Magnetic Sensor

Abstract

The object is to provide a magnetic sensor that can measure small magnetic fields with high accuracy and also contribute to miniaturization. [Solution] A magnetic sensor 1 is characterized by including a variable magnetic field detection unit 100a having a magnetoresistance effect element 10a having a first layer 13 that can be magnetized in a direction along a measurement magnetic field, a second layer 11 that can maintain the magnetization direction in a first direction (X direction), and a nonmagnetic layer 12 located between the first layer 13 and the second layer 11, and a magnetization control unit 20 that reversibly reverses the direction of magnetization 11m of the second layer 11, in which the magnetization control unit 20 may be a magnetization control unit 201 whose magnetization direction is reversed by energization, or may have a spin torque generation unit 21 and an anisotropy variable unit 22. The magnetization control unit 20 may have the spin torque generation unit 21 and the second layer 11 may be a variable second layer 111, or the second layer 11 may be integrated with the magnetization control unit 20 to be a current-variable second layer 112.

Description

[Technical field]

[0001] The present invention relates to a magnetic sensor equipped with a magnetoresistive effect element. [Background technology]

[0002] Some magnetic sensors that detect and measure magnetic fields are equipped with a magnetoresistance effect element that uses the GMR (giant magnetoresistance) effect or the TMR (tunneling magnetoresistance) effect. The magnetoresistance effect element in these magnetic sensors has a structure in which a fixed magnetic layer, a non-magnetic intermediate layer, and a free magnetic layer are laminated in this order. In the magnetoresistance effect element, when an external magnetic field to be measured is applied, the magnetization direction of the free magnetic layer changes, and a resistance change occurs according to the angle between the magnetization direction of the free magnetic layer and the magnetization direction of the fixed magnetic layer. A magnetic sensor equipped with a magnetoresistance effect element can detect a magnetic field using the resistance change of the magnetoresistance effect element.

[0003] Magnetic sensors equipped with magnetoresistance effect elements have 1 / f noise that cannot be removed by filters. 1 / f noise is inversely proportional to frequency and becomes larger as the frequency decreases, so it can be an obstacle to high-precision measurements. For this reason, various methods are used to remove 1 / f noise.

[0004] Patent Document 1 discloses an even-function magnetic sensor that removes 1 / f noise by taking the difference between the output when a bias magnetic field is applied in a certain direction (+X direction) and the output when a bias magnetic field is applied in the opposite direction (-X direction).

[0005] Patent Document 2 discloses a measuring device that, when measuring the Hall electromotive force of a semiconductor sample, shifts the frequency band of the voltage difference Vm to the lower frequency side in order to remove noise caused by a Schottky barrier that occurs between an electrode and a sample, thereby removing the frequency band of the voltage difference Vm that is significantly affected by 1 / f noise.

[0006] Patent document 3 discloses a magnetic field sensing device that samples bridge signals at a first current and a second current by switching between two sample holds, and determines the value of the magnetic field from the difference between the sampled first and second bridge signals.

[0007] Patent Document 4 discloses a sensor device that uses a modulator to switch the positive and negative sides of a sensor signal and obtain a difference between the modulated signals in order to remove 1 / f noise from the output signal. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2018-115972 A [Patent Document 2] JP 2020-148727 A [Patent Document 3] Special Publication No. 2012-518788 [Patent Document 4] Special Publication No. 2009-544004 Summary of the Invention [Problem to be solved by the invention]

[0009] There is a strong demand for improving the resolution (magnetic resolution) of magnetic sensors equipped with magnetoresistance effect elements, and various devices and methods have been proposed to meet this demand. The present invention aims to provide a magnetic sensor equipped with a magnetoresistance effect element that can measure small magnetic fields with high accuracy using a configuration different from that of the conventional one. [Means for solving the problem]

[0010] In one aspect, the present invention is a magnetic sensor characterized by comprising a magnetoresistive element having a first layer that can be magnetized in a direction along a measurement magnetic field, a second layer that can maintain its magnetization along a first direction, and a non-magnetic layer located between the first layer and the second layer, and a variable magnetic field detection unit having a magnetization control unit that reversibly reverses the magnetization of the second layer.

[0011] In a magnetoresistance effect element according to the prior art, when measuring an external magnetic field to be measured, one of the two magnetic layers becomes a magnetization fixed layer and the direction of magnetization is fixed, but in a magnetic sensor according to an embodiment of the present invention, the external magnetic field is measured in two states: a state (first state) in which the magnetization of the second layer corresponding to this magnetization fixed layer is fixed in one direction, and a state (second state) in which the magnetization of the second layer is fixed in the opposite direction (anti-parallel) to the first state. By taking the difference between the electric signals including the measurement results in each state, highly accurate measurement is possible.

[0012] The above magnetic sensor may further include a magnetic field calculation unit that calculates the measured magnetic field based on a first output from the variable magnetic field detection unit when the magnetization of the second layer is in one direction of the first direction and a second output from the variable magnetic field detection unit when the magnetization of the second layer is in the other direction of the first direction.

[0013] When there is a correlation between noise contained in the electrical signal based on the first output and the electrical signal based on the second output, the noise signal, particularly 1 / f noise, can be removed by taking the difference between these electrical signals.

[0014] In the above magnetic sensor, the variable magnetic field detection unit has a first variable magnetic field detection unit and a second variable magnetic field detection unit connected in series, each of which has the magnetoresistive element and the magnetization control unit, and is controlled so that the second layers are magnetized in opposite directions to each other, and an output unit that outputs an electrical signal related to the potential between the first variable magnetic field detection unit and the second variable magnetic field detection unit connected in series, and the first variable magnetic field detection unit and the second variable magnetic field detection unit are controlled so that their respective second layers are magnetized in opposite directions to each other, and further includes a magnetic field calculation unit that performs arithmetic processing using the electrical signal from the output unit as an input and calculates the measured magnetic field, and the arithmetic processing may include calculating a difference between a first electrical signal output from the output unit when the magnetization of the second layer of the first variable magnetic field detection unit is in one direction of the first direction, and a second electrical signal output from the output unit when the magnetization of the second layer of the first variable magnetic field detection unit is in the other direction of the first direction.

