In-plane magnetization film, in-plane magnetization film multilayer structure, hard bias layer, magnetoresistive element, and sputtering target

Abstract

To provide an in-plane magnetization film which allows 2.00 kOe or more in coercive force Hc and 2.00 memu / cm2 or more in residual magnetization Mrt per unit area to be achieved by means of neither using a nonmagnetic underlying layer for accelerating the in-plane orientation of a magnetic layer nor performing a film formation by heating.SOLUTION: An in-plane magnetization film comprises an initial magnetic layer 12A containing Co, Pt and a nonmagnetic grain boundary material, including Co of 44-82 at% and Pt of 18-56 at% to a total quantity of metal components, including the nonmagnetic grain boundary material of 2.0-31.0 vol.% to a whole volume, and having a thickness of 1-32 nm, and a magnetic layer main body part 12B formed on the initial magnetic layer 12A, containing Co, Pt and a nonmagnetic oxide, including Co of 44-82 at% and Pt of 18-56 at% to a total quantity of metal components, and including the nonmagnetic oxide of 2.0-31.0 vol.% to a whole volume. The nonmagnetic grain boundary material of the initial magnetic layer 12A contains at least one kind of Zn oxide and Ta oxide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an in-plane magnetized film, an in-plane magnetized film multilayer structure, a hard bias layer, a magnetoresistive element, and a sputtering target, and more specifically, to a coercivity Hc of 2.00 kOe or more and a remanent magnetization Mrt per unit area of ​​2.00 memu / cm². 2 The present invention relates to an in-plane magnetized film and an in-plane magnetized film multilayer structure that can achieve the above magnetic performance without performing film deposition by heating the substrate (hereinafter sometimes referred to as heated film deposition), as well as a hard bias layer having the in-plane magnetized film or the in-plane magnetized film multilayer structure, and also to magnetoresistive elements and sputtering targets related thereto.

[0002] The coercivity Hc is 2.00 kOe or higher, and the remanent magnetization Mrt per unit area is 2.00 memu / cm². 2 A hard bias layer meeting the above criteria is considered to have coercivity and remanent magnetization per unit area that are equivalent to or better than the hard bias layers of current magnetoresistive elements. In this application, "remanent magnetization per unit area" of an in-plane magnetized film refers to the value obtained by multiplying the remanent magnetization per unit volume of the in-plane magnetized film by the thickness of the in-plane magnetized film.

[0003] In this application, a hard bias layer refers to a thin-film magnet to which a bias magnetic field is applied to a magnetic layer that exhibits a magnetoresistance effect (hereinafter sometimes referred to as a free magnetic layer).

[0004] Furthermore, in this application, metal Co may be simply referred to as Co, metal Pt as Pt, and metal Ru as Ru. Other metallic elements may also be referred to similarly. [Background technology]

[0005] Magnetic sensors are currently used in many fields, and one of the most commonly used magnetic sensors is the magnetoresistive element.

[0006] The magnetoresistive element has a magnetic layer (free magnetic layer) that exhibits the magnetoresistive effect and a hard bias layer that applies a bias magnetic field to the magnetic layer (free magnetic layer), and it is required that a magnetic field of a predetermined magnitude or more can be stably applied to the free magnetic layer by the hard bias layer.

[0007] Therefore, the hard bias layer is required to have a high coercive force and a remanent magnetization.

[0008] However, the coercive force of the hard bias layer of the current magnetoresistive element is about 2 kOe (for example, FIG. 7 of Patent Document 1), and the realization of a higher coercive force is desired.

[0009] Also, the remanent magnetization per unit area is desired to be 2 memu / cm 2 or more (for example, paragraph 0007 of Patent Document 2).

[0010] Conventionally, an in-plane magnetization film formed by orienting the c-axis of a CoPt alloy with an hcp structure in the plane has been used to form a hard bias layer that can stably apply a magnetic field of a predetermined magnitude or more to a magnetoresistive element portion including a free magnetic layer. As a technique for obtaining such an in-plane magnetization film, there is a technique using a non-magnetic underlayer (Cr, Ti, Cr alloy, Ti alloy, etc.) that promotes the orientation of the c-axis of a CoPt alloy with an hcp structure in the plane (for example, paragraph 0028 of Patent Document 2).

[0011] However, in this technique, it is necessary to use a non-magnetic underlayer (Cr, Ti, Cr alloy, Ti alloy, etc.) that promotes the orientation of the c-axis of a CoPt alloy with an hcp structure in the plane, and the distance between the magnetoresistive element portion and the hard bias layer increases by the thickness of the non-magnetic underlayer, and the applied magnetic field of the hard bias layer to the magnetoresistive element portion decreases.

[0012] In addition, as a technique using an in-plane magnetization film in which the c-axis of Co is oriented in the plane, there is a technique of an in-plane magnetic recording film (for example, paragraph 0010 of Patent Document 3). However, this technique is a technique in which film formation is performed by heating the substrate temperature to 200 ° C or higher. Since the magnetoresistive element portion composed of an extremely thin film is easily damaged by heating, film formation accompanied by substrate heating is inappropriate as a method for forming the hard bias layer.

