JP2006269955A - Magnetic field detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress errors in the detection of angle dependent upon the applied intensity of a magnetic field and a temperature in a magnetic field detecting device using a spin valve type-magnetoresistance effect element. <P>SOLUTION: The magnetoresistance effect element includes an antiferromagnetic layer (8), a sticking layer (9A) where the magnetization direction is fixedly set, and a free layer (12) where the magnetization direction varies with applied magnetic field (Hap). The fixed layer (9A) includes a first antiferromagnetic layer (9a) that performs switched connection with the antiferromagnetic layer (8) to fix the magnetization direction, and a second ferromagnetic layer (9b) that is connected in antiparallel with the first ferromagnetic layer through a non-ferromagnetic layer (10). The magnetic filed detecting device is further provided with a magnetic field applying mechanism that applies a magnetic field stronger than anisotropic magnetic field of the free layer (12) to the direction of the free layer film surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for detecting a magnetic field using a magnetoresistive effect element, and more particularly, the present invention relates to a configuration of a magnetic field detecting apparatus using a spin valve type tunnel magnetoresistive effect element.

  In recent years, to a memory and a magnetic head of a tunneling magneto-resistance (TMR) effect element (TMR element) that can obtain a larger resistance change rate than the conventional giant magneto-resistance (GMR) effect. Application of is being studied.

  In the TMR element, a three-layer laminated structure including a ferromagnetic layer / insulating layer / ferromagnetic layer is used as an element structure. By setting the spins of the two ferromagnetic layers in parallel or antiparallel to each other by an external magnetic field, the fact that the magnitude of the tunnel current flowing through the insulating layer in the direction perpendicular to the film surface changes is utilized.

  As this TMR element, as shown in Patent Document 1 (Japanese Patent No. 2786601), a spin valve magnetoresistive element has been studied. In a spin valve magnetoresistive element, one ferromagnetic layer is exchange-coupled with an antiferromagnetic layer, and the magnetization of the ferromagnetic layer is fixed regardless of an externally applied magnetic field and used as a so-called pinned layer. The other ferromagnetic layer is used as a free layer whose magnetization is freely rotated according to an external magnetic field.

  The structure of the spin-valve magnetoresistive element shown in Patent Document 1 shows a structure when applied to a magnetic head for reading data on a disk, and the magnetization direction of the fixed layer and the magnetization direction of the free layer are orthogonal to each other. Set the direction. In the pinned layer, a nonmagnetic layer is inserted between the ferromagnetic layers as a spacer layer, causing antiferromagnetic exchange coupling in these ferromagnetic layers, and setting the magnetization of these ferromagnetic layers in the antiparallel direction. To do. This antiparallel magnetic field of the pinned layer cancels out the leakage magnetic field from the pinned layer, and reduces the influence of the leakage magnetization on the free layer.

  In the configuration shown in Patent Document 1, when used for a disk read head, the magnetization of the pinned layer is arranged perpendicular to the disk surface, and the magnetization of the free layer is arranged parallel to the disk surface. A change in resistance of the spin valve magnetoresistive element corresponding to the magnetization is detected. By aligning the magnetization of the pinned layer parallel to the signal magnetic field and making the magnetization of the free layer perpendicular to the signal magnetic field, the linear response and dynamic range are expanded.

  As can be seen from the above-mentioned Patent Document 1, the spin valve magnetoresistive element can be used as a highly sensitive magnetic field detector. That is, when a magnetic field is applied to the spin-valve magnetoresistive element, since the magnetization of the pinned layer is fixed, only the magnetization of the free layer rotates according to the applied magnetic field. Thereby, the relative angle of magnetization of the fixed layer and the ferromagnetic layer of the free layer changes, and the element resistance changes due to the magnetoresistance effect. This change in resistance value is detected as a change in voltage by passing a constant current of a constant magnitude through the magnetoresistive element, for example, and signal reading is performed, thereby enabling highly sensitive magnetic field detection.

  In order to detect the magnitude of the magnetic field with high accuracy using this spin valve type magnetic field detector, the magnetization directions of the fixed layer and the free layer are orthogonalized in the absence of a magnetic field (in the state where the magnitude of the externally applied magnetic field is 0). Is disclosed, for example, in Patent Document 2 (Japanese Patent No. 2111893).

  In the configuration shown in Patent Document 2, the magnitude of the magnetic field applied in the fixed layer magnetization direction is detected by the magnetization direction of the free layer. This operation region is below a magnetic field in which the magnetization of the free layer is saturated in the direction of the hard axis, that is, a so-called anisotropic magnetic field.

  Further, for example, Patent Document 3 (Japanese Patent Laid-Open No. 10-70325) discloses a configuration in which the application direction of a magnetic field is detected by using a spin valve magnetoresistive element while canceling the influence of ambient temperature.

  In the configuration shown in Patent Document 3, a resistance bridge circuit is configured using a magnetoresistive effect element. A magnetoresistive element having a different magnetization direction of the pinned layer is arranged on the opposite side of the resistance bridge circuit, and a magnetoresistive element having the pinned layer magnetized in the antiparallel direction in the series path is arranged. A signal that depends on the temperature and the applied magnetic field angle and does not depend on the magnetic field strength is generated, and temperature compensation is performed on the signal.

Non-Patent Document 1 ("Field sensing using the magnetoresistance of IrMr exchange-biased tunnel junctions", D. Lacour et al., Journal of Applied Physics, Vol.91, No.7 April 1, 2002, pp.4655- 4658) shows a characteristic evaluation of a stacked sensor using a spin valve type magnetoresistive element. In the element structure shown in Non-Patent Document 1, a substrate forming layer composed of a cobalt (Co) film is formed on a silicon (Si) substrate, and an aluminum oxide film (Al ₂ O ₃ ) is formed on the substrate forming layer. A tunnel insulating film composed of a film is formed. On the tunnel insulating layer, an upper ferromagnetic layer (Co film) and an antiferromagnetic layer (Ir—Mn film) for fixing the magnetization of the upper ferromagnetic layer are sequentially stacked.
Japanese Patent No. 2786601 Japanese Patent No. 2111893 Japanese Patent Laid-Open No. 10-70325 “Field sensing using the magnetoresistance of IrMr exchange-biased tunnel junctions”, D. Lacour et al. Journal of Applied Physics, Vol.91, No.7 April 1, 2002, pp.4655-4658

  When detecting the magnetic field direction using a spin valve magnetoresistive element, the following equation is usually used.

R = R0− (ΔR / 2) · cos (θap) (1)
In the above formula (1), R represents the element resistance, R0 is the center value of the element resistance, and ΔR represents the resistance change amount of the element. θap represents a relative angle of the externally applied magnetic field to the magnetization direction of the pinned layer. The free layer changes its magnetization direction with respect to the magnetization direction of the pinned layer by an angle θap. At the time of detecting the magnetic field direction, a magnetic field having a strength sufficient to saturate the free layer in the direction of the externally applied magnetic field Hap is applied.

