Element with magnetoresistive effect

Abstract

Use of a magnetoresistive element (1 or 1A) for a magnetic sensor, wherein the magnetoresistive element (1 or 1A) has: a layer with free magnetization (4) extending along a first plane; an intermediate layer (3) extending along the first plane and stacked on the layer with free magnetization (4); and a layer with fixed magnetization (2) extending along the first plane and provided on one side opposite the layer with free magnetization (4), wherein the intermediate layer (3) is arranged between them, the layer with free magnetization (4) comprises: a flat part (R1) that has an essentially constant first thickness (T1), and an inclined part (R2) comprising an end surface (41), wherein the inclined part (R2) has a second thickness (T2) which decreases with a distance from the flat part (R1), and where the layer (4) with free magnetization satisfies the following conditional expression (expression 1): L 2 * (L 1 ) 2 ≥ 0.4 μ m 3 where L1 denotes a length of the flat part (R1) of the layer with free magnetization (4) along the first plane, and L2 denotes a length of the inclined part (R2) of the layer with free magnetization (4) along the first plane.

Description

BACKGROUND

[0001] The disclosure relates to a magnetoresistive effect element comprising a layer of free magnetization.

[0002] As a magnetic field sensing device that detects an external magnetic field, a magnetic field sensing device using a Hall element or an element with a magnetoresistive effect is known. Reference is made, for example, to International Publication No. WO 2008 / 146809 A1. A thin-film magnetic element is known from US Pat. No. 6,667,493 B2. A magnetoresistive element is known from US Pat. No. 6,987,652 B2. DEPICTION

[0003] There is a need to improve the accuracy of detecting a magnetic field in a magnetic field detecting device.

[0004] It is desired to provide a magnetoresistive effect element comprising a free magnetization layer with a smaller saturation magnetic field.

[0005] A magnetoresistive effect element according to an embodiment of the disclosure includes: a free magnetization layer extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; and a fixed magnetization layer extending along the first plane and provided on a side opposite to the free magnetization layer, with the intermediate layer interposed therebetween. Here, the free magnetization layer includes an end face having a maximum inclination angle of 42° or less with respect to the first plane. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this document. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the disclosure. Fig. 1 is a perspective view of an overall configuration of a magnetoresistive effect device including a magnetoresistive effect element according to an embodiment of the disclosure. Fig. 2 is a schematic diagram of an overall configuration of a magnetoresistive effect device including a magnetoresistive effect element according to an embodiment of the disclosure. Fig. 3A is a schematic cross-sectional view of a Fig. 1 shown layer with free magnetization, with one magnetization state. Fig. 3B is a schematic cross-sectional view of a free magnetization layer as a reference example with one magnetization state. Fig. 4A is a first schematic plan view of the Fig. 3B shown layer with free magnetization, with one magnetization state; Fig. 4B is a second schematic plan view of the Fig. 3B shown layer with free magnetization, with one magnetization state; Fig. Figure 4C is a third schematic plan view of the Fig. 3B shown layer with free magnetization, with one magnetization state; Fig. 5 is a perspective view of an overall configuration of a magnetoresistive effect device including a magnetoresistive effect element according to a modification example; Fig. 6A is a characteristic diagram showing a relationship between a maximum inclination angle of an end face and an angle error in Experimental Example 1; Fig. 6B is a characteristic diagram showing a relationship between a maximum inclination angle of an end face and an angle error in Experimental Example 2; Fig. 7A is a characteristic diagram showing a relationship between a film thickness of a free magnetization layer and a saturation magnetic field of the free magnetization layer in Experimental Example 3; Fig. 7B is a characteristic diagram showing a relationship between a film thickness of a free magnetization layer and a resistance change rate of the free magnetization layer in Experimental Example 4; Fig. 7C is a characteristic diagram showing a relationship between a length of a free magnetization layer and a saturation magnetic field of the free magnetization layer in Experimental Example 5; Fig. 8 is a characteristic diagram showing a relationship between a respective length of a flat part and an inclined part of a free magnetization layer and a saturation magnetic field of the free magnetization layer in Experimental Example 6. DETAILED DESCRIPTION

[0007] Some embodiments of the disclosure are described in detail below with reference to the accompanying drawings.

[0008] Furthermore, elements in the following embodiments that are not included in a most general independent claim of the technology are optional and may be provided as needed. The drawings are schematic and should not be considered to scale. It is noted that equivalent elements are provided with the same reference numerals, and redundant descriptions of these elements will not be described in detail. It is noted that the descriptions are presented in the following order. 1. An example of implementation 2. Experimental examples 3. Other modification examples [1. An embodiment][Design of a device with a magnetoresistive effect]

[0009] Fig. Figure 1 is a perspective view of a magnetoresistive effect device according to one embodiment of the disclosure. The magnetoresistive effect device may, for example, include a magnetoresistive effect element 1, an upper electrode 5, and a lower electrode 6.

