A magnetoresistive element, a magnetic switch sensor and an electronic device

Abstract

The present invention relates to the field of magnetic field measurement technology, and discloses a magnetoresistive element, a magnetic switch sensor and an electronic device. The magnetoresistive element includes 4N magnetoresistive stacks and a soft magnetic layer. The magnetoresistive stack includes at least one first ferromagnetic layer, at least one second ferromagnetic layer and a non-magnetic layer between the first ferromagnetic layer and the second ferromagnetic layer; the first ferromagnetic layer and the second ferromagnetic layer have a closed vortex magnetization pattern; there is an anti-ferromagnetic coupling between the first ferromagnetic layer and the second ferromagnetic layer; the soft magnetic layer is parallel to the magnetoresistive plane and close to each magnetoresistive stack for converting the Z-axis magnetic field acting on each magnetoresistive stack into a magnetic field parallel to the magnetoresistive plane; within a preset magnetic field range perpendicular to or parallel to the magnetoresistive plane, the magnetoresistive element can be sensitive to an external magnetic field. The present invention enables the magnetoresistive element to respond to an in-plane magnetic field or a Z-axis magnetic field through the synergistic effect of the soft magnetic layer, the first ferromagnetic layer, the second ferromagnetic layer and the non-magnetic layer. The magnetoresistive element has a simple structure and is easy to implement.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic field measurement, and in particular to a magnetoresistive element, a magnetic switch sensor and electronic equipment. Background Art

[0002] In the fields of consumer electronics and industrial control, there are some applications that hope to detect the three-dimensional magnetic field in space. That is, as long as the external magnetic field is the same in size, the magnetic sensor can have the same or similar response to different magnetic field directions.

[0003] To achieve this requirement, multiple magnetic sensors can be installed in different detection directions to measure the magnetic field components in each direction, and then the data of multiple sensors can be numerically calculated to achieve response. However, this implementation method is complicated to install, occupies a large space, is costly, and requires additional calculations, which is not convenient in actual use.

[0004] Among the commonly used magnetoresistive sensors, anisotropic magnetoresistive sensors, giant magnetoresistive sensors and tunneling magnetoresistive sensors are mainly used to sense the magnetic field in a certain direction in the plane where the sensor is located, and cannot meet the requirements of a single chip to detect magnetic fields in different directions.

[0005] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0006] The purpose of the present invention is to provide a magnetoresistive element, a magnetic switch sensor and an electronic device, aiming to solve the problem of how to detect the magnetic field in space.

[0007] To achieve the above object, a first aspect of the present invention provides a magnetoresistive element, the magnetoresistive element comprising a soft magnetic layer and 4N magnetoresistive stacks distributed around the soft magnetic layer; the magnetoresistive stack comprises:

[0008] At least one first ferromagnetic layer, the first ferromagnetic layer is parallel to the magnetoresistive plane and has a closed vortex magnetization pattern;

[0009] at least one second ferromagnetic layer, the second ferromagnetic layer being parallel to the magnetoresistive plane and having a closed vortex magnetization pattern;

[0010] a non-magnetic layer, located between the first ferromagnetic layer and the second ferromagnetic layer, and configured to provide anti-ferromagnetic coupling between the first ferromagnetic layer and the second ferromagnetic layer;

[0011] The soft magnetic layer is parallel to the magnetoresistive plane and close to each of the magnetoresistive stacks, and is used to convert the Z-axis magnetic field perpendicular to the magnetoresistive plane acting on each of the magnetoresistive stacks into a magnetic field parallel to the magnetoresistive plane;

[0012] The magnetoresistive element is sensitive to external magnetic fields within a second preset magnetic field range perpendicular to the magnetoresistive plane and within a first preset magnetic field range parallel to the magnetoresistive plane;

[0013] Wherein, N is a positive integer not less than 1.

[0014] According to some embodiments of the present invention, the first ferromagnetic layer and the second ferromagnetic layer are disk-shaped ferromagnetic films having opposite ground-state vortex magnetization directions.

[0015] According to some embodiments of the present invention, the material of the first ferromagnetic layer and the second ferromagnetic layer is CoFe; the material of the non-magnetic layer is Cu; and the thickness of the non-magnetic layer is 0.7-1.1 nm.

[0016] According to some embodiments of the present invention, the magnetic state resistance value of each magnetoresistive stack under an external magnetic field is lower than its ground state resistance value; and the magnetic state resistance value is independent of the magnetic field direction of the external magnetic field.

