JP7651767B1 - Magnetic Sensors - Google Patents

Abstract

An object of the present invention 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 its magnetization direction in a first direction (X direction) even when subjected to a measurement magnetic field, 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 current flow, 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.
[Selected Figure] Figure 1

Description

The present invention relates to a magnetic sensor equipped with a magnetoresistance effect element.

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 stacked 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.

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 at lower frequencies, so it can be an obstacle to high-precision measurements. For this reason, various methods are used to remove 1/f noise.

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).

Patent Document 2 discloses a measurement 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 the Schottky barrier that occurs between the electrodes and the sample, thereby removing the frequency band of the voltage difference Vm that is significantly affected by 1/f noise.

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.

Patent document 4 discloses a sensor device that uses a modulator to switch the sensor signal between positive and negative to remove 1/f noise from the output signal, and then takes the difference between the modulated signals.

JP 2018-115972 A JP 2020-148727 A Special Publication No. 2012-518788 Special Publication No. 2009-544004

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 conventional ones.

In one aspect, the present invention is a magnetic sensor characterized by comprising a magnetoresistance effect element having a first layer that can be magnetized in a direction along the measurement magnetic field, a second layer that can maintain a state in which the magnetization is 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.

In magnetoresistance effect elements according to conventional technology, 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 one aspect of the present invention, the external magnetic field is measured in two states: a state in which the magnetization of the second layer corresponding to this magnetization fixed layer is fixed in one direction (first state), and a state in which the magnetization of the second layer is fixed in the opposite direction (anti-parallel) to the first state (second state). By taking the difference between the electrical signals containing the measurement results in each state, highly accurate measurements are possible.

The 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.

When there is a correlation between the 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.

In the magnetic sensor described above, the variable magnetic field detection unit includes a first variable magnetic field detection unit and a second variable magnetic field detection unit that are connected in series and controlled so that the second layers are magnetized in opposite directions, 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 that are connected in series, and 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, 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 determining the 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.

In measurements using a full-bridge circuit, which is one method for achieving highly accurate measurements, four magnetoresistance effect elements must be prepared for one magnetic sensor. In order to achieve highly accurate measurements, 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 electrical signals related to two types of midpoint potentials output from the full-bridge circuit from a half-bridge circuit in which two magnetoresistance effect elements are connected in series, thereby making it possible to miniaturize the magnetic sensor. Moreover, since two types of electrical 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 in a full-bridge circuit, and that the measurement accuracy will be higher.

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.

When 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.

When the spin torque generating 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 generating unit, and the variable second layer may have a portion made of an antiferromagnetic material.

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

In the above magnetic sensor, the magnetization control unit may be an electromagnetization control unit that can reversibly reverse magnetization by passing current through it.

The present invention provides a magnetic sensor with high magnetic resolution, and also contributes to further miniaturization of the magnetic sensor.

1 is a block diagram of a magnetic sensor according to an embodiment of the present invention; 3 is an explanatory diagram (first state) of a magnetic field detection portion included in the magnetic sensor according to the embodiment of the present invention; FIG. 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. 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. 10A to 10C 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. 4 is a flowchart illustrating a first measurement method using the magnetic sensor according to the first embodiment of the present invention. 5 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. 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. 5A to 5C are diagrams illustrating a first state of another example of the variable magnetic field detection unit of the magnetic sensor according to the first embodiment of the present invention. 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. 11A to 11C 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. 10A and 10B 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. 13A and 13B 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. 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. 8A to 8C are diagrams illustrating a second measurement method (second state) using the magnetic sensor according to the first embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the attached drawings. The same components in each drawing will be given the same numbers and their explanations will be omitted. Reference coordinates will be shown in each drawing as appropriate to show the positional relationship of each component.

Figure 1 is a block diagram of a magnetic sensor according to one embodiment of the present invention. Figure 2 is an explanatory diagram of a magnetic field detection unit provided in a magnetic sensor according to one embodiment of the present invention. In addition, in Figure 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 part that constitutes the magnetic sensor 1, and is configured as a CPU (central processing unit), a program, etc.

The magnetic field detection unit 2 detects the external magnetic field to be measured (measurement magnetic field H). As shown in FIG. 2, the magnetic field detection unit 2 is composed of a full bridge circuit 15 having magnetoresistance effect elements 10a, 10b, 10c, and 10d that measure the 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.

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 the 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 the 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.

In the magnetic sensor 1, the magnetic field calculation unit 4 calculates the measured magnetic field H, and then 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.

The four magnetoresistance effect elements 10a, 10b, 10c, and 10d provided 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.