[0015] In a measurement using a full-bridge circuit, which is one method for achieving high-precision measurement, four magnetoresistance effect elements must be prepared in one magnetic sensor. In order to achieve high-precision measurement, it is necessary that the characteristics of these four magnetoresistance effect elements are as equal as possible. Since the magnetization of the second layer of the magnetoresistance effect element of the magnetic sensor according to the present invention can be reversed by the magnetization control unit, it is possible to output two types of electric signals related to the midpoint potential output from the full-bridge circuit from a half-bridge circuit in which two magnetoresistance effect elements are connected in series, and therefore the magnetic sensor can be made smaller in size. Moreover, since two types of electric signals can be obtained with fewer magnetoresistance effect elements than in a full-bridge circuit, it is expected that the homogeneity of the magnetoresistance effect elements will be higher than that of a full-bridge circuit, and the measurement accuracy will be higher.

[0016] In the above magnetic sensor, the magnetization control unit may have a spin torque generation unit that generates a spin orbit torque when current is applied, and the magnetization of the second layer may be reversibly reversed based on the spin orbit torque from the spin torque generation unit.

[0017] In the case where the magnetization control unit has the above-mentioned spin torque generation unit, the magnetization control unit has an anisotropy variable unit that can reversibly reverse magnetization based on the spin orbit torque from the spin torque generation unit, and the anisotropy variable unit may be magnetically coupled to the second layer, and further, the anisotropy variable unit may have a portion made of an antiferromagnetic material.

[0018] In the case where the above-mentioned spin torque generation unit is included, the second layer may be a variable second layer having a portion whose magnetization can be reversibly reversed based on the spin-orbit torque from the spin torque generation unit, and the variable second layer may have a portion made of an antiferromagnetic material.

[0019] In the above magnetic sensor, the second layer may be a variable current-carrying second layer that is integrated with the magnetization control section and has a portion made of an antiferromagnetic material whose magnetization can be reversibly reversed when a current is applied.

[0020] In the above magnetic sensor, the magnetization control section may be an electromagnetization control section capable of reversibly inverting magnetization by energization. Effect of the Invention

[0021] According to the present invention, a magnetic sensor with high magnetic resolution is provided, and the present invention also contributes to further miniaturization of the magnetic sensor. [Brief description of the drawings]

[0022] [Figure 1] 1 is a block diagram of a magnetic sensor according to an embodiment of the present invention; [Diagram 2] 1 is an explanatory diagram (first state) of a magnetic field detection portion included in a magnetic sensor according to an embodiment of the present invention. [Diagram 3] 3A to 3C are diagrams illustrating an example of a variable magnetic field detection unit included in the magnetic sensor according to the first embodiment of the present invention. [Figure 4] 3A to 3C are diagrams illustrating a first state of an example of a variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention. [Diagram 5]5A to 5C are diagrams illustrating a second state of an example of a variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention. [Figure 6] 4 is a flowchart illustrating a first measurement method using the magnetic sensor according to the first embodiment of the present invention. [Figure 7] 4 is an explanatory diagram (second state) of a magnetic field detection portion included in the magnetic sensor according to the embodiment of the present invention. FIG. [Figure 8] 5A to 5C are diagrams illustrating another example of the variable magnetic field detection unit included in the magnetic sensor according to the first embodiment of the present invention. [Figure 9] 5A to 5C are diagrams illustrating a first state of another example of a variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention. [Figure 10] 10A to 10C are diagrams illustrating a second state of another example of the variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention. [Figure 11] 5A to 5C are diagrams illustrating modified examples of the variable magnetic field detection unit included in the magnetic sensor according to the first embodiment of the present invention. [Figure 12] 10A to 10C are diagrams illustrating an example of a variable magnetic field detection unit included in a magnetic sensor according to a second embodiment of the present invention. [Figure 13] 13A to 13C are diagrams illustrating an example of a variable magnetic field detection unit included in a magnetic sensor according to a third embodiment of the present invention. [Figure 14] 5A to 5C are diagrams illustrating a second measurement method (first state) using the magnetic sensor according to the first embodiment of the present invention. [Figure 15] 5A to 5C are diagrams illustrating a second measurement method (second state) using the magnetic sensor according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In each drawing, the same components are given the same reference numerals and the description will be omitted. In order to show the positional relationship of each component, reference coordinates are appropriately shown in each drawing.

[0024] Fig. 1 is a block diagram of a magnetic sensor according to an embodiment of the present invention. Fig. 2 is an explanatory diagram of a magnetic field detection unit provided in the magnetic sensor according to an embodiment of the present invention. In Fig. 2, variable magnetic field detection units 100a, 100b, 100c, and 100d of the magnetic field detection unit 2 are in a first state (details will be described later). The magnetic sensor 1 of this embodiment includes the magnetic field detection unit 2, a control power supply 3, a magnetic field calculation unit 4, an amplifier 5, an analog-digital conversion circuit (A / D conversion circuit 6), and a control unit 7. The control unit 7 controls each unit constituting the magnetic sensor 1, and is configured as a CPU (central processing unit), a program, etc.

[0025] The magnetic field detection unit 2 detects an external magnetic field (measurement magnetic field H) to be measured. As shown in Fig. 2, the magnetic field detection unit 2 is configured with a full bridge circuit 15 having magnetoresistance effect elements 10a, 10b, 10c, and 10d for measuring a magnetic field along the X direction. In this embodiment, the magnetic field detection unit 2 has variable magnetic field detection units 100a, 100b, 100c, and 100d corresponding to the magnetoresistance effect elements 10a, 10b, 10c, and 10d, respectively. The control power supply 3 applies a predetermined current or a predetermined voltage to each unit based on a control signal from the control unit 7.

[0026] The magnetic field calculation unit 4 calculates the measured magnetic field H based on the output of the magnetic field detection unit 2, and is composed of, for example, a CDS (Correlated Double Sampling) circuit. In one specific example, the magnetic field calculation unit 4 calculates the measured magnetic field H based on a first signal which is an output signal of the magnetic field detection unit 2 when the variable magnetic field detection units 100a, 100b, 100c, and 100d are in a first state, and a second signal which is an output signal of the magnetic field detection unit 2 when the variable magnetic field detection units 100a, 100b, 100c, and 100d are in a second state. For example, a measurement signal from which 1 / f noise has been removed can be obtained by calculating the difference between a signal based on the first signal and a signal based on the second signal.