[0017] According to some embodiments of the present invention, the soft magnetic layer has a rectangular structure, including a first edge, a second edge, a third edge and a fourth edge that are perpendicular to each other;

[0018] The 4N magnetoresistive stacks include a magnetoresistive stack 1 located at the first edge, a magnetoresistive stack 2 located at the second edge, a magnetoresistive stack 3 located at the third edge, and a magnetoresistive stack 4 located at the fourth edge;

[0019] Each of the magnetoresistive stacks, the magnetoresistive stack 1, the magnetoresistive stack 2, the magnetoresistive stack 3 and the magnetoresistive stack 4, is coupled in series to form a second bridge arm;

[0020] Within the first preset magnetic field range parallel to the magnetoresistive plane, the second bridge arm can generate an isotropic response to the external magnetic field.

[0021] According to some embodiments of the present invention, the 4N magnetoresistive stacks further include a magnetoresistive stack five located at the first edge, a magnetoresistive stack six located at the second edge, a magnetoresistive stack seven located at the third edge, and a magnetoresistive stack eight located at the fourth edge;

[0022] Each of the magnetoresistive stacks, the magnetoresistive stack 5, the magnetoresistive stack 6, the magnetoresistive stack 7 and the magnetoresistive stack 8, is coupled in series to form a fourth bridge arm;

[0023] The number of magnetoresistive stacks in the magnetoresistive stack 1, the magnetoresistive stack 2, the magnetoresistive stack 3, the magnetoresistive stack 4, the magnetoresistive stack 5, the magnetoresistive stack 6, the magnetoresistive stack 7 and the magnetoresistive stack 8 is M, where M is a positive integer not less than 1;

[0024] The 4N magnetoresistive stacks also include a magnetoresistive stack nine and a magnetoresistive stack ten covered by the soft magnetic layer, which are not sensitive to external magnetic fields;

[0025] The number of magnetoresistive stacks in the magnetoresistive stack nine and the magnetoresistive stack ten is 4M;

[0026] Each of the magnetoresistive stacks in the magnetoresistive stack nine is coupled in series to form a first bridge arm;

[0027] Each of the magnetoresistive stacks in the ten magnetoresistive stacks is coupled in series to form a third bridge arm;

[0028] The third bridge arm, the first bridge arm and the fourth bridge arm all have the same base state resistance value as the second bridge arm;

[0029] The first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are electrically coupled in sequence to form a Wheatstone full bridge structure.

[0030] According to some embodiments of the present invention, the magnetoresistive element further includes a first resistor and a second resistor; the resistance values ​​of the first resistor and the second resistor are the same as the ground state resistance value of the second bridge arm;

[0031] The first resistor, the second bridge arm, the second resistor and the fourth bridge arm are electrically coupled in sequence to form a Wheatstone full-bridge structure.

[0032] To achieve the above object, a second aspect of the present invention provides a magnetic switch sensor, which includes the above magnetoresistive element; and the magnetic switch sensor is sensitive to an external magnetic field.

[0033] According to some embodiments of the present invention, the magnetoresistive element outputs a differential voltage under the action of an external magnetic field;

[0034] The magnetic switch sensor further includes a control unit; the control unit is electrically coupled to the magnetoresistive element and is used to determine whether an external magnetic field exists based on the differential voltage and a threshold voltage.

[0035] To achieve the above objective, a third aspect of the present invention provides an electronic device, the electronic device comprising the above magnetoresistive element or the above magnetic switch sensor.

[0036] In summary, the magnetoresistive element disclosed in the present invention includes 4N magnetoresistive stacks and soft magnetic layers, and the magnetoresistive stack includes at least one first ferromagnetic layer, at least one second ferromagnetic layer and a non-magnetic layer between the first ferromagnetic layer and the second ferromagnetic layer; the first ferromagnetic layer and the second ferromagnetic layer have a closed vortex magnetization pattern; there is anti-ferromagnetic coupling between the first ferromagnetic layer and the second ferromagnetic layer; the soft magnetic layer is parallel to the magnetoresistive plane and close to each magnetoresistive stack for converting the Z-axis magnetic field acting on each magnetoresistive stack into a magnetic field parallel to the magnetoresistive plane; within a preset magnetic field range perpendicular or parallel to the magnetoresistive plane, the magnetoresistive element can be sensitive to an external magnetic field. The present invention enables the magnetoresistive element to respond to an in-plane magnetic field or a Z-axis magnetic field through the synergistic effect of the soft magnetic layer, the first ferromagnetic layer, the second ferromagnetic layer and the non-magnetic layer. The magnetoresistive element has a simple structure and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the structure of a magnetoresistive stack in a magnetoresistive element according to an embodiment of the present invention;

