 0.1 T. Furthermore, Figure 7 The thick solid line in the figure represents the response to the magnetic field when a current exceeding the critical current density is provided, and shows that the width of the hysteresis curve disappears. Within a predetermined magnetic field range including zero magnetic field, the read signal responds linearly to the magnetic field.

[0042] In order to eliminate background noise using the magnetic sensor element 100, a first current greater than the critical current density and a second current less than the critical current density can be alternately and repeatedly supplied to the heavy metal layer 12, and the difference between the resulting read signals can be calculated.

[0043] If the current supply unit 1002 supplies a first current to the heavy metal layer 12, the permeability of the antiferromagnetic layer 14 increases, allowing the detection of the magnetic field and noise of the measured object. Conversely, when the current supply unit 1002 provides a second current to the heavy metal layer 12, the permeability of the antiferromagnetic layer 14 decreases, making it difficult to detect the magnetic field; only noise is detected. The processor 1004 reads the first read signal (Hall resistivity ρ) obtained when the first current flows through it. H Or Hall voltage V H The second read signal (Hall resistivity ρ) obtained when the second current flows through it. H Or Hall voltage V HThe two signals are compared. For example, the processor 1004 normalizes the first and second read signals according to the magnitude of the current and calculates the difference between the two signals. This eliminates background noise. Furthermore, by controlling the permeability of the antiferromagnetic layer 14, the magnitude of the magnetic field applied to the magnetic sensor portion can be changed, thereby providing a highly sensitive magnetic sensor.

[0044] <Second Implementation> Next, we will refer to Figures 8A to 13 A second embodiment of the present invention will be described. The magnetic sensor element of the second embodiment includes a bias layer that causes an exchange bias with the antiferromagnetic material of the antiferromagnetic layer. The antiferromagnetic layer of the second embodiment is also the same as that of the antiferromagnetic layer of the first embodiment, and is composed of a first antiferromagnetic material having a macroscopically broken time-reversal symmetry.

[0045] like Figure 8A As shown, the magnetic sensor element 200 of the second embodiment includes a substrate 10, a heavy metal layer 12 stacked on the substrate 10, an antiferromagnetic layer 14 stacked on the heavy metal layer 12, a bias layer 28 stacked on the antiferromagnetic layer 14, and a capping layer 26 stacked on the bias layer 28. Alternatively, as... Figure 8B As shown, a magnetic sensor element 202 (substrate / bias layer / antiferromagnetic layer / heavy metal layer / cap layer) can also be used, in which the stacking positions of the heavy metal layer 12 and the bias layer 28 are interchanged.

[0046] The bias layer 28 is composed of antiferromagnets (second antiferromagnets) such as Mn-Pt, Mn-Ir, Mn-N, NiO, and CoO. When the bias layer 28 comes into contact with the antiferromagnetic layer 14, a magnetic coupling effect known as exchange bias is generated at the interface of the bilayer film.

[0047] Next, an example of the fabrication method of the magnetic sensor element 200 will be described. Below, an example of forming W (10 nm) / Mn3Sn (15 nm) / MnPt (15 nm) / AlO on a MgO (110) substrate will be given. x (5 nm) Example of a multilayer film. Furthermore, the thickness (nm) of each layer of the magnetic sensor element 200 is only an example and is not intended to limit it.

[0048] First, a MgO (110) substrate / W ​​(10 nm) / Mn3Sn (15 nm) / MgO (5 nm) multilayer film, as an example of the magnetic sensor element 100 in the first embodiment, was fabricated using the method described above. Next, the MgO (5 nm) layer was milled by dry etching using argon (Ar) ion milling. Then, at room temperature, 15 nm of MnPt was deposited on the outermost surface of the Mn3Sn (15 nm) layer using sputtering. Afterward, 5 nm of AlO was deposited using sputtering at room temperature. x .

[0049] Alternatively, if a MgO(110) substrate / W / Mn3Sn / MnPt / AlO is formed sequentially from the bottom layer... x In the fabrication method of the multilayer film, the reaction between the Mn3Sn layer and the MnPt layer during the fabrication process affects the magnetic state. Therefore, after capping annealing the MgO(110) substrate / W / Mn3Sn / MgO multilayer film of the first embodiment, the MgO layer serving as the capping layer is removed, and then MnPt / AlO is formed on the Mn3Sn layer. x layer.

[0050] Next, the magnetic field measurement results of the magnetic sensor element 200, which serves as a Hall element, will be explained. The multilayer film of the magnetic sensor element 200 used for the measurement is MgO (110) substrate / W ​​(10 nm) / Mn3Sn (15 nm) / MnPt (15 nm) / AlO x (5 nm), a Hall bar with a width of 2 μm and a length of 12 μm was fabricated by photolithography.