[0027] In the magnetic sensor 1, after the magnetic field calculation unit 4 calculates the measured magnetic field H, the signal corresponding to the calculated measured magnetic field H is amplified by the amplifier 5 and then converted into digital data by the A / D conversion circuit 6.

[0028] The four magnetoresistance effect elements 10a, 10b, 10c, and 10d included in the magnetic field detection unit 2 of the magnetic sensor 1 according to one embodiment of the present invention may be provided on the same substrate (one chip). In this embodiment, the four magnetoresistance effect elements 10a, 10b, 10c, and 10d are provided on the same substrate (not shown), and FIG. 2 is a view of the magnetic field detection unit 2 of the magnetic sensor 1 as viewed from the stacking surface (front surface) side of the substrate in the normal direction of the substrate. That is, in FIG. 2, the Z1 side is the front surface side of the substrate, and the Z2 side is the back surface side of the substrate. The Z direction is along the stacking direction of the magnetoresistance effect elements 10a, 10b, 10c, and 10d.

[0029] The magnetic field detection unit 2 has a full bridge circuit 15 in parallel connected between a power supply terminal Vdd, which is a power supply point, and a ground terminal GND. The full bridge circuit is made up of a first half bridge circuit in which a magnetoresistance effect element 10a and a magnetoresistance effect element 10b, both of which extend in the Y direction, are connected in series, and a second half bridge circuit in which a magnetoresistance effect element 10c and a magnetoresistance effect element 10d, both of which extend in the Y direction, are connected in series.

[0030] The first half-bridge circuit has an output terminal V1 between the magnetoresistance effect element 10a and the magnetoresistance effect element 10b. The second half-bridge circuit has an output terminal V2 between the magnetoresistance effect element 10c and the magnetoresistance effect element 10d. The magnitude of the external magnetic field applied from the outside as the measurement magnetic field H can be quantitatively measured by the potential difference (midpoint potential Va of the first half-bridge circuit-midpoint potential Vb of the second half-bridge circuit) between these two output terminals V1 and V2. In this embodiment, the magnetic field detection unit 2 outputs a first signal including the midpoint potential Va from the output terminal V1 and a second signal including the midpoint potential Vb from the output terminal V2, and the process performed by the magnetic field calculation unit 4 includes calculating the midpoint potential difference using these first and second signals as inputs.

[0031] In a pair of magnetoresistance effect elements 10a, 10b forming a first half-bridge circuit, the second layer 11 (see FIG. 3), which corresponds to the "fixed magnetic layer" of the magnetoresistance effect element according to the conventional technology, can maintain the magnetization 11m in a predetermined direction even when subjected to a measurement magnetic field H within the measurement range. Specifically, the magnetization 11m of the second layer 11 is oriented in the X2 direction (magnetoresistance effect element 10a) and the X1 direction (magnetoresistance effect element 10b) as shown by the white arrows in FIG. 2. In addition, in a pair of magnetoresistance effect elements 10c, 10d forming a second half-bridge circuit, the magnetization 11m of the second layer 11 is oriented in the X1 direction (magnetoresistance effect element 10c) and the X2 direction (magnetoresistance effect element 10d) as shown by the white arrows in FIG. 2.

[0032] In the first half-bridge circuit and the second half-bridge circuit, the magnetization 11m of the second layer 11 of the magnetoresistance effect element 10b on the power supply terminal Vdd side and the magnetoresistance effect element 10d is opposite (anti-parallel). Also, the magnetization 11m of the second layer 11 of the magnetoresistance effect element 10a on the ground terminal GND side and the magnetoresistance effect element 10c is opposite (anti-parallel). Therefore, the sensitivity axis direction of the magnetoresistance effect elements 10a, 10b, 10c, and 10d is the X direction (X1-X2 direction), which is also referred to as the "first direction" in this specification. Also, the Z direction (Z1-Z2 direction) is also referred to as the "second direction", and the Y direction (Y1-Y2 direction) is also referred to as the "third direction".

[0033] In the four magnetoresistance effect elements 10a, 10b, 10c, and 10d, the magnetization 13m of the first layer 13 (see FIG. 3), which corresponds to the "free magnetic layer" of the magnetoresistance effect element according to the conventional technology, is directed in the same direction, along the Y direction Y2 direction (hereinafter abbreviated as "Y2 direction"; the same applies to other directions), as indicated by the black arrow in FIG. 3. When the first layer 13 receives the measurement magnetic field H in the first direction (X direction), it can be magnetized in the direction along the measurement magnetic field H. There is no limitation on the method for aligning the magnetization 13m of the first layer 13 in the state in which the measurement magnetic field H is not applied. A bias magnetic field or an induced magnetic field may be applied from the outside, or exchange coupling with an antiferromagnetic layer that interacts with the first layer 13 may be used.

[0034] With the above-mentioned configuration, the output from the output terminal V1 from the first half-bridge circuit and the output terminal V2 from the second half-bridge circuit change in the opposite direction as the magnitude of the measured magnetic field H in the X direction changes. Therefore, a large output is obtained as the potential difference (Va-Vb) between the two output terminals V1 and V2. Therefore, the magnetic sensor 1 can detect the measured magnetic field H with high accuracy. Note that the first half-bridge circuit or the second half-bridge circuit can be used instead of the full-bridge circuit 15, or the magnetoresistance effect element 10a can be used alone.

[0035] 2, the magnetic sensor 1 according to this embodiment includes variable magnetic field detection units 100a, 100b, 100c, and 100d that correspond to the magnetoresistance effect elements 10a, 10b, 10c, and 10d, respectively, and measure the measurement magnetic field H by reversing the magnetization 11m of the second layer 11. Hereinafter, the variable magnetic field detection unit 100a will be described as a specific example.

[0036] (First embodiment) Fig. 3 is a diagram illustrating an example of a variable magnetic field detection unit included in the magnetic sensor according to the first embodiment of the present invention. Fig. 4 is a diagram illustrating a first state of the example of the variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention. Fig. 5 is a diagram illustrating a second state of the example of the variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention.

[0037] The variable magnetic field detection unit 100a has a first layer 13 that can be magnetized in a direction along the measurement magnetic field H, a second layer 11 that can maintain a state in which magnetization 11m is aligned with the first direction (X direction) in Figure 3, and a non-magnetic layer 12 located between the first layer 13 and the second layer 11, and comprises a magnetoresistance effect element 10a that exhibits a magnetoresistance effect, and a magnetization control unit 20 that reversibly reverses the magnetization 11m of the second layer 11.