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

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 measured 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, 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 are output from the magnetic field detection unit 2, and the processing performed by the magnetic field calculation unit 4 includes calculating the midpoint potential difference using these first and second signals as inputs.

In the pair of magnetoresistance effect elements 10a, 10b forming the 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 prior art, 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 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 the pair of magnetoresistance effect elements 10c, 10d forming the second half-bridge circuit, the magnetization 11m of the second layer 11 is 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.

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 in the opposite direction (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 in the opposite direction (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".

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 oriented 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.

With the above-mentioned configuration, as the magnitude of the measured magnetic field H in the X direction changes, 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 opposite directions. 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 instead of the full-bridge circuit 15, the first half-bridge circuit or the second half-bridge circuit can be used, or the magnetoresistance effect element 10a can be used alone.

As shown in FIG. 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. Below, the variable magnetic field detection unit 100a will be described as a specific example.

First Embodiment
Fig. 3 is a diagram illustrating an example of a variable magnetic field detector 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 detector 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 detector of the magnetic sensor according to the first embodiment of the present invention.

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 the magnetization 11m is aligned with the first direction (X direction) in FIG. 3, a non-magnetic layer 12 located between the first layer 13 and the second layer 11, 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.

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 "fixed magnetic layer" in a magnetoresistance effect element according to the conventional technology. By detecting the resistance value caused by the misalignment of 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.

The second layer 11 of the magnetoresistance effect element 10a provided in the variable magnetic field detection unit 100a of the magnetic sensor 1 according to this embodiment differs from the "fixed magnetic layer" of the magnetoresistance effect element according to 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 magnetoresistance effect element 10a, but can be reversed by the magnetization control unit 20.

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, Al ₂ O ₃ , 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. In addition, when the magnetoresistance effect element 10a is a giant magnetoresistance effect element (GMR), a nonmagnetic material such as Cu is used as the 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.

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 in order to measure the electrical characteristics of the magnetoresistance effect element 10a. 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 conductive material, 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.

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

The spin torque generating unit 21 generates a spin orbit torque when current is applied, and the magnetization 11m of the second layer 11 is reversed based on the spin orbit torque from the spin torque generating unit 21. In this embodiment, the spin starting torque generated in the spin torque generating unit 21 affects the anisotropy variable unit 22, and the magnetization 20m of the anisotropy variable unit 22 is aligned in a predetermined direction. Since the anisotropy variable unit 22 is magnetically connected to the second layer 11, the second layer 11 is magnetized to follow the magnetization 20m of the anisotropy variable unit 22.

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, or the like is generated, and a spin orbit torque is applied to the anisotropy variable unit 22 . Examples of materials constituting the spin torque generation unit 21 include heavy metals ( _5d transition metals) such as Hf, Ta, W, Pt, and Ir, which have high specific gravity among paramagnetic transition metals; topological insulators such as BiSb, BiSe, _Bi2Se3 , _{and Bi2Te3} ; antiferromagnetic materials such as _Mn3X (X = Sn, Ge, Ga, RH, Pt, Ir) and Mn1 _{- xTrx} gamma-phase (Tr = Ni, Fe, Cu, Ru, Pd, Ir, RH, Pd, Pt); and half-Heusler alloy topological semimetals such as LuPtSb, LuPdBi, LuPtBi, ScPtBi, YAuPb, LaPtBi, CePtBi, THPtPb, and LaAuPb, as well as mixed crystals of these.

In one specific example shown in FIG. 3, the spin torque generating unit 21 is a film-like body, but this film-like body may be composed of a single structure, i.e., a single layer film, or may be composed of a laminated film. In the case of a laminated film, a boundary region may be formed between adjacent films. The spin torque generating 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 it 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 generating unit 21.

The anisotropy variable section 22 can reversibly reverse its magnetization 20m based on the spin orbit torque from the spin torque generating section 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 generating section 21. The anisotropy variable section 22 may be made of a single material, as with the spin torque generating section 21, or may be made of multiple materials. When made of multiple materials, it may have a dispersed structure, or a compositional distribution may be set in the anisotropy variable section 22.

The anisotropy variable section 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 it may be made of an antiferromagnetic material. Specific examples of antiferromagnetic materials include at least some of the materials that make up the spin torque generation section 21 described above. When the anisotropy variable section 22 includes an antiferromagnetic material, a magnetic field may be generated inside the anisotropy variable section 22 based on a physical phenomenon different from the magnetization when the anisotropy variable section 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 section 22 and the like also includes the generation of a magnetic field inside the anisotropy variable section 22 based on a physical phenomenon different from the magnetization of such a ferromagnetic material.

(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.

