JP6726040B2 - Magnetic sensor and current sensor - Google Patents

Description

The present invention relates to a magnetic sensor and a current sensor including the magnetic sensor.

In fields such as motor drive technology for electric vehicles and hybrid cars, and infrastructure related fields such as columnar transformers, relatively large currents are handled, so there is a need for current sensors that can measure large currents in a non-contact manner. There is. As such a current sensor, one using a magnetic sensor that detects an induced magnetic field from a measured current is known. Examples of the magnetic detection element for the magnetic sensor include a magnetoresistive effect element such as a GMR (giant magnetoresistive effect) element.

Although the magnetoresistive effect element has a high detection sensitivity, it has a characteristic that the detectable magnetic field strength range is relatively narrow with a high linearity. Therefore, as in the current sensor shown in FIG. 3 of Patent Document 1, a magnetic shield is arranged between the current to be measured and the magnetoresistive effect element, and the induced magnetic field substantially applied to the magnetoresistive effect element. There is a case where a method is used in which the strength of is reduced so that the magnitude of the magnetic field to be measured falls within the magnetic field strength range having good detection characteristics.

International Publication No. 2011/111493

By using the magnetic shield in this manner, it is possible to reduce the strength of the magnetic field substantially applied to the magnetoresistive effect element and expand the measurement range of the magnetic field strength. When the magnetic field is as strong as several tens of mT, even if the magnetic shield is made of a soft magnetic material, residual magnetization is likely to occur in the magnetic shield. When a magnetic field based on the remanent magnetization of the magnetic shield thus generated is applied to the magnetoresistive effect element, it adversely affects the measurement accuracy of the magnetoresistive effect element, such that the zero magnetic field hysteresis of the magnetoresistive effect element increases to the negative side. There is a risk that

In view of the present situation, the present invention is a magnetic sensor including a magnetic shield and a magnetoresistive effect element, and even if the magnetic field applied to the magnetic sensor is large, the measurement accuracy of the magnetoresistive effect element is unlikely to decrease. An object is to provide a magnetic sensor. The present invention also aims to provide a current sensor including such a magnetic sensor.

In one aspect, the present invention provided to solve the above problem reduces a magnetoresistive effect element having a sensitivity axis in a specific direction and a strength of a measured magnetic field applied to the magnetoresistive effect element. A magnetic sensor including a magnetic shield, wherein the magnetic shield has a laminated structure in which a plurality of unit laminated bodies each including a soft magnetic layer and an antiferromagnetic layer in contact with the soft magnetic layer are laminated, The soft magnetic layer of the laminated body is exchange-coupled with the antiferromagnetic layer of the unit laminated body.

The soft magnetic material forming the magnetic shield, that is, the soft magnetic layer is exchange-coupled with the antiferromagnetic layer. Therefore, the soft magnetic layer can be made into a single magnetic domain in a state where no external magnetic field is applied. Therefore, even when the magnetic field applied to the magnetic shield is large, residual magnetization that affects the magnetoresistive effect element is less likely to occur in the magnetic shield, and the measurement accuracy of the magnetic sensor is less likely to decrease.

In the above magnetic sensor, the direction of the magnetic field based on exchange coupling in the soft magnetic layer included in one of the unit laminates included in the laminate structure, and the unit laminate closest to one of the unit laminates is It is preferable to have an antiparallel relationship with the direction of the magnetic field based on exchange coupling in the soft magnetic layer provided. In this case, the magnetic field generated in the magnetic shield due to the residual magnetization becomes a return magnetic field due to the group of unit laminates in which the directions of the magnetic fields are antiparallel, and the magnetic field based on the residual magnetization of the magnetic shield is affected by the magnetic field. The possibility of reaching a position remote from the shield is particularly reduced. Therefore, it is preferable that the magnetoresistive effect element is more stably prevented from being affected by the residual magnetization of the magnetic shield.