[0010] The magnetoresistive effect device can, for example, detect the presence or absence of an external magnetic field and the strength of the external magnetic field. The external magnetic field can be a target detection magnetic field that influences the magnetoresistive effect device itself. The magnetoresistive effect device can, for example, be mounted on an electronic compass, an angle detection sensor, or any other device that detects the presence or absence and the strength of the external magnetic field. A direction in which the external magnetic field is applied can, for example, be an X-axis direction.

[0011] The upper electrode 5 and the lower electrode 6 may be a pair of electrodes each extending in both the X-axis direction and a Y-axis direction. The upper electrode 5 and the lower electrode 6 may be provided so that the magnetoresistive effect element 1 is sandwiched between them in a direction in which the layers are stacked (e.g., in a Z-axis direction). The layers may form the magnetoresistive effect element 1. In other words, the upper electrode 5 and the lower electrode 6 may serve to supply a signal current to the magnetoresistive effect element 1 in a direction intersecting a surface of each of the layers constituting the magnetoresistive effect element 1. The intersecting direction may, for example, be a direction perpendicular to the surface of each of the layers (i.e., a thickness direction) constituting the magnetoresistive effect element 1.In one embodiment, the upper electrode 5 and the lower electrode 6 may each be formed, for example, by a single-layer film or a stacked-layer film. The single-layer film may contain aluminum (Al), tantalum (Ta), copper (Cu), gold (Au), a gold-copper alloy (AuCu), or ruthenium (Ru) as a main component. The stacked-layer film may be formed by two or more stacked single-layer films, each containing the above material as a main component. Note that an XY plane is a concrete example corresponding to a "first plane" of the disclosure.

[0012] The magnetoresistive effect element 1 may comprise a layered body in which, for example, a fixed magnetization layer 2, an intermediate layer 3, and a free magnetization layer 4 are stacked one after the other on the lower electrode 6.

[0013] For example, the pinned magnetization layer 2 may contain a ferromagnetic material as the main material, and its magnetization direction is fixed in substantially one direction. In one embodiment, examples of the ferromagnetic material contained in the pinned magnetization layer 2 may include a material with high-spin polarizability, such as a simple substance comprising iron (Fe), cobalt (Co), and nickel (Ni), as well as a nickel-iron alloy, an iron-cobalt alloy, and an iron-cobalt-boron (B) alloy. Selecting such a material with high-spin polarizability enables the achievement of a high magnetoresistive change rate in the magnetoresistive effect element 1.

[0014] Further, examples of the ferromagnetic material constituting the pinned magnetization layer 2 may include cobalt (CO), a cobalt-chromium-based alloy (Co-Cr-based), a cobalt (CO) multilayer, a cobalt-chromium-platinum-based (Co-Cr-Pt-based) alloy, an iron-platinum-based (Fe-Pt-based) alloy, a samarium-cobalt-based (Sm-Co-based) alloy containing a rare earth element, and a terbium-iron-cobalt-based (Tb-Fe-Co-based) alloy containing a rare earth element. The pinned magnetization layer 2, which contains the ferromagnetic material as a main component, has a magnetization pinned along a normal direction of a film surface.Examples of the ferromagnetic material forming the pinned magnetization layer 2 with the magnetization pinned along the normal direction of the film surface may include, in addition to those mentioned above, a cobalt / platinum (Co / Pt) artificial lattice film, a cobalt / palladium (Co / Pd) artificial lattice film, an iron / palladium (Fe / Pd) artificial lattice film, and iron-boron (FeB). The pinned magnetization layer 2 may also contain a Heusler alloy as the main material. The pinned magnetization layer 2 may have a film thickness of, for example, about 1 nm to about 10 nm. To stabilize the magnetization 2 of the pinned magnetization layer, an antiferromagnetic layer may be further provided so as to contact a surface of the pinned magnetization layer 2 opposite the intermediate layer 3.In an alternative embodiment, magnetic anisotropy caused by a crystal structure or shape can be used to stabilize the magnetization of the pinned magnetization layer 2. Examples of a component of such an antiferromagnetic layer may include iron oxide (FeO), cobalt oxide (CoO), nickel(II) oxide (NiO), chalcopyrite (CuFeS2), iridium manganese (IrMn), iron manganese (FeMn), platinum manganese (PtMn), chromium (Cr), and manganese (Mn).

[0015] The magnetization-pinned layer 2 may have a synthetic structure comprising a pair of ferromagnetic films and a non-magnetic, electrically conductive film between them, in which the pair of ferromagnetic films are antiferromagnetically coupled to each other. In this case, the magnetization-pinned layer 2 may have a self-pinned structure in which the magnetization of the magnetization-pinned layer 2 is stabilized without using an antiferromagnetic layer by adjusting the respective thicknesses of the pair of ferromagnetic films and the thickness of the non-magnetic, electrically conductive film arranged between them.

[0016] The intermediate layer 3 can be arranged between the fixed magnetization layer 2 and the free magnetization layer 4. The magnetoresistive effect element 1 experiences a magnetoresistive effect through an interaction between the magnetization of the fixed magnetization layer 2 and the magnetization of the free magnetization layer 4 via the intermediate layer 3. The intermediate layer 3 can be formed by a layer comprising an electrical conductor, an insulator, or a semiconductor. In an alternative embodiment, the intermediate layer 3 can comprise a layer (i.e., a current blocking layer) comprising an electrically conductive point formed by a conductor in an insulator.

