Magnetoresistive effect probe and magnetic sensor

Abstract

It improves both linearity and sensitivity with a simple configuration. [Solution] The MR element 50 comprises a magnetized fixed layer 51, a free layer 53 that can have a magnetic vortex structure and is configured so that the center of the magnetic vortex structure moves according to the target magnetic field, and a gap layer 52 disposed between the magnetized fixed layer 51 and the free layer 53. The free layer 53 has a lower surface 53a and an upper surface 53b located at both ends in the stacking direction of the magnetized fixed layer 51, the gap layer 52, and the free layer 53, and a side surface 53d connecting the lower surface 53a and the upper surface 53b. The side surface 53d includes an inclined portion that is inclined with respect to the stacking direction.

Description

Technical Field

[0001] The present disclosure relates to a magnetoresistive element including a free layer configured to have a magnetic vortex structure, and a magnetic sensor including the magnetoresistive element.

Background Art

[0002] In recent years, magnetic sensors have been used in various applications. As a magnetic sensor, a spin valve type magnetoresistive element provided on a substrate is known. The spin valve type magnetoresistive element has a magnetization fixed layer having a magnetization with a fixed direction, a free layer having a magnetization whose direction can change according to the direction of a target magnetic field, and a gap layer disposed between the magnetization fixed layer and the free layer.

[0003] Patent Document 1 discloses a magnetic sensor device having a plurality of TMR (tunnel magnetoresistance) elements. The TMR element has a free layer having a disk-shaped structure. In the free layer, a magnetization pattern having a closed magnetic flux, also called a vortex state, is spontaneously formed. In a magnetoresistive element including a free layer having a magnetic vortex structure as described in Patent Document 1, the center of the magnetic vortex structure moves according to the magnetic field to be detected, and thereby the resistance value of the magnetoresistive element changes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In magnetic sensors using magnetoresistive elements, it is preferable that the resistance value of the magnetoresistive element changes linearly or nearly linearly in response to changes in the applied magnetic field, that is, that the resistance value of the magnetoresistive element has good linearity. In magnetoresistive elements including a free layer having a magnetic vortex structure, such as the magnetoresistive element in Patent Document 1, the magnitude of magnetization of the entire free layer changes nearly linearly in response to changes in the applied magnetic field. Therefore, by using a magnetoresistive element including a free layer having a magnetic vortex structure, the linearity of the resistance value of the magnetoresistive element can be improved. In order to further improve the linearity of the resistance value in this magnetoresistive element, it is necessary to improve the linearity of the magnitude of magnetization of the entire free layer itself.

[0006] Incidentally, in order to increase the sensitivity of a magnetic sensor, it is necessary to increase the sensitivity of the magnetoresistive element. In a magnetoresistive element that includes a free layer with a magnetic vortex structure, it is possible to increase the sensitivity of the magnetoresistive element by configuring the free layer so that the magnitude of the magnetization of the entire free layer changes significantly in response to changes in the applied magnetic field. However, conventionally, methods for improving both linearity and sensitivity with a simple configuration in a magnetoresistive element that includes a free layer with a magnetic vortex structure have not been sufficiently considered.

[0007] This disclosure has been made in view of the aforementioned problems, and its purpose is to provide a magnetoresistive element including a free layer having a magnetic vortex structure, which can improve linearity and sensitivity with a simple configuration, and a magnetic sensor equipped with this magnetoresistive element. [Means for solving the problem]

[0008] The magnetoresistive element of this disclosure comprises a magnetization-fixed layer having magnetization with a fixed direction, a free layer that can have a magnetic vortex structure and is configured so that the center of the magnetic vortex structure moves in accordance with the target magnetic field, and a gap layer disposed between the magnetization-fixed layer and the free layer. The free layer has a first lower surface and a first upper surface located at both ends in the stacking direction of the magnetization-fixed layer, the gap layer, and the free layer, and a first side surface connecting the first lower surface and the first upper surface. The first side surface includes an inclined portion that is inclined with respect to the stacking direction.

[0009] The magnetic sensor of this disclosure is a magnetic sensor comprising a plurality of magnetic sensing elements. Each of the plurality of magnetic sensing elements is a magnetoresistive element of this disclosure. [Effects of the Invention]

[0010] In the magnetoresistive element of this disclosure, the first side surface of the free layer includes a sloped portion that slopes with respect to the stacking direction. This provides the effect that, according to this disclosure, it is possible to realize a magnetoresistive element and a magnetic sensor that can improve sensitivity and linearity. [Brief explanation of the drawing]

[0011] [Figure 1] This is a plan view showing a magnetic sensor according to the first embodiment of the present disclosure. [Figure 2] This is a circuit diagram showing the circuit configuration of a magnetic sensor according to the first embodiment of this disclosure. [Figure 3] This is a plan view showing a part of a magnetic sensor according to the first embodiment of the present disclosure. [Figure 4] This is a perspective view showing a magnetoresistive element in the first embodiment of the present disclosure. [Figure 5] This is a plan view showing the free layer of a magnetoresistive element in the first embodiment of the present disclosure. [Figure 6] This is an explanatory diagram showing the direction of magnetization of the free layer of a magnetoresistive element in the first embodiment of the present disclosure. [Figure 7]It is an explanatory diagram showing the direction of magnetization of a free layer when a target magnetic field is applied to a magnetoresistive element in the first embodiment of the present disclosure. [Figure 8] It is an explanatory diagram showing the direction of magnetization of a free layer when a target magnetic field is applied to a magnetoresistive element in the first embodiment of the present disclosure. [Figure 9] It is a side view showing a free layer and a magnetization fixing layer of a magnetoresistive element in the first embodiment of the present disclosure. [Figure 10] It is an explanatory diagram showing the relationship between the intensity of a magnetic field component and the magnitude of magnetization of the entire free layer in the first embodiment of the present disclosure. [Figure 11] It is a characteristic diagram showing the relationship between the intensity of a magnetic field component obtained by the first simulation and the magnitude of magnetization of the entire free layer. [Figure 12] It is a characteristic diagram showing the relationship between the tilt angle and the slope obtained by the first simulation. [Figure 13] It is a characteristic diagram showing the relationship between the tilt angle and the linearity obtained by the first simulation. [Figure 14] It is a characteristic diagram showing the relationship between the tilt angle and the intensity of a magnetic field component at which a magnetic vortex structure disappears and the relationship between the tilt angle and the intensity of a magnetic field component at which a magnetic vortex structure is generated, obtained by the first simulation. [Figure 15] It is a characteristic diagram showing the relationship between the intensity of a magnetic field component and the linearity obtained by the second simulation. [Figure 16] It is a side view showing a magnetoresistive element in the second embodiment of the present disclosure. [Figure 17] It is a side view showing a free layer and a magnetization fixing layer of a magnetoresistive element in the second embodiment of the present disclosure. [Figure 18] It is a characteristic diagram showing the relationship between the intensity of a magnetic field component and the magnitude of magnetization of the entire free layer obtained by the third simulation. [Figure 19] It is a characteristic diagram showing the relationship between the intensity of a magnetic field component and the magnitude of magnetization of the entire free layer obtained by the third simulation. [Figure 20] It is a characteristic diagram showing the relationship between the inclination angle obtained by the third simulation and the slope. [Figure 21] It is a characteristic diagram showing the relationship between the inclination angle obtained by the third simulation and the linearity. [Figure 22] It is a side view showing the magnetoresistive element in the third embodiment of the present disclosure. [Figure 23] It is a side view showing the free layer and the magnetization fixing layer of the magnetoresistive element in the third embodiment of the present disclosure. <unk> [Figure 24] It is a characteristic diagram showing the relationship between the intensity of the magnetic field component obtained by the fourth simulation and the magnitude of the magnetization of the entire free layer. [Figure 25] It is a characteristic diagram showing the relationship between the intensity of the magnetic field component obtained by the fourth simulation and the magnitude of the magnetization of the entire free layer. [Figure 26] It is a characteristic diagram showing the relationship between the inclination angle obtained by the fourth simulation and the slope. [Figure 27] It is a characteristic diagram showing the relationship between the inclination angle obtained by the fourth simulation and the linearity.