In the above magnetic sensor, it may be preferable that the antiferromagnetic layer is made of a disordered antiferromagnetic material. When the antiferromagnetic layer is made of a disordered antiferromagnetic material, heat treatment in a magnetic field is not required to cause exchange coupling between the antiferromagnetic layer and the soft magnetic layer in contact with it. Therefore, it becomes easy to individually control the exchange coupling generated in each of the plurality of unit laminated bodies included in the magnetic shield.

The antiferromagnetic layer may preferably contain a platinum group element and Mn, and may preferably be composed of IrMn. IrMn is a specific example of disordered antiferromagnetic material.

The laminated structure in the above magnetic sensor may have an alternating laminated structure of the antiferromagnetic layer and the soft magnetic layer. In this case, the unit laminated body is composed of the antiferromagnetic layer and the soft magnetic layer.

In the above magnetic sensor, the magnetoresistive effect element may be composed of at least one element selected from the group consisting of an anisotropic magnetoresistive effect element, a giant magnetoresistive effect element, and a tunnel magnetoresistive effect element. ..

The magnetoresistive effect element of the magnetic sensor may be a giant magnetoresistive effect element, and the giant magnetoresistive effect element may include a fixed layer having a self-pin structure.

The above magnetic sensor has a structure in which the magnetoresistive effect element is formed on a substrate, and the magnetic shield is formed on the substrate, and the unit laminate body located at the lowermost layer of the magnetic shield is made of NiFe. And the antiferromagnetic layer formed on the soft magnetic layer. In this case, the magnetic shield may include an oxidation protection layer provided most distally from the magnetoresistive effect element.

In the above magnetic sensor, it may be preferable that the direction of the magnetic field based on exchange coupling in the soft magnetic layer is orthogonal to the direction along the sensitivity axis of the magnetoresistive effect element.

The above magnetic sensor may further include a magnetic balancing coil, and may measure the strength of the magnetic field to be measured based on the current flowing through the magnetic balancing coil. The arrangement of the magnetic balancing coil in this case is arbitrary, but it may be preferable that the magnetic balancing coil is a spiral coil and is located between the magnetoresistive effect element and the magnetic shield. ..

As another aspect, the present invention provides a current sensor including the above magnetic sensor, wherein the magnetic sensor uses an induced magnetic field of a measured current as the measured magnetic field.

According to the present invention, there is provided a magnetic sensor including a magnetic shield and a magnetoresistive effect element, in which the measurement accuracy of the magnetoresistive effect element is less likely to decrease even when the applied magnetic field is large. A current sensor using such a magnetic sensor is also provided.

It is sectional drawing which shows notionally the structure of the magnetic sensor which concerns on one Embodiment of this invention. It is a partially expanded view of the magnetic shield shown in FIG. It is sectional drawing which shows notionally the structure of the magnetic sensor which concerns on other embodiment of this invention. 6 is a graph showing the relationship between zero magnetic field hysteresis and maximum applied magnetic field.

FIG. 1 is a sectional view conceptually showing the structure of a magnetic sensor according to an embodiment of the present invention.

A magnetic sensor 1 according to an embodiment of the present invention includes a magnetoresistive effect element 11 and a magnetic shield 15, as shown in FIG.

The magnetoresistive effect element 11 of the magnetic sensor 1 according to the embodiment of the present invention is a giant magnetoresistive effect element (GMR element) having a meander shape (a shape in which a plurality of long patterns are connected so as to be folded back). Prepare FIG. 1 is a cross-sectional view obtained by cutting the magnetic sensor 1 along a plane whose normal is a direction along the long axis direction of a plurality of long patterns forming a meandering shape. The X1-X2 direction, which is one of the directions in the cross section, is the sensitivity axis direction of the magnetoresistive effect element 11. The magnetoresistive effect element 11 is formed on the layer IM1 made of an insulating material (alumina) provided on the substrate 29, and is electrically connected to the electrode EL1 having a three-layer structure in FIG. The electrode EL1 is electrically connected to the contact electrode EL2. The magnetoresistive effect element 11 and the electrode EL1 are covered with a layer IM1 made of an insulating material (alumina). A layer IM2 made of another insulating material (silicon nitride) is provided so as to cover the layer IM1 made of this insulating material (alumina).