  From the above equation (1), the relative angle θap between the free layer magnetization and the fixed layer magnetization can be obtained by measuring the element resistance R. That is, by saturating the magnetization of the free layer, it is possible to detect the application direction of the external magnetic field based on the above equation. However, in the above formula (1), the magnetization direction of the pinned layer is used as a reference, and is based on the premise that the magnetization direction of the pinned layer does not rotate. When a magnetic field that saturates the magnetization of the free layer is applied, the magnetic field strength increases, the magnetization of the pinned layer is rotated by an external magnetic field, and an error occurs in the direction θap of the externally applied magnetic field by a change in the magnetization direction of the pinned layer. . In addition, even when the operating temperature rises, the exchange coupling between the antiferromagnetic layer and the ferromagnetic layer of the pinned layer becomes weak, the magnetization direction of the pinned layer is rotated by an external magnetic field, and similarly the detection error increases. Therefore, when the temperature rises or the magnetization direction of the pinned layer changes (rotates) due to an externally applied magnetic field, there is a problem that accurate external magnetic field angle detection cannot be performed.

  Non-Patent Document 1 clearly states that the detection error increases when the temperature rises, and measures such as improving the film quality of the antiferromagnetic layer in order to optimize the detection performance at high temperatures. However, the configuration for suppressing the magnetic field direction detection error is not specifically shown.

  Similarly, in Patent Document 1, the pinned layer has a laminated structure of a ferromagnetic layer / nonmagnetic layer / ferromagnetic layer, and the leakage magnetic field to the free layer is reduced to improve detection accuracy. However, this Patent Document 1 does not consider any countermeasure against the rotation of the magnetization of the pinned layer due to an external magnetic field or temperature.

  In Patent Document 2, although it is disclosed that the detection accuracy is increased by setting the magnetization direction of the fixed layer and the free layer in the absence of a magnetic field to be orthogonal, the operating region is below an anisotropic magnetic field. Yes, when the external magnetic field is detected by saturating the magnetization of the free layer, no consideration is given to the rotation of the magnetization of the pinned layer due to the external magnetic field, and the magnetization rotation of the pinned layer when the temperature rises Is not considered.

  Patent Document 3 shows a configuration in which a resistance bridge circuit is formed using a magnetoresistive effect element to detect an external magnetic field angle. Although temperature compensation of the magnetoresistive effect element can be performed, The rotation of the layer magnetization cannot be suppressed, and there is no disclosure about a configuration for suppressing the rotation of the fixed layer magnetization or a technique for reducing an error caused by the rotation.

  Therefore, an object of the present invention is to provide a magnetic field detector capable of detecting the direction of an externally applied magnetic field with high accuracy.

  A magnetic field detection device according to the present invention includes a magnetization fixed layer whose magnetization direction is fixedly fixed, a free layer whose magnetization direction changes by an externally applied magnetic field, and a tunnel formed between the free layer and the magnetization fixed layer A magnetoresistive effect element provided with an insulating layer is provided. The magnetization fixed layer includes an antiferromagnetic layer and a pinned layer stacked in contact with the antiferromagnetic layer. The pinned layer has a laminated structure including first and second ferromagnetic layers and a nonmagnetic layer disposed between the first and second ferromagnetic layers. The magnetizations of the first and second ferromagnetic layers are coupled antiparallel through the nonmagnetic layer.

  The magnetic field detection apparatus according to the present invention further includes a magnetic field application mechanism that applies a magnetic field to the magnetoresistive effect element. This magnetic field application mechanism applies a magnetic field equal to or greater than the anisotropic magnetic field of the free layer in parallel with the film surface of the free layer during the magnetic field detection operation.

  The pinned layer has a laminated structure in which a nonmagnetic layer is interposed between ferromagnetic layers, and the first and second ferromagnetic layers of the pinned layer are antiferromagnetic exchange coupled through the nonmagnetic layer, and their magnetizations are The anti-parallel direction results in canceling out the leakage magnetic fields from these pinned layers, and the influence of torque on the pinned layer magnetization caused by the externally applied magnetic field can be suppressed, and the rotation of the pinned layer magnetization can be suppressed.

  In addition, by applying a magnetic field greater than the anisotropic magnetic field of the free layer, the magnetic field can be detected with the free layer magnetization saturated, and the magnetic field direction detection error due to the externally applied magnetic field is stably and highly accurate. The direction of the external magnetic field can be detected with suppression.

[Embodiment 1]
FIG. 1 is a diagram showing a schematic configuration of a magnetic field detector used in Embodiment 1 of the present invention. In FIG. 1, the magnetic field detector detects a magnetoresistive effect element 1, a DC power source 2 that supplies a DC current of a certain magnitude to the magnetoresistive effect element 1, and a voltage across the magnetoresistive effect element 1. A voltmeter 3 is included. In FIG. 1, a mechanism for applying an external magnetic field to be detected is not shown.

  Since the resistance value of the magnetoresistive effect element 1 varies depending on the direction of an externally applied magnetic field (not shown in FIG. 1), the magnetoresistive effect element 1 is indicated by a symbol of a variable resistance element in FIG.

  In FIG. 1, the DC power source 2 is shown as being connected between the magnetoresistive effect element and the ground node. However, the DC power supply 2 includes a constant current circuit connected between the power supply node and the ground node, and supplies a certain amount of DC current from the power supply node to the magnetoresistive effect element 1.

  In the configuration of the magnetic field detector shown in FIG. 1, the resistance value of the magnetoresistive effect element 1 varies depending on the application direction of the external magnetic field, and accordingly, the magnetoresistive effect element 1 is driven by a constant current supplied from the DC power supply 2. The voltage at both ends changes. By detecting this voltage change with the voltmeter 3, the resistance value of the magnetoresistive effect element is detected, and the direction of the externally applied magnetic field is detected accordingly.

  FIG. 2 is a diagram schematically showing a cross-sectional structure of a conventional magnetoresistive element 1. FIG. 2 shows a structure of a conventionally used spin valve TMR element for comparison with the present invention. Hereinafter, in order to clarify the operational effects of the magnetoresistive effect element of the present invention, a conventional configuration and operation will be briefly described as a comparison target.

  In FIG. 2, the magnetoresistive effect element 1 is formed on a substrate 14, a lower electrode layer 6 formed on the surface of the substrate 14, a base layer 7 formed on the lower electrode layer 6, and a base layer 7. The antiferromagnetic layer 8 is included. The underlayer 7 functions as a buffer layer for matching the crystal orientation with the antiferromagnetic layer 8.

  The magnetoresistive effect element 1 further includes a pinned layer 9 composed of a ferromagnetic layer formed in contact with the antiferromagnetic layer 8, a tunnel insulating layer 11 formed on the pinned layer 9, and a tunnel insulating layer. 11 includes a free layer 12 formed of a ferromagnetic film formed on 11 and an upper electrode layer 13 formed on the free layer 12.