Embodiments for Carrying Out the Invention

[0012] [First Embodiment] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. First, referring to FIGS. 1 and 2, the schematic configuration of the magnetic sensor according to the first embodiment of the present disclosure will be described. FIG. 1 is a plan view showing the magnetic sensor 1 according to the present embodiment. FIG. 2 is a circuit diagram showing the circuit configuration of the magnetic sensor 1 according to the present embodiment.

[0013] The magnetic sensor 1 according to this embodiment includes a power terminal 11, a ground terminal 12, a first output terminal 13, a second output terminal 14, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a substrate 10. The first to fourth resistors R1 to R4, the power terminal 11, the ground terminal 12, and the first and second output terminals 13 and 14 are provided on the substrate 10.

[0014] Each of the first to fourth resistive sections R1 to R4 includes multiple magnetic detection elements and is configured to detect a target magnetic field and generate at least one detection signal. In this embodiment, the multiple magnetic detection elements are in particular multiple magnetoresistive elements. Hereinafter, magnetoresistive elements will be referred to as MR elements. Since each of the first to fourth resistive sections R1 to R4 includes multiple MR elements, it can also be said that the magnetic sensor 1 is equipped with multiple MR elements.

[0015] As shown in Figure 2, the first resistor R1 is located between the power supply terminal 11 and the first output terminal 13 in the circuit configuration. The second resistor R2 is located between the ground terminal 12 and the first output terminal 13 in the circuit configuration. The third resistor R3 is located between the ground terminal 12 and the second output terminal 14 in the circuit configuration. The fourth resistor R4 is located between the power supply terminal 11 and the second output terminal 14 in the circuit configuration. In this application, the expression "in the circuit configuration" refers to the arrangement on the circuit diagram, not the arrangement in the physical configuration.

[0016] A predetermined voltage or current is applied to the power terminal 11. The ground terminal 12 is connected to ground.

[0017] Here, as shown in Figure 1, we define the X, Y, and Z directions. The X, Y, and Z directions are orthogonal to each other. Furthermore, the direction opposite to the X direction is defined as the -X direction, the direction opposite to the Y direction is defined as the -Y direction, and the direction opposite to the Z direction is defined as the -Z direction. In this embodiment, in particular, the direction perpendicular to the surface of the substrate 10 is defined as the Z direction.

[0018] Furthermore, below, a position located at the end of the Z-direction relative to a certain reference position will be referred to as "above," and a position opposite to "above" relative to a certain reference position will be referred to as "below." Also, with respect to the components of magnetic sensor 1, the surface located at the end in the Z-direction will be referred to as the "top surface," and the surface located at the end in the -Z-direction will be referred to as the "bottom surface." In addition, the expression "when viewed from a predetermined direction (for example, the Z-direction)" means viewing the object from a position at a distance in a predetermined direction or a direction parallel to the predetermined direction.

[0019] Figure 1 shows an example of the arrangement of the first to fourth resistors R1 to R4. In this example, the first and second resistors R1 and R2 are aligned parallel to the X direction. The second resistor R2 is positioned ahead of the first resistor R1 in the X direction.

[0020] The third and fourth resistors R3 and R4 are aligned parallel to the X direction. The fourth resistor R4 is positioned ahead of the third resistor R3 in the -X direction. The third resistor R3 is positioned ahead of the second resistor R2 in the -Y direction. The fourth resistor R4 is positioned ahead of the first resistor R1 in the -Y direction.

[0021] Note that the arrangement of the first to fourth resistors R1 to R4 is not limited to the example shown in Figure 1. For example, the first to fourth resistors R1 to R4 may be arranged in a predetermined order in a direction parallel to the X direction or parallel to the Y direction.

[0022] Next, with reference to Figure 3, the specific structure of the magnetic sensor 1 will be described in detail. Figure 3 is a plan view showing a part of the magnetic sensor 1.

[0023] The magnetic sensor 1 in this embodiment comprises a plurality of MR elements 50, and a plurality of lower electrodes 41 and a plurality of upper electrodes 42 for electrically connecting the plurality of MR elements 50. The plurality of lower electrodes 41 are arranged on a substrate 10 (see Figure 1). The plurality of MR elements 50 are arranged on the plurality of lower electrodes 41. The plurality of upper electrodes 42 are arranged on the plurality of MR elements 50.

[0024] Multiple MR elements 50 may be connected in series by multiple lower electrodes 41 and multiple upper electrodes 42. In this case, the method of connecting the multiple MR elements 50 is as follows. As shown in Figure 3, each lower electrode 41 has an elongated shape. A gap is formed between two lower electrodes 41 that are adjacent in the longitudinal direction of the lower electrode 41. On the upper surface of the lower electrode 41, MR elements 50 are arranged near both ends in the longitudinal direction. Each upper electrode 42 also has an elongated shape and is arranged on two lower electrodes 41 that are adjacent in the longitudinal direction of the lower electrode 41, electrically connecting two adjacent MR elements 50. This connects multiple MR elements 50 in series.

[0025] Next, the configuration of the MR element 50 will be described with reference to Figures 4 to 6. Figure 4 is a perspective view showing the MR element 50. Figure 5 is a plan view showing the free layer of the MR element 50. Figure 6 is an explanatory diagram showing the direction of magnetization of the free layer of the MR element 50.

[0026] The MR element 50 comprises a magnetization-fixed layer 51 having a magnetization 51m with a fixed direction, a free layer 53, a gap layer 52 disposed between the magnetization-fixed layer 51 and the free layer 53, and a cap layer 54 disposed on top of the free layer 53. The material and shape of the free layer 53 are selected so that it can have a magnetic vortex structure (also called a vortex structure). The gap layer 52 is a tunnel barrier layer or a non-magnetic conductive layer. The cap layer 54 is made of a non-magnetic metallic material such as Ta or Ru.

[0027] At least a portion of the free layer 53 has a frustoconical or nearly frustoconical shape. In the example shown in Figure 4, the entire free layer 53 has a frustoconical shape, and the entire MR element 50 also has a frustoconical shape.

[0028] As shown in Figure 5, the free layer 53 has a lower surface 53a and an upper surface 53b located at both ends in the stacking direction of the magnetized fixed layer 51, the gap layer 52, and the free layer 53, and a side surface 53d connecting the lower surface 53a and the upper surface 53b. The lower surface 53a is located at the -Z end of the free layer 53 and faces the gap layer 52. The upper surface 53b is located at the Z end of the free layer 53 and faces the cap layer 54.