The magnetic shield 15 is provided on the layer IM2 made of another insulating material (silicon nitride). The distance between the magnetic shield 15 and the magnetoresistive effect element 11 is adjusted by the thickness of the layer IM1 made of an insulating material (alumina) and the thickness of the layer IM2 made of another insulating material (silicon nitride).

In the magnetic sensor 1 according to the embodiment of the present invention, the magnetic shield 15 includes a unit laminate body 15-i (15-1 to 15-15) including a soft magnetic layer SM and an antiferromagnetic layer AF in contact with the soft magnetic layer SM. -6) has a laminated structure in which 6 layers are laminated, and these soft magnetic layer SM and antiferromagnetic layer AF are exchange-coupled. In the magnetic sensor 1 shown in FIG. 1, the magnetic shield 15 includes the six-layer unit laminated bodies 15-1 to 15-6, but the invention is not limited thereto. The number of laminated layers of the unit laminated body 15-i is appropriately set according to the characteristics required for the magnetic shield 15.

The soft magnetic layer SM is made of a soft magnetic material containing an iron group element such as Fe, Co and Ni. The thickness of the soft magnetic layer SM is not limited. It is exemplified that the thickness is 3 to 30 nm.

The antiferromagnetic layer AF is made of an antiferromagnetic material containing platinum group elements such as Ir and Pt and Mn. The thickness of the antiferromagnetic layer AF is appropriately set depending on the constituent material. When the antiferromagnetic layer AF is made of IrMn, the thickness is set to 4 to 10 nm, and when the antiferromagnetic layer AF is made of PtMn, the thickness is set to 10 to 30 nm. When the material forming the antiferromagnetic layer AF is a disordered antiferromagnetic material (a specific example is IrMn), the exchange coupling of the antiferromagnetic layer AF is formed by film formation in a magnetic field. Since the orientation can be set, it is possible to individually set the orientation of the exchange coupling of the antiferromagnetic layers AF of each of the plurality of unit stacked bodies 15-1 to 15-6. As a result, the direction of magnetization generated by exchange coupling with the antiferromagnetic layer AF in each soft magnetic layer SM of each of the plurality of unit stacked bodies 15-1 to 15-6 can be individually set.

Both the soft magnetic layer SM and the antiferromagnetic layer AF can be formed by a known technique such as sputtering. The crystal structure of the soft magnetic layer SM of the unit laminated body 15-1 located in the lowermost layer (nearest to the substrate 29) is preferably composed of NiFe in order to have (111) orientation in the fcc structure.

The stacking direction of the soft magnetic layer SM and the antiferromagnetic layer AF forming each of the plurality of unit stacked bodies 15-1 to 15-6 is the Y1-Y2 direction, and the soft magnetic layer SM is in the Y1-Y2 direction Y1 side. The antiferromagnetic layer AF is located on the Y2 side in the Y1-Y2 direction (distal side to the magnetoresistive effect element 11). The stacking direction of each of the plurality of unit stacked bodies 15-1 to 15-6 is also the Y1-Y2 direction. The magnetic shield 15 has an oxidation protection layer PL made of Ta or the like at a position most distal to the magnetoresistive effect element 11 (Y2-Y2 direction Y2 side end). The oxidation protection layer PL can also be formed by a known technique such as sputtering.

In the magnetic shield 15, the soft magnetic layer SM and the antiferromagnetic layer AF are exchange-coupled with each other as described above, so that the soft magnetic layer SM is separated from the magnetic sensor 1 when an external magnetic field is not applied. It can be magnetic domain. Therefore, even when the magnetic field applied to the magnetic shield 15 is large, the residual magnetization that affects the magnetoresistive effect element 11 is less likely to occur in the magnetic shield 15, and the measurement accuracy of the magnetic sensor 1 deteriorates. Hard to do.