[0051] Figure 9A and Figure 9B The results show the measurement of the Hall effect obtained by applying a magnetic field of +2T perpendicular to the surface at 450K and then field-cooling it to 300K.

[0052] Figure 9A The plane-perpendicular magnetic field dependence of the Hall resistivity of the Mn3Sn layer at 300 K is shown when a read current of 0.5 mA is applied to the entire multilayer film. Figure 9A It can be seen that within a predetermined magnetic field range including zero magnetic field, the read signal exhibits a linear response to the magnetic field (refer to the dashed line). Specifically, within the range of -100mT to +100mT, the slope dρ H / dB=-0.0105(μΩ·cm / mT).

[0053] The resistivity of the three-layer W (10 nm) / Mn3Sn (15 nm) / MnPt (15 nm) was measured to be 156 μΩ·cm. Furthermore, according to the measurements of the first embodiment, the resistivity of W is 40 μΩ·cm, the resistivity of Mn3Sn is 200 μΩ·cm, and therefore the resistivity of MnPt is calculated to be 190 μΩ·cm.

[0054] Figure 9B The diagram illustrates the application of a pulsed current of -5 mA (pulse width 0.5 ns) to the entire multilayer film (on the W layer, I...). write =-3 mA, J w =-15 MA / cm 2 The surface-perpendicular magnetic field dependence of the Hall resistivity of the Mn3Sn layer at 300K when reading signals with a current of 0.5 mA. Figure 9B It can be seen that the antiferromagnetic order of the Mn3Sn layer is reversed by applying a negative current. Furthermore, a linear response is observed in the range of -100mT to +100mT (refer to the dashed line), with a slope dρ H / dB=+0.0105(μΩ·cm / mT).

[0055] Next, a pulsed current of +5 mA (pulse width 0.5 ns) was applied to the entire multilayer film (on the W layer, I...). write =+3mA、J w =+15 MA / cm 2 Then the antiferromagnetic order of the Mn3Sn layer reverses, returning to the previous state. Figure 9A The hysteresis curve.

[0056] Compared with the first embodiment Figure 6A Compared to the hysteresis curve shown, Figure 9A and Figure 9B The hysteresis curve is shifted in the direction of the magnetic field. This means that an exchange bias is generated between the MnPt layer as bias layer 28 and the Mn3Sn layer as antiferromagnetic layer 14. It is difficult to achieve this. Figure 6A The magnetic field is measured under the normal hysteresis curve shown. However, if the hysteresis curve is shifted towards the magnetic field direction by the exchange bias effect, such as... Figure 9A and Figure 9B As shown, by adjusting the zero point in the linear response region to be near the zero magnetic field, appropriate magnetic field measurements can be performed without generating a leakage magnetic field.

[0057] In order to eliminate background noise using the magnetic sensor element 200, positive and negative currents can be alternately and repeatedly supplied to the heavy metal layer 12, and the difference of the obtained read signals can be calculated.

[0058] Specifically, such as Figure 10As shown, when a positive current I with a predetermined pulse width is supplied by the current supply unit 1002... write Then supply the reading current I read At that time, the Hall resistivity ρ was obtained from the antiferromagnetic layer 14. H (+, B) or Hall voltage V H (+, B) (thick solid line portion) serves as the first read signal. Next, when a negative current -I is supplied by the current supply unit 1002... write Then supply the reading current I read At that time, the Hall resistivity ρ was obtained from the antiferromagnetic layer 14. H (-, B) or Hall voltage V H (-, B) (thick solid line portion) serves as the second read signal. A positive current I is alternately and repeatedly supplied. write and negative current -I write With the help of SOT (spin orbital moment), the magnetic order of the antiferromagnetic layer 14 transitions between two states.

[0059] Processor 1004 calculates when a positive current I is supplied. write The first read signal from the antiferromagnetic layer 14 is when a negative current -I is supplied. write The difference (Δρ) between the second readout signals from the antiferromagnetic layer 14 H or ΔV H For example, in alternating acquisition Figure 9A The first read signal shown and Figure 9B In the case of the second readout signal shown, the difference in Hall resistivity under a 50 mT surface-perpendicular magnetic field is Δρ H =ρ H (+, B)-ρ H (-, B) = 0.525 (μΩ·cm).

[0060] Through high-speed (e.g., sub-nanosecond) repeated accumulation Figure 10 The operation shown in A can improve the denoising accuracy and the signal-noise ratio.