[0017] Examples of a non-magnetic, electrically conductive material to be deposited on the intermediate layer 3 may include copper (Cu), silver (Ag), gold (Au), and ruthenium (Ru). In a case where the intermediate layer 3 is formed by such a non-magnetic, electrically conductive material, the magnetoresistive effect element 1 exhibits a giant magnetoresistance (GMR) effect. In this case, the film thickness of the intermediate layer 3 may be set to, for example, about 0.5 nm to about 3.5 nm.

[0018] Examples of a non-magnetic insulating material to be applied to the intermediate layer 3 may include aluminum oxide (Al2O3) and magnesium oxide (MgO). In a case where the intermediate layer 3 is formed by such a non-magnetic insulating material, the magnetoresistive effect element 1 exhibits a TMR effect. In this case, the film thickness of the intermediate layer 3 may be set to exhibit a coherent tunneling effect between the pinned magnetization layer 2 and the free magnetization layer 4. The film thickness of the intermediate layer 3 may be set, for example, to about 0.5 nm to about 3.5 nm.

[0019] Examples of a non-magnetic semiconductor material to be applied to the intermediate layer 3 may be zinc oxide (ZnO), indium (III) oxide (In2O3), tin dioxide (SnO2), indium tin oxide (ITO), gallium oxide (GaO x ), and gallium oxide (Ga2O x). In this case, the film thickness of the intermediate layer 3 may be set, for example, to about 1.0 nm to about 4.0 nm in one embodiment.

[0020] In one embodiment, the current blocking layer to be deposited on the intermediate layer 3 may have a structure provided with the electrically conductive point formed by a conductor in the non-magnetic insulator such as Al2O3 or MgO. Examples of the conductor may include cobalt iron (CoFe), cobalt iron boron (CoFeB), cobalt iron silicon (CoFeSi), cobalt manganese germanium (CoMnGe), cobalt manganese silicon (CoMnSi), cobalt manganese aluminum (CoMnAl), iron (Fe), cobalt (Co), gold (Au), copper (Cu), aluminum (Al), and magnesium (Mg). In this case, the film thickness of the intermediate layer 3 may be set to, for example, about 0.5 nm to about 2.0 nm in one embodiment.

[0021] The free magnetization layer 4 has a magnetization direction that varies depending on an externally applied magnetic field or a spin-polarized electron. The free magnetization layer 4 can be formed by a ferromagnetic material. Examples of the ferromagnetic material forming the free magnetization layer 4 can include nickel-iron (NiFe), cobalt-iron (CoFe), cobalt-iron-boron (CoFeB), cobalt-iron-silicon (CoFeSi), cobalt-manganese-germanium (CoMnGe), cobalt-manganese-silicon (CoMnSi), and cobalt-manganese-aluminum (CoMnAl). In a case where such a ferromagnetic material is included as a main component, the free magnetization layer 4 has an easy magnetization axis along an intra-film plane direction. The layer 4 with free magnetization can, for example, have a thickness of about 1 nm to about 20 nm.In one embodiment, the free magnetization layer 4 may have a thickness in a range of 6 nm to 13 nm.

[0022] As in Fig. 2, the free magnetization layer 4 includes an end face 41 having a maximum inclination angle θ2 of 42° or less with respect to the XY plane. Furthermore, the end face 41 has a minimum inclination angle θ1 of 25° or less with respect to the XY plane. In a concrete example, the end face 41 has the minimum inclination angle θ1 of 25° or less (≤ 25°) with respect to the XY plane at a position P1. The position P1 may be a position where the end face 41 and a bottom surface 42 intersect. The end face 41 has the maximum inclination angle θ2 of 42° or less (≤ 42°) with respect to the XY plane at a position P2. The position P2 may be a position where the end face 41 and a top surface 43 intersect.Furthermore, the free magnetization layer 4 further comprises a flat portion R1 having a substantially constant thickness T1, and an inclined portion R2 comprising the end surface 41 and having a thickness T2. The thickness T2 decreases with the distance from the flat portion R1. Fig. Fig. 2 is a schematic diagram showing a cross-sectional shape of a part of the magnetoresistive effect element used in Fig. 1. For example, in a case where the flat part R1 has a length L1 of 6 μm or less in a direction of the detection target magnetic field along the XY plane, for example, in the X-axis direction, effects of the inclination of the end surface 41 of the free magnetization layer 4 become apparent as described later.

[0023] Layer 4 with free magnetization satisfies the following conditional expression (Expression 1): L2*(L1)2≥0.4 where L1 represents a length of the flat part R1 of the layer 4 with free magnetization along the XY plane, and L2 represents a length of the inclined part R2 of the layer 4 with free magnetization along the XY plane.