[0038] The components of the magnetoresistance effect element 10a are stacked in the second direction (Z direction), and as described above, the first layer 13 corresponds to the "free magnetic layer" in a magnetoresistance effect element according to the conventional technology, and the second layer 11 corresponds to the "pinned magnetic layer" in a magnetoresistance effect element according to the conventional technology. By detecting the resistance value caused by the deviation in the magnetization directions of these layers sandwiching the nonmagnetic layer 12, the strength of the measurement magnetic field H applied to the first layer 13 can be measured.

[0039] The second layer 11 of the magnetoresistive effect element 10a provided in the variable magnetic field detection unit 100a of the magnetic sensor 1 of this embodiment is different from the ``fixed magnetic layer'' of the magnetoresistive effect element of the conventional technology in that the magnetization 11m of the second layer 11 maintains a state along a predetermined direction in the first direction even when subjected to a measurement magnetic field H within the measurement range of the magnetoresistive effect element 10a, but can be reversed by the magnetization control unit 20.

[0040] The second layer 11 is made of a magnetic material such as a CoFe alloy (cobalt-iron alloy). When the magnetoresistance effect element 10a is a tunnel magnetoresistance effect element (TMR), the nonmagnetic layer 12 is an insulating barrier layer made of, for example, MgO, Al2O3, titanium oxide, or the like. The first layer 13 is made of a soft magnetic material such as a CoFe alloy or a NiFe alloy (nickel-iron alloy). The second layer 11 and the first layer 13 may have a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, it may be preferable to have a laminated ferrimagnetic structure. When the magnetoresistance effect element 10a is a giant magnetoresistance effect element (GMR), a nonmagnetic material such as Cu is used as a constituent material of the nonmagnetic layer 12. In this embodiment, the first layer 13 is located on the Z1 side of the magnetoresistance effect element 10a, and the detection center 10P of the magnetoresistance effect element 10a is located at the center of the first layer 13.

[0041] The magnetoresistance effect element 10a of the variable magnetic field detection unit 100a according to this embodiment is composed of a tunnel magnetoresistance effect element (TMR) as a specific example, and measurement wiring 62 is provided so that a voltage from a measurement voltage source V is applied in the second direction (Z direction) between the first layer 13 and the second layer 11 of the magnetoresistance effect element 10a for the purpose of measuring the electrical characteristics of the magnetoresistance effect element 10a. Note that in this embodiment, the magnetoresistance effect element 10a and the magnetization control unit 20 are stacked in the second direction (Z direction), and the magnetization control unit 20 is made of a material having electrical conductivity, so that the measurement wiring 62 is provided so that the voltage from the measurement voltage source V is applied to the first layer 13 via the magnetization control unit 20.

[0042] In the variable magnetic field detection unit 100 a according to this embodiment, the magnetization control unit 20 includes a spin torque generation unit 21 and an anisotropy variable unit 22 .

[0043] The spin torque generator 21 generates a spin orbit torque when energized, and the magnetization 11m of the second layer 11 is reversed based on the spin orbit torque from the spin torque generator 21. In this embodiment, the spin induced torque generated in the spin torque generator 21 affects the anisotropy variable section 22, and the magnetization 20m of the anisotropy variable section 22 is aligned in a predetermined direction. Since the anisotropy variable section 22 is magnetically connected to the second layer 11, the second layer 11 is magnetized to follow the magnetization 20m of the anisotropy variable section 22.

[0044] When a current is applied to the spin torque generation unit 21 in the XY in-plane direction, the spin Hall effect, the Rashba-Edelstein effect, and the like are generated, and a spin orbit torque is applied to the anisotropy variable unit 22. Materials constituting the spin torque generation unit 21 include heavy metals (5d transition metals) such as Hf, Ta, W, Pt, and Ir, which have a high specific gravity among paramagnetic transition metals; topological insulators such as BiSb, BiSe, Bi2Se3, and Bi2Te3, Mn3X (X=Sn, Ge, Ga, RH, Pt, Ir), Mn 1-x Tr x Examples include antiferromagnetic materials such as gamma-phase (Tr = Ni, Fe, Cu, Ru, Pd, Ir, RH, Pd, Pt); half-Heusler alloy topological semimetals such as LuPtSb, LuPdBi, LuPtBi, ScPtBi, YAuPb, LaPtBi, CePtBi, THPtPb, and LaAuPb, as well as mixed crystals of these.

[0045] In a specific example shown in FIG. 3, the spin torque generation unit 21 is a film-like body, and this film-like body may be composed of a single structure, that is, a single layer film, or may be composed of a laminated film. In the case of a laminated film, a boundary region may be generated between adjacent films. The spin torque generation unit 21 may be composed entirely of a single material, or may be composed of multiple materials. In the case of being composed of multiple materials, it may have a laminated structure as described above, or may have a dispersed structure. In the case of having a dispersed structure, the degree of dispersion is arbitrary, and it may be a structure in which nanocrystals are dispersed, or a certain pattern may be formed. In addition, a compositional distribution may be set in the spin torque generation unit 21.

[0046] The anisotropy variable section 22 can reversibly reverse its magnetization 20m based on the spin orbit torque from the spin torque generator 21. In addition, since the anisotropy variable section 22 is magnetically coupled to the second layer 11 of the magnetoresistance effect element 10a, the magnetization 11m of the second layer 11 is reversed based on the spin orbit torque from the spin torque generator 21. The anisotropy variable section 22 may be made of a single material or a plurality of materials, similar to the spin torque generator 21. When made of a plurality of materials, it may have a dispersed structure, or a compositional distribution may be set in the anisotropy variable section 22.

[0047] The anisotropy variable part 22 may be made of any material as long as it performs this magnetization reversal function. It may be made of a ferromagnetic material like the second layer 11, or may be made of an antiferromagnetic material. Specific examples of antiferromagnetic materials include at least some of the materials constituting the spin torque generating part 21 described above. When the anisotropy variable part 22 includes an antiferromagnetic material, a magnetic field may be generated inside the anisotropy variable part 22 based on a physical phenomenon different from the magnetization when the anisotropy variable part 22 includes a ferromagnetic material (e.g., a virtual magnetic field). Therefore, in this specification, the concept of the term "magnetization" related to the anisotropy variable part 22 and the like also includes the generation of a magnetic field inside the anisotropy variable part 22 based on a physical phenomenon different from the magnetization of such a ferromagnetic material.