[0029] At least a portion of the side surface 53d is inclined with respect to the stacking direction, i.e., the Z direction. The side surface 53d may be flat or curved. The planar shape of the side surface 53d when viewed from one direction parallel to the stacking direction, i.e., the Z direction, is annular. The planar shapes (shapes when viewed from the Z direction) of the bottom surface 53a and the top surface 53b are circular. The planar shape of the top surface 53b is smaller than that of the bottom surface 53a. In Figure 5, the numeral 53ae indicates the outer edge of the bottom surface 53a when viewed from the Z direction, and the numeral 53be indicates the outer edge of the top surface 53b when viewed from the Z direction. When viewed from the stacking direction (Z direction), the outer edge 53be of the top surface 53b is inside the outer edge 53ae of the bottom surface 53a.

[0030] Figure 6 shows the direction of magnetization of the free layer 53 in an arbitrary cross-section parallel to the plane perpendicular to the stacking direction (XY plane). The free layer 53 has a magnetization 53m that is vortex-shaped around the center 53c of the magnetic vortex structure. When no magnetic field is applied to the MR element 50, the center 53c of the magnetic vortex structure coincides with or approximately coincides with the axis of the frustum of the cone. The free layer 53 is configured such that the center 53c of the magnetic vortex structure can move in response to the target magnetic field MF.

[0031] The center 53c of the magnetic vortex structure moves when a component of the target magnetic field MF perpendicular to the Z direction is applied to the free layer 53. Within the range of change in the intensity of this component, it is preferable that the free layer 53 does not saturate.

[0032] In this embodiment, the magnetization 51m of the magnetized fixed layer 51 includes a component in a direction parallel to the X direction. If the magnetization 51m of the magnetized fixed layer 51 includes a component in a specific direction, that component may be the main component of the magnetization 51m of the magnetized fixed layer 51. In this embodiment, if the magnetization 51m of the magnetized fixed layer 51 includes a component in a specific direction, the direction of the magnetization 51m of the magnetized fixed layer 51 will be a specific direction or approximately a specific direction.

[0033] The MR element 50 may further include an antiferromagnetic layer. The antiferromagnetic layer is made of an antiferromagnetic material and creates exchange coupling with the magnetization fixed layer 51 to fix the direction of the magnetization 51m of the magnetization fixed layer 51. Alternatively, the magnetization fixed layer 51 may be a so-called self-pinned fixed layer (Synthetic Ferri Pinned layer, SFP layer). The self-pinned fixed layer has a laminated ferri structure in which a ferromagnetic layer, a non-magnetic intermediate layer, and a ferromagnetic layer are stacked, and the two ferromagnetic layers are antiferromagnetically coupled.

[0034] Here, we will explain the resistance value of the MR element 50, taking the case where the direction of the magnetization 51m of the magnetized fixed layer 51 is the -X direction as an example. Figures 7 and 8 show the free layer 53 when a magnetic field component MFx parallel to the X direction of the target magnetic field MF is applied to the free layer 53.

[0035] Figure 7 shows the free layer 53 when the direction of the magnetic field component MFx is in the X direction. In this case, the center 53c of the magnetic vortex structure moves due to the magnetic field component MFx, and the amount of magnetization 53m oriented in the X direction becomes greater than the amount of magnetization 53m oriented in the -X direction. In this case, the resistance value of the MR element 50 increases.

[0036] Figure 8 shows the free layer 53 when the direction of the magnetic field component MFx is in the -X direction. In this case, the center 53c of the magnetic vortex structure moves due to the magnetic field component MFx, and the amount of magnetization 53m oriented in the -X direction becomes greater than the amount of magnetization 53m oriented in the X direction. In this case, the resistance value of the MR element 50 decreases.

[0037] The change in the resistance of the MR element 50 depends on the strength of the magnetic field component MFx. When the direction of the magnetic field component MFx is in the X direction, as the strength of the magnetic field component MFx increases, the amount of magnetization 53m oriented in the X direction increases. The resistance of the MR element 50 increases as the amount of magnetization 53m oriented in the X direction increases. Also, when the direction of the magnetic field component MFx is in the -X direction, as the strength of the magnetic field component MFx increases, the amount of magnetization 53m oriented in the -X direction increases. The resistance of the MR element 50 decreases as the amount of magnetization 53m oriented in the -X direction increases. When the strength of the magnetic field component MFx increases, the resistance of the MR element 50 changes in a direction in which its increase or decrease is larger, respectively. When the strength of the magnetic field component MFx decreases, the resistance of the MR element 50 changes in a direction in which its increase or decrease is smaller, respectively. In this embodiment, in particular, the relationship between the intensity Hx of the magnetic field component MFx and the resistance value of the MR element 50 is linear or nearly linear, as long as the requirement that the free layer 53 does not saturate is met.

[0038] Next, referring to Figure 2, the direction of magnetization 51m of the magnetization fixed layer 51 in each of the first to fourth resistance sections R1 to R4 will be explained. In the first resistance section R1, the magnetization 51m of each magnetization fixed layer 51 of the multiple MR elements 50 includes a component in the first magnetization direction. In the second resistance section R2, the magnetization 51m of each magnetization fixed layer 51 of the multiple MR elements 50 includes a component in the second magnetization direction, opposite to the first magnetization direction. In the third resistance section R3, the magnetization 51m of each magnetization fixed layer 51 of the multiple MR elements 50 includes a component in the first magnetization direction. In the fourth resistance section R4, the magnetization 51m of each magnetization fixed layer 51 of the multiple MR elements 50 includes a component in the second magnetization direction. In Figure 2, the two arrows drawn in the first and third resistance sections R1 and R3, respectively, indicate the first magnetization direction. In Figure 2, the two arrows drawn on the second and fourth resistors R2 and R4, respectively, indicate the second magnetization direction. In this embodiment, the first magnetization direction is in the X direction, and the second magnetization direction is in the -X direction.

[0039] Next, with reference to Figure 2, at least one detection signal generated by the magnetic sensor 1 will be described. When the direction of the magnetic field component MFx is the X direction, the resistance values ​​of each of the multiple MR elements 50 in the first and third resistive sections R1 and R3 decrease, and the resistance values ​​of each of the multiple MR elements 50 in the second and fourth resistive sections R2 and R4 increase, compared to the state in which the magnetic field component MFx is absent. As a result, the resistance values ​​of each of the first and third resistive sections R1 and R3 decrease, and the resistance values ​​of each of the second and fourth resistive sections R2 and R4 increase.

[0040] When the direction of the magnetic field component MFx is in the -X direction, the changes in the resistance values ​​of the first to fourth resistance sections R1 to R4 are reversed compared to the case where the direction of the magnetic field component MFx is in the X direction.

[0041] Thus, when the direction and intensity of the magnetic field component MFx change, the resistance values ​​of the first to fourth resistors R1 to R4 change such that the resistance values ​​of the first and third resistors R1 and R3 increase while the resistance values ​​of the second and fourth resistors R2 and R4 decrease, or the resistance values ​​of the first and third resistors R1 and R3 decrease while the resistance values ​​of the second and fourth resistors R2 and R4 increase. As a result, the potential at the connection point of the first and second resistors R1 and R2, i.e., the potential of the first output terminal 13, and the potential at the connection point of the third and fourth resistors R3 and R4, i.e., the potential of the second output terminal 14, change. The magnetic sensor 1 may generate a signal corresponding to the potential of the first output terminal 13 and a signal corresponding to the potential of the second output terminal 14 as detection signals. Alternatively, the magnetic sensor 1 may generate a signal corresponding to the potential difference between the first output terminal 13 and the second output terminal 14 as a detection signal. In this case, the magnetic sensor 1 may further include a differential amplifier (difference detector) that outputs a signal corresponding to the potential difference between the first output terminal 13 and the second output terminal 14 as a detection signal.