[0038] Figure 2 It is a schematic structural diagram of a magnetoresistive element according to an embodiment of the present invention;

[0039] Figure 3 A schematic diagram of the resistance change of a magnetoresistive element under an external magnetic field in the X direction, the Y direction and the Z direction according to an embodiment of the present invention;

[0040] Figure 4 Schematic diagram of a differential voltage variation curve of a magnetoresistive element under an external magnetic field in the X direction, the Y direction and the Z direction according to an embodiment of the present invention;

[0041] Figure 5 It is a schematic diagram of the structure of each magnetoresistive stack and soft magnetic layer in a magnetoresistive element according to an embodiment of the present invention;

[0042] Figure 6 It is another structural schematic diagram of a magnetoresistive element according to an embodiment of the present invention;

[0043] Figure 7 It is a structural schematic diagram of a magnetoresistive element according to another embodiment of the present invention;

[0044] Figure 8 It is another structural schematic diagram of a magnetoresistive element according to another embodiment of the present invention;

[0045] Fig. 9 Schematic diagram of the Wheatstone bridge structure of the magnetoresistive element according to an embodiment of the present invention;

[0046] Fig.10 Schematic diagram of the structure of a magnetic switch sensor according to an embodiment of the present invention.

[0047] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0048] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0049] In fields such as consumer electronics and industrial control, there are some applications that hope to detect three-dimensional magnetic fields in space.

[0050] To achieve this requirement, multiple magnetic sensors can be installed in different detection directions to measure the magnetic field components in each direction, and then the data of multiple sensors can be numerically calculated to achieve response. However, this implementation method is complicated to install, occupies a large space, is costly, and requires additional calculations, which is not convenient in actual use.

[0051] Among the commonly used magnetoresistive sensors, anisotropic magnetoresistive sensors, giant magnetoresistive sensors and tunneling magnetoresistive sensors are mainly used to sense the magnetic field in a certain direction in the plane where the sensor is located, and cannot meet the requirements of a single chip to detect magnetic fields in different directions.

[0052] To achieve the above object, an embodiment of the present invention provides a magnetoresistive element, which includes 4N magnetoresistive stacks and a soft magnetic layer, wherein N is a positive integer not less than 1. Each magnetoresistive stack is distributed around the soft magnetic layer.

[0053] The magnetoresistance stack of the embodiment of the present invention includes at least one first ferromagnetic layer, at least one second ferromagnetic layer and a non-magnetic layer between the first ferromagnetic layer and the second ferromagnetic layer. The first ferromagnetic layer and the second ferromagnetic layer are parallel to the magnetoresistance plane and have a closed vortex magnetization pattern. The non-magnetic layer is used to make the first ferromagnetic layer and the second ferromagnetic layer have antiferromagnetic coupling, and make the magnetoresistance stack have a structure of ferromagnetic layer / non-magnetic layer / ferromagnetic layer, thereby having a giant magnetoresistance effect under an external magnetic field. The soft magnetic layer is parallel to the magnetoresistance plane and close to each magnetoresistance stack, and is used to convert the Z-axis magnetic field perpendicular to the magnetoresistance plane acting on each magnetoresistance stack into a magnetic field parallel to the magnetoresistance plane. Among them, the magnetoresistance plane is a plane in the magnetoresistance stack that is parallel to the first ferromagnetic layer, the second ferromagnetic layer and the non-magnetic layer, and is not specifically limited.

[0054] like Figure 1As shown, in the magnetoresistive stack of the embodiment of the present invention, the first ferromagnetic layer 110, the non-magnetic layer 120, and the second ferromagnetic layer 130 are sequentially stacked into a cylindrical shape. The closed vortex magnetization pattern of the first ferromagnetic layer 110 is in a clockwise direction, and the closed vortex magnetization pattern of the second ferromagnetic layer 130 is in a counterclockwise direction, that is, the magnetization directions of the closed vortex magnetization patterns of the first ferromagnetic layer 110 and the second ferromagnetic layer 130 are opposite. Since their magnetization patterns are all closed vortex magnetization patterns and the magnetoresistive stack has a giant magnetoresistance effect, the magnetoresistive stack has the same feedback to the external magnetic field parallel to any direction on the magnetoresistive plane, that is, the magnetoresistive stack can have an isotropic response in an external magnetic field in any direction parallel to the magnetoresistive plane.