[0024] The free magnetization layer 4 may further comprise the bottom surface 42 extending along the XY plane and facing the intermediate layer 3, and the top surface 43 extending along the XY plane and positioned opposite the intermediate layer 3. A part of the end surface 41 between the position P1 and the position P2 may be recessed relative to a position on a straight line L12 connecting the position P1 and the position P2 in an XZ plane orthogonal to the XY plane, as shown in Fig. 2. The position P1 may be a position where the end surface 41 and the bottom surface 42 intersect each other, and the position P2 may be a position where the end surface 41 and the top surface 43 intersect each other. In other words, the end surface may have a concave shape relative to the outer side. The end surface 41 having such a concave shape causes an inclination angle near the position P1 of the end surface 41, near the intermediate layer 3, to be smaller than an inclination angle of another part (e.g., near the position P2) of the end surface 41. Therefore, it becomes possible to more effectively reduce the hysteresis of an output caused by the shape anisotropy of the free magnetization layer 4 near the intermediate layer 3.

[0025] A cap layer, a seed layer, or a buffer layer may be disposed between the upper electrode 5 and the magnetoresistive effect element 1, and between the lower electrode 6 and the magnetoresistive effect element 1. Examples of each of the cap layer, the seed layer, and the buffer layer may include, for example, a single-layer film of ruthenium (Ru), tantalum (Ta), copper (Cu), or chromium (Cr), and a stacked-layer film formed by a plurality of stacked single-layer films. In one embodiment, each of the cap layer, the seed layer, and the buffer layer may have a film thickness of about 1 nm to about 20 nm.

[0026] Fig. Figure 1 illustrates a case where the magnetoresistive element 1 has a truncated cone shape, and the free magnetization layer 4 has a circular shape (i.e., a planar shape) along the XY plane. The planar shape of the free magnetization layer 4 can also be, for example, elliptical or quadrangular. [Operation and effects of the magnetoresistive effect device]

[0027] Now, a description will be given of the operation and effects of the magnetoresistive effect device with reference to the Fig. 3A and Fig. 3B and the Fig. 4A to 4C. Fig. 3A is an enlarged cross-sectional view of a vicinity of the end face 41 of the free magnetization layer 4 in the magnetoresistive effect element 1, and schematically shows the distribution of the strength of magnetization and a direction of magnetization along the XZ cross section. Fig. 3B is an enlarged cross-sectional view of a vicinity of an end face 141 of a free magnetization layer 104, as a reference example, with a constant thickness. Fig. 4A to 4C each schematically show a distribution of the magnetization strength and a magnetization direction in the XY plane of the free magnetization layer 104 as a reference example. Fig. 3A and Fig. 3B and in the Fig. 4A to 4C, a length of an arrow indicates a strength of magnetization, and a direction of the arrow indicates a direction of magnetization.

[0028] The magnetoresistive effect device can be used, for example, with a bias magnetic field Hb applied in the +X direction. Fig. 3B and Fig. 4A each illustrates the free magnetization layer 104 in the XY plane with a magnetization state, for example, in a case where only the bias magnetic field Hb is applied in the +X direction and a detection target magnetic field Hs is zero (0). In this case, the free magnetization layer 104 has, as its main magnetization component, a magnetization M1 in substantially the same direction (+X direction) as that of the bias magnetic field Hb. The main magnetization component can also be regarded as the sum total of all spins in the free magnetization layer 104. However, at both ends R102 and R103 in the X-axis direction, for example, magnetizations M2 (M2A to M2D) and magnetizations M3 (M3A to M3D) exist along the end surface 141 due to the shape anisotropy of the free magnetization layer 104. Fig. 4A, the magnetizations M2A to M2D have essentially the same magnitudes as those of the magnetizations M3A and M3D, respectively. The magnetizations M2A, M2B, M3C, and M3D are essentially oriented in the +Y direction, and the magnetizations M2C, M2D, M3A, and M3B are essentially oriented in the -Y direction.

[0029] For example, when the detection target magnetic field Hs is applied in the +Y direction, the magnetization M1, which is oriented in the +X direction, is slightly tilted in the +Y direction, as shown in Fig. 4B. Further, the magnetization M2C and the magnetization M3B, each oriented substantially in the -Y direction, are reversed to be oriented substantially in the +Y direction. Thereafter, when the application of the detection target magnetic field H1 is stopped, the magnetization M1, which is slightly inclined toward the +Y direction relative to the +X direction, returns to the +X direction along the bias magnetic field Hb, as shown in Fig. 4C. However, there may be a case where the magnetization M2C and the magnetization M3B are kept substantially aligned in the +Y direction. In this case, the magnetization M2C and the magnetization M3B influence a direction of the total magnetization of the free magnetization layer 104 as magnetization components that do not follow the detection target magnetic field Hs, resulting in an error in an output signal.