[0042] Next, with reference to Figure 9, the shape of the side surface 53d of the free layer 53 and the shape of the side surface of the magnetized fixed layer 51 will be described. Figure 9 is a side view showing the free layer 53 and the magnetized fixed layer 51 of the MR element 50. The side surface 53d of the free layer 53 includes an inclined portion that slopes with respect to the stacking direction, i.e., the Z direction. In the example shown in Figure 9, the entire side surface 53d is the inclined portion. Also, in the example shown in Figure 9, the entire side surface 53d (inclined portion) is a plane. However, at least a part of the side surface 53d (inclined portion) may be a curved surface. In addition, the side surface 53d of the free layer 53 may include a portion that is parallel or nearly parallel to the Z direction, in addition to the inclined portion.

[0043] In Figure 9, the symbol θ1 represents the angle that the inclined portion of the side surface 53d makes with respect to the lower surface 53a of the free layer 53. Hereafter, angle θ1 will be referred to as the inclination angle of the side surface 53d.

[0044] At least a portion of the magnetized fixed layer 51 has a frustoconical or substantially frustoconical shape. The magnetized fixed layer 51 has a lower surface 51a and an upper surface 51b located at both ends in a direction parallel to the stacking direction, i.e., the Z direction, and a side surface 51d connecting the lower surface 51a and the upper surface 51b. The lower surface 51a is located at the -Z end of the magnetized fixed layer 51. The upper surface 51b is located at the Z end of the magnetized fixed layer 51 and faces the gap layer 52.

[0045] Side surface 51d includes an inclined portion that slopes with respect to a direction parallel to the Z direction. In the example shown in Figure 9, the entire side surface 51d is the inclined portion. In Figure 9, the symbol θ2 represents the angle that the inclined portion of side surface 51d makes with respect to the lower surface 51a of the magnetization fixed layer 51. Hereinafter, angle θ2 will be referred to as the inclination angle of side surface 51d. The inclination angle θ2 of side surface 51d may or may not coincide with the inclination angle θ1 of side surface 53d. In the example shown in Figure 9, the inclination angle θ2 of side surface 51d coincides with or approximately coincides with the inclination angle θ1 of side surface 51d.

[0046] Next, with reference to Figure 10, the relationship between the intensity of the magnetic field component MFx and the magnitude of the magnetization of the free layer 53 will be explained. Figure 10 is a schematic diagram illustrating the relationship between the intensity of the magnetic field component MFx and the magnitude of the magnetization of the free layer 53. In Figure 10, the horizontal axis represents the intensity Hx of the magnetic field component MFx, and the vertical axis represents the magnitude Mx of the magnetization of the free layer 53. In Figure 10, the intensity Hx when the direction of the magnetic field component MFx is in the X direction is represented by a positive value, and the intensity Hx when the direction of the magnetic field component MFx is in the -X direction is represented by a negative value. When the direction of the magnetic field component MFx is in the X direction, as the amount of magnetization 53m directed in the X direction increases, the magnitude Mx of the magnetization of the free layer 53 increases. When the direction of the magnetic field component MFx is in the -X direction, as the amount of magnetization 53m directed in the -X direction increases, the magnitude Mx of the magnetization of the free layer 53 decreases.

[0047] First, let's explain the case where the intensity Hx is increased from 0. When the intensity Hx is gradually increased from 0, the magnitude of the magnetization Mx also gradually increases. When the intensity Hx reaches a value of Hx1 or greater, the magnitude of the magnetization Mx becomes constant, and the free layer 53 becomes magnetically saturated.

[0048] Next, we will explain the case where the intensity Hx is decreased from 0. When the intensity Hx is gradually decreased from 0, the magnitude of the magnetization Mx also gradually decreases. When the intensity Hx becomes less than or equal to Hx2, the magnitude of the magnetization Mx becomes constant, and the free layer 53 becomes magnetically saturated.

[0049] As shown in Figure 10, within a predetermined range where the intensity Hx is greater than value Hx2 and less than value Hx1, the magnetization magnitude Mx changes linearly with respect to the change in intensity Hx. "Linearly changing" means that, in the characteristic diagram showing the relationship between intensity Hx and magnetization magnitude Mx, the magnetization magnitude Mx changes linearly or nearly linearly with respect to the change in intensity Hx.

[0050] In this embodiment, it is preferable that the free layer 53 does not become magnetically saturated within the range of change in intensity Hx, and it is more preferable that the magnitude of magnetization Mx changes linearly with respect to the change in intensity Hx.

[0051] Furthermore, if the intensity Hx becomes greater than the value Hx1 and the free layer 53 becomes magnetically saturated, and then the intensity Hx is decreased from a value Hx3 greater than Hx1, the magnitude of magnetization Mx hardly changes until it reaches a value Hx4 less than Hx1. When the intensity Hx becomes less than the value Hx4, the magnitude of magnetization Mx changes linearly with respect to the change in intensity Hx, similar to when the intensity Hx is changed within a predetermined range greater than Hx2 and less than Hx1.

[0052] Similarly, if the intensity Hx is increased from a value Hx5 (which is less than Hx2) after the free layer 53 has become magnetically saturated when the intensity Hx is less than Hx2, the magnitude of magnetization Mx hardly changes until it reaches a value Hx6 (which is greater than Hx2). Once the intensity Hx is greater than Hx6, the magnitude of magnetization Mx changes linearly with respect to the change in intensity Hx, similar to when the intensity Hx is varied within a predetermined range greater than Hx2 and less than Hx1.

[0053] Although not shown in the diagram, the relationship between intensity Hx and the resistance of the MR element 50 is similar to the relationship between intensity Hx and the magnitude of the magnetization of the entire free layer 53.

[0054] Next, we will explain the results of the first and second simulations that investigated the effect of the tilt angle θ1 of the side surface 53d of the free layer 53 on the characteristics of the MR element 50. First, we will explain the first simulation. In the first simulation, the tilt angle θ1 is varied within the range of 30° to 90° while keeping the diameter of the lower surface 53a of the free layer 53 the same. Then, for each tilt angle θ1, the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of magnetization is determined. In the first simulation, the diameter of the lower surface 53a of the free layer 53 is set to 500 nm. Note that when the tilt angle θ1 is 90°, the free layer 53 has a cylindrical or nearly cylindrical shape.

[0055] Furthermore, the ratio of the change in the magnitude of magnetization Mx to the change in the intensity Hx of the magnetic field component MFx, i.e., the slope, is determined from the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of magnetization. The slope is determined within the range of the intensity Hx of the magnetic field component MFx in which the free layer 53 does not become magnetically saturated. The slope is a parameter that corresponds to the sensitivity of the MR element 50. The larger the slope, the higher the sensitivity of the MR element 50.

[0056] Furthermore, the linearity of the magnetization magnitude Mx is determined from the relationship between the magnetic field component MFx intensity Hx and the magnetization magnitude Mx. Linearity is defined using a characteristic curve representing the relationship between the magnetic field component MFx intensity Hx and the magnetization magnitude Mx, and an approximate straight line of this characteristic curve. In other words, linearity is the residual between the value on the approximate straight line and the value on the characteristic curve when the value of the magnetic field component MFx intensity Hx is kept the same. Linearity is determined within the range of magnetic field component MFx intensity Hx where the free layer 53 does not experience magnetic saturation. A smaller linearity value indicates better linearity.