  The magnetization direction of the pinned layer 9 is fixed by exchange coupling with the antiferromagnetic layer 8, while the magnetization direction of the free layer 12 changes in an externally applied magnetic field. In this magnetoresistive effect element 1, in order to increase the detection sensitivity, the magnetization 22 of the pinned layer 9 and the magnetization 21 of the free layer 12 are set in directions orthogonal to each other when there is no magnetic field (when no externally applied magnetic field is present). The In FIG. 2, when there is no magnetic field, the magnetization 21 of the free layer 12 is parallel to the paper surface from left to right, while the magnetization 22 of the pinned layer 9 is perpendicular to the paper surface from the back surface to the front surface. Orient.

  The magnetization 21 of the free layer 12 is rotated by an externally applied magnetic field to change the resistance value between the upper electrode 13 and the lower electrode 6 of the magnetoresistive effect element 1.

  FIG. 3 is a diagram schematically showing the relative relationship between the magnetization of the free layer and the fixed layer when an external magnetic field is applied to the magnetoresistive effect element 1 shown in FIG. In FIG. 3, in the magnetoresistive effect element 1, the magnetization 22 of the pinned layer 9 is set to an angle θ (Pinned), and the direction of the magnetization 22 of the pinned layer 9 is the reference angle (0 ° when the angle of the applied magnetic field is detected. ). The magnetization 21 of the free layer rotates in response to the external magnetic field, and the magnetizations 21 and 22 form a relative angle θ (Free). The resistance value of the magnetoresistive effect element 1 varies depending on the angle θ (Free). The direction of the magnetization 21 of the free layer is the same as the angle θ (Field) formed by the external magnetic field with respect to the pinned layer magnetization. In the ideal state, as shown in FIG.

θ (Field) = θ (Free) = θ (Free)-θ (Pinned)
In this case, the element resistance R of the magnetoresistive effect element 1 is expressed by the following equation (2).

R = R0− (ΔR / 2) · cos (θ (Free) −θ (Pinned)) (2)
Therefore, by measuring the element resistance R, the relative angle θ (Free) −θ (Pinned) between the fixed layer magnetization 12 and the free layer magnetization 21 can be obtained. When the fixed layer magnetization 22 is fixed without being affected by an external magnetic field, the angle of the fixed layer magnetization 22 can be set to a reference angle of 0 °. Further, since the free layer magnetization 21 is saturated in the direction of the external magnetic field due to the externally applied magnetic field, the direction of the free layer magnetic field 21 and the external magnetic field is the same, and the above-described angular relationship is obtained. In the ideal state, the above equation (2) can be transformed into the following equation (3).

R = R0− (ΔR / 2) · cos (θ (Field)) (3)
Therefore, in the ideal state, by obtaining the element resistance R, the direction θ (Field) of the externally applied magnetic field can be obtained directly.

  FIG. 4 is a diagram showing the externally applied magnetic field dependence of the element output voltage when the magnetoresistive effect element shown in FIG. 2 is used. In FIG. 4, the curve I shows the output characteristics in the ideal state shown by the above equation (3), the curve II shows the output characteristics when 100 Oe (Oersted) is applied as an external magnetic field, and the curve III is As an external magnetic field, an output characteristic when 200 Oe is applied is shown, and a curve IV shows an output characteristic when 300 Oe is applied as an external magnetic field. In FIG. 4, the angle θ (Field) of the externally applied magnetic field with respect to the fixed layer magnetic field is indicated in units (deg) in the horizontal axis direction, and the output voltage V (unit arbitrary) of the magnetoresistive effect element is indicated in the vertical axis. . The measurement temperature is constant at room temperature.

  As shown in FIG. 4, as the externally applied magnetic field strength increases, the output characteristic curve deviates from the ideal state curve I and the angle detection error of the externally applied magnetic field increases.

  FIG. 5 is a diagram showing the temperature dependence of the output characteristics when the magnetoresistive effect element shown in FIG. 2 is used. In FIG. 5 as well, the curve I shows the ideal output characteristic, the curve I shows the output characteristic at room temperature, and the curve VI shows the output characteristic in a temperature environment of 150 ° C., as in the configuration shown in FIG. Show. Also in FIG. 5, the horizontal axis indicates the angle θ (Field) with respect to the pinned layer magnetization direction of the externally applied magnetic field in unit deg, and the vertical axis indicates the output voltage of the magnetoresistive effect element. The external magnetic field is constant at about 100 Oe as in the case of the curve II shown in FIG.

  As shown in FIG. 5, as the operating temperature increases, the deviation of the output curve from the ideal output characteristic curve I increases, and the magnetic field angle (direction) detection error increases.

  The occurrence of this detection error increase phenomenon is considered to be caused mainly by the rotation of the fixed layer magnetization 22 and the change in the relative angle between the fixed layer magnetization and the free layer magnetization of the externally applied magnetic field.

  FIG. 6 is a diagram schematically showing the relative relationship between the magnetization 22A of the pinned layer and the externally applied magnetic field 21 in the magnetoresistive element 1. As shown in FIG. When the pinned layer magnetization 22 does not rotate, the angle θ (Pinned) of the pinned layer magnetization 22 is equal to 0 °. However, when the pinned layer magnetization 22 is not sufficiently fixed with respect to the externally applied magnetic field, the pinned layer magnetization 22 rotates and the pinned layer magnetization 22A deviates from the reference value by an angle θ (Pinned) ≠ 0. Set in the direction. Further, due to the temperature rise, exchange coupling acting between the antiferromagnetic layer 8 and the pinned layer 9 is reduced, and the pinned layer magnetization 22 is not sufficiently fixed as the temperature rises.

  Therefore, even if the free layer magnetization 21 is saturated by an external magnetic field and the condition of θ (Field) = θ (Free) is satisfied, the previous equation (3) is not satisfied, and the relationship of the following equation is satisfied. To do.

θ (Field) = θ (Free) ≠ θ (Free) −θ (Pinned) (4)
Therefore, when the applied magnetic field direction θ (Field) is obtained based on the previous equation (2) on the assumption that the fixed layer magnetization 22 does not rotate, an error occurs in the detection angle of the externally applied magnetic field. By considering the rotation of the pinned layer magnetization 22, an increase in the distortion of the output signal of the magnetoresistive effect element shown in FIGS. 4 and 5 can be explained.

  Further, it is assumed that the free layer magnetization 21 is saturated in the application direction of the external magnetic field. However, when the external magnetic field strength is small and the free layer magnetization 21 is not saturated, the free layer does not exhibit isotropic magnetic properties due to its shape and crystalline magnetic anisotropy. Accordingly, even when such an external magnetic field strength is small, an error between the direction of application of the external magnetic field and the magnetization direction of the free layer 21 occurs in the same manner, which causes a magnetic field angle detection error of the magnetic field detector.

  In the present invention, detection errors caused by such rotation of the pinned layer magnetization and unsaturation of the free layer are suppressed.

  FIG. 7 is a diagram showing the magnetic characteristics of the free layer (12) of the magnetoresistive effect element shown in FIG. In FIG. 7, a nickel-iron alloy film (Ni-Fe film) is used as the free layer. In FIG. 7, the horizontal axis represents the intensity (unit Oe) of the externally applied magnetic field H, and the vertical axis represents the magnetization M (unit arbitrary).