[0055] like Figure 2 As shown, the magnetoresistive stack 100 of the embodiment of the present invention includes 4N, wherein N magnetoresistive stacks are located near the first edge of the soft magnetic layer, N magnetoresistive stacks are located near the second edge of the soft magnetic layer, N magnetoresistive stacks are located near the third edge of the soft magnetic layer, and N magnetoresistive stacks are located near the fourth edge of the soft magnetic layer. The first edge, the second edge, the third edge, and the fourth edge are perpendicular to each other.

[0056] The soft magnetic layer 200 of the embodiment of the present invention is parallel to the magnetoresistive plane and close to each magnetoresistive stack 100. When the magnetoresistive stack 100 is located at the edge of the soft magnetic layer 200 and arranged in a direction away from the soft magnetic layer 200, the Z-axis magnetic field acting on the magnetoresistive stack 100 and perpendicular to the magnetoresistive plane can be converted into a magnetic field parallel to the magnetoresistive plane and in a direction away from the soft magnetic layer; in the Z-direction magnetic field perpendicular to the magnetoresistive plane, the resistance of the magnetoresistive stack can change with the intensity of the external magnetic field. Therefore, the magnetoresistive element can be sensitive to the external magnetic field in the Z direction.

[0057] It should be noted that the soft magnetic layer 200 of the embodiment of the present invention may be located above or below each magnetoresistive stack 100, and each magnetoresistive stack 100 may be located above or below each magnetoresistive stack 100. Figure 5 (a) is located at the edge of the soft magnetic layer 200 and away from the first position of the soft magnetic layer 200, or at Figure 5 (c) The second position of the edge of the soft magnetic layer 200 and close to the soft magnetic layer 200, or the ... Figure 5 (b) Between the first position and the second position shown.

[0058] Considering that the soft magnetic layer may gather the magnetic field around the magnetoresistive stack when it is located at the edge of the magnetoresistive stack, the magnetic field response sensed by each magnetoresistive stack will be closely related to the position of the soft magnetic layer. In order to avoid the influence of the position of the soft magnetic layer on the magnetic field sensed by the magnetoresistive stack, the number of magnetoresistive stacks in the magnetoresistive element of the embodiment of the present invention is a multiple of 4. Specifically, 1 / 4 of the magnetoresistive stacks in the magnetoresistive element are located at the first edge of the soft magnetic layer, 1 / 4 of the magnetoresistive stacks are located at the second edge of the soft magnetic layer; 1 / 4 of the magnetoresistive stacks are located at the third edge of the soft magnetic layer; 1 / 4 of the magnetoresistive stacks are located at the fourth edge of the soft magnetic layer; the first edge, the second edge, the third edge and the fourth edge are connected in sequence to form a closed area, and the closed area is preferably a rectangle, and each adjacent edge is perpendicular to each other.

[0059] like Figure 2 As shown, the soft magnetic layer 200 is square, and a plurality of magnetoresistive stacks 100 are arranged on its four edges. The magnetoresistive element of the embodiment of the present invention sequentially couples the same number of magnetoresistive stacks 100 on the four edges in series or in parallel to obtain a bridge arm; since the four edges are perpendicular to each other, the resistance of the bridge arm can be independent of the position of the soft magnetic layer, and the strength of the external magnetic field can be fed back truthfully. Therefore, on the basis that a single magnetoresistive stack has an isotropic response under an external magnetic field parallel to the magnetoresistive plane, the bridge arm of the embodiment of the present invention and the magnetoresistive element including the bridge arm can achieve an isotropic response under an external magnetic field parallel to the magnetoresistive plane.

[0060] In the magnetoresistive element of the embodiment of the present invention, the Z-direction magnetic field can be converted into a magnetic field parallel to the magnetoresistive plane through the soft magnetic layer in the magnetoresistive element to act on each magnetoresistive stack, so that the magnetoresistive element responds to the Z-direction magnetic field.

[0061] It should be understood that under an external magnetic field of the same magnetic field strength, the strength of the magnetic field parallel to the magnetoresistive plane acting on each magnetoresistive stack after the Z-direction magnetic field is transformed by the soft magnetic layer is generally weaker than the strength of the magnetic field directly acting on each magnetoresistive stack in the X-direction or Y-direction.