[0030] Accordingly, in the present embodiment, one end of the free magnetization layer 4 is set as the inclination part R2, and arranged to become increasingly thinner in thickness with smaller distance to a tip part R21, as shown in Fig. 3A. However, the free magnetization layer 104 as a reference example shown in Fig. 3B, a substantially constant thickness up to an end face 141. This causes more magnetization M2 (or M3) oriented in a direction different from that of the bias magnetic field Hb to be present in the end R102 (or R103) near the end face 141. On the other hand, the free magnetization layer 4 of the present embodiment includes the inclined part R2 at its end, thereby enabling a reduction in an area to be affected by the shape anisotropy. This makes it possible to reduce the rate of magnetization M2 (or M3) present in the entire free magnetization layer 4, compared to the rate of magnetization M2 (or M3) present in the free magnetization layer 104.As a result, the magnetoresistive effect element 1 including the free magnetization layer 4 becomes possible to reduce the magnetization component that does not follow the detection target magnetic field Hs, compared with the case where the free magnetization layer 104 is included, thereby enabling a reduction in the error in an output signal.

[0031] Therefore, in the present embodiment, the free magnetization layer 4 includes an end surface 41 that is inclined with respect to the XY plane in which the free magnetization layer 4 extends. This mitigates the influence of the shape anisotropy of the free magnetization layer 4, making it possible to reduce the magnetostatic energy of the end surface 41 and therefore reduce an amount of magnetization positioned near the end surface 41 that is less likely to follow the detection magnetic field Hs. As a result, it becomes possible to achieve a smaller saturation magnetic field in the free magnetization layer 4 and therefore reduce the error in an output signal supplied from the magnetoresistive effect element 1. In particular, in a case where the flat part R1 has a length of 6 μm or less as shown in Fig. 1, in a direction of the detection target magnetic field along the XY direction, for example, in the X-axis direction, the above-described effects of the inclination of the end surface 41 of the free magnetization layer 4 become apparent.

[0032] Furthermore, in the present embodiment, the free magnetization layer 4 satisfies the conditional expression (Expression 1), where L1 denotes a length of the flat part R1 of the free magnetization layer 4 along the XY plane, and L2 denotes a length of the inclined part R2 of the free magnetization layer 4 along the XY plane. In such a case, it becomes possible to further reduce the amount of magnetization positioned near the end surface 41, which is less likely to follow the detection target magnetic field H2. As a result, it becomes possible to reduce the error in an output signal supplied from the magnetoresistive effect element 1. [2. Experimental examples][Experimental example 1]

[0033] Next, an investigation was conducted on the magnetoresistive effect element 1 according to the above embodiment regarding a relationship between the maximum inclination angle θ2 of the end surface 41 and an angular error of an angle of a signal magnetic field with a predetermined strength. The angular error of the angle of the signal magnetic field with a predetermined strength is to be detected when the signal magnetic field is applied to the magnetoresistive effect element 1. The results are shown in Fig. 6A. In Fig. In Figure 6A, the horizontal axis indicates the maximum inclination angle θ2 (in degrees, i.e., °) of the end face 41 of the free magnetization layer 4, and the vertical axis indicates an angular error (in degrees, i.e., °) of the signal magnetic field to be detected by the magnetoresistive effect element 1. In this experimental example, the strength of each of the signal magnetic fields was measured at four levels of 20 mT, 21 mT, 22 mT, and 23 mT. The maximum inclination angle θ2 of the end face 41 was set at four levels of 30°, 42°, 47°, and 54°. For example, the fixed magnetization layer 2 had a stacked structure of a pair of iron-cobalt (FeCo) films and a ruthenium (Ru) film sandwiched between the pair of Fe-Co films. The thickness of fixed magnetization layer 2 was set to 5 nm.An antiferromagnetic layer was further provided in such a manner that it contacted a surface of the pinned magnetization layer 2 opposite the intermediate layer 3. Magnesium oxide (MgO) was used as the constituent of the intermediate layer 3, and the thickness of the intermediate layer 3 was set to 3 nm. Iron cobalt (FeCo) and nickel iron (NiFe) were each used as the constituent of the free magnetization layer 4, and the thickness of the free magnetization layer 4 was set to 18 nm.

[0034] It was confirmed that as in Fig. 6A, when the maximum inclination angle θ2 of the end face 41 is 42° or less, the angle error has been successfully reduced regardless of the strength of the signal magnetic field. [Experiment Example 2]

[0035] Next, an investigation was conducted on the magnetoresistive effect element 1 according to the aforementioned embodiment regarding a relationship between the minimum inclination angle θ1 of the end surface 41 and an angular error of an angle of a signal magnetic field with a predetermined strength. The angular error of the angle of the signal magnetic field with a predetermined strength is to be detected when the signal magnetic field is applied to the magnetoresistive effect element 1. The results are shown in Fig. 6B. In Fig. In Figure 6B, the horizontal axis indicates the minimum inclination angle θ1 (in degrees, i.e., °) of the end face 41 of the free magnetization layer 4, and the vertical axis indicates an angular error (in degrees, i.e., °) of the signal magnetic field detected by the magnetoresistive effect element 1. In this experimental example, the experimental conditions were similar to those of Experiment Example 1 described above.