[0057] Furthermore, from the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of magnetization, we determine the intensity Ha (corresponding to Hx1 in Figure 10) of the magnetic field component MFx at which the magnetic vortex structure disappears when the intensity Hx of the magnetic field component MFx is increased, and the intensity Hn (corresponding to Hx4 in Figure 10) of the magnetic field component MFx at which the magnetic vortex structure is generated when the intensity Hx of the magnetic field component MFx is decreased after the free layer 53 has reached magnetic saturation. The larger the intensities Ha and Hn of the magnetic field component MFx, the wider the measurement range of the magnetic field component MFx can be.

[0058] Figure 11 is a characteristic diagram showing the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of the magnetization. In Figure 11, the horizontal axis represents the intensity Hx (in mT), and the vertical axis represents the magnitude Mx (in T). In Figure 11, reference numeral 71 represents the case when the tilt angle θ1 is 90°, reference numeral 72 represents the case when the tilt angle θ1 is 75°, reference numeral 73 represents the case when the tilt angle θ1 is 60°, reference numeral 74 represents the case when the tilt angle θ1 is 45°, and reference numeral 75 represents the case when the tilt angle θ1 is 30°.

[0059] Figure 12 is a characteristic diagram showing the relationship between the tilt angle θ1 and the slope. In Figure 12, the horizontal axis represents the tilt angle θ1, and the vertical axis represents the slope. In Figure 12, the slope is determined as the ratio of the change in magnetization magnitude Mx (unit: T) to the change in intensity magnitude Hx (unit: A / m). Specifically, for each tilt angle θ1, the intensity magnitude Hx is 0 or greater than 4.8 × 10⁻⁶. 4Within the range specified below, the slope of the approximate straight line obtained by linearly approximating the characteristic curve representing the relationship between intensity Hx and magnetization magnitude Mx is determined. In Figure 12, the slopes at each tilt angle θ1 are connected by lines. Note that in figures similar to Figure 12 used in the following explanation, the method for determining the slope is the same as in Figure 12. As shown in Figure 12, the slope increases as the tilt angle θ1 decreases.

[0060] Figure 13 is a characteristic diagram showing the relationship between the inclination angle θ1 and linearity. In Figure 13, the horizontal axis represents the inclination angle θ1, and the vertical axis represents linearity. In Figure 13, the unit of linearity is T. In Figure 13, the magnitude of the intensity Hx is 4.8 × 10⁻⁶. 4 Linearity is calculated by determining the residual between the value on the approximate straight line and the value on the characteristic curve when the A / m value is small. In Figure 13, the linearity at each inclination angle θ1 is connected by a line. Note that the method for calculating linearity in figures similar to Figure 13 used in the following explanation is the same as the method for calculating linearity in Figure 13. As shown in Figure 13, when the inclination angle θ1 is 75° or less, the value of linearity decreases as the inclination angle θ1 decreases.

[0061] Figure 14 is a characteristic diagram showing the relationship between the tilt angle θ1 and the intensity Ha of the magnetic field component MFx at which the magnetic vortex structure disappears, and the relationship between the tilt angle θ1 and the intensity Hn of the magnetic field component MFx at which the magnetic vortex structure is generated. In Figure 14, the horizontal axis represents the tilt angle θ1, and the vertical axis represents the intensity Ha,Hn (in mT). Also, the symbol 76 represents the intensity Ha, and the symbol 77 represents the intensity Hn. As shown in Figure 14, when the tilt angle θ1 is 75° or less, the intensities Ha,Hn decrease as the tilt angle θ1 decreases.

[0062] As can be seen from the results of the first simulation, reducing the inclination angle θ1 increases the slope and decreases the linearity value. In other words, according to this embodiment, both linearity and sensitivity can be improved with a simple configuration of providing an inclined portion on the side surface 53d of the free layer 53.

[0063] From the results of the first simulation, it is preferable that the tilt angle θ1 is 60° or less. On the other hand, as shown in Figure 14, as the tilt angle θ1 decreases, the intensities Ha and Hn decrease. From the viewpoint of widening the measurement range of the magnetic field component MFx to some extent, it is preferable that the tilt angle θ1 is 30° or more.

[0064] Next, the second simulation will be described. The second simulation uses the model of the embodiment and the model of the comparative example. The model of the embodiment is the model of the free layer 53 in this embodiment. In the model of the embodiment, the inclination angle θ1 is set to 45°. The model of the comparative example is the model of the free layer 53 of the comparative example with an inclination angle θ1 of 90°.

[0065] The diameter of the lower surface 53a of the free layer 53 in the example model and the comparative example model is designed so that the ratio of the change in the magnitude of magnetization Mx to the change in the intensity Hx of the magnetic field component MFx, i.e., the slope, is the same for both the example model and the comparative example model. In the example model, the diameter of the lower surface 53a of the free layer 53 is 500 nm. In the comparative example model, the diameter of the lower surface 53a of the free layer 53 is 530 nm.

[0066] In the second simulation, the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of magnetization is determined for both the example model and the comparative example model. Then, the linearity of the magnitude Mx of magnetization is determined from the determined relationship. In particular, the linearity value is determined for each intensity Hx in the second simulation.

[0067] Figure 15 is a characteristic diagram showing the relationship between intensity Hx and linearity. In Figure 15, the horizontal axis represents intensity Hx (in mT), and the vertical axis represents linearity (in T). The curve labeled 78 represents the linearity of the model in the example. The curve labeled 79 represents the linearity of the model in the comparative example. As shown in Figure 15, the linearity value of the model in the example (labeled 78) is smaller than the linearity value of the model in the comparative example (labeled 79).

[0068] As can be seen from the second simulation, according to this embodiment, linearity can be improved by providing an inclined portion on the side surface 53d of the free layer 53.

[0069] Although not shown in the diagram, similar to the first simulation, the intensities Ha and Hn are smaller in the example model compared to the comparative example model. Therefore, it is desirable to determine the inclination angle θ1 while taking the intensities Ha and Hn into consideration.

[0070] [Second Embodiment] Next, a second embodiment of the present disclosure will be described. In this embodiment, the magnetic sensor 1 includes an MR element 150 instead of the MR element 50 in the first embodiment. The configuration of the MR element 150 will be described below with reference to Figures 16 and 17. Figure 16 is a side view showing the MR element 150. Figure 17 is a side view showing the free layer and the magnetized fixed layer of the MR element 150.

[0071] The MR element 150 comprises a magnetization fixed layer 151 having magnetization with a fixed direction, a free layer 153, a gap layer 152 disposed between the magnetization fixed layer 151 and the free layer 153, and a cap layer 154 disposed on top of the free layer 153. The configurations of the magnetization fixed layer 151, the gap layer 152, the free layer 153, and the cap layer 154 are the same as those of the magnetization fixed layer 51, the gap layer 52, the free layer 53, and the cap layer 54 in the first embodiment, except for the shapes of the magnetization fixed layer 151 and the free layer 153, which will be described later.

[0072] In this embodiment, in particular, a portion of the free layer 53 has a frustoconical or substantially frustoconical shape, while another portion of the free layer 53 has a different frustoconical or substantially frustoconical shape from the aforementioned portion.

[0073] As shown in Figure 17, the free layer 153 has a lower surface 153a and an upper surface 153b located at both ends in the stacking direction of the magnetized fixed layer 151, the gap layer 152, and the free layer 153, and a side surface 153d connecting the lower surface 153a and the upper surface 153b. The lower surface 153a is located at the -Z end of the free layer 153 and faces the gap layer 152. The upper surface 153b is located at the Z end of the free layer 153 and faces the cap layer 154.