  A curve VII shows a characteristic curve of magnetization along the hard axis direction, and a curve VIII shows a characteristic curve of magnetization along the easy axis direction.

  As shown in FIG. 7, the saturation magnetic field Ms along the hard axis direction, that is, the anisotropic magnetic field Hk is about 20 Oe. Magnetization is saturated.

  An anisotropic magnetic field is defined by “the strength of a magnetic field that attempts to align spins in a certain direction”, and a magnetic field is applied perpendicular to the magnetization direction of the magnetic material, and the magnetization of this magnetic material is completely rotated by 90 °. It corresponds to the magnetic field necessary to make it. The anisotropy magnetic field Hk is expressed by the following equation, where Ku is the magnetocrystalline anisotropy constant and Ms is the saturation magnetization.

Hk = 2 · Ku / Ms (5)
The magnetocrystalline anisotropy constant Ku is determined depending on the structure and orientation of the crystal, and therefore the anisotropic magnetic field Hk is determined accordingly if the material used for the free layer is determined.

  As shown in FIG. 7, the anisotropic magnetic field Hk is 20 Oe in the free layer Ni—Fe film, and therefore, under the magnetic field applied under the measurement conditions shown in FIG. 4 and FIG. , All of the magnetization is saturated in the direction of magnetic field application from the outside.

  From the above, when the magnetoresistive effect element shown in FIG. 2 is used, it is difficult to suppress the rotation of the magnetization of the pinned layer when a saturation magnetic field (anisotropic magnetic field) is applied to the free layer. Prove.

  FIG. 8 schematically shows a cross-sectional structure of magnetoresistive element 1 according to the first embodiment of the present invention. In FIG. 8, the magnetoresistive effect element 1 includes a lower electrode layer 6 formed on the substrate 14 and a base layer 7 formed on the lower electrode layer 6. As an example, the base electrode layer 6 is formed of a tantalum film (Ta film) having a thickness of 10 nm according to the DC magnetron sputtering method. The underlayer 7 is made of a nickel-iron alloy film (Ni-Fe film) and has a thickness of 2 nm.

  An antiferromagnetic layer 8 is formed on the underlayer 7, and a fixed layer 9 A is formed on the antiferromagnetic layer 8. The plate ferromagnetic layer 8 and the pinned layer 9A correspond to a magnetization fixed layer.

  The antiferromagnetic layer 8 is composed of an iridium-manganese film (Ir—Mn film) having a thickness of 10 nm, and the crystal orientation is controlled by the underlayer 7.

  The pinned layer 9A has a laminated structure in which a ferromagnetic layer 9a, a nonmagnetic layer 10, and a ferromagnetic layer 9b are sequentially deposited. The ferromagnetic layers 9a and 9b are both composed of a cobalt-iron alloy film (Co-Fe film), and the film thickness thereof is 3 nm. The nonmagnetic layer 10 is made of, for example, a ruthenium film (Ru film) and has a thickness of 0.8 nm. The magnetizations of the ferromagnetic layers 9 a and 9 b are coupled antiparallel through the nonmagnetic layer 10. Since the ferromagnetic layers 9a and 9b have the same film thickness and the magnetization is antiparallel, the leakage magnetic field from the ferromagnetic layers 9a and 9b in the fixed layer 9A is substantially canceled. Therefore, the torque received by the pinned layer 9A by the externally applied magnetic field Hap can be reduced, and the rotation of the magnetization of the pinned layer 9A by the externally applied magnetic field Hap can be suppressed. The externally applied magnetic field Hap has a strength greater than or equal to the anisotropic magnetic field Hk.

  As a method of setting the magnetizations 22a and 22b of the ferromagnetic layers 9a and 9b to be antiparallel to each other, the following method is used.

  That is, a magnetic field is applied during the heat treatment step after the formation of the ferromagnetic layers 9a and 9b to determine the magnetization directions thereof. A magnetic field larger than the coupling of the ferromagnetic layers 9a and 9b via the nonmagnetic layer 10 composed of a Ru film, for example, 7 KOe, is applied and held at a temperature of 300 ° C. for 1 hour. Due to exchange coupling with the antiferromagnetic layer 8, the magnetization 22a of the ferromagnetic layer (Co—Fe film) 9a is fixed along this magnetic field application direction. On the other hand, the ferromagnetic layer 9b composed of a Co—Fe film is antiparallel coupled to the ferromagnetic layer 9a via the nonmagnetic layer 10, and the magnetization 22b of the ferromagnetic layer 9b is changed to the magnetization 22a of the ferromagnetic layer 9a. It faces in a direction that makes an angle of 180 °. Thereby, the ferromagnetic layers 9a and 9b having magnetizations 22a and 22b antiparallel to each other can be formed.

A tunnel insulating layer 11 is formed on the fixed layer 9A. This tunnel insulating layer 11 is formed of an aluminum oxide film (Al ₂ O ₃ film). The tunnel insulating layer 11 is formed by forming a metal aluminum film having a thickness of 2 nm using, for example, a DC magnetron sputtering method, and then performing an oxidation treatment with oxygen plasma to form an aluminum oxide film. The film thickness of the tunnel insulating layer 11 may be any film thickness that causes a tunnel phenomenon.

  A free layer 12 is formed on the tunnel insulating layer 11. The free layer 12 is composed of a nickel-iron alloy film (Ni-Fe film), and its film thickness is 5 nm. The free layer 12 is required to have its magnetization 21 saturated with respect to an externally applied magnetic field Hap.

  An upper electrode layer 13 is formed on the free layer 12. The upper electrode layer 13 is formed of a tantalum film (Ta film) having a thickness of 10 nm, and is formed by using, for example, a DC magnetron sputtering method.

  These upper electrode layer 13 and lower electrode layer 6 are connected to an external direct current source and a voltmeter via an aluminum wiring formed by, for example, a DC magnetron sputtering method.

  The pattern of the magnetoresistive effect element 1 is formed according to a photolithography method. In this case, after the layers up to the upper electrode layer 13 are laminated, a desired pattern is formed with a photoresist, and the shape of the element is obtained by ion milling according to the pattern. As an example, the magnetoresistive effect element 1 has a rectangular planar shape and a short side × long side of 5 μm × 10 μm.

  In the magnetoresistive effect element 1 shown in FIG. 8, the ferromagnetic layers 9a and 9b in the pinned layer 9A show a film thickness of 3 nm as an example, but the thinner the film thickness, the antiferromagnetic exchange coupling (antiparallel). From the viewpoint of (bonding), it is preferable. When the film thickness is thick, the magnetization cancellation of the Co—Fe films anti-parallel coupled via the nonmagnetic layer 10 is insufficient. For this reason, the leakage magnetic field is not canceled out, the torque is easily received by the externally applied magnetic field Hap, and the effect of suppressing the magnetization rotation of the fixed layer 9A is reduced. However, there is a limit to thinning the ferromagnetic layers 9a and 9b.