[0048] (First state) 4 is a state in which a first signal is output from the variable magnetic field detection unit 100a. In this example, the control wiring 61 is provided so that a current (control current 20c) from the control current source I is applied to the spin torque generation unit 21 in the X1-X2 direction.

[0049] In the first state, the control current 20c of the spin torque generator 21 is oriented in the X2 direction, and the magnetization 11m of the second layer 11 is oriented in the X1 direction. A current flowing through the spin torque generator 21 generates a spin current 20s1 in the Z direction in the spin torque generator 21, and spins oriented in a predetermined direction are injected into the anisotropy variable unit 22 from the Z direction Z1 side of the spin torque generator 21. The magnetization 20m of the anisotropy variable unit 22 is oriented in the X1 direction by the spin orbit torque based on the injected spin. From the viewpoint of improving the controllability of the direction of the magnetization 20m of the anisotropy variable unit 22 by the injected spin, it may be preferable that a magnetic field in the Z direction (second direction) is applied to the magnetization controller 20. The method of applying the magnetic field is not limited, and specific examples include arranging a permanent magnet or an electromagnet in the vicinity of the variable magnetic field detector 100a, and providing an antiferromagnetic body capable of generating a magnetic field based on exchange coupling.

[0050] Since the anisotropy variable part 22 and the second layer 11 are magnetically coupled, the magnetization 11m of the second layer 11 is also oriented in the X1 direction.

[0051] Therefore, in the first state, the magnetization 11m of the second layer 11 of the magnetoresistance effect element 10a is fixed in the X1 direction. In this state, the variable magnetic field detection unit 100a measures the measurement magnetic field H, and outputs a first output.

[0052] (Second state) The second state shown in FIG. 5 is a state in which the second signal is output from the variable magnetic field detection unit 100a. In the second state, the control current 20c of the spin torque generation unit 21 is set to the X1 direction, and the magnetization 11m of the second layer 11 is set to the X2 direction. The spin current 20s2 generated in the spin torque generation unit 21 by this current has a spin orientation opposite to that of the spin current 20s1 shown in FIG. 4. Therefore, the spin injected from the spin torque generation unit 21 to the anisotropy variable unit 22 is oriented in the opposite direction to that in the first state. Therefore, the magnetization 20m of the anisotropy variable unit 22 oriented by the spin orbit torque based on the injected spin becomes the opposite direction (X2 direction) to that in the first state. That is, the magnetization reversal of the anisotropy variable unit 22 occurs by reversing the control current 20c of the spin torque generation unit 21. And, since the anisotropy variable unit 22 and the second layer 11 are magnetically coupled, the magnetization 11m of the second layer 11 also becomes the X2 direction.

[0053] Therefore, in the second state, the magnetization 11m of the second layer 11 of the magnetoresistance effect element 10a is fixed in the X2 direction. In this state, the variable magnetic field detection unit 100a measures the measurement magnetic field H, and thereby outputs a second output.

[0054] (First measurement method) FIG. 6 is a flow chart for explaining a first measurement method using the magnetic sensor according to the first embodiment of the present invention. In the first measurement method, as shown in FIG. 6, first, as a first measurement step, a control signal output from the control unit 7 causes the control power supply 3 to output a signal for setting the variable magnetic field detection units 100a, 100b, 100c, and 100d included in the magnetic field detection unit 2 to the first state. Specifically, the direction of the current flowing through the spin torque generation unit 21 of the magnetization control unit 20 is set to a predetermined direction. In the magnetic field detection unit 2 shown in FIG. 2, the directions of the magnetizations 11m of the second layers 11 of the four magnetoresistance effect elements 10a, 10b, 10c, and 10d in the first state are indicated by white arrows.

[0055] In this way, the variable magnetic field detectors 100a, 100b, 100c, and 100d are set in the first state, and the magnetoresistance effect elements 10a, 10b, 10c, and 10d measure the measured magnetic field H, and the first output is obtained from each of the variable magnetic field detectors 100a, 100b, 100c, and 100d. These signals cause the magnetic field detector 2 to output a first signal (a signal including a midpoint potential Va from the output terminal V1) and a second signal (a signal including a midpoint potential Vb from the output terminal V2) (step S101). These two signals output from the magnetic field detector 2 are input to the magnetic field calculator 4, and are stored in the magnetic field calculator 4 or in a memory (not shown) as data indicating these signals, or as data indicating a midpoint potential difference signal, which is the difference between the two signals.

[0056] Next, as a second measurement step, a control signal output from the control unit 7 causes the control power supply 3 to output a signal for setting the variable magnetic field detection units 100a, 100b, 100c, and 100d included in the magnetic field detection unit 2 to the second state. Specifically, the direction of the current flowing through the spin torque generation unit 21 of the magnetization control unit 20 is set to the opposite direction to that in the first state. FIG. 7 is an explanatory diagram (second state) of the magnetic field detection unit included in the magnetic sensor according to one embodiment of the present invention. In the magnetic field detection unit 2 shown in FIG. 7, the directions of magnetization 11m of the second layers 11 of the four magnetoresistance effect elements 10a, 10b, 10c, and 10d in the second state are indicated by white arrows, and these magnetizations are opposite to those in the first state.

[0057] In this way, the variable magnetic field detectors 100a, 100b, 100c, and 100d are set to the second state, the magnetoresistance effect elements 10a, 10b, 10c, and 10d measure the measurement magnetic field H, and the variable magnetic field detectors 100a, 100b, 100c, and 100d each obtain a second output. These signals cause the magnetic field detector 2 to output a first signal and a second signal (step S102). The measurement times of steps S101 and S102 are both sufficiently shorter than 1 microsecond (e.g., 0.01 microseconds), and the time required for steps S101 and S102 is also sufficiently shorter than 1 microsecond (e.g., 0.03 microseconds). For this reason, steps S101 and S102 are performed in an environment in which the 1 / f noise is substantially equal, and the 1 / f noise included in the first output and the 1 / f noise included in the second output are substantially equal. The two signals output from the magnetic field detection unit 2 are input to the magnetic field calculation unit 4 and stored in the magnetic field calculation unit 4 or in a memory not shown as data indicating those signals, or as data indicating a signal of the midpoint potential difference, which is the difference between the two signals.