[0036] It was confirmed, as in Fig. 6B shows that when the minimum inclination angle θs of the end face 41 is 25° or less, the angle error was successfully reduced regardless of the strength of the signal magnetic field. [Comparison example 3]

[0037] Next, an investigation was conducted on the magnetoresistive effect element 1 according to the aforementioned embodiment regarding a relationship between the thickness T1 [in the unit nm] of the free magnetization layer 4 and a saturation magnetic field [in the unit mT] of the free magnetization layer 4. The results of this are shown in Fig. 7A. In Fig. In Figure 7A, the horizontal axis indicates the thickness T1 (in nm) of the free magnetization layer 4, and the vertical axis indicates the saturation magnetic field (in mT) of the free magnetization layer 4. In this experimental example, the maximum inclination angle θ2 of the end face 41 was set to 31°; the minimum inclination angle θ1 of the end face 41 was set to 16°; and the thickness T1 was set to 7 nm, 13 nm, and 19 nm. Except for these conditions, the experimental conditions were similar to those of Experimental Example 1 described above.

[0038] It was confirmed, as in Fig. 7A shows that when the thickness T1 is 13 nm or less, the saturation magnetic field of the free magnetization layer 4 was successfully reduced to 12 mT or less. [Experiment Example 4]

[0039] Next, an investigation was conducted on the magnetoresistive effect element 1 according to the aforementioned embodiment regarding a relationship between the thickness T1 [in nm] of the free magnetization layer 4 and a resistance change rate, that is, a magnetoresistive (MR) ratio [unitless] of the free magnetization layer 4. The results of this are shown in Fig. 7B. In Fig. In FIG. 7B, the horizontal axis indicates the thickness T1 (in nm) of the free magnetization layer 4, and the vertical axis indicates the MR ratio (unitless) of the free magnetization layer 4. In this experimental example, the magnetostriction was set to 0. Further, the maximum inclination angle θ2 of the end face 41 was set to 31°; the minimum inclination angle θ1 of the end face 41 was set to 16°; and the thickness T1 was varied within a range of 5 nm to 16 nm. Apart from these conditions, experimental conditions similar to those of Experimental Example 1 described above were set. Note that the MR ratio is represented unitless, provided that a value of the MR ratio is set to 100 when the thickness T1 is 16 nm.

[0040] It was confirmed, as in Fig. 7B that when the thickness T1 is 6 nm or more, a comparatively high and stable MR ratio of the free magnetization layer 4 was obtained. It was therefore found, with reference to Experimental Example 3 shown in Fig. 7A, and Experimental Example 4, shown in Fig. 7B shows that the thickness T1 in a range of 6 nm to 13 nm makes it possible to improve both the sensitivity (i.e., the MR ratio) and to reduce an output error (i.e., the saturation magnetic field) while keeping the magnetostriction low. [Experiment Example 5]

[0041] Next, an investigation was conducted on the magnetoresistive effect element 1 according to the above embodiment regarding a relationship between the length L1 [in the unit of µm] of the free magnetization layer 4 and a saturation magnetic field [in the unit of mT] of the free magnetization layer 4. The results of this are shown in Fig. 7C. In Fig. In Figure 7C, the horizontal axis indicates the length L1 [in the unit µm] of the free magnetization layer 4, and the vertical axis indicates the saturation magnetic field [in the unit mT] of the free magnetization layer 4. In this experimental example, the maximum inclination angle θ2 of the end face 41 was set to 31°; the minimum inclination angle θ1 of the end face 41 was set to 16°; and the thickness T1 was set to 7 nm, 13 nm, and 19 nm. Except for these conditions, the experimental conditions were set similarly to those of Experimental Example 1 described above.

[0042] It was, as in Fig. 7C, it is confirmed that when the length L1 is 6 μm or less, the saturation magnetic field of the free magnetization layer 4 has greatly increased. Therefore, the present disclosure is expected to have effects of controlling the maximum inclination angle θ2 of the end face 41 and the minimum inclination angle θ1 of the end face 41 in a case where the length L1 is 6 μm or less. [Experiment Example 6]

[0043] Next, an investigation was made with respect to the magnetoresistive effect element 1 according to the above-mentioned embodiment with respect to a relationship between a product [in the unit µm 3 ] of the length L2 [in the unit µm] of the layer 4 with free magnetization and the length 1 [in the unit µm] of the layer 4 with free magnetization and a saturation magnetic field [in the unit mT] of the layer 4 with free magnetization. The results are shown in Fig. 8. In Fig. 8 gives the horizontal axis L2 * (L1) 2 [in the unit µm 3 ], and the vertical axis indicates the saturation magnetic field [in the unit mT] of the free magnetization layer 4. In this experimental example, the maximum inclination angle θ2 of the end face 41 was varied within a range of 16° to 50°, and the minimum inclination angle θ1 of the end face 41 was varied within a range of 6° to 40°. The thickness T1 was set to 7 nm, 13 nm, and 19 nm. Apart from these conditions, experimental conditions were set similar to those of Experimental Example 1 described above.