[0061] Alternatively, it is also possible to not perform... Figure 10 The magnetic sensor element shown is used for noise reduction. In this case, the heavy metal layer 12 is not required. Figure 11A It shows from Figure 8A The magnetic sensor element 204, which is a structure in which the heavy metal layer 12 has been removed from the magnetic sensor element 200, Figure 11B It shows from Figure 8B The magnetic sensor element 206 is a structure in which the heavy metal layer 12 has been removed from the magnetic sensor element 202.

[0062] To provide an antiferromagnetic layer with excellent response characteristics, as described above, it is preferable to reduce the coercivity of the antiferromagnetic layer. For example, Figure 12 The magnetic sensor element 208 shown is a multilayer film consisting of a substrate 220, a heavy metal layer 222, an antiferromagnetic layer 224, a bias layer 228, and a capping layer 226. The antiferromagnetic layer 224 is a granular first antiferromagnetic layer. By dispersing the first antiferromagnetic material into particles of about 10 nm, the coercivity of the antiferromagnetic layer 224 can be reduced.

[0063] When an antiferromagnetic layer is formed in a continuous film (a film in which crystals are arranged without gaps), coercivity can be reduced by forming a thin film with a thickness of less than 10 nm.

[0064] also, Figure 13 The magnetic sensor element 210 shown is a multilayer film consisting of a substrate 230, a heavy metal layer 232, an antiferromagnetic layer 234, a bias layer 238, and a capping layer 236. The antiferromagnetic layer 234 is a single-crystal film or an epitaxial film. The antiferromagnetic layer 234 has large crystal domains. In an extremely weak magnetic field, the magnetic order orientation of the first antiferromagnetic body changes, and the switching of the domain walls propagates coherently. This reduces coercivity. The slope dρ in the linear response region near zero magnetic field of this antiferromagnetic layer 234 is shown. H The / dB becomes steep, narrowing the range of measurable magnetic fields, but making the sensitivity very high.

[0065] in addition, Figure 12 and Figure 13 The magnetic sensor elements 208 and 210 do not necessarily have to have heavy metal layers 222 and 232.

[0066] <Third Implementation Method> Next, refer to Figure 14 and Figure 15 The third embodiment of the present invention will be described. The magnetic sensor element of the third embodiment does not include a heavy metal layer and a bias layer.

[0067] like Figure 14 As shown, the magnetic sensor element 300 of the third embodiment includes a substrate 30 made of an insulator, an antiferromagnetic layer 34 stacked on the substrate 30, and a capping layer 36 made of oxide and stacked on the antiferromagnetic layer 34. The antiferromagnetic layer 34, like the antiferromagnetic layers of the first and second embodiments, is composed of a first antiferromagnetic material having a macroscopically broken time-reversal symmetry antiferromagnetic magnetic structure. Furthermore, the antiferromagnetic layer 34 is a granular layer with a thickness approximately the same as the size of the particles.

[0068] Next, an example of the fabrication method for the magnetic sensor element 300 will be described. The following example illustrates the formation of a thermally oxidized SiO2 / Si substrate / Mn3Sn (5 nm) / AlO2. x Example of a (10 nm) multilayer film. Furthermore, the thickness (nm) of each layer of the magnetic sensor element 300 is merely an example and is not intended to be limiting.

[0069] First, a 5 nm Mn3Sn layer was deposited on a SiO2 / Si substrate by DC sputtering at room temperature. The chamber was under an Ar atmosphere, with the pressure maintained at 0.5 Pa and the power set to 60 W. Then, AlO2 was deposited on the 5 nm Mn3Sn layer by DC sputtering at room temperature. x (10 nm) layer. Here, the chamber is under an Ar atmosphere, the pressure is maintained at 0.3 Pa, and the power is set to 100 W. Finally, at 5 × 10 -6 In a vacuum of Pa, thermal oxidation of SiO2 / Si substrate / Mn3Sn (5 nm) / AlO x (10 nm) multilayer film was annealed at 500 °C for 30 minutes.

[0070] Next, the magnetic field measurement results of the magnetic sensor element 300, which serves as a Hall element, will be explained. The multilayer film of the magnetic sensor element 300 used for measurement is thermally oxidized SiO2 / Si substrate / Mn3Sn (5 nm) / AlO x A Hall strip with a width of 2 μm and a length of 12 μm was fabricated by photolithography (10 nm). The resistivity of Mn3Sn was determined to be 250 μΩ·cm by the four-terminal method.