[0058] Next, the magnetic field calculation unit 4 reads out the data stored in the magnetic field calculation unit 4 or a memory (not shown) in steps S101 and S102, and performs a process of calculating the difference between a signal based on the first output (a signal including the midpoint potential difference in the first state) and a signal based on the second output (a signal including the midpoint potential difference in the second state) as a magnetic field calculation step (step S103). Note that, when the data stored in the magnetic field calculation unit 4 or a memory (not shown) indicates the first signal and the second signal before calculating the midpoint potential difference, the magnetic field calculation unit 4 performs a process of calculating the difference between the first signal and the second signal in the first state to obtain a signal including the midpoint potential difference in the first state, and a process of calculating the difference between the first signal and the second signal in the second state to obtain a signal including the midpoint potential difference in the second state, and further performs a process of calculating the difference between these two signals including the midpoint potential differences as a magnetic field calculation step.

[0059] By performing the above process by the magnetic field calculation unit 4, a measurement signal from which 1 / f noise has been appropriately removed is obtained. This measurement signal is amplified by the amplifier 5 and converted into a digital signal by the A / D conversion circuit 6. Therefore, since the measurement signal obtained by the measurement method using the magnetic sensor 1 according to this embodiment has 1 / f noise appropriately removed, the resolution (magnetic resolution) of the signal based on the measured magnetic field H is higher than that of the signal based on the first output (signal including the midpoint potential difference in the first state) and the signal based on the second output (signal including the midpoint potential difference in the second state).

[0060] In this embodiment, since the magnetic field detection unit 2 has a full bridge circuit 15, the signals to be processed to find the difference in the magnetic field calculation unit 4 are the signal of the midpoint potential difference in the first state based on the first output and the signal of the midpoint potential difference in the second state based on the second output, but the signals to be processed by the magnetic field calculation unit 4 are appropriately set according to the output signal from the magnetic field detection unit 2. For example, when the magnetic field detection unit 2 has only one variable magnetic field detection unit 100a, the magnetic field calculation unit 4 finds the difference between the first signal and the second signal from the variable magnetic field detection unit 100a.

[0061] (Another example of the first embodiment) Fig. 8 is a diagram for explaining another example of a variable magnetic field detection unit included in the magnetic sensor according to the first embodiment of the present invention. Fig. 9 is a diagram for explaining a first state of the other example of the variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention. Fig. 10 is a diagram for explaining a second state of the other example of the variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention.

[0062] In the example shown in FIG. 8, in comparison with the example shown in FIG. 3, the control wiring 61 is provided so that the current from the control current source I is applied to the spin torque generation unit 21 in the Y direction. In the first state, as shown in FIG. 9, the control current 20c is in the Y1 direction, and the magnetization 20m of the anisotropy variable unit 22 is in the X1 direction based on the spin current 20s1 generated thereby. Since the anisotropy variable unit 22 and the second layer 11 are magnetically coupled, in the first state, the magnetization 11m of the second layer 11 is "fixed" in the X1 direction. On the other hand, in the second state, as shown in FIG. 10, the control current 20c is in the Y2 direction, and the magnetization 20m of the anisotropy variable unit 22 is in the X2 direction based on the spin current 20s2 generated thereby, which is opposite to the first state. Since the anisotropy variable part 22 and the second layer 11 are magnetically coupled, in the second state, the magnetization 11m of the second layer 11 is "fixed" in the X2 direction.

[0063] (Modification of the first embodiment) FIG. 11 is a diagram for explaining a modified example of the variable magnetic field detector included in the magnetic sensor according to the first embodiment of the present invention. In the example shown in FIG. 3 and the like, the magnetization control unit 20 has the spin torque generating unit 21 and the anisotropy variable unit 22, but in the variable magnetic field detection unit 100a according to the modified example shown in FIG. 11, the magnetization control unit 20 is integrated and is composed of the magnetization control unit 201 that can reversibly reverse magnetization by energization. In this case, the control wiring 61 is connected to the magnetization control unit 201, and a current from the control current source I flows through the magnetization control unit 201, thereby generating a spin current 20s1 and setting the direction of the magnetization 20m of the magnetization control unit 201 to a predetermined direction (X1 direction in FIG. 11). As a result, the direction of the magnetization 11m of the second layer 11 magnetically coupled to the magnetization control unit 201 is also fixed to the X1 direction. The magnetization control unit 201 is not limited to being a uniform structure, and may have structural nonuniformity such as a laminated structure or a distributed structure.

[0064] Second embodiment 12 is a diagram for explaining an example of a variable magnetic field detector included in the magnetic sensor according to the second embodiment of the present invention. The variable magnetic field detector 100a of the magnetic sensor 1 according to the second embodiment of the present invention is different from the variable magnetic field detector 100a of the magnetic sensor 1 according to the first embodiment in that it has both the functions of the second layer 11 and the anisotropy variable part 22 of the variable magnetic field detector 100a of the magnetic sensor 1, and has a variable second layer 111 having a part that can be reversibly magnetized based on the spin orbit torque from the spin torque generator 21. In other words, in the variable magnetic field detector 100a of the magnetic sensor 1 according to the second embodiment of the present invention, the second layer 11 of the variable magnetic field detector 100a of the magnetic sensor 1 according to the first embodiment is the variable second layer 111, and the magnetization controller 20 has the spin torque generator 21 but does not have the anisotropy variable part 22.

[0065] The material constituting the variable second layer 111 is not particularly limited as long as the magnetization can be reversibly reversed by the spin ignition torque from the spin torque generation unit 21, and the variable second layer 111 may have a portion made of an antiferromagnetic material such as those exemplified as the constituent materials of the anisotropy variable unit 22. The variable second layer 111 may have a homogeneous structure, or may have a layered structure or a dispersed structure of portions made of different materials. In addition, the variable second layer 111 may have a non-uniform structure in which the composition changes continuously or stepwise.