[0074] The side surface 153d includes a first portion 153d1 and a second portion 153d2 located between the first portion 153d1 and the top surface 153b. At least one of the first portion 153d1 and the second portion 153d2 corresponds to an inclined portion that is inclined with respect to the stacking direction, i.e., the Z direction. If the first portion 153d1 corresponds to an inclined portion, the second portion 153d2 may also correspond to an inclined portion. Alternatively, if the first portion 153d1 corresponds to an inclined portion, the second portion 153d2 does not have to correspond to an inclined portion. That is, the second portion 153d2 does not have to be inclined with respect to the direction parallel to the Z direction. In this embodiment in particular, both the first portion 153d1 and the second portion 153d2 correspond to an inclined portion.

[0075] The planar shape of the side surface 153d when viewed from one direction parallel to the stacking direction, i.e., the Z direction, is annular. Furthermore, the planar shapes of the first portion 153d1 and the second portion 153d2 when viewed from the Z direction are both annular.

[0076] In Figure 17, the symbol θ3 represents the angle that the first portion 153d1 of the side surface 153d makes with respect to the bottom surface 153a of the free layer 153. Hereafter, angle θ3 will be referred to as the inclination angle of the first portion 153d1. Also, the symbol θ4 represents the angle that the second portion 153d2 of the side surface 153d makes with respect to the bottom surface 153a of the free layer 153. Hereafter, angle θ4 will be referred to as the inclination angle of the second portion 153d2. For convenience, in Figure 17, the inclination angle θ4 of the second portion 153d2 is represented as the angle that the second portion 153d2 makes with respect to a hypothetical plane P1 parallel to the bottom surface 153a of the free layer 153. The inclination angle θ3 of the first portion 153d1 may be smaller than the inclination angle θ4 of the second portion 153d2.

[0077] The magnetized fixed layer 151 has a frustoconical or nearly frustoconical shape. The magnetized fixed layer 151 has a lower surface 151a and an upper surface 151b located at both ends in a direction parallel to the stacking direction, i.e., the Z direction, and a side surface 151d connecting the lower surface 151a and the upper surface 151b. The lower surface 151a is located at the -Z end of the magnetized fixed layer 151. The upper surface 151b is located at the Z end of the magnetized fixed layer 151 and faces the gap layer 152.

[0078] Side surface 151d includes an inclined portion that slopes with respect to the stacking direction, i.e., the Z direction. In the example shown in Figure 17, the entire side surface 151d is the inclined portion. In Figure 17, the symbol θ5 represents the angle that the inclined portion of side surface 151d makes with respect to the lower surface 151a of the magnetized fixed layer 151. Hereafter, angle θ5 will be referred to as the inclination angle of side surface 151d.

[0079] In this embodiment, the absolute value of the difference between the inclination angle θ3 of the first portion 153d1 and the inclination angle θ5 of the side surface 151d is smaller than the absolute value of the difference between the inclination angle θ4 of the second portion 153d2 and the inclination angle θ5 of the side surface 151d. Note that the inclination angle θ5 of the side surface 151d may be the same as or approximately the same as the inclination angle θ3 of the first portion 153d1.

[0080] Next, we will explain the results of a third simulation that investigated the effect of the tilt angle θ3 of the first portion 153d1 of the side surface 153d of the free layer 153 on the characteristics of the MR element 150. In the third simulation, the diameter of the lower surface 153a of the free layer 153a, the diameter of the upper surface 153b of the free layer 153, and the dimensions of the free layer 153 in the direction parallel to the Z direction were kept the same, while the tilt angle θ3 was varied within the range of 5° to 30°. Then, for each tilt angle θ3, the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of the magnetization was determined.

[0081] In the third simulation, the diameter of the lower surface 153a of the free layer 153 is set to 589 nm, the diameter of the upper surface 153b of the free layer 153 is set to 471 nm, and the dimension of the free layer 153 in the direction parallel to the Z direction is set to 50 nm. In addition, in the third simulation, the inclination angle θ4 of the second portion 153d2 of the side surface 153d is set to 60°.

[0082] In the third simulation, the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of magnetization is also determined for the case where the side surface 153d of the free layer 153 does not include the first portion 153d1 but includes only the second portion 153d2. In this case, the shape of the free layer 153 is substantially the same as the free layer 53 in the first embodiment, with the tilt angle θ1 of the side surface 53d being 60°.

[0083] Furthermore, the ratio of the change in the magnitude of magnetization Mx to the change in the intensity of the magnetic field component MFx, i.e., the slope, is determined from the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of magnetization. The slope is determined within the range of the intensity Hx of the magnetic field component MFx in which the free layer 153 does not become magnetically saturated.

[0084] Furthermore, the linearity of the magnetization magnitude Mx is determined from the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx. Linearity is determined within the range of the magnetic field component MFx intensity Hx where the free layer 153 does not experience magnetic saturation.

[0085] Figures 18 and 19 are characteristic diagrams showing the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of the magnetization. In Figures 18 and 19, the horizontal axis represents the intensity Hx, and the vertical axis represents the magnitude Mx of the magnetization. In Figures 18 and 19, the unit of intensity Hx is A / m, and the unit of magnitude Mx of the magnetization is T. Figure 18 shows the relationship between intensity Hx and magnitude Mx when the intensity Hx is increased from 0 to magnetically saturate the free layer 153. Figure 19 shows the relationship between intensity Hx and magnitude Mx when the intensity Hx is decreased after the intensity Hx has been increased from 0 to magnetically saturate the free layer 153.

[0086] In Figures 18 and 19, reference numeral 81 indicates the case where the side surface 153d of the free layer 153 does not include the first portion 153d1 but includes only the second portion 153d2; reference numeral 82 indicates the case where the inclination angle θ3 is 5°; reference numeral 83 indicates the case where the inclination angle θ3 is 10°; reference numeral 84 indicates the case where the inclination angle θ3 is 20°; and reference numeral 85 indicates the case where the inclination angle θ3 is 30°.

[0087] Figure 20 is a characteristic diagram showing the relationship between the inclination angle θ3 and the slope. In Figure 20, the horizontal axis represents the inclination angle θ3, and the vertical axis represents the slope. In Figure 20, the slopes at each inclination angle θ3 are connected by lines. Also, for convenience, in Figure 20, the slope when the side surface 153d of the free layer 153 does not include the first part 153d1 but includes only the second part 153d2 (indicated by 81 in Figures 18 and 19) is plotted as the slope when the inclination angle θ3 is 0°. As shown in Figure 20, the slope increases as the inclination angle θ3 increases.

[0088] Figure 21 is a characteristic diagram showing the relationship between the inclination angle θ3 and linearity. In Figure 21, the horizontal axis represents the inclination angle θ3, and the vertical axis represents linearity. In Figure 21, the linearity at each inclination angle θ3 is connected by a line. Also, for convenience, in Figure 21, the linearity when the side surface 153d of the free layer 153 does not include the first part 153d1 but includes only the second part 153d2 (indicated by 81 in Figures 18 and 19) is plotted as the linearity when the inclination angle θ3 is 0°. As shown in Figure 21, when the inclination angle θ3 is between 0° and 20°, the value of linearity increases as the inclination angle θ3 increases.

[0089] As can be seen from the results of the third simulation, increasing the inclination angle θ3 increases the tilt. In other words, according to this embodiment, the sensitivity of the MR element 150 can be improved with a simple configuration of providing the first portion 153d1 on the side surface 153d of the free layer 153.