  FIG. 9 is a diagram showing the film thickness dependence of the magnetization of the Co—Fe film constituting the ferromagnetic layers 9a and 9b. The horizontal axis represents the film thickness tCoFe of the Co—Fe film (unit: nm), and the vertical axis represents the saturation magnetization Ms (unit arbitrary). As shown in FIG. 9, the saturation magnetization Ms increases almost linearly according to the film thickness. However, from the extrapolation of the straight line in the figure, when the film thickness is 1 nm, there is no saturation magnetization, and in order for the Co—Fe film used for the pinned layer to act as a ferromagnetic material having saturation magnetization, a film of 1 nm or more Thickness is required.

  In addition, since the ferromagnetic layers 9a and 9b are formed using the same material and using the same manufacturing process, their strengths are made equal to each other in the antiparallel coupling state. The magnitudes of the leakage magnetic fields of the magnetic layers 9a and 9b are equal to each other in the opposite directions, and the leakage magnetic field can be canceled out. However, when the product M · Vol of the saturation magnetization M and the volume Vol of the ferromagnetic films constituting the ferromagnetic layers 9a and 9b are equal to each other, the total magnetization of each of the ferromagnetic layers 9a and 9b excludes the sign. And the leakage magnetic field can be canceled out.

  FIG. 10 is a diagram schematically showing a configuration of a magnetic field detector using the magnetoresistive effect element shown in FIG. In FIG. 10, the magnetic field detector includes a direct current power source 2 that supplies a certain amount of direct current to the magnetoresistive effect element 1, and between the two electrodes of the magnetoresistive effect element 1 by the direct current from the direct current power source 2. Includes a voltmeter 3 for measuring the voltage generated in the circuit. The DC power source 2 and the voltmeter 3 are connected to the upper electrode layer and the lower electrode layer of the magnetoresistive effect element 1 via wirings 4 and 5 made of, for example, aluminum. In FIG. 10, these upper electrode layer and lower electrode layer are not shown. Wirings 4 and 5 are respectively connected to upper electrode layer 13 and lower electrode layer 6 through aluminum wirings in the configuration of magnetoresistive element 1 shown in FIG. The aluminum wiring forming the wirings 4 and 5 is formed in parallel with the element formation using, for example, a DC magnetron sputtering method.

  In FIG. 10, only the main part of the magnetoresistive effect element 1 is shown, and includes an antiferromagnetic layer 8, a fixed layer 9 </ b> A, and a free layer 12. In the fixed layer 9A, the ferromagnetic layers 9a and 9b have antiparallel magnetizations 22a and 22b, respectively, and the free layer 12 has a magnetization 21 in a direction orthogonal to the magnetizations 22a and 22b of the fixed layer 9A.

  An applied magnetic field Hap from a magnetization application mechanism (not shown) is applied in a direction parallel to the film surface of the free layer 12. The applied magnetic field Hap has a strength that saturates the magnetization of the free layer 12, and the free layer magnetization 21 is set in the same direction as the applied magnetic field Hap from the outside.

  In the case of the configuration at the time of magnetic field detection shown in FIG. 10, the voltage V detected by the voltmeter 3 is expressed by the following equation (6).

V = I ・ R
= I · (R0− (ΔR / 2) · cos θ (Free) −θ (Pinned)) (6)
In the above equation (6), I represents a DC constant current supplied from the DC power source 2 to the magnetoresistive element 1. In this case, the measurement reference angle θ = 0 is the direction θ (Pinned) of the magnetization 22b of the ferromagnetic layer 9b of the fixed layer 9A.

  FIG. 11 is a diagram showing the output voltage and applied magnetic field dependence of the magnetoresistive effect element 1 of the magnetic field detector shown in FIG. In FIG. 11, the horizontal axis represents the angle θ (unit deg) of the externally applied magnetic field with respect to the fixed layer magnetization 22 b, and the vertical axis represents the detected voltage (unit arbitrary) by the voltmeter 3. Curve I shows the magnetic field angle dependence of the ideal output voltage, Curve XI shows the output characteristics when 100 Oe is applied as an externally applied magnetic field, Curve XII shows the output characteristics when an external magnetic field of 200 Oe is applied, Curve XIII shows the output characteristics when an external time of 300 Oe is applied. The measurement temperatures are all the same at room temperature. The strength of the externally applied magnetic field is higher than the anisotropic magnetic field that causes saturation magnetization in the free layer.

  As shown in FIG. 11, when the angle θ of the externally applied magnetic field is 0 ° and is in the same direction as the magnetization 22b, the resistance value of the magnetoresistive effect element 1 is low, and the resistance until the angle becomes 180 ° and becomes antiparallel. The value increases and the output voltage V increases accordingly. By further rotating the direction of the external magnetic field Hap from the antiparallel state, the resistance value decreases because the antiparallel state moves further from the parallel state.

  The output characteristic has a symmetric curve with the applied magnetic field angle θ = 180 ° as the center, and there is no angle detection anisotropy, and accurate magnetic field direction (angle) detection can be realized. . In addition, the deviation from the curve I in the ideal state is extremely small regardless of the externally applied magnetic field strength, and it can be seen that the rotation of the pinned layer magnetization is suppressed even when a magnetic field exceeding the anisotropic magnetic field is applied. It is done.

  FIG. 12 is a diagram showing the temperature dependence of the output voltage of the magnetoresistive element of the magnetic field detector shown in FIG. The externally applied magnetic field is set to, for example, 100 Oe, the curve XIV shows the output characteristics at room temperature, and the curve XV shows the output characteristics at 150 ° C. The horizontal axis indicates the angle θ (unit deg) of the applied magnetic field with respect to the fixed layer magnetization 22b, and the vertical axis indicates the detection voltage V of the voltmeter 3 (see FIG. 10) (unit arbitrary).

  As shown in FIG. 12, output characteristic curves XIV and XV similar to the curve I in the ideal state are obtained even at the room temperature and at 150 ° C., and the detection error can be made sufficiently small.

  Regardless of the externally applied magnetic field strength and ambient temperature, the deviation of the element output characteristic from the ideal characteristic curve can be reduced by using the magnetoresistive effect element (see FIG. 8) according to the present invention. This is because the torque received by the pinned layer due to the magnetic field applied from can be reduced. Thereby, rotation of pinned layer magnetization can be suppressed, detection errors caused by applied magnetic field strength and environmental temperature can be suppressed, and accurate angle detection can be performed.

  In the magnetoresistive element shown in FIG. 8, tantalum (Ta film) is used for the lower electrode layer 6 and the upper electrode layer 12, but copper (Cu), ruthenium (Ru), aluminum (Al), A metal film such as platinum (Pt) may be used, and these metal films may be used as a laminated structure.

  Further, although a nickel-iron alloy film (Ni-Fe film) is used for the underlayer 7, a Ta film may be used similarly to the lower electrode layer 6, which is a metal film and an antiferromagnetic layer. It suffices to have a function (lattice constant) for adjusting the crystal orientation.

  As the antiferromagnetic layer 8, a Pt—Mn film, a Ni—Mn film, a Ni—O film, or a Fe—Mn film may be used.