[0066] The control method of the first state and the second state in the variable magnetic field detector 100a of the magnetic sensor 1 according to the second embodiment of the present invention is the same as that of the variable magnetic field detector 100a of the magnetic sensor 1 according to the first embodiment. That is, the wiring of the control current source I is connected to the spin torque generator 21, and the direction of the magnetization 111m of the variable second layer 111 is set by the direction of the control current 20c flowing to the spin torque generator 21, so that the first output which is the output of the variable magnetic field detector 100a in the first state and the second output which is the output of the variable magnetic field detector 100a in the second state can be obtained by flowing the control current 20c in the opposite directions. Note that FIG. 12 shows the first state as in FIG. 4. In FIG. 12, the control wiring 61 is provided so that the control current 20c applied to the spin torque generator 21 is in the X1 direction or the X2 direction, but is not limited thereto, and the control wiring 61 may be provided so that the control current 20c is in the Y1 direction or the Y2 direction.

[0067] Third embodiment 13 is a diagram illustrating an example of a variable magnetic field detector included in the magnetic sensor according to the third embodiment of the present invention. The variable magnetic field detector 100a of the magnetic sensor 1 according to the third embodiment of the present invention is different from the variable magnetic field detector 100a of the magnetic sensor 1 according to the first embodiment in that it has the functions of the second layer 11 and the magnetization control unit 20 of the variable magnetic field detector 100a of the magnetic sensor 1 according to the first embodiment, in other words, the second layer 11 and the magnetization control unit 20 are integrated, and the current from the control wiring 61 generates a spin orbit torque inside the variable current layer 112 having a part that can be reversibly reversed in magnetization.

[0068] The material constituting the variable current conducting second layer 112 is not particularly limited as long as it is a material whose magnetization can be reversed depending on the direction of current, and the variable current conducting second layer 112 may have a portion made of an antiferromagnetic material such as the example of the material constituting the anisotropy variable part 22. The variable current conducting second layer 112 may have a homogeneous structure, or may have a layered structure or a dispersed structure of portions made of different materials. The variable current conducting second layer 112 may also have a non-uniform structure in which the composition changes continuously or stepwise.

[0069] The control method of the first state and the second state in the variable magnetic field detection unit 100a of the magnetic sensor 1 according to the third embodiment of the present invention is almost the same as that of the variable magnetic field detection unit 100a of the magnetic sensor 1 according to the first embodiment. That is, the wiring of the control current source I is connected to the current variable second layer 112 instead of the spin torque generation unit 21 in the first embodiment, and the direction of the magnetization 112m of the current variable second layer 112 is set by the direction of the control current 20c flowing through the current variable second layer 112, so that the first output which is the output of the variable magnetic field detection unit 100a in the first state and the second output which is the output of the variable magnetic field detection unit 100a in the second state can be obtained by flowing the control current 20c in mutually opposite directions. Note that FIG. 13 shows the first state, as in FIG. 9. In FIG. 13, the control wiring 61 is arranged so that the control current 20c applied to the spin torque generation unit 21 is in the Y1 direction or the Y2 direction, but this is not limited to this, and the control wiring 61 may be arranged so that the control current 20c is in the X1 direction or the X2 direction.

[0070] (Second measurement method) Fig. 14 is a diagram for explaining a second measurement method (first state) using the magnetic sensor according to the first embodiment of the present invention. Fig. 15 is a diagram for explaining a second measurement method (second state) using the magnetic sensor according to the first embodiment of the present invention. In the second measurement method, the flowchart of the measurement method is the same as the flowchart of the first measurement method shown in Fig. 6, but the configuration of the magnetic field detection unit 2A included in the magnetic sensor 1 is different.

[0071] In the second measurement method, as shown in FIG. 14, the magnetic field detection unit 2A has a half-bridge circuit 16. The half-bridge circuit 16 has two variable magnetic field detection units. That is, the half-bridge circuit 16 has a first variable magnetic field detection unit 101 and a second variable magnetic field detection unit 102 connected in series, and an output unit VA that outputs an electrical signal related to the potential between the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 connected in series. The first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 are controlled so that the second layers 11 are magnetized in opposite directions to each other, and in FIG. 14, as shown by the white arrows, the magnetization 11m of the second layer 11 of the first variable magnetic field detection unit 101 is oriented in the X2 direction, and the magnetization 11m of the second layer 11 of the second variable magnetic field detection unit 102 is oriented in the X1 direction. The first layers 13 of the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 are set to be aligned in the same direction when they are not subjected to the measurement magnetic field H. In Fig. 14, as shown by the black arrow, the magnetization 13m of the first layer 13 is set to the Y2 direction when they are not subjected to the measurement magnetic field H. The magnetization direction of the first layer 13 can be set by a bias magnetic field source (permanent magnet, induced magnetic field source, structure that generates exchange coupling) not shown.

[0072] The magnetic field calculation unit 4 performs arithmetic processing using the electrical signal from the output unit VA as an input, and calculates the measured magnetic field H. This arithmetic processing includes finding the difference between a first electrical signal output from the output unit VA when the magnetization 11m of the second layer 11 of the first variable magnetic field detection unit 101 is in a first state in one direction of the first direction, and a second electrical signal output from the output unit VA when the magnetization 11m of the second layer 11 of the first variable magnetic field detection unit 101 is in a second state in the other direction of the first direction.

[0073] Specifically, first, in a first measurement step, a signal for putting the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 included in the magnetic field detection unit 2A into the first state is output from the control power supply 3 in response to a control signal output from the control unit 7. Specifically, the direction of the current flowing through the spin torque generation unit 21 of the magnetization control unit 20 is set to a predetermined direction. In Fig. 14, the directions of the magnetization 11m of the second layer 11 of the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 in the first state are indicated by white arrows.

[0074] In this way, the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 are set in the first state, the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 measure the measurement magnetic field H, and a first electrical signal is obtained from the output unit VA (step S101). The first electrical signal is input to the magnetic field calculation unit 4 and stored in the magnetic field calculation unit 4 or a memory not shown.

[0075] Next, as a second measurement step, a control signal output from the control unit 7 causes the control power supply 3 to output a signal for putting the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 included in the magnetic field detection unit 2A into the second state. Specifically, the direction of the current flowing through the spin torque generation unit 21 of the magnetization control unit 20 is set to the opposite direction to that in the first state. FIG. 15 is an explanatory diagram (second state) of the magnetic field detection unit included in the magnetic sensor according to one embodiment of the present invention. In FIG. 15, the directions of the magnetization 11m of the second layer 11 of the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 in the second state are indicated by white arrows, and these magnetizations 11m are opposite to those in the first state.

[0076] In this way, the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 are put in the second state, the first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 measure the measurement magnetic field H, and a second electric signal is obtained from the output unit VA (step S102). The second electric signal is input to the magnetic field calculation unit 4 and stored in the magnetic field calculation unit 4 or in a memory (not shown).