[0071] Figure 15 The plane-perpendicular magnetic field dependence of the Hall resistivity of the Mn3Sn layer at 300 K is shown when a read current of 0.2 mA is applied across the entire multilayer film of the magnetic sensor element 300. Figure 15 It can be seen that within a predetermined magnetic field range including zero magnetic field, the read signal exhibits a linear response to the magnetic field (refer to the dashed line). Specifically, within the range of -50 mT to +50 mT, the slope dρ H / dB=-0.016(μΩ·cm / mT).

[0072] As described above, when fabricating thermally oxidized SiO2 / Si substrate / Mn3Sn (5 nm) / AlO x When the Mn3Sn multilayer film (10 nm) is made smaller, the grain size of Mn3Sn becomes smaller, and the width of the hysteresis curve near zero magnetic field almost disappears. In addition, when the size of the Hall bar becomes smaller, the coercivity further decreases.

[0073] In the third embodiment, unlike the first and second embodiments, it is not necessary to set a heavy metal layer for current flow or to set a bias layer to shift the hysteresis curve, thus enabling a good response characteristic with a simple structure.

[0074] Furthermore, in each of the magnetic sensor elements in the first to third embodiments, a layer to prevent interlayer diffusion may be provided. Additionally, in the magnetic sensor element of the second embodiment, a layer to enhance the exchange bias effect may be provided.

[0075] The temperature range for magnetic field measurement shown in the first to third embodiments can be controlled by substitution at the Mn and Sn sites. Furthermore, the slope dρ H / dB temperature change or Hall voltage V H Temperature changes can be regulated by the substitution of Mn and Sn.

[0076] In the above embodiments, the following methods for reducing the coercivity of the antiferromagnetic layer are proposed, but these methods can be used in appropriate combinations. (i) After all the layers of the multilayer film are formed, the multilayer film is annealed (capping annealing). (ii) Magnetic rotation induced by the current in the antiferromagnetic layer ( Figure 3 , Figure 6B ). (iii) Set a granular layer as an antiferromagnetic layer ( Figure 12 ). (iv) Set a continuous film (thin film) with a thickness of less than 10 nm as an antiferromagnetic layer. (v) A single-crystal film or epitaxial film with domain wall switching propagating coherently is used as an antiferromagnetic layer. Figure 13 ).

[0077] According to the first to third embodiments, by making the read signal in the antiferromagnetic layer composed of a first antiferromagnetic material having macroscopically broken time reversal symmetry exhibit a linear response to the magnetic field within a predetermined magnetic field range including zero magnetic field, it is possible to provide a magnetic sensor element with excellent response characteristics.

[0078] Next, refer to Figure 16 The magnetic sensor system is described below. The magnetic sensor system 2000 is a Hall element array, containing multiple magnetic sensor elements 100 (…). Figure 4 The Hall elements in the matrix are configured as an M×N matrix and connected as M parallel and N series (M and N are positive integers).

[0079] The electrodes 18b of the M magnetic sensor elements 100 in the first column are interconnected (connection point denoted as P), and the electrodes 18a of the M magnetic sensor elements 100 in the Nth column are interconnected (connection point denoted as Q). The electrodes 17a of the M magnetic sensor elements 100 in the first column are interconnected, and the electrodes 17b of the M magnetic sensor elements 100 in the Nth column are interconnected.

[0080] In each row, electrodes 18a and 18b of two adjacent magnetic sensor elements 100 are connected. Thus, the Hall voltages generated in the N magnetic sensor elements 100 in each row are summed. Additionally, in each row, electrodes 17b and 17a of two adjacent magnetic sensor elements 100 are connected. Thus, the same current flows through the N magnetic sensor elements 100 in each row. If the current flows in the +x direction, then the current I... + There are M branches, and in each row, the branch current flows through N magnetic sensor elements 100. The M branch currents combine to form a current I. － The potential V at point P can be calculated. + With respect to the potential V at point Q － The difference between them is used to determine the magnetic field.

[0081] Alternatively, in the magnetic sensor system 2000, the magnetic sensor element 100 can be replaced by... Figure 1B , Figure 8A , Figure 8B , Figures 11A to 14 Other magnetic sensor elements are shown.

[0082] In the case of using magnetic sensor elements with a bias layer in the magnetic sensor system 2000, although there is a deviation in the exchange bias of each magnetic sensor element, by arranging multiple magnetic sensor elements, it is expected that the deviation in exchange bias can be eliminated without changing the overall resistance value of the system.

[0083] This invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of this invention.