  Although the fixed layer and the free layer need to be composed of a ferromagnetic film, examples of the ferromagnetic layer include cobalt (Co), nickel such as Cu—Ni alloy, Cu—Fe—Ni alloy, and Fe—Ni alloy. A metal containing either (Ni) or iron (Fe) as a main component, or an alloy film material such as NiMnSb or Co2MnGe may be used. Further, these metal films and alloy films may be formed in a laminated structure to form a ferromagnetic layer.

  The nonmagnetic layer used for the pinned layer is preferably composed of a 3d transition metal film in order to obtain strong antiparallel coupling, but is not limited to a ruthenium film (Ru film), and other transition metal films are used. Also, the thickness thereof is not limited to 0.8 nm, and any thickness can be used as long as antiparallel coupling is realized.

The tunnel insulating layer may be an oxide film such as tantalum oxide Ta ₂ O ₅ , silicon oxide SiO ₂ , manganese oxide MgO, nitride film, or fluoride film. Further, as the oxidation treatment of the tunnel insulating layer, radical oxidation, natural oxidation, and oxidation by ozone may be used. The tunnel insulating layer may be formed by nitriding treatment or fluorination treatment depending on the type of insulating layer used. In these nitriding treatments and fluorination treatments, nitriding or fluorination treatment using plasma, radicals, or reactive gases may be performed. Alternatively, the tunnel insulating layer may be directly formed by using a method such as RF (radio frequency) magnetron sputtering or chemical vapor deposition (CVD).

  The wirings 4 and 5 for connecting the magnetoresistive effect element to the outside may be any good conductor such as a copper (Cu) film.

  In forming the metal film, instead of the DC magnetron sputtering method, a molecular beam epitaxy (MBE) method, various sputtering methods, a chemical vapor deposition (CVD) method, a vapor deposition method, or the like may be used.

  Further, the magnetoresistive effect element can be formed by photolithography and reactive ion etching instead of ion milling, or pattern formation by electron beam lithography or focused ion beam.

[Example of change]
FIG. 13 schematically shows a configuration of the magnetic field detector according to the modification of the first embodiment of the present invention. In FIG. 13, the magnetic field detector includes a bridge circuit 30 connected between the DC power supply 2 and the ground node, a differential amplifier 32 that amplifies a complementary signal from the bridge circuit 30, and an output signal of the differential amplifier 32. A voltmeter 3 for detecting the voltage of

  Bridge circuit 30 is connected between nodes N1 and N4, magnetoresistive element 1a connected between nodes N1 and N2, fixed resistance element 31b connected between nodes N2 and N3, and node N1 and node N4. Fixed resistance element 31a and magnetoresistive effect element 1b connected between nodes N4 and N3 are included. Node N1 is coupled to DC power supply 2 and receives a constant DC constant current I from DC power supply 2. Node N3 is connected to the ground node.

  The magnetoresistive effect elements 1a and 1b have the configuration shown in FIG. 8, the magnetization direction of the pinned layer (9A) is the same, and the operating characteristics such as temperature characteristics are the same. The resistance values of the fixed resistance elements 31a and 31b are the same.

  A magnetic field from the magnetic field application mechanism is commonly applied to these magnetoresistive elements 1a and 1b. Consider a state where the resistance values of the magnetoresistive effect elements 1a and 1b are increased in accordance with an applied magnetic field (not shown). In this case, the voltage drop due to the current I1 flowing through the magnetoresistive effect element 1a increases, and the voltage level of the node N2 decreases. On the other hand, the voltage level of node N4 rises due to current I2 from fixed resistance element 31a. The voltage change directions of the nodes N2 and N4 are opposite to each other, and the differential value is amplified by the differential amplifier 32.

  When the resistance values of the magnetoresistive effect elements 1a and 1b are reduced by the applied magnetic field, the voltage level of the node N2 increases, while the voltage level of the node N4 decreases, and similarly, a complementary voltage change occurs at the node N2. And N4.

  Therefore, by using this resistance bridge circuit 30, the temperature dependence of the operating characteristics of the magnetoresistive effect elements 1a and 1b can be offset, and the magnetic field detection with temperature compensation can be performed. A minute voltage change due to a magnetic field can be reliably detected, and highly accurate magnetic field angle detection can be realized.

  FIG. 14 schematically shows an overall configuration of the magnetic field detection device according to the first embodiment of the present invention. FIG. 14A shows a side cross-sectional view, and FIG. 14B shows a plan view.

  In FIG. 14A, the magnetic field detection device includes a magnetic field detection unit 41 placed on a support 44. The support body 44 has a hill-shaped protrusion at the center, and the magnetic field detector 41 is placed on the hill-shaped protrusion. A hollow rotating body 43 is arranged so as to face the support body 44 and include a hill-shaped protrusion. Permanent magnets 42 a and 42 b are arranged on the inner wall of the rotating body 43 so as to face the outer peripheral portion of the hill-like protrusion of the support body 44. The permanent magnets 42a and 42b are made of, for example, a samarium-cobalt alloy (Sm—Co alloy), and the applied magnetic field Hap is, for example, a magnetic field direction from the permanent magnet 42a toward the permanent magnet 42b.

  The magnetic field detector 41 is connected to a power source and external devices (control device, monitor device, etc.) via wirings 45a, 45b and 45c installed in the support body 44. The magnetic field detector 41 includes a magnetoresistive element group wiring and a peripheral circuit (DC power supply or the like: a configuration including a bridge circuit or a voltmeter may be included). The magnetic field detection unit 41 is fixedly placed on the hill-shaped protrusion of the support 44 in correspondence with the rotation center of the rotator 43.

  The magnetoresistive effect element disposed in the magnetic field detection unit 41 is disposed such that the inner free layer film surface and the rotation surface of the rotating body 43 are parallel to each other. That is, the applied magnetic field Hap between the permanent magnets 42a and 42b is applied with a strength equal to or greater than the anisotropic magnetic field in a direction parallel to the film surface of the free layer of the magnetoresistive element in the magnetic field detector 41. As an example, the applied magnetic field Hap by the permanent magnets 42a and 42b has a strength of 100 Oe.

  The rotating shaft of the rotating body 43 is coupled to a drive unit to be detected, and the driving unit rotates the rotating body 43 according to the movement of the detection target object.

  In FIG. 14B, the rotating body 43 is arranged so that the central axis thereof coincides with the magnetic field detection unit 41, and the planar shape is formed in a circular shape. Permanent magnets 42 a and 42 b are arranged to face each other along the diameter direction of the inner wall of the rotating body 43. The magnetic field detector 41 is arranged corresponding to the center of rotation of the rotating body 43. Therefore, the magnetic field detector 41 and the permanent magnets 42a and 42b are arranged on a straight line. The support body 44 disposed opposite to the rotating body 43 has, for example, a square shape including a square shape portion and a circular shape portion, and wirings 45 a and 45 b for driving the magnetic field detection portion 41 and deriving signals, and By 45c, it connects with an external apparatus.