[0062] Therefore, if Figure 3 As shown, the magnetoresistive element can respond to both the magnetic field parallel to the magnetoresistive plane and the magnetic field perpendicular to the magnetoresistive plane; under the same magnetic field strength, the degree of reduction in the resistance value of the same magnetoresistive element when inducing an external magnetic field in the Z direction is less than the degree of reduction in the resistance value when inducing an external magnetic field in the X direction or the Y direction, that is, under the same external magnetic field, the resistance value of the magnetoresistive element when used to induce an external magnetic field in the Z direction is higher than the resistance value when used to induce an external magnetic field in the X direction or the Y direction.

[0063] It should be noted that the number of soft magnetic layers in the embodiment of the present invention can be 1, 2 or more. The soft magnetic layer has at least 2 mutually perpendicular extension directions, so that the soft magnetic layer gathers four directions perpendicular to each other on the magnetoresistive stack.

[0064] The first ferromagnetic layer and the second ferromagnetic layer of the magnetoresistive stack of the magnetoresistive element in the embodiment of the present invention have antiferromagnetic coupling; in the presence of an external magnetic field, the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer in the magnetoresistive stack tend toward the direction of the external magnetic field, even if the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are the same. At this time, the magnetic state resistance value of the magnetoresistive stack under the external magnetic field is smaller than the ground state resistance value, and its size is independent of the direction of the external magnetic field, but only related to the magnetic field strength of the external magnetic field.

[0065] In summary, the magnetoresistive element disclosed in the present invention includes 4N magnetoresistive stacks and soft magnetic layers, and the magnetoresistive stack includes at least one first ferromagnetic layer, at least one second ferromagnetic layer and a non-magnetic layer between the first ferromagnetic layer and the second ferromagnetic layer; the first ferromagnetic layer and the second ferromagnetic layer have a closed vortex magnetization pattern; there is an antiferromagnetic coupling between the first ferromagnetic layer and the second ferromagnetic layer; the soft magnetic layer is parallel to the magnetoresistive plane and close to each magnetoresistive stack for converting the Z-axis magnetic field acting on each magnetoresistive stack into a magnetic field parallel to the magnetoresistive plane; within a preset magnetic field range perpendicular or parallel to the magnetoresistive plane, the magnetoresistive element can be sensitive to an external magnetic field. The present invention enables the magnetoresistive element to respond to an in-plane magnetic field or a Z-axis magnetic field through the synergistic effect of the soft magnetic layer, the first ferromagnetic layer, the second ferromagnetic layer and the non-magnetic layer. In addition, the magnetoresistive element also has the beneficial effect of being simple in structure and easy to implement.

[0066] In the magnetoresistive element of the embodiment of the present invention, the first ferromagnetic layer and the second ferromagnetic layer may be made of CoFe or other ferromagnetic layer materials; the non-magnetic layer may be made of Cu; and the thickness of the non-magnetic layer may be 0.7-1.1 nm, preferably 0.8-1 nm.

[0067] The soft magnetic layer of the embodiment of the present invention may have the following Figure 2 or Figure 7 The rectangular structure shown includes a first edge, a second edge, a third edge and a fourth edge that are perpendicular to each other; wherein the angle between the first edge and the X-axis parallel to the magnetic resistance plane can be any angle between 0 and 90 degrees, such as 0 degrees, 45 degrees, and 90 degrees.

[0068] like Figure 6 and Figure 8 As shown, the 4N magnetoresistive stacks of the embodiment of the present invention include not only magnetoresistive stacks that are sensitive to external magnetic fields and are located near the edges of the soft magnetic layer, but also magnetoresistive stacks that are not sensitive to external magnetic fields and are covered by the soft magnetic layer.

[0069] Specifically, the 4N magnetoresistive stacks of the embodiment of the present invention include magnetoresistive stack one located at the first edge, magnetoresistive stack two located at the second edge, magnetoresistive stack three located at the third edge and magnetoresistive stack four located at the fourth edge; each magnetoresistive stack among magnetoresistive stack one, magnetoresistive stack two, magnetoresistive stack three and magnetoresistive stack four can be coupled in series to form a second bridge arm of a Wheatstone bridge; within a first preset magnetic field range parallel to the magnetoresistive plane, the second bridge arm can produce an isotropic response to an external magnetic field.