[0044] It was confirmed, as in Fig. 8 shows that if L2 * (L1) 2 ≥ 0.4, the saturation magnetic field of layer 4 with free magnetization was successfully reduced to 12 mT or less. [3. Other modification examples]

[0045] The disclosure has been described above with reference to the embodiment. For example, the above embodiment exemplifies the magnetoresistive effect element 1 in which the fixed magnetization layer 2, the intermediate layer 3, and the free magnetization layer 4 are stacked on the lower electrode 6. The magnetoresistive effect element of the disclosure may, for example, be a magnetoresistive effect element 1A according to a Fig. 5. The magnetoresistive effect element 1A may have a configuration in which the free magnetization layer 4, the intermediate layer 3, and the fixed magnetization layer 2 are sequentially stacked on a base extending along the XY plane, with the lower electrode 6 disposed between the base and the free magnetization layer 4.

[0046] Furthermore, the disclosure encompasses any possible combination of some or all of the various embodiments and modification examples described and incorporated herein.

[0047] It is possible to achieve at least the following configurations from the above-described embodiments of the disclosure. (1) A magnetoresistive effect element comprising: a layer of free magnetization extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; and a fixed magnetization layer extending along the first plane and provided on a side opposite to the free magnetization layer, with the intermediate layer disposed between them, wherein the free magnetization layer comprises an end face having a maximum inclination angle of 42° or less with respect to the first plane. (2) A magnetoresistive effect element comprising: a layer of free magnetization extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; and a fixed magnetization layer extending along the first plane and provided on a side opposite to the free magnetization layer, with the intermediate layer disposed between them, wherein the free magnetization layer comprises an end face having a minimum inclination angle of 25° or less with respect to the first plane. (3) A magnetoresistive effect element comprising: a layer of free magnetization extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; and a fixed magnetization layer extending along the first plane and provided on a side opposite to the free magnetization layer, with the intermediate layer disposed between them, wherein the layer with free magnetization comprises: a flat part having a substantially constant first thickness, and an inclined part comprising an end surface, wherein the inclined part has a second thickness that decreases with a distance from the flat part, and wherein the free magnetization layer satisfies the following conditional expression (Expression 1): L2*(L1)2≥0.4 where L1 denotes a length of the flat part of the layer with free magnetization along the first plane, and L2 denotes a length of the inclined part of the layer with free magnetization along the first plane. (4) The magnetoresistive effect element according to any one of (1) to (3), wherein the free magnetization layer further comprises a first main surface extending along the first plane and facing the intermediate layer, and a second main surface extending along the first plane and positioned on a side opposite the intermediate layer, and the end surface comprises a part positioned between a first position and a second position and recessed opposite a position on a straight line connecting the first position and the second position in a second plane orthogonal to the first plane, wherein the first position is a position at which the end surface and the first main surface intersect each other, wherein the second position is a position at which the end surface and the second main surface intersect each other. (5) The magnetoresistive effect element according to any one of (1) to (4), wherein the intermediate layer comprises a first material which is non-magnetic and electrically conductive or a second material which is non-magnetic and electrically non-conductive. (6) The magnetoresistive effect element according to any one of (1) to (5), wherein the free magnetization layer has a thickness in a range of 6 nm to 13 nm in a thickness direction orthogonal to the first plane. (7) The magnetoresistive effect element according to any one of (1) to (5), wherein the free magnetization layer has a length of 6 µm or less in a direction of a detection target magnetic field along the first plane. (8) The magnetoresistive effect element according to any one of (1) to (7), wherein an area of ​​the free magnetization layer along the first plane is smallest at a position closest to the intermediate layer. (9) Magnetoresistive effect element according to item (8), wherein the area of ​​the layer with free magnetization along the first plane becomes smaller the closer it is to the intermediate layer.

[0048] According to one embodiment of the present disclosure, a magnetoresistive effect element comprises: a free magnetization layer extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; and a fixed magnetization layer extending along the first plane and provided on a side opposite to the free magnetization layer, with the intermediate layer sandwiched between them. Here, the free magnetization layer includes an end face having a maximum inclination angle of 42° or less with respect to the first plane.

[0049] In the magnetoresistive effect element according to an embodiment of the disclosure, the free magnetization layer includes an end face having a maximum inclination angle of 42° or less with respect to the first plane, thereby mitigating the influence of the shape anisotropy of the free magnetization layer, enabling a reduction in an amount of magnetization positioned near the end face that is less likely to follow the external magnetic field.

[0050] A magnetoresistive effect element according to an embodiment of the disclosure includes: a free magnetization layer extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; and a fixed magnetization layer extending along the first plane and provided on a side opposite to the free magnetization layer, with the intermediate layer sandwiched between them. Here, the free magnetization layer includes an end face having a minimum inclination angle of 25° or less with respect to the first plane.

[0051] In the magnetoresistive effect element according to an embodiment of the disclosure, the free magnetization layer includes an end face having a minimum inclination angle of 25° or less with respect to the first plane, thereby mitigating the influence of the shape anisotropy of the free magnetization layer, enabling a reduction in an amount of magnetization positioned near the end face that is less likely to follow the external magnetic field.