  In the configuration of the magnetic field detection device shown in FIGS. 14A and 14B, the direction of the applied magnetic field Hap from the permanent magnets 42a and 42b changes according to the rotation angle of the rotating body 43, and the magnetic field of the magnetic field detection unit. The magnetization direction of the free layer of the resistance effect element is set to the direction of the applied magnetic field Hap. The resistance value of the magnetoresistive element varies depending on the magnetic field direction of the free layer, that is, the direction of the applied magnetic field Hap. Therefore, in the magnetic field detection unit 41, the resistance value of the magnetoresistive effect element included in the magnetic field detection unit 41 is taken out in the form of a voltage change or the like, so that the applied magnetic field Hap is The angle formed can be detected. Thereby, the rotation angle of the rotating body 43 can be detected.

  The rotation of the rotating body 43 can correspond to various monitor amounts such as the amount of movement of the moving object according to the usage, and position detection and rotation amount detection can be performed. Therefore, the structure of the drive mechanism of the rotating body 43 is appropriately determined according to the application.

  As described above, according to the first embodiment of the present invention, the fixed layer is antiparallelly coupled between the two ferromagnetic layers with the spacer layer (nonmagnetic layer) interposed therebetween, so that the leakage magnetic field is canceled out. An external magnetic field with a strength higher than the isotropic magnetic field is applied. Therefore, the influence of the torque of the magnetic field applied from the outside can be suppressed from being exerted on the pinned layer. Rotation can be suppressed and accurate angle detection can be performed.

  In the magnetic field detection method, a constant current of a direct current is supplied to read a voltage change and a magnetic field angle is detected. However, an alternating current power source that supplies a constant alternating current may be used. Conversely, a configuration for detecting a current flowing through the magnetoresistive element under a constant voltage may be used.

  Further, the permanent magnets 42a and 42b shown in FIGS. 14A and 14B may be magnets capable of applying a magnetic field larger than the anisotropic magnetic field of the free layer of the magnetoresistive effect element.

[Embodiment 2]
FIG. 15 schematically shows a configuration of a magnetic field detector according to the second embodiment of the present invention. FIG. 15 does not show a configuration of a mechanism for applying a magnetic field to the magnetic field detector. The configuration of the magnetic field detector shown in FIG. 15 differs from that shown in FIG. 10 in the following points. That is, the magnetoresistive effect element 1 is formed in a substantially circular shape in plan rather than a rectangular shape. Its diameter is 5 μm. Also in this case, the magnetizations 22a and 22b of the pinned layer are coupled to each other via the antiparallel spacer layer (nonmagnetic layer), and the direction of the free layer magnetization 21 changes according to the externally applied magnetic field Hap.

  The other configuration of the magnetic field detector shown in FIG. 15 is the same as the configuration of the magnetic field detector shown in FIG. 10, and corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted. By forming the free layer 12, the pinned layer, and the ferromagnetic layers 9 a and 9 b in an isotropic shape having substantially a circular shape and no anisotropy, crystal anisotropy of the ferromagnetic layer of the magnetoresistive element is obtained. The influence of the characteristic magnetization can be suppressed, and the angle of the applied magnetic field can be detected with high accuracy.

  FIG. 16 is a diagram showing the relationship between the applied magnetic field and the magnetization of the free layer 12 of the magnetoresistive effect element 1 shown in FIG. In FIG. 16, the horizontal axis represents the applied magnetic field strength H (unit Oe), and the vertical axis represents the magnetization M (unit arbitrary). In FIG. 16, the solid curve indicates the magnetization in the easy axis direction, and the broken line indicates the magnetization in the hard axis direction. The free layer is composed of a Ni—Fe film.

  As shown in FIG. 16, the difference in magnetic characteristics is small both in the easy axis direction and the hard axis direction, and the saturation magnetic field (anisotropic magnetic field Hk) is about 15 Oe, which is more isotropic. Magnetic characteristics can be obtained. In the magnetic characteristics shown in FIG. 16, the free layer is composed of a Ni—Fe film, and anisotropy due to the magnetocrystalline anisotropy appears only slightly (deviation of the characteristic curve). Therefore, the magnetic anisotropy in the magnetoresistive effect element 1 can be sufficiently suppressed, and the influence of the magnetic property anisotropy depending on the shape can be eliminated.

  The magnetic field detection operation of the magnetic field detector shown in FIG. 16 and the overall configuration of the magnetic field detection device are the same as the configuration shown in FIG.

  By making the planar shape of the magnetoresistive effect element an isotropic circular shape, it is possible to suppress the orientation dependency of the output signal error, and to perform highly accurate angle detection even in a low magnetic field. A magnetic field detection device can be realized. As a result, it is possible to realize a highly accurate magnetic field detection device that can operate in a wide range of magnetic field strength regions.

  Further, in the magnetic field detector shown in FIG. 15, by applying the bridge circuit shown in FIG. 13, the temperature dependence of the resistance change of the magnetoresistive effect element can be compensated, and accurate magnetic field angle detection is performed. Can do.

[Example of change]
FIG. 17 schematically shows a configuration of magnetoresistive effect element 1 according to a modification of the second embodiment of the present invention. The magnetoresistive element 1 shown in FIG. 17 has a square shape whose one side is a length L. The structure of this element is the same as the magnetoresistive effect element shown in FIGS. 8 and 15 except for the planar shape. The ferromagnetic layers 9a and 9b of the pinned layer are antiparallel coupled via their spacer layers (nonmagnetic layers) between the magnetizations 22a and 22b. The direction of the magnetization 21 of the free layer 12 changes according to the applied magnetic field Hap.

  As shown in FIG. 17, even if the magnetoresistive effect element 1 is formed so that its planar shape has a square shape, the magnetoresistive effect element 1 has an isotropic shape and magnetic anisotropy of the hard axis and the easy axis. The effect similar to the case where the magnetoresistive effect element shown in FIG. 15 is used can be acquired.

  The magnetoresistive effect element 1 shown in FIG. 17 is used as a magnetic field detection element and used in the magnetic field detection unit 41 of the magnetic field detection device shown in FIGS. 14 (A) and 14 (B).

  As described above, according to the second embodiment of the present invention, the magnetoresistive effect element and the planar shape are formed in an isotropic shape, and the influence of anisotropy depending on the shape of the magnetic characteristics is suppressed. Accordingly, the anisotropic magnetic field strength can be reduced, angle detection can be performed with high accuracy even in a low magnetic field, and the range of operable applied magnetic field strength can be widened.

[Embodiment 3]
FIG. 18 schematically shows an overall configuration of the magnetic field detection device according to the third embodiment of the present invention. In FIG. 18, the magnetic field detection device includes a magnetic field detection unit 41 disposed on the support 50 and a permanent magnet 42 disposed on the support 50 adjacent to the magnetic field detection unit 41. The configuration of the magnetic field detection unit 41 is the same as the configuration of the first embodiment or the second embodiment.

  The magnetic field from the permanent magnet 2 is in a direction parallel to the film surface of the free layer of the magnetoresistive effect element included in the magnetic field detector 41. The magnetic field detection device is disposed in the vicinity of the gear 46 to be detected. This gear 46 is formed with teeth 47a, 47b,... At predetermined intervals on the outer peripheral portion thereof, and rotates through a rotation center 46a.