FIG. 2 is an enlarged view of the magnetic shield 15 in FIG. In the soft magnetic layers SM of the unit laminated bodies 15-1 to 15-6 of the magnetic shield 15, the direction of magnetization generated by exchange coupling with the antiferromagnetic layer AF is not limited. As shown in FIG. 2, a direction perpendicular to the X1-X2 direction and the Y1-Y2 direction (a direction perpendicular to the paper surface and referred to as "Z1-Z2 direction"), that is, orthogonal to the sensitivity axis direction. May be. In this case, even if the leakage magnetic field from the unit laminates 15-1 to 15-6 of the magnetic shield 15 may affect the magnetoresistive effect element 11 in the state where the external magnetic field is not applied, the magnetic sensor It is unlikely to be a factor for increasing the zero magnetic field hysteresis of 1.

As shown in FIG. 2, the soft magnetic layer SM of the unit laminate body 15-1 of the magnetic shield 15 is exchange-coupled with the antiferromagnetic layer AF which is laminated so as to be in contact with the soft magnetic layer SM, so that it appears on the paper surface. It is magnetized on the front side in the vertical direction (this direction is referred to as "Z1-Z2 direction Z1 side"). Then, the direction of the magnetic field based on the exchange coupling of the soft magnetic layer SM in the unit laminated body 15-2 located closest to the unit laminated body 15-1 is the back side in the direction perpendicular to the paper surface (this direction is referred to as “Z1-Z2 direction”). Z2 side”), and is in antiparallel with the direction of the magnetic field based on the exchange coupling of the soft magnetic layer SM of the unit laminate body 15-1.

As described above, since the directions of the magnetic fields based on the exchange coupling of the soft magnetic layers SM in the two most recent unit laminates have an antiparallel relationship, these two unit laminates (specifically, In the unit laminated body 15-1 and the unit laminated body 15-2), the soft magnetic layers SM are magnetically coupled to each other to form a reflux magnetic field. Therefore, the influence of the magnetic field due to the exchange coupling of the soft magnetic layer SM of the magnetic shield 15 is limited to the vicinity of the magnetic shield 15. Therefore, in the state where the external magnetic field is not applied, the elements located around the magnetic shield 15, especially the magnetoresistive effect element 11, are less susceptible to the magnetic influence from the magnetic shield 15. From the viewpoint of facilitating the direction of the magnetic field based on the exchange coupling of the pair of soft magnetic layers SM located at the most recent position to be antiparallel, the antiferromagnetic layer AF included in the magnetic shield 15 is irregular such as IrMn. It is preferably composed of a system antiferromagnetic material. As described above, the direction of the exchange coupling of the antiferromagnetic layer AF made of the disordered antiferromagnetic material can be set by the direction of the magnetic field during film formation in the magnetic field. By forming the magnetic layer AF in the magnetic field, the influence on the soft magnetic layer SM of the lower unit laminated body 15-1 is suppressed, and it is antiparallel to the magnetization direction of the soft magnetic layer SM of the unit laminated body 15-1. It is possible to magnetize the soft magnetic layer SM of the unit laminated body 15-2 so as to have the relationship of

In the magnetic shield 15 shown in FIG. 2, the direction of the magnetic field based on the exchange coupling of the soft magnetic layer SM is also in each of the unit laminates 15-3 to 15-6 laminated on the unit laminate 15-2. The magnetization based on the exchange coupling of the soft magnetic layer SM is performed so as to have an antiparallel relationship with the direction of the magnetic field based on the exchange coupling of the soft magnetic layer SM in the most recent unit laminated body. Thus, in the magnetic shield 15, even if the soft magnetic layer SM is magnetized based on the exchange coupling with the antiferromagnetic layer AF, the leakage magnetic field flowing out of the magnetic shield 15 is limited. Therefore, the elements located around the magnetic shield 15 are suppressed from being magnetically affected by the leakage magnetic field.