[0070] The 4N magnetoresistive stacks of the embodiment of the present invention further include a magnetoresistive stack 5 located at the first edge, a magnetoresistive stack 6 located at the second edge, a magnetoresistive stack 7 located at the third edge, and a magnetoresistive stack 8 located at the fourth edge; wherein each magnetoresistive stack of the magnetoresistive stack 5, the magnetoresistive stack 6, the magnetoresistive stack 7, and the magnetoresistive stack 8 is coupled in series to form a fourth bridge arm. Similarly, within the first preset magnetic field range parallel to the magnetoresistive plane, the fourth bridge arm can generate an isotropic response to the external magnetic field.

[0071] In order to make the output signals of the fourth bridge arm and the second bridge arm the same, the number of magnetoresistive stacks in the magnetoresistive stack 1, magnetoresistive stack 2, magnetoresistive stack 3, magnetoresistive stack 4, magnetoresistive stack 5, magnetoresistive stack 6, magnetoresistive stack 7 and magnetoresistive stack 8 is M, where M is a positive integer not less than 1;

[0072] The 4N magnetoresistive stacks of the embodiment of the present invention also include a magnetoresistive stack nine and a magnetoresistive stack ten covered by a soft magnetic layer; due to the shielding effect of the soft magnetic layer, the magnetoresistive stack nine and the magnetoresistive stack ten are not sensitive to the external magnetic field; the number of magnetoresistive stacks in the magnetoresistive stack nine and the magnetoresistive stack ten is 4M; the magnetoresistive stacks in the magnetoresistive stack nine are coupled in series to form a first bridge arm; the magnetoresistive stacks in the magnetoresistive stack ten are coupled in series to form a third bridge arm;

[0073] Therefore, the third bridge arm, the first bridge arm and the fourth bridge arm of the embodiment of the present invention all have the same ground state resistance value as the second bridge arm; the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are electrically coupled in sequence to form the following Fig. 9 The Wheatstone full bridge structure is shown.

[0074] In the embodiment of the present invention, when forming a Wheatstone full-bridge structure, the first bridge arm and the third bridge arm may be replaced by a first resistor and a second resistor, wherein the resistance values ​​of the first resistor and the second resistor are the same as the ground state resistance value of the second bridge arm.

[0075] The magnetoresistive element with a Wheatstone full-bridge structure in the embodiment of the present invention has a differential voltage under an external magnetic field. The curve of the differential voltage changing with the external magnetic field is as follows: Figure 4 shown.

[0076] like Figure 4As shown, the differential voltage of the ground state magnetoresistive element gradually increases with the increase of the external magnetic field strength; when the differential voltage increases to V1, the growth rate of the differential voltage is obvious; when the differential voltage increases to V2, the growth rate of the differential voltage slows down to remain unchanged.

[0077] in accordance with Figure 4 , when the magnetic field strength of the external magnetic field is ±H1 in the X-axis direction parallel to the magnetoresistive plane, the differential voltage is V1; when the magnetic field strength of the external magnetic field is ±H3, the differential voltage is V2. When the magnetic field strength of the external magnetic field is ±H1 in the Y-axis direction parallel to the magnetoresistive plane, the differential voltage is V1; when the magnetic field strength of the external magnetic field is ±H3, the differential voltage is V2. This shows that the magnetoresistive element of the embodiment of the present invention has an isotropic response to the external magnetic field parallel to the magnetoresistive plane.

[0078] in accordance with Figure 4 , when the magnetic field strength of the magnetoresistive element is ±H2 in the Z-axis direction perpendicular to the magnetoresistive plane, the differential voltage is V1, where H2 is greater than H2; when the magnetic field strength of the external magnetic field is ±H4, the differential voltage is V2. Where H2 is greater than H1, and H4 is greater than H3. In addition, the magnetic field sensitivity range of the magnetoresistive element in the Z-axis direction is wider than that in the X-axis direction or the Y-axis direction.

[0079] An embodiment of the present invention further provides a magnetic switch sensor, which includes the above-mentioned magnetoresistive element; the magnetic switch sensor can be sensitive to an external magnetic field in space.

[0080] Since the magnetoresistive element is sensitive to an external magnetic field parallel to or perpendicular to the magnetoresistive plane, the external magnetic field is not limited to the magnetic field parallel to the magnetoresistive plane, but also includes magnetic fields in other directions in three-dimensional space.

[0081] The magnetoresistive element of the embodiment of the present invention has the following features: Fig. 9 The Wheatstone bridge structure shown in FIG. 1 ; when the magnetoresistive element is in an external magnetic field, it can output a differential voltage related to the magnetic field strength of the external magnetic field.