In the first state, the control current 20c of the spin torque generating unit 21 is oriented in the X2 direction, and the magnetization 11m of the second layer 11 is oriented in the X1 direction. The current flowing through the spin torque generating unit 21 generates a spin current 20s1 in the Z direction in the spin torque generating unit 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 generating unit 21. The magnetization 20m of the anisotropy variable unit 22 is oriented in the X1 direction due to the spin orbit torque based on this injected spin. From the viewpoint of improving the controllability of the direction of the magnetization 20m of the anisotropy variable unit 22 by this injected spin, it may be preferable that a magnetic field in the Z direction (second direction) is applied to the magnetization control unit 20. The method of applying the magnetic field is not limited, and specific examples include placing a permanent magnet or an electromagnet in the vicinity of the variable magnetic field detection unit 100a, and providing an antiferromagnetic material capable of generating a magnetic field based on exchange coupling.

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

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 a first output is output.

(Second state)
The second state shown in FIG. 5 is a state in which the second signal is output from the variable magnetic field detector 100a. In the second state, the control current 20c of the spin torque generator 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 generator 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 generator 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 is oriented in 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 generator 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.

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 a second output is output.

(First measurement method)
6 is a flow chart for explaining the 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 is used to output a signal from the control power supply 3 for setting the variable magnetic field detectors 100a, 100b, 100c, and 100d included in the magnetic field detector 2 to the first state. Specifically, the direction of the current flowing through the spin torque generator 21 of the magnetization controller 20 is set to a predetermined direction. In the magnetic field detector 2 shown in FIG. 2, the directions of the magnetization 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.

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 a 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 the midpoint potential Va from the output terminal V1) and a second signal (a signal including the 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.

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 of 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 of 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.

In this way, the variable magnetic field detection units 100a, 100b, 100c, and 100d are set to the second state, and the measurement magnetic field H is measured by the magnetoresistance effect elements 10a, 10b, 10c, and 10d, and a second output is obtained from each of the variable magnetic field detection units 100a, 100b, 100c, and 100d. These signals cause the magnetic field detection unit 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 are stored in the magnetic field calculation unit 4 or in a memory (not shown) as data indicating those signals, or as data indicating the midpoint potential difference signal, which is the difference between the two signals.

Then, the magnetic field calculation unit 4 reads out the data stored in the magnetic field calculation unit 4 or in a memory (not shown) in steps S101 and S102, and performs a process of calculating the difference between the signal based on the first output (a signal including the midpoint potential difference in the first state) and the 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 in 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 midpoint potential differences as a magnetic field calculation step.

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, the measurement signal obtained by the measurement method using the magnetic sensor 1 according to this embodiment has 1/f noise appropriately removed, and therefore 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).

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, if the magnetic field detection unit 2 has only one variable magnetic field detection unit 100a, the magnetic field calculation unit 4 will find the difference between the first signal and the second signal from the variable magnetic field detection unit 100a.

Another Example of the First Embodiment
Fig. 8 is a diagram for explaining another example of a variable magnetic field detector 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 another example of a variable magnetic field detector of the magnetic sensor according to the first embodiment of the present invention. Fig. 10 is a diagram for explaining a second state of another example of a variable magnetic field detector of the magnetic sensor according to the first embodiment of the present invention.

8, in contrast to 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 generating 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 section 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.

(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 a spin torque generating unit 21 and an 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 an electromagnetization control unit 201 that can reversibly reverse magnetization by energization. In this case, a control wiring 61 is connected to the electromagnetization control unit 201, and a current from a control current source I flows through the electromagnetization control unit 201, thereby generating a spin current 20s1 and setting the direction of the magnetization 20m of the electromagnetization 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 electromagnetization control unit 201 is also fixed to the X1 direction. The electromagnetization control unit 201 is not limited to being a uniform structure, and may have structural non-uniformity such as a stacked structure or a distributed structure.

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 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 is provided with 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.

The material constituting the variable second layer 111 is not particularly limited as long as it is a material whose magnetization can be reversibly reversed by the spin starting torque from the spin torque generating 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.

The control method of the first and second states in the variable magnetic field detection unit 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 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 spin torque generation unit 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 through the spin torque generation unit 21, 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 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 generation unit 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.

Third Embodiment
13 is a diagram for explaining 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 and has a portion that can be reversibly reversed in magnetization.

The material constituting the variable current 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 flow, and the variable current second layer 112 may have a portion made of an antiferromagnetic material such as those exemplified as the constituent materials of the anisotropy variable section 22. The variable current 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 second layer 112 may also have a non-uniform structure in which the composition changes continuously or stepwise.