[0077] Next, the magnetic field calculation unit 4 performs a process of calculating the difference between the first electric signal and the second electric signal stored in the magnetic field calculation unit 4 or a memory (not shown) in steps S101 and S102 as a magnetic field calculation step (step S103). The magnetic field calculation unit 4 performs the above process, and thereby a measurement signal obtained in the full bridge circuit 15 can be obtained using the half bridge circuit 16. Therefore, the magnetic field detection unit 2A of the second measurement method can have a smaller device area than the case where the magnetic field detection unit 2 having the full bridge circuit 15 is used for measurement in the first measurement method.

[0078] In addition, in the full bridge circuit 15, an ideal output is obtained when the electrical characteristics of the four magnetoresistance effect elements 10a, 10b, 10c, and 10d are completely equal, but in reality, since the four elements are manufactured differently, differences in electrical characteristics are unavoidable, and these differences are one of the causes of a decrease in measurement accuracy in the full bridge circuit 15. In contrast, in the second measurement method, the number of elements used for measurement is half compared to the full bridge circuit 15, so that a decrease in measurement accuracy caused by variations in the electrical characteristics of the elements is suppressed. Therefore, by combining the second measurement method with the first measurement method, it is possible to particularly increase the magnetic resolution of the magnetic sensor 1.

[0079] The above-described embodiment is described for the purpose of facilitating understanding of the present invention, and is not described for the purpose of limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. For example, in the above description, the magnetization control unit 20 generates a spin-orbit torque to reverse the magnetization 11m of the second layer 11, but is not limited to this. The magnetization 11m of the second layer 11 may be reversed by a spin transfer torque, and both the spin-orbit torque and the spin transfer torque may contribute to the reversal of the magnetization 11m of the second layer 11. In particular, in the variable second layer 111 and the current-variable second layer 112 that have both the function of the second layer 11 and at least a part of the function of the magnetization control unit 20, both the spin-orbit torque and the spin transfer torque are likely to contribute to the reversal of the magnetization 11m of the second layer 11. [Industrial Applicability]

[0080] The present invention is useful as a magnetic sensor with high magnetic resolution that can detect an external magnetic field with high sensitivity. [Explanation of symbols]

[0081] 1: Magnetic sensor 2, 2A: Magnetic field detection unit 3: Control power supply 4: Magnetic field calculation section 5: Amplifier 6: A / D conversion circuit 7: Control section 10P: Detection center 10a, 10b, 10c, 10d: magnetoresistance effect element 11: 2nd layer 12: Non-magnetic layer 13: 1st layer 15: Full bridge circuit 16: Half-bridge circuit 20: Magnetization control section 21: Spin torque generating unit 22: Anisotropic variable section 61: Control wiring 62: Measurement wiring 100a, 100b, 100c, 100d: Variable magnetic field detection unit 101: First variable magnetic field detection unit 102: Second variable magnetic field detection unit 111: Variable second layer 112: Variable current second layer 20c: Control current 11m, 13m, 20m, 111m, 112m: Magnetization 20s1, 20s2: spin current 201 Electromagnetic control unit GND: Ground terminal H: Measurement magnetic field I: Control current source V: Measurement voltage source V1, V2: Output terminal VA: Output section Vdd: Power supply terminal

Claims

1. a magnetoresistance effect element including a first layer that can be magnetized in a direction along a measurement magnetic field, a second layer that can maintain a state in which magnetization is along a first direction even when the measurement magnetic field is applied, and a non-magnetic layer located between the first layer and the second layer; a magnetization control unit that reversibly reverses the magnetization of the second layer by a spin-orbit torque generated by current application; A magnetic sensor comprising a variable magnetic field detection unit having a variable magnetic field detection section.

2. and a magnetic field calculation unit that calculates the measured magnetic field based on a first output from the variable magnetic field detection unit when the magnetization of the second layer is in one direction of the first direction and a second output from the variable magnetic field detection unit when the magnetization of the second layer is in the other direction of the first direction. The magnetic sensor according to claim 1 .

3. The variable magnetic field detection unit is a first variable magnetic field detection unit and a second variable magnetic field detection unit, each of which has the magnetoresistive element and the magnetization control unit, and which are controlled so that the second layers are magnetized in opposite directions to each other and are connected in series; an output unit that outputs an electrical signal related to a potential between the first variable magnetic field detection unit and the second variable magnetic field detection unit that are connected in series; having the first variable magnetic field detection unit and the second variable magnetic field detection unit are controlled so that the second layers are magnetized in opposite directions to each other; a magnetic field calculation unit that performs arithmetic processing using the electrical signal from the output unit as an input and calculates the measured magnetic field; The magnetic sensor of claim 1, wherein the calculation processing includes calculating a difference between a first electrical signal output from the output section when the magnetization of the second layer of the first variable magnetic field detection section is in one direction of the first direction and a second electrical signal output from the output section when the magnetization of the second layer of the first variable magnetic field detection section is in the other direction of the first direction.

4. 4. The magnetic sensor according to claim 2, wherein the magnetization control unit has a spin torque generation unit that generates the spin orbit torque when current is applied, and the magnetization of the second layer is reversibly reversed based on the spin orbit torque from the spin torque generation unit.

5. The magnetic sensor according to claim 4 , wherein the magnetization control unit has an anisotropy variable unit capable of reversibly reversing magnetization based on the spin orbit torque from the spin torque generation unit, and the anisotropy variable unit is magnetically coupled to the second layer.

6. 6. The magnetic sensor according to claim 5, wherein the anisotropy variable portion has a portion made of an antiferromagnetic material.

7. The magnetic sensor according to claim 4 , wherein the second layer is a variable second layer having a portion whose magnetization can be reversibly reversed based on the spin-orbit torque from the spin torque generation unit.

8. 8. The magnetic sensor of claim 7, wherein the deformable second layer has a portion made of an antiferromagnetic material.

9. 4. The magnetic sensor according to claim 2, wherein the second layer is a variable current-carrying second layer that is integrated with the magnetization control section and has a portion made of an antiferromagnetic material whose magnetization can be reversibly reversed when a current is applied.

10. 4. The magnetic sensor according to claim 2, wherein the magnetization control section is an electromagnetization control section whose magnetization can be reversibly reversed by energization.

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