[0082] like Fig.10 As shown, the magnetic switch sensor of the embodiment of the present invention includes not only a magnetoresistive element of a Wheatstone bridge structure, but also a control unit ASIC; the control unit ASIC is electrically coupled to the magnetoresistive element and is used to determine whether an external magnetic field exists based on the differential voltage output by the magnetoresistive element and a threshold voltage.

[0083] When the magnetic field direction of the external magnetic field is parallel to the X / Y direction of the magnetoresistive plane (at this time, the magnetic field direction of the external magnetic field is any direction parallel to the magnetoresistive plane), the magnetic switch sensor of the embodiment of the present invention determines that there is no external magnetic field when the differential voltage is lower than V1, that is, the strength of the external magnetic field is within the magnetic field range of -H1~H1; when the differential voltage is higher than V1, that is, the strength of the external magnetic field is higher than H1 or lower than -H1, it determines that there is an external magnetic field. Furthermore, the working state is adjusted to the "on" or "off" state by whether the differential voltage of the magnetoresistive element is lower than V1. Among them, H1 is a positive integer greater than 0.

[0084] When the magnetic field direction of the external magnetic field is perpendicular to the Z direction of the magnetoresistive plane, the magnetic switch sensor of the embodiment of the present invention can judge that there is no external magnetic field when the differential voltage is lower than V1, that is, the strength of the external magnetic field is within the magnetic field range between -H2 and H2; when the differential voltage is higher than V1, that is, the strength of the external magnetic field is higher than H2 or lower than -H2, it can judge that there is an external magnetic field. Furthermore, the working state is adjusted to the "on" or "off" state by whether the differential voltage of the magnetoresistive element is lower than V1. H2 is a positive integer greater than 0, and H2>H1.

[0085] The magnetic switch sensor provided in the embodiment of the present invention can determine the working state as "on" or "off" according to the strength of the external magnetic field. Specifically, the magnetic switch sensor determines whether there is an external magnetic field based on the differential voltage output by the magnetoresistive element and the threshold voltage. For example, the differential voltage output by the magnetoresistive element is compared with the threshold voltage. When the differential voltage is lower than the threshold voltage, it is determined that there is no external magnetic field, and the working state is adjusted to a low level state.

[0086] The magnetic switch sensor of the embodiment of the present invention can respond to the three-axis spatial magnetic field when the magnetic field strength of the external magnetic field is higher than H2, thereby expanding the application range of the magnetic switch sensor.

[0087] An embodiment of the present invention further provides an electronic device, which includes the above-mentioned magnetoresistive element or the above-mentioned magnetic switch sensor.

[0088] The electronic device according to the embodiment of the present invention can be applied to application scenarios such as contactless wake-up, position detection, and speed detection.

[0089] The electronic device of the embodiment of the present invention can be a Bluetooth headset, which can realize contactless wake-up through a magnetic switch sensor. The Bluetooth headset includes a compartment box; when the compartment box is opened, the magnetic switch sensor is separated from the magnet on the compartment box cover, so that the output of the magnetic switch sensor is high level, and the headset automatically detects external Bluetooth signals and connects to them; when the compartment box is closed, the magnetic switch sensor is separated from the magnet on the compartment box cover, so that the output of the magnetic switch sensor is low level, and the headset automatically disconnects from the Bluetooth signal and enters sleep mode.

[0090] The electronic device of the embodiment of the present invention can also be a float liquid level transmitter, which realizes position detection through a magnetic switch sensor. The float liquid level transmitter includes a liquid level sensor and a current converter. When the liquid level changes, the limit sensor realizes position detection through a magnetic switch sensor.

[0091] It should be understood that the above is only an example and does not constitute any limitation on the technical solution of the present invention. In specific applications, technicians in this field can make settings as needed, and the present invention does not limit this.