The magnetic shield 15 shown in FIG. 2 has a laminated structure in which six unit laminated bodies 15-1 to 15-6 are laminated, and each of the unit laminated bodies 15-1 to 15-6 has a soft magnetic layer SM. Therefore, it can be said that the magnetic shield 15 shown in FIG. 2 has a structure in which the soft magnetic layers SM and the antiferromagnetic layers AF are alternately laminated.

FIG. 3 is a sectional view conceptually showing the structure of a magnetic sensor according to another embodiment of the present invention. The magnetic sensor 1A shown in FIG. 3 includes the magnetoresistive effect element 11 and the magnetic shield 15 similarly to the magnetic sensor 1 shown in FIG. 1, and further has a spiral shape between the magnetoresistive effect element 11 and the magnetic shield 15. The magnetic balance coil 16 is provided. The magnetic balance coil is located between the magnetoresistive effect element 11 and the magnetic shield 15, so that an induced magnetic field that cancels the external magnetic field applied in a state attenuated by the magnetic shield 15 is generated by a relatively small current. Can be generated. Therefore, it is possible to operate the magnetic balance type magnetic sensor with low power consumption.

In the above embodiment, the case where the magnetoresistive effect element 11 included in the magnetic sensor 1 is a GMR element is a specific example, but the present invention is not limited to this. In one non-limiting example, the magnetoresistive effect element is one selected from the group consisting of an anisotropic magnetoresistive effect element (AMR element), a giant magnetoresistive effect element (GMR element), and a tunnel magnetoresistive effect element (TMR element). It consists of the above elements.

When the fixed layer of the GMR element that constitutes the magnetoresistive effect element 11 included in the magnetic sensor 1 has a self-pinned structure, the fixed layer can be magnetized by film formation in a magnetic field. No heat treatment is required. Therefore, it is possible to dispose the GMR elements in which the magnetization directions of the fixed layers are different on the same substrate, and it is possible to configure a full bridge circuit on one substrate.

The magnetic sensor including the magnetoresistive effect element according to the embodiment of the present invention can be preferably used as a current sensor.

Specific examples of the current sensor according to the embodiment of the present invention include a magnetic proportional current sensor and a magnetic balanced current sensor.

A specific example of the magnetic proportional current sensor is a case where the magnetic sensor 1 shown in FIG. 1 is used. In such a current sensor, in the upper part of FIG. 1 (from the oxidation protection layer PL of the magnetic shield 15 when viewed from the magnetoresistive effect element 11). Further distal), the current line through which the current to be measured flows is located so as to extend in the Z1-Z2 direction. The induced magnetic field of the measured current, which is the measured magnetic field, is applied to the magnetoresistive effect element 11 in the direction along the sensitivity axis direction (X1-X2 direction). Since a part of the measured magnetic field passes through the magnetic shield 15 having a higher magnetic permeability, the strength of the measured magnetic field substantially applied to the magnetoresistive effect element 11 can be reduced. Therefore, the measurement range of the magnetic sensor 1 can be expanded. Moreover, since the soft magnetic layer SM of the magnetic shield 15 is magnetized by the exchange coupling with the antiferromagnetic layer AF positioned so as to be in contact with the soft magnetic layer SM, when the application of the measured magnetic field composed of the induced magnetic field of the measured current is terminated. The residual magnetization that adversely affects the magnetoresistive effect element 11 is unlikely to occur in the magnetic shield 15.

In a preferred example, the magnetic proportional current sensor has four magnetic resistance effect elements 11 and a magnetic field detection bridge circuit having two outputs that generate a potential difference according to the magnetic field to be measured, which is an induced magnetic field of the current to be measured. In the magnetic proportional current sensor having this bridge circuit, the measured current is measured by the potential difference output from the magnetic field detection bridge circuit according to the measured magnetic field.