[0090] As shown in Figure 21, when the tilt angle θ3 is between 0° and 20°, the linearity value increases as the tilt angle θ3 increases. From the viewpoint of suppressing deterioration of the linearity of the MR element 150, it is desirable to determine the tilt angle θ3 while considering the linearity value.

[0091] Other configurations, operations, and effects in this embodiment are the same as those in the first embodiment.

[0092] [Third Embodiment] Next, a third embodiment of the present disclosure will be described. In this embodiment, the magnetic sensor 1 includes an MR element 250 instead of the MR element 50 in the first embodiment. The configuration of the MR element 250 will be described below with reference to Figures 22 and 23. Figure 22 is a side view showing the MR element 250. Figure 23 is a side view showing the free layer and the magnetized fixed layer of the MR element 250.

[0093] The MR element 250 comprises a magnetization fixed layer 251 having magnetization with a fixed direction, a free layer 253, a gap layer 252 disposed between the magnetization fixed layer 251 and the free layer 253, and a cap layer 254 disposed on top of the free layer 253. The configurations of the magnetization fixed layer 251, the gap layer 252, the free layer 253, and the cap layer 254 are the same as those of the magnetization fixed layer 51, the gap layer 52, the free layer 53, and the cap layer 54 in the first embodiment, except for the shapes of the magnetization fixed layer 251 and the free layer 253, which will be described later.

[0094] In this embodiment, in particular, a portion of the free layer 53 has a frustoconical or substantially frustoconical shape, while another portion of the free layer 53 has a cylindrical or substantially cylindrical shape.

[0095] As shown in Figure 23, the free layer 253 has a lower surface 253a and an upper surface 253b located at both ends in the stacking direction of the magnetized fixed layer 251, gap layer 252, and free layer 253, and a side surface 253d connecting the lower surface 253a and the upper surface 253b. The lower surface 253a is located at the -Z end of the free layer 253 and faces the gap layer 252. The upper surface 253b is located at the Z end of the free layer 253.

[0096] The side surface 253d includes a first portion 253d1 and a second portion 253d2 located between the first portion 253d1 and the top surface 253b. At least one of the first portion 253d1 and the second portion 253d2 corresponds to an inclined portion that is inclined with respect to the stacking direction, i.e., the Z direction. If the second portion 253d2 corresponds to an inclined portion, the first portion 253d1 does not have to correspond to an inclined portion. That is, the first portion 253d1 does not have to be inclined with respect to the direction parallel to the Z direction. Alternatively, if the second portion 253d2 corresponds to an inclined portion, the first portion 253d1 may also correspond to an inclined portion. In particular in this embodiment, the second portion 253d2 corresponds to an inclined portion, and the first portion 253d1 does not correspond to an inclined portion.

[0097] The planar shape of the side surface 253d, viewed from one direction parallel to the stacking direction, i.e., the Z direction, is annular. Furthermore, the planar shape of the second portion 253d2, viewed from the Z direction, is also annular.

[0098] In Figure 23, the symbol θ6 represents the angle that the first portion 253d1 of the side surface 253d makes with respect to the bottom surface 253a of the free layer 253. The angle θ6 is 90° or approximately 90°. Hereafter, for convenience, angle θ6 will be referred to as the inclination angle of the first portion 253d1. Also, the symbol θ7 represents the angle that the second portion 253d2 of the side surface 253d makes with respect to the bottom surface 253a of the free layer 253. Hereafter, angle θ7 will be referred to as the inclination angle of the second portion 253d2. Note that in Figure 23, for convenience, the inclination angle θ7 of the second portion 253d2 is represented as the angle that the second portion 253d2 makes with respect to a hypothetical plane P2 parallel to the bottom surface 253a of the free layer 253. The inclination angle θ7 of the second portion 153d2 may be smaller than the inclination angle θ6 of the first portion 153d1.

[0099] The magnetized fixed layer 251 has a cylindrical or nearly cylindrical shape. The magnetized fixed layer 251 has a lower surface 251a and an upper surface 251b located at both ends in a direction parallel to the stacking direction, i.e., the Z direction, and a side surface 251d connecting the lower surface 251a and the upper surface 251b. The lower surface 251a is located at the -Z end of the magnetized fixed layer 251. The upper surface 251b is located at the Z end of the magnetized fixed layer 251 and faces the gap layer 252.

[0100] In Figure 23, the symbol θ8 represents the angle that the side surface 251d makes with respect to the lower surface 251a of the magnetized fixed layer 251. The angle θ8 is 90° or approximately 90°. Hereafter, for convenience, the angle θ8 will be referred to as the inclination angle of the side surface 251d.

[0101] In this embodiment, the absolute value of the difference between the inclination angle θ6 of the first portion 253d1 and the inclination angle θ8 of the side surface 251d is smaller than the absolute value of the difference between the inclination angle θ7 of the second portion 253d2 and the inclination angle θ8 of the side surface 251d. Note that the inclination angle θ8 of the side surface 251d may be the same as or approximately the same as the inclination angle θ6 of the first portion 253d1.

[0102] Next, we will describe the results of a fourth simulation that investigated the effect of the tilt angle θ7 of the second portion 253d2 of the side surface 253d of the free layer 253 on the characteristics of the MR element 250. In the fourth simulation, the tilt angle θ7 was varied within the range of 40° to 90° while keeping the diameter of the lower surface 253a of the free layer 253 and the dimensions of the first portion 253d1 and the second portion 253d2 of the side surface 253d in the direction parallel to the Z direction the same. For each tilt angle θ7, the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of the magnetization was determined. Note that when the tilt angle θ7 is 90°, the free layer 253 has a cylindrical or nearly cylindrical shape.

[0103] In the third simulation, the diameter of the lower surface 253a of the free layer 253 is set to 500 nm, the dimension of the first portion 253d1 of the side surface 253d in the direction parallel to the Z direction is set to 20 nm, and the dimension of the second portion 253d2 of the side surface 253d in the direction parallel to the Z direction is set to 30 nm.

[0104] Furthermore, the ratio of the change in the magnitude of magnetization Mx to the change in the intensity of the magnetic field component MFx, i.e., the slope, is determined from the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of magnetization. The slope is determined within the range of the intensity Hx of the magnetic field component MFx in which the free layer 253 does not become magnetically saturated.

[0105] Furthermore, the linearity of the magnetization magnitude Mx is determined from the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx. Linearity is determined within the range of the magnetic field component MFx intensity Hx where the free layer 253 does not experience magnetic saturation.

[0106] Figures 24 and 25 are characteristic diagrams showing the relationship between the intensity Hx of the magnetic field component MFx and the magnitude Mx of the magnetization. In Figures 24 and 25, the horizontal axis represents the intensity Hx, and the vertical axis represents the magnitude Mx of the magnetization. In Figures 24 and 25, the unit of intensity Hx is A / m, and the unit of magnitude Mx of the magnetization is T. Figure 24 shows the relationship between intensity Hx and magnitude Mx when the intensity Hx is increased from 0 to magnetically saturate the free layer 253. Figure 25 shows the relationship between intensity Hx and magnitude Mx when the intensity Hx is decreased after the intensity Hx has been increased from 0 to magnetically saturate the free layer 253.