The control method of the first and second states 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 variable current second layer 112 instead of the spin torque generation unit 21 in the first embodiment, and the direction of the magnetization 112m of the variable current second layer 112 is set by the direction of the control current 20c flowing through the variable current 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 opposite directions. Note that FIG. 13 shows the first state, as in FIG. 9. In FIG. 13, the control wiring 61 is provided so that the control current 20c applied to the spin torque generation unit 21 is oriented in the Y1 direction or the Y2 direction, but this is not limited thereto, and the control wiring 61 may be provided so that the control current 20c is oriented in the X1 direction or the X2 direction.

(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 flow chart of the measurement method is the same as the flow chart of the first measurement method shown in Fig. 6, but the configuration of the magnetic field detection unit 2A provided in the magnetic sensor 1 is different.

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 in the X2 direction, and the magnetization 11m of the second layer 11 of the second variable magnetic field detection unit 102 is in the X1 direction. The first layers 13 of the first variable magnetic field detector 101 and the second variable magnetic field detector 102 are both set to be aligned in the same direction when not receiving 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 not receiving 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.

The magnetic field calculation unit 4 performs arithmetic processing using the electrical signal from the output unit VA as input to calculate 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.

Specifically, 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 first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 of the magnetic field detection unit 2A 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 FIG. 14, the direction of 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 is indicated by a hollow arrow.

In this way, the first variable magnetic field detector 101 and the second variable magnetic field detector 102 are set to the first state, the first variable magnetic field detector 101 and the second variable magnetic field detector 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 calculator 4 and stored in the magnetic field calculator 4 or in a memory not shown.

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 first variable magnetic field detection unit 101 and the second variable magnetic field detection unit 102 of the magnetic field detection unit 2A 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. 15 is an explanatory diagram (second state) of the magnetic field detection unit provided 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.

In this way, the first variable magnetic field detector 101 and the second variable magnetic field detector 102 are set to the second state, the first variable magnetic field detector 101 and the second variable magnetic field detector 102 measure the measurement magnetic field H, and a second electrical signal is obtained from the output unit VA (step S102). The second electrical signal is input to the magnetic field calculator 4 and stored in the magnetic field calculator 4 or in a memory not shown.

Then, the magnetic field calculation unit 4 performs a process of calculating the difference between the first electrical signal and the second electrical signal stored in the magnetic field calculation unit 4 or in a memory (not shown) in steps S101 and S102 as a magnetic field calculation step (step S103). By performing the above process by the magnetic field calculation unit 4, 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 reduce the device area compared to the case where measurement is performed by the first measurement method using the magnetic field detection unit 2 having the full bridge circuit 15.

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 exactly the same. However, in reality, since the four elements are manufactured differently, differences in electrical characteristics are unavoidable, and these differences are one of the causes of reduced 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 the reduction 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 improve the magnetic resolution of the magnetic sensor 1.

The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiments 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 combine the functions of the second layer 11 and at least a portion of the functions 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.

The present invention includes the following aspects.
(1) A magnetic sensor comprising: a variable magnetic field detection unit having a magnetoresistive effect 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 even when subjected to the measurement magnetic field, and a non-magnetic layer located between the first layer and the second layer; and a magnetization control unit that reversibly reverses the magnetization of the second layer, wherein the magnetization control unit has a spin torque generation unit that generates a spin orbit torque when current is applied, and an anisotropy variable unit whose magnetization direction can be reversibly changed based on the spin orbit torque from the spin torque generation unit, the anisotropy variable unit is magnetically coupled to the second layer, and the magnetization of the second layer reversibly changes based on the spin orbit torque from the spin torque generation unit.
(2) The magnetic sensor according to (1), wherein the anisotropy variable portion has a portion made of an antiferromagnetic material.
(3) The magnetic sensor according to (1) above, wherein the spin torque generation section is capable of reversing the direction of magnetization of the anisotropy variable section based on reversal of a current flow direction.
(4) A magnetic sensor 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 even when subjected to the measurement magnetic field, 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, wherein the magnetization control unit is an electromagnetization control unit that can reversibly change the direction of magnetization by passing current through it.
(5) The magnetic sensor according to (4) above, wherein the magnetization control section has a uniform structure .
(6) The magnetic sensor according to (4) above, wherein the magnetization control section generates a spin orbit torque inside the magnetization control section when a current is applied.
(7) The magnetic sensor according to (4) above, wherein the magnetization control section has a portion made of an antiferromagnetic material.
(8) A magnetic sensor comprising: a variable magnetic field detection unit having a magnetoresistive effect element having a first layer magnetizable in a direction along a measurement magnetic field, a second layer capable of maintaining its magnetization along a first direction even when subjected to the measurement magnetic field, and a non-magnetic layer located between the first layer and the second layer; and a magnetization control unit that reversibly reverses the magnetization of the second layer, wherein the magnetization control unit has a spin torque generation unit that generates a spin orbit torque when current is applied, and 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.
(9) The magnetic sensor according to (8), wherein the variable second layer has a portion made of an antiferromagnetic material.
(10) A magnetic sensor comprising a variable magnetic field detection unit having a magnetoresistance effect 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 even when subjected to the measurement magnetic field, and a non-magnetic layer located between the first layer and the second layer, wherein the second layer is a current-variable second layer having a portion made of an antiferromagnetic material whose magnetization can be reversibly reversed when current is applied.
(11) The magnetic sensor according to (10) above, wherein the current variable second layer generates a spin-orbit torque therein by applying a current thereto.
(12) A magnetic sensor described in any of (1), (4), (8) and (10), further comprising 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.
(13) The magnetic sensor described in any one of (1), (4), (8) and (10), wherein the variable magnetic field detection units each have the magnetoresistive effect element, and are controlled so that the second layers are magnetized in opposite directions to each other, and include a first variable magnetic field detection unit and a second variable magnetic field detection unit connected in series, 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, wherein 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 includes calculating the 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.