[0052] A magnetoresistive effect element according to an embodiment of the disclosure comprises: a free magnetization layer extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; and a fixed magnetization layer extending along the first plane and provided on a side opposite to the free magnetization layer, with the intermediate layer interposed therebetween. Here, the free magnetization layer includes a flat portion having a substantially constant thickness and an inclined portion including an end surface and having a second thickness that decreases with distance from the flat portion. The free magnetization layer satisfies the following conditional expression (Eq. 1): L2*(L1)2≥0.4 where L1 denotes a length of the flat part of the free magnetization layer along the first plane, and L2 denotes a length of the inclined part of the free magnetization layer along the first plane.

[0053] In the magnetoresistive effect element according to an embodiment of the disclosure, the conditional expression (Expression 1) is satisfied, thereby mitigating the influence of the shape anisotropy of the free magnetization layer, enabling a reduction in the amount of magnetization positioned near the end face that is less likely to follow the external magnetic field.

[0054] A magnetoresistive effect element according to an embodiment of the disclosure includes: a free magnetization layer extending along a first plane; an intermediate layer extending along the first plane and stacked on the free magnetization layer; a fixed magnetization layer extending along the first plane and provided on the side opposite to the free magnetization layer, with the intermediate layer interposed therebetween. Here, an area of ​​the free magnetization layer along the first plane is minimal at a position closest to the intermediate layer.

[0055] In the magnetoresistive effect element according to an embodiment of the disclosure, an area of ​​the free magnetization layer along the first plane is minimal at a position closest to the intermediate layer, thereby making it possible to maintain the magnetization positioned near the end face that is less likely to follow the external magnetic field away from the intermediate layer.

[0056] According to the magnetoresistive effect element of one embodiment of the disclosure, it is possible to suppress the influence of the shape anisotropy of the free magnetization layer and therefore to achieve a smaller saturation magnetic field in the free magnetization layer.

Claims

[1] Use of a magnetoresistive effect element (1 or 1A) for a magnetic sensor, the magnetoresistive effect element (1 or 1A) comprising: a layer of free magnetization (4) extending along a first plane; an intermediate layer (3) extending along the first plane and stacked on the free magnetization layer (4); and a fixed magnetization layer (2) extending along the first plane and provided on a side opposite the free magnetization layer (4), the intermediate layer (3) being arranged between them, wherein the layer with free magnetization (4) comprises: a flat part (R1) having a substantially constant first thickness (T1), and an inclined part (R2) comprising an end surface (41), the inclined part (R2) having a second thickness (T2) which decreases with a distance from the flat part (R1), and where the layer (4) with free magnetization satisfies the following conditional expression (Expression 1): L2*(L1)2≥0.4 μm3 where L1 denotes a length of the flat part (R1) of the layer with free magnetization (4) along the first plane, and L2 denotes a length of the inclined part (R2) of the layer with free magnetization (4) along the first plane. [2] Use of the magnetoresistive effect element (1 or 1A) for the magnetic sensor according to claim 1, wherein an end surface (41) has a maximum inclination angle (θ2) of 42° or less with respect to the first plane. [3] Use of the magnetoresistive effect element (1 or 1A) for the magnetic sensor according to claim 1 or 2, wherein the end surface (41) has a minimum inclination angle (θ1) of 25° or less with respect to the first plane. [4] Use of the magnetoresistive effect element (1 or 1A) for the magnetic sensor according to any one of claims 1 to 3, wherein the free magnetization layer (4) further comprises: a first main surface (42) extending along the first plane and facing the intermediate layer (3), and a second main surface (43) extending along the first plane and positioned on a side opposite the intermediate layer (3), and the end surface (41) comprises a part positioned between a first position (P1) and a second position (P2) and recessed opposite a position on a straight line (L12) connecting the first position (P1) and the second position (P2) in a second plane that is orthogonal to the first plane and that includes the first position and the second position, wherein the first position (P1) is a position at which the end surface (41) and the first main surface (42) intersect each other, wherein the second position (P2) is a position at which the end surface (41) and the second main surface (43) intersect each other. [5] Use of the magnetoresistive effect element (1 or 1A) for the magnetic sensor according to any one of claims 1 to 4, wherein the intermediate layer (3) comprises a first material which is non-magnetic and electrically conductive or a second material which is non-magnetic and electrically non-conductive. [6] Use of the magnetoresistive effect element (1 or 1A) for the magnetic sensor according to any one of claims 1 to 5, wherein the free magnetization layer (4) has a thickness in a range of 6 nm to 13 nm in a thickness direction orthogonal to the first plane. [7] Use of the magnetoresistive effect element (1 or 1A) for the magnetic sensor according to any one of claims 1 to 5, wherein the free magnetization layer (4) has a length of 6 µm or less in a direction of a detection target magnetic field along the first plane. [8] Use of the magnetoresistive effect element (1A) for the magnetic sensor according to any one of claims 1 to 7, wherein an area of ​​the free magnetization layer (4) along the first plane is smallest at a position closest to the intermediate layer (3). [9] Use of the magnetoresistive effect element (1A) for the magnetic sensor according to claim 8, wherein the area of ​​the free magnetization layer (4) along the first plane becomes smaller the closer it is to the intermediate layer (3).

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