  A gear 46 and a permanent magnet 42 are arranged so as to face each other with respect to the magnetic field detector 41. The applied magnetic field Hap from the permanent magnet 42 has a strength equal to or higher than the saturation magnetic field (anisotropic magnetic field) of the free layer magnetization included in the magnetization detector 41, and for example, 200 Oe magnetization is supplied as the applied magnetic field Hap. The gear 46 is made of a high magnetic permeability material together with the teeth 47a and 47b, and attracts the applied magnetic field Hap from the permanent magnet 42.

  In the configuration of the magnetic field detection device shown in FIG. 18, the gear 46 is made of a high magnetic permeability material, and the applied magnetic field Hap from the permanent magnet 42 is guided to the closest tooth 47a. In this state, the free layer magnetization of the magnetoresistive effect element included in the magnetic field detection unit 41 faces the same direction as the magnetic flux of the applied magnetic field Hap.

  When the gear 46 rotates, the teeth 47a move away from the permanent magnet 42 (the gear 46 rotates clockwise), the direction of the applied magnetic field Hap guided from the permanent magnet 42 to the teeth 47a changes, and accordingly, the applied magnetic field Hap The direction of magnetization of the free layer of the magnetoresistive effect element of the magnetic field detector 41 changes according to the change of the direction of the magnetic flux.

  When the rotation of the gear 46 further proceeds and the tooth 47b comes close, the applied magnetic field Hap from the permanent magnet 42 is guided to the tooth 47b.

  By detecting the change in the direction of these magnetic fluxes by the magnetoresistive effect element in the magnetic field detection unit 41, the angle and the rotation amount of the gear 46 can be detected.

  The drive unit that drives the rotation shaft coupled to the rotation center 46a of the gear 46 is appropriately determined according to the application of the magnetic field detection device. For example, this magnetic field detection device may be used as a position detection unit of a positioning device. By extracting signals from the magnetic field detection unit 41 to the outside via the wirings 45a to 45c arranged on the support body 50, the state of the gear 46 (such as the rotation angle) can be monitored.

  In the configuration of the magnetic field detection device shown in FIG. 18, since the permanent magnet 42 and the magnetic field detection unit 41 of the magnetic field generation mechanism are both fixed on the support 50, the magnetic field application mechanism and the magnetic field detection unit are integrally formed. be able to. Therefore, the magnetic field detection device can be obtained by simply arranging the magnetic field detection device in the vicinity of the existing detection target, and necessary information such as the amount of rotation can be obtained. Can do.

  As described above, according to the third embodiment of the present invention, the magnetic field detector and the permanent magnet for applying a magnetic field are integrally arranged on the support, and are arranged close to the detection target of high permeability. Therefore, it is possible to realize a highly accurate magnetic field detection device excellent in simplicity.

  The magnetic field detection apparatus according to the present invention can be applied to an apparatus that performs position detection and rotation amount detection by detecting a magnetic field direction (angle). The magnetic field detection unit according to the present invention may be used as a component of an electronic circuit that uses magnetic field detection.

It is a figure which shows schematic structure of the magnetic field detector according to Embodiment 1 of this invention. It is a figure which shows roughly the cross-section of the magnetoresistive effect element used in Embodiment 1 of this invention. It is a figure for demonstrating the magnetization direction of the ferromagnetic layer of a magnetoresistive effect element. It is a figure which shows the applied magnetic field strength dependence of the output signal of the magnetoresistive effect element shown in FIG. It is a figure which shows the temperature dependence of the output signal of the magnetoresistive effect element shown in FIG. It is a figure for demonstrating magnetization of the ferromagnetic layer of the magnetoresistive effect element shown in FIG. It is a figure which shows the magnetic characteristic of the free layer of the magnetoresistive effect element shown in FIG. It is a figure which shows roughly the cross-section of the magnetoresistive effect element according to Embodiment 1 of this invention. It is a figure which shows the film thickness dependence of the magnetization of the ferromagnetic layer of the pinned layer of the magnetoresistive effect element shown in FIG. It is a figure which shows concretely the structure of the magnetic field detector according to Embodiment 1 of this invention. It is a figure which shows the magnetic field strength dependence of the output signal voltage of the magnetoresistive effect element according to Embodiment 1 of this invention. It is a figure which shows the temperature dependence of the output signal of the magnetoresistive effect element according to Embodiment 1 of this invention. It is a figure which shows the structure of the magnetic field detection part of the example of a change of Embodiment 1 of this invention. (A) And (B) is a figure which shows roughly the structure of the magnetic field detection apparatus according to Embodiment 1 of this invention. It is a figure which shows schematically the structure of the magnetic field detector according to Embodiment 2 of this invention. It is a figure which shows the magnetic field dependence of magnetization of the free layer of the magnetoresistive effect element shown in FIG. It is a figure which shows roughly the structure of the magnetoresistive effect element of the modification of Embodiment 2 of this invention. It is a figure which shows roughly the structure of the magnetic field detection apparatus according to Embodiment 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Magnetoresistance effect element, 8 Antiferromagnetic layer, 9A Fixed layer, 9a, 9b Ferromagnetic layer, 11 Tunnel insulating layer, 12 Free layer, 10 Antimagnetic layer, 2 DC power supply, 3 Voltmeter, 1a, 1b Magnetoresistance Effect element, 31a, 32b Fixed resistance element, 32 Differential amplifier, 44 Support body, 41 Magnetic field detection part, 43 Rotating body, 42a, 42b Permanent magnet, 42 Permanent magnet, 46 Gear, 47a, 47b Gear.

Claims (5)

Magnetoresistive effect comprising: a magnetization fixed layer whose magnetization direction is fixedly fixed; a free layer whose magnetization direction is changed by an externally applied magnetic field; and a tunnel insulating layer formed between the free layer and the magnetization fixed layer The magnetization fixed layer is laminated in contact with the antiferromagnetic layer and between the first and second ferromagnetic layers and the first and second ferromagnetic layers. A pinned layer having a laminated structure including a nonmagnetic layer disposed, the magnetization of the first ferromagnetic layer being fixed by the antiferromagnetic layer, and the magnetization of the first and second ferromagnetic layers Are coupled antiparallel through the nonmagnetic layer, and include a magnetic field applying mechanism that applies a magnetic field to the magnetoresistive effect element, and the magnetic field applying mechanism is parallel to the film surface of the free layer during a magnetic field detecting operation. Magnetic field that applies a magnetic field greater than the anisotropic magnetic field of the free layer Detection device.   The magnetic field detection device according to claim 1, wherein the first and second ferromagnetic layers of the pinned layer have a product of magnetization and volume equal to each other.   3. The magnetic field detection device according to claim 1, wherein the first and second ferromagnetic layers of the pinned layer have a thickness of 1 nm or more.   4. The magnetic field detection device according to claim 1, wherein the magnetoresistive element has one of a circular shape and a square shape as a planar shape. 5.   The said magnetoresistive effect element is provided with two or more and comprises a resistance bridge circuit, and the signal according to the magnetic field applied from the said magnetic field application mechanism is output from the said bridge circuit. Magnetic field detection device.

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