A specific example of the magnetic balance type current sensor is the case where the magnetic sensor 1A shown in FIG. 3 is used. In such a current sensor, the magnetic sensor 1A shown in the upper part of FIG. 3 (when viewed from the magnetoresistive effect element 11 is more than the protective layer PL of the magnetic shield 15). Further distal), the current line through which the current to be measured flows is located so as to extend in the Z1-Z2 direction. The induced magnetic field of the measured current, which is the measured magnetic field, is applied to the magnetoresistive effect element 11 in the direction along the sensitivity axis direction (X1-X2 direction). Since a part of the measured magnetic field passes through the magnetic shield 15 having a higher magnetic permeability, the strength of the measured magnetic field substantially applied to the magnetoresistive effect element 11 can be reduced. Therefore, it is possible to reduce the amount of current flowing through the magnetic balancing coil 16 in order to generate an induced magnetic field that cancels the magnetic field due to the current to be measured that is substantially applied to the magnetoresistive element 11, and the current sensor The power saving of is realized. Moreover, since the soft magnetic layer SM of the magnetic shield 15 is magnetized by exchange coupling with the antiferromagnetic layer AF positioned so as to be in contact with the soft magnetic layer SM, the magnetic field to be measured, which is an induced magnetic field of the current to be measured, is applied to the magnetic sensor 1. When the above, the residual magnetization that adversely affects the magnetoresistive effect element 11 is unlikely to occur in the magnetic shield 15.

In a preferred example, the magnetic balance type current sensor includes four magnetoresistive effect elements 11, a magnetic field to be measured which is an induced magnetic field from a current to be measured, and a coil for magnetic balance applied so as to cancel the magnetic field to be measured. It has a magnetic field detection bridge circuit having two outputs that generate a potential difference according to the induced magnetic field from 16. In the magnetic balance type current sensor having this bridge circuit, the measured current is measured based on the current flowing through the magnetic balance coil 16 when the potential difference output from the magnetic field detection bridge circuit becomes zero.

The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes and equivalents within the technical scope of the present invention.

Hereinafter, the present invention will be described more specifically with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

(Example 1)
A magnetic sensor having a structure similar to the cross-sectional structure shown in FIG. 1 was produced. The magnetoresistive effect element was a GMR element. The magnetic shield has a planar shape of 650 μm×100 μm, and has a unit laminated body including a soft magnetic layer made of NiFe and having a thickness of 10 nm and an antiferromagnetic layer made of IrMn and laminated thereon and having a thickness of 6 nm. It was formed by laminating 30 layers and further laminating an oxidation protection layer made of Ta and having a thickness of 10 nm. The soft magnetic layer, antiferromagnetic layer, and oxidation protection layer were formed by sputtering.

(Comparative Example 1)
A magnetic sensor having the same structure as in Example 1 but using a plated layer made of NiFe and having a thickness of 300 nm as the magnetic shield instead of the magnetic shield having the laminated structure was produced.

(Measurement Example 1) Measurement of Zero-Field Hysteresis For each of the magnetic sensor manufactured in Example 1 and the magnetic sensor manufactured in Comparative Example 1, a hysteresis loop was formed while changing the maximum strength of the applied external magnetic field (maximum applied magnetic field). It was measured. From this hysteresis loop, zero magnetic field hysteresis ZH (unit: %/FS) was measured. The zero magnetic field hysteresis ZH is the magnitude of the output in the zero magnetic field (the maximum positive value when the positive maximum magnetic field is applied-the value when the maximum negative magnetic field is applied) in the full bridge output curve. It is the ratio of the value when the application of the magnetic field is changed to zero applied magnetic field-the value when the application of the maximum negative magnetic field is changed to zero applied magnetic field. The measurement results are shown in FIG.