Claims

1. A magnetoresistive element, characterized in that: It includes a soft magnetic layer and 4N magnetoresistive stacks distributed around the soft magnetic layer; The magnetoresistive stack comprises: At least one first ferromagnetic layer, the first ferromagnetic layer is parallel to the magnetoresistive plane and has a closed vortex magnetization pattern; at least one second ferromagnetic layer, the second ferromagnetic layer being parallel to the magnetoresistive plane and having a closed vortex magnetization pattern; a non-magnetic layer, located between the first ferromagnetic layer and the second ferromagnetic layer, and configured to provide anti-ferromagnetic coupling between the first ferromagnetic layer and the second ferromagnetic layer; The soft magnetic layer is parallel to the magnetoresistive plane and close to each magnetoresistive stack, and is used to convert the Z-axis magnetic field perpendicular to the magnetoresistive plane acting on each magnetoresistive stack into a magnetic field parallel to the magnetoresistive plane; the soft magnetic layer is in a rectangular structure, including a first edge, a second edge, a third edge and a fourth edge perpendicular to each other; the 4N magnetoresistive stacks include a magnetoresistive stack 1 located at the first edge, a magnetoresistive stack 2 located at the second edge, a magnetoresistive stack 3 located at the third edge and a magnetoresistive stack 4 located at the fourth edge; within a second preset magnetic field range perpendicular to the magnetoresistive plane and within a first preset magnetic field range parallel to the magnetoresistive plane, the magnetoresistive element can be sensitive to an external magnetic field; Wherein, N is a positive integer not less than 1; Each of the magnetoresistive stacks, the magnetoresistive stack 1, the magnetoresistive stack 2, the magnetoresistive stack 3 and the magnetoresistive stack 4, is coupled in series to form a second bridge arm; Within the first preset magnetic field range parallel to the magnetoresistive plane, the second bridge arm can generate an isotropic response to the external magnetic field.

2. The magnetoresistive element according to claim 1, wherein: The first ferromagnetic layer and the second ferromagnetic layer are disk-shaped ferromagnetic films having opposite ground-state vortex magnetization directions.

3. The magnetoresistive element according to claim 2, characterized in that The material of the first ferromagnetic layer and the second ferromagnetic layer is CoFe; The material of the non-magnetic layer is Cu; the thickness of the non-magnetic layer is 0.7-1.1 nm.

4. The magnetoresistive element according to claim 1, wherein: The magnetic state resistance value of each magnetoresistive stack under an external magnetic field is lower than its ground state resistance value; and the magnetic state resistance value is independent of the magnetic field direction of the external magnetic field.

5. The magnetoresistive element according to claim 4, characterized in that The 4N magnetoresistive stacks further include a magnetoresistive stack 5 located at the first edge, a magnetoresistive stack 6 located at the second edge, a magnetoresistive stack 7 located at the third edge, and a magnetoresistive stack 8 located at the fourth edge; Each of the magnetoresistive stacks, the magnetoresistive stack 5, the magnetoresistive stack 6, the magnetoresistive stack 7 and the magnetoresistive stack 8, is coupled in series to form a fourth bridge arm; The number of magnetoresistive stacks in the magnetoresistive stack 1, the magnetoresistive stack 2, the magnetoresistive stack 3, the magnetoresistive stack 4, the magnetoresistive stack 5, the magnetoresistive stack 6, the magnetoresistive stack 7 and the magnetoresistive stack 8 is M, where M is a positive integer not less than 1; The 4N magnetoresistive stacks also include a magnetoresistive stack nine and a magnetoresistive stack ten covered by the soft magnetic layer, which are not sensitive to external magnetic fields; The number of magnetoresistive stacks in the magnetoresistive stack nine and the magnetoresistive stack ten is 4M; Each of the magnetoresistive stacks in the magnetoresistive stack nine is coupled in series to form a first bridge arm; Each of the magnetoresistive stacks in the ten magnetoresistive stacks is coupled in series to form a third bridge arm; The third bridge arm, the first bridge arm and the fourth bridge arm all have the same base state resistance value as the second bridge arm; The first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are electrically coupled in sequence to form a Wheatstone full bridge structure.

6. The magnetoresistive element according to claim 5, characterized in that The magnetoresistive element further includes a first resistor and a second resistor; the resistance values ​​of the first resistor and the second resistor are the same as the ground state resistance value of the second bridge arm; The first resistor, the second bridge arm, the second resistor and the fourth bridge arm are electrically coupled in sequence to form a Wheatstone full-bridge structure.

7. A magnetic switch sensor, characterized in that: The invention comprises a magnetoresistive element as described in any one of claims 1 to 6; the magnetic switch sensor is sensitive to an external magnetic field.

8. The magnetic switch sensor according to claim 7, characterized in that: The magnetoresistive element outputs a differential voltage under an external magnetic field; The magnetic switch sensor further includes a control unit; the control unit is electrically coupled to the magnetoresistive element and is used to determine whether an external magnetic field exists based on the differential voltage and a threshold voltage.

9. An electronic device, characterized in that: The invention comprises the magnetoresistive element according to any one of claims 1 to 6, or comprises the magnetic switch sensor according to claim 7 or 8.

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