[0107] In Figures 24 and 25, reference numeral 91 indicates the case where the inclination angle θ7 is 90°, reference numeral 92 indicates the case where the inclination angle θ7 is 80°, reference numeral 93 indicates the case where the inclination angle θ7 is 70°, reference numeral 94 indicates the case where the inclination angle θ7 is 60°, reference numeral 95 indicates the case where the inclination angle θ7 is 50°, and reference numeral 96 indicates the case where the inclination angle θ7 is 40°. In Figure 24, except for the case where the angle θ7 is 40° (reference numeral 96), the curves showing the relationship between intensity Hx and magnetization magnitude Mx at each inclination angle θ7 almost overlap. In Figure 25, the curve for the case where the angle θ7 is 90° (reference numeral 91) and the curve for the case where the angle θ7 is 80° (reference numeral 92) almost overlap. Also, in Figure 25, the curve for the case where the angle θ7 is 70° (reference numeral 93) and the curve for the case where the angle θ7 is 60° (reference numeral 94) almost overlap.

[0108] Figure 26 is a characteristic diagram showing the relationship between the inclination angle θ7 and the slope. In Figure 26, the horizontal axis represents the inclination angle θ7, and the vertical axis represents the slope. In Figure 26, the slopes at each inclination angle θ7 are connected by lines. As shown in Figure 26, when the inclination angle θ7 is between 30° and 60°, the slope increases as the inclination angle θ7 decreases. Also, when the inclination angle θ7 is between 60° and 90°, the slope decreases as the inclination angle θ7 decreases.

[0109] Figure 27 is a characteristic diagram showing the relationship between the inclination angle θ7 and linearity. In Figure 27, the horizontal axis represents the inclination angle θ7, and the vertical axis represents linearity. In Figure 27, the linearity for each inclination angle θ7 is connected by a line. As shown in Figure 27, when the inclination angle θ7 is between 50° and 90°, the value of linearity decreases as the inclination angle θ7 decreases.

[0110] As can be seen from the results of the fourth simulation, reducing the inclination angle θ7 reduces the linearity value. In other words, according to this embodiment, linearity can be improved with a simple configuration of providing a second portion 253d2 on the side surface 253d of the free layer 253.

[0111] As shown in Figure 26, when the tilt angle θ7 is between 60° and 90°, the inclination decreases as the tilt angle θ7 decreases. From the viewpoint of suppressing deterioration of the sensitivity of the MR element 250, it is desirable to determine the tilt angle θ7 while taking the inclination into consideration.

[0112] Other configurations, operations, and effects in this embodiment are the same as those in the first embodiment.

[0113] This disclosure is not limited to the embodiments described above, and various modifications are possible. For example, the shape of the side surface 53d of the free layer 53 of the MR element 50 is not limited to the examples shown in each embodiment. For example, the side surface 53d of the free layer 53 may include three or more portions with different inclination angles.

[0114] As described above, the magnetoresistive element of this disclosure comprises a magnetization-fixed layer having magnetization with a fixed direction, a free layer that can have a magnetic vortex structure and is configured so that the center of the magnetic vortex structure moves in accordance with the target magnetic field, and a gap layer disposed between the magnetization-fixed layer and the free layer. The free layer has a first lower surface and a first upper surface located at both ends in the stacking direction of the magnetization-fixed layer, the gap layer, and the free layer, and a first side surface connecting the first lower surface and the first upper surface. The first side surface includes an inclined portion that is inclined with respect to the stacking direction.

[0115] In the magnetoresistive element of this disclosure, the first side surface may include a first portion and a second portion located between the first portion and the first upper surface. Either the first portion or the second portion may be a sloped portion.

[0116] Furthermore, in the magnetoresistive element of this disclosure, the first portion may be an inclined portion. The angle that the first portion makes with respect to the first lower surface may be smaller than the angle that the second portion makes with respect to the first lower surface.

[0117] Furthermore, in the magnetoresistive element of this disclosure, the second portion may be an inclined portion. The angle that the second portion makes with respect to the first lower surface may be smaller than the angle that the first portion makes with respect to the first lower surface. The first portion may be inclined with respect to the stacking direction.

[0118] Furthermore, in the magnetoresistive element of this disclosure, the magnetization fixed layer may have a second lower surface and a second upper surface located at both ends in the stacking direction, and a second side surface connecting the second lower surface and the second upper surface. The second side surface may include a third portion that is inclined with respect to the stacking direction. The first side surface may include a first portion and a second portion located between the first portion and the first upper surface. The first portion may be an inclined portion. When the angle that the first portion makes with the first lower surface is defined as the first angle, the angle that the second portion makes with the first lower surface is defined as the second angle, and the angle that the third portion makes with the second lower surface is defined as the third angle, the absolute value of the difference between the first angle and the third angle may be smaller than the absolute value of the difference between the second angle and the third angle.

[0119] Furthermore, in the magnetoresistive element of this disclosure, the planar shape of the inclined portion when viewed from the stacking direction may be annular.

[0120] The magnetic sensor of this disclosure is a magnetic sensor comprising a plurality of magnetic sensing elements. Each of the plurality of magnetic sensing elements is a magnetoresistive element of this disclosure. [Explanation of symbols]

[0121] 1...Magnetic sensor, 10...Substrate, 41...Lower electrode, 42...Upper electrode, 50...MR element, 51m...Magnetization, 51...Magnetization fixed layer, 52...Gap layer, 53...Free layer, 53a...Bottom surface, 53b...Top surface, 53d...Side surface, 53m...Magnetization, 54...Cap layer, R1~R4...Resistance section.

Claims

1. A magnetization-fixed layer having magnetization with a fixed direction, A free layer that can have a magnetic vortex structure and is configured so that the center of the magnetic vortex structure can move in accordance with the target magnetic field, The system comprises a gap layer disposed between the magnetization fixed layer and the free layer, The free layer has a first lower surface and a first upper surface located at both ends in the stacking direction of the magnetization-fixed layer, the gap layer, and the free layer, and a first side surface connecting the first lower surface and the first upper surface. The magnetoresistive element is characterized in that the first side surface includes an inclined portion that is inclined with respect to the stacking direction.

2. The first side surface includes a first portion and a second portion located between the first portion and the first upper surface. The magnetoresistive element according to claim 1, characterized in that one of the first portion and the second portion is the inclined portion.

3. The first part is the inclined portion, The magnetoresistive element according to claim 2, characterized in that the angle the first portion makes with respect to the first lower surface is smaller than the angle the second portion makes with respect to the first lower surface.

4. The second part is the inclined portion, The magnetoresistive element according to claim 2, characterized in that the angle the second portion makes with respect to the first lower surface is smaller than the angle the first portion makes with respect to the first lower surface.

5. The magnetoresistive element according to claim 4, characterized in that the first portion is inclined with respect to the stacking direction.

6. The magnetization-fixing layer has a second lower surface and a second upper surface located at both ends in the stacking direction, and a second side surface connecting the second lower surface and the second upper surface. The magnetoresistive element according to claim 1, characterized in that the second side surface includes a third portion that is inclined with respect to the stacking direction.

7. The first side surface includes a first portion and a second portion located between the first portion and the first upper surface. The first part is the inclined portion, The magnetoresistive element according to claim 6, characterized in that when the angle made by the first portion with respect to the first lower surface is defined as the first angle, the angle made by the second portion with respect to the first lower surface is defined as the second angle, and the angle made by the third portion with respect to the second lower surface is defined as the third angle, the absolute value of the difference between the first angle and the third angle is smaller than the absolute value of the difference between the second angle and the third angle.

8. The magnetoresistive element according to claim 1, characterized in that the planar shape of the inclined portion when viewed from the stacking direction is annular.

9. A magnetic sensor comprising multiple magnetic detection elements, A magnetic sensor characterized in that each of the plurality of magnetic detection elements is a magnetoresistive element according to any one of claims 1 to 8.

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