[0084] For example, although examples of Hall elements for magnetic sensor elements have been shown in the above embodiments, these magnetic sensor elements can also be designed as TMR sensor elements. Explanation of reference numerals in the attached figures

[0085] 10, 30, 220, 230: Base; 12, 222, 232: Heavy metal layer; 14, 34, 224, 234: Antiferromagnetic layer; 16, 26, 36, 226, 236: capping layer; 28, 228, 238: Bias layers; 17a, 17b, 18a, 18b: Electrodes; 100, 102, 200, 202, 204, 206, 208, 210, 300: Magnetic sensor elements; 1000: Magnetic sensor device; 1002: Current supply unit; 1004: Processor; 1006: Memory; 1008: Voltage Detection Unit; 2000: Magnetic sensor system.

Claims

1. A magnetic sensor element, which is used to measure a magnetic field, wherein, include: An antiferromagnetic layer is composed of a first antiferromagnet, wherein the first antiferromagnet has an antiferromagnetic magnetic structure with macroscopically broken time reversal symmetry, and the read signal of the antiferromagnetic layer responds linearly to the magnetic field within a predetermined magnetic field range including zero magnetic field.

2. The magnetic sensor element according to claim 1, wherein, Also includes: The heavy metal layer, in contact with the antiferromagnetic layer, is composed of heavy metals. When current flows in the in-plane direction, it generates a spin current in the direction perpendicular to the surface. In the antiferromagnetic layer, the spin orbital moment generated by the spin current acts on the magnetic order of the first antiferromagnet, thereby controlling the magnetic order.

3. The magnetic sensor element according to claim 2, wherein, The coercivity of the antiferromagnetic layer is reduced by allowing a current exceeding the threshold current that causes the current-induced magnetic rotation of the first antiferromagnet to flow through the heavy metal layer.

4. The magnetic sensor element according to claim 2, wherein, The permeability of the antiferromagnetic layer is controlled based on the current density of the current flowing through the heavy metal layer.

5. The magnetic sensor element according to claim 1, wherein, Also includes: The bias layer, which is in contact with the antiferromagnetic layer, is composed of a second antiferromagnet, which is different from the first antiferromagnet, and causes an exchange bias with the first antiferromagnet.

6. The magnetic sensor element according to claim 1, wherein, The antiferromagnetic layer is a granular layer.

7. The magnetic sensor element according to claim 1, wherein, The antiferromagnetic layer is a continuous film with a thickness of less than 10 nm.

8. The magnetic sensor element according to claim 1, wherein, The antiferromagnetic layer is a single crystal film or an epitaxial film.

9. The magnetic sensor element according to claim 1, wherein, The antiferromagnetic layer is a polycrystalline film.

10. The magnetic sensor element according to claim 1, wherein, The first antiferromagnet is a non-collinear antiferromagnet.

11. The magnetic sensor element according to claim 1, wherein, The antiferromagnetic layer exhibits an anomalous Hall effect. The readout signal from the antiferromagnetic layer is a signal based on the anomalous Hall effect.

12. A magnetic sensor device, wherein, include: The magnetic sensor element according to claim 2; The current supply unit supplies power to the magnetic sensor element; as well as The processor processes the readout signal from the antiferromagnetic layer of the magnetic sensor element.

13. The magnetic sensor device according to claim 12, wherein, The current supply unit alternately and repeatedly supplies positive and negative current to the heavy metal layer. The processor calculates the difference between a first read signal from the antiferromagnetic layer when a positive current is supplied to the heavy metal layer and a second read signal from the antiferromagnetic layer when a negative current is supplied to the heavy metal layer.

14. The magnetic sensor device according to claim 12, wherein, The current supply unit alternately and repeatedly supplies a first current and a second current to the heavy metal layer, wherein the first current is greater than the critical current density that imparts maximum permeability, and the second current is less than the critical current density. The processor calculates the difference between a first read signal from the antiferromagnetic layer when the first current is supplied to the heavy metal layer and a second read signal from the antiferromagnetic layer when the second current is supplied to the heavy metal layer.

15. A magnetic sensor system comprising a plurality of magnetic sensor elements arranged thereon, wherein, Each of the plurality of magnetic sensor elements is defined as a magnetic sensor element according to any one of claims 1 to 11.

16. A method for manufacturing a magnetic sensor element according to claim 1, wherein, A multilayer film is formed, the multilayer film comprising at least a substrate made of an insulator, a capping layer made of an oxide, and an antiferromagnetic layer disposed between the substrate and the capping layer. After the multilayer film is formed, the multilayer film is annealed.

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