The present invention is useful as a magnetic sensor with high magnetic resolution that can detect external magnetic fields with high sensitivity.

1: magnetic sensor 2, 2A: magnetic field detection unit 3: control power supply 4: magnetic field calculation unit 5: amplifier 6: A/D conversion circuit 7: control unit 10P: detection center 10a, 10b, 10c, 10d: magnetoresistance effect element 11: second layer 12: non-magnetic layer 13: first layer 15: full bridge circuit 16: half bridge circuit 20: magnetization control unit 21: spin torque generation unit 22: anisotropy variable unit 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: current variable second layer 20c: control current 11m, 13m, 20m, 111m, 112m : Magnetization 20s1, 20s2 : Spin current 201 Magnetization control unit GND : Ground terminal H : Measurement magnetic field I : Control current source V : Measurement voltage source V1, V2 : Output terminal VA : Output unit Vdd : Power supply terminal

Claims (12)

a variable magnetic field detection unit including a magnetoresistance effect element having 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, and a magnetization control unit that reversibly reverses the magnetization of the second layer;
the magnetization control unit includes a spin torque generation unit that generates a spin orbit torque when a current is applied, and an anisotropy variable unit that can reversibly change the direction of magnetization based on the spin orbit torque from the spin torque generation unit;
A magnetic sensor comprising: the anisotropy variable section magnetically coupled to the second layer; and the magnetization of the second layer reversibly changing based on the spin-orbit torque from the spin torque generation section. The magnetic sensor according to claim 1, wherein the anisotropy variable portion has a portion made of an antiferromagnetic material. The magnetic sensor according to claim 1, wherein the spin torque generating unit is capable of reversing the magnetization direction of the anisotropy variable unit based on a reversal of the current flow direction. a variable magnetic field detection unit including a magnetoresistance effect element having 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, and a magnetization control unit that reversibly reverses the magnetization of the second layer;
The magnetic sensor is characterized in that the magnetization control unit is an electromagnetization control unit that can reversibly change the direction of magnetization by a spin orbit torque generated by energization. The magnetic sensor according to claim 4, wherein the magnetization control section has a uniform structure. The magnetic sensor according to claim 4, wherein the magnetization control section has a portion made of an antiferromagnetic material. a variable magnetic field detection unit including a magnetoresistance effect element having 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, and a magnetization control unit that reversibly reverses the magnetization of the second layer;
the magnetization control unit has a spin torque generation unit that generates a spin-orbit torque when a current is applied,
The magnetic sensor according to claim 1, 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. The magnetic sensor of claim 7 , wherein the deformable second layer has a portion made of an antiferromagnetic material. a variable magnetic field detection unit having 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;
The magnetic sensor according to claim 1, wherein the second layer is a variable current-carrying second layer having a portion made of an antiferromagnetic material whose magnetization can be reversibly reversed when a current is applied. The magnetic sensor according to claim 9 , wherein the current variable second layer generates a spin-orbit torque therein by energizing the current variable second layer. A magnetic sensor as described in any one of claims 1, 4, 7 and 9, further comprising 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 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 magnetoresistance effect element, the second layers of which are controlled to be magnetized in opposite directions to each other and which 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;
A magnetic sensor as described in any one of claims 1, 4, 7 and 9, 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 .