As shown in FIG. 4, in the magnetic sensor according to Example 1, no change was observed in the zero magnetic field hysteresis even when the maximum applied magnetic field increased. On the other hand, in the magnetic sensor according to Comparative Example 1, when the maximum applied magnetic field exceeds 100 mT and becomes large, the zero magnetic field hysteresis has a large negative value. This is because the applied external magnetic field causes remanent magnetization in the magnetic shield in the same direction as the direction of the external magnetic field, and the reflux magnetic field based on this residual magnetic field is applied to the magnetic sensor. It is considered that this is because the direction is opposite to the direction of applying the magnetic field.)

A magnetic sensor including a magnetoresistive effect element according to an embodiment of the present invention is preferably used as a component of a current sensor of infrastructure equipment such as a columnar transformer or a component of a current sensor of an electric vehicle, a hybrid car, or the like. sell.

1, 1A Magnetic sensor 11 Magnetoresistive element IM1 Layer IM2 made of an insulating material Layer IM2 made of another insulating material EL1 Electrode EL2 Contact electrode 15 Magnetic shields 15-1 to 15-6 Unit laminate 16 Magnetic balance coil SM Soft magnetic layer AF Antiferromagnetic layer PL Oxidation protection layer 29 Substrate

Claims (13)

A magnetic sensor comprising a magnetoresistive effect element having a sensitivity axis in a specific direction, and a magnetic shield for reducing the strength of a magnetic field to be measured applied to the magnetoresistive effect element,
The magnetic shield has a laminated structure in which a plurality of unit laminated bodies each including a soft magnetic layer and an antiferromagnetic layer in contact with the soft magnetic layer are laminated.
The soft magnetic layer included in the unit laminate is exchange-coupled with the antiferromagnetic layer included in the unit laminate ,
The direction of the magnetic field based on exchange coupling in the soft magnetic layer, a magnetic sensor characterized that you orthogonal to the direction along the sensitivity axis of the magnetoresistive element. A direction of a magnetic field based on exchange coupling in the soft magnetic layer included in one of the unit laminated bodies included in the laminated structure, and the soft magnetic layer included in the unit laminated body closest to one of the unit laminated bodies. The magnetic sensor according to claim 1, which has an antiparallel relationship with a direction of a magnetic field based on exchange coupling. The magnetic sensor according to claim 2, wherein the antiferromagnetic layer is made of a disordered antiferromagnetic material. The magnetic sensor according to claim 1, wherein the antiferromagnetic layer contains a platinum group element and Mn. The magnetic sensor according to claim 1, wherein the antiferromagnetic layer is made of IrMn. The magnetic sensor according to claim 1, wherein the laminated structure has an alternating laminated structure of the antiferromagnetic layer and the soft magnetic layer. 7. The magnetoresistive effect element comprises one or more kinds of elements selected from the group consisting of an anisotropic magnetoresistive effect element, a giant magnetoresistive effect element and a tunnel magnetoresistive effect element. Magnetic sensor according to. The magnetic sensor according to claim 1, wherein the magnetoresistive effect element is a giant magnetoresistive effect element, and the giant magnetoresistive effect element includes a fixed layer having a self-pin structure. The magnetic sensor has a structure in which the magnetoresistive effect element is formed on a substrate, and the magnetic shield is formed on the substrate, and the unit laminate body located at the lowermost layer of the magnetic shield is made of NiFe. The magnetic sensor according to claim 1, comprising the soft magnetic layer and the antiferromagnetic layer formed thereon. The magnetic sensor according to claim 9, wherein the magnetic shield includes an oxidation protection layer provided most distally from the magnetoresistive effect element. The magnetic sensor according to any one of claims 1 to 10 , further comprising a magnetic balance coil, and measuring the strength of the magnetic field to be measured based on a current flowing through the magnetic balance coil. The magnetic sensor according to claim 11 , wherein the magnetic balancing coil is a spiral coil and is located between the magnetoresistive effect element and the magnetic shield. A current sensor comprising the magnetic sensor according to claim 1 , wherein the magnetic sensor uses an induced magnetic field of a measured current as the measured magnetic field.