[0013] As a film formation method not accompanied by substrate heating, there is a technique of improving the coercive force Hc of the Co-Pt-based in-plane magnetization film formed on the Ru underlayer used as the underlayer for forming the Co-Pt-based in-plane magnetization film by using a high gas pressure when forming the Ru underlayer (for example, paragraph 0016 of Patent Document 3, Non-Patent Document 1). However, in this technique, in order to improve the coercive force Hc, it is necessary to make the thickness of the Ru underlayer 15 nm or more. The distance between the magnetoresistive element portion and the hard bias layer increases by the thickness of the non-magnetic Ru underlayer, and the applied magnetic field of the hard bias layer to the magnetoresistive element portion decreases. Therefore, there are the same problems as the technique described in Patent Document 2.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0015]

Non-Patent Document 1

Summary of the Invention

[0016] The present invention has been made in view of the above, and has a coercivity Hc of 2.00 kOe or more, and a remanent magnetization Mrt per unit area of ​​2.00 memu / cm². 2 The objective is to provide an in-plane magnetized film, an in-plane magnetized film multilayer structure, and a hard bias layer that can achieve the above magnetic performance without using a non-magnetic underlayer to promote in-plane orientation of the magnetic layer and without performing heat deposition. A supplementary objective is to provide a magnetoresistive element and a sputtering target related to the in-plane magnetized film, the in-plane magnetized film multilayer structure, or the hard bias layer. [Means for solving the problem]

[0017] The present invention solves the aforementioned problems and includes the following: an in-plane magnetization film, an in-plane magnetization film multilayer structure, a hard bias layer, a magnetoresistive element, and a sputtering target.

[0018] That is, the first embodiment of the in-plane magnetized film according to the present invention is an in-plane magnetized film used as a hard bias layer for a magnetoresistive element, comprising an initial magnetic layer containing metallic Co, metallic Pt and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm, and the initial magnetic layer The in-plane magnetized film comprises a magnetic layer body formed on top of a base, containing metallic Co, metallic Pt, and a non-magnetic oxide, wherein the magnetic layer body contains 44 at% to 82 at% of metallic Co, 18 at% to 56 at% of metallic Pt, and 2.0 vol% to 31.0 vol% of the non-magnetic oxide relative to the total volume, and the non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide.

[0019] A second embodiment of the in-plane magnetized film according to the present invention is the in-plane magnetized film according to the first embodiment, wherein the initial magnetic layer further contains metallic Fe, and the total amount of metallic Co and metallic Fe is 44 at% to 82 at% with respect to the total amount of metallic components, and metallic Pt is 18 at% to 56 at%.

[0020] A third embodiment of the in-plane magnetized film according to the present invention is an embodiment in which the non-magnetic oxide of the magnetic layer body contains boron oxide, in the in-plane magnetized film of the first or second embodiment.

[0021] A fourth aspect of the in-plane magnetized film according to the present invention is an in-plane magnetized film according to any of the first to third aspects, wherein the initial magnetic layer is formed on a substrate having a surface roughness of 0.1 nm or more and 1.5 nm or less.

[0022] Here, in this application, surface roughness refers to the arithmetic mean roughness Ra.

[0023] A fifth aspect of the in-plane magnetized film according to the present invention is the in-plane magnetized film of the fourth aspect, wherein the underlying layer is an insulating layer.

[0024] A first embodiment of the in-plane magnetized film multilayer structure according to the present invention is an in-plane magnetized film multilayer structure used as a hard bias layer for a magnetoresistive element, comprising: an initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm; and a non-magnetic initial layer formed on the initial magnetic layer. The in-plane magnetized film multilayer structure comprises an interlayer and a magnetic layer body formed on the non-magnetic initial interlayer, containing metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co accounting for 44 at% to 82 at% of the total metallic components, metallic Pt accounting for 18 at% to 56 at% of the total metallic components, and the non-magnetic oxide accounting for 2.0 vol% to 31.0 vol% of the total volume, wherein the non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide.

[0025] A second embodiment of the in-plane magnetized film multilayer structure according to the present invention is an in-plane magnetized film multilayer structure used as a hard bias layer for a magnetoresistive element, comprising an initial magnetic layer, a plurality of magnetic layer main bodies, and a non-magnetic intermediate layer, wherein the initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material, with metallic Co at 44 at% to 82 at% and metallic Pt at 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material at 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm, and the plurality of magnetic layer main bodies each contain metallic Co, metallic Pt, and a non-magnetic oxide, The in-plane magnetized film multilayer structure is characterized by containing 44 at% to 82 at% of metallic Co and 18 at% to 56 at% of metallic Pt relative to the total amount of metallic components, and containing 2.0 vol% to 31.0 vol% of the nonmagnetic oxide relative to the total volume, the lowest magnetic layer body of the plurality of magnetic layer body parts being formed on the initial magnetic layer, the nonmagnetic intermediate layer being arranged between the magnetic layer body parts, and the adjacent magnetic layer body parts separated by the nonmagnetic intermediate layer being ferromagnetically coupled, and the nonmagnetic grain boundary material of the initial magnetic layer containing at least one of Zn oxide and Ta oxide.

[0026] Here, the lowest magnetic layer body among the plurality of magnetic layer body parts is the magnetic layer body part formed at the position closest to the initial magnetic layer among the plurality of magnetic layer body parts.

[0027] A third aspect of the in-plane magnetized film multilayer structure according to the present invention is an in-plane magnetized film multilayer structure used as a hard bias layer for a magnetoresistive element, comprising an initial magnetic layer, a non-magnetic initial intermediate layer formed on the initial magnetic layer, a plurality of magnetic layer main bodies, and a non-magnetic intermediate layer, wherein the initial magnetic layer contains metal Co, metal Pt, and a non-magnetic grain boundary material, with metal Co at 44 at% to 82 at% and metal Pt at 18 at% to 56 at% of the total metal components, and the non-magnetic grain boundary material at 2.0 vol% to 31.0 vol% of the total volume, and a thickness of 1 nm to 32 nm, and the plurality of magnetic layer main bodies each contain metal Co, metal Pt, and The in-plane magnetized film multilayer structure is characterized by containing a non-magnetic oxide, containing 44 at% to 82 at% of metallic Co and 18 at% to 56 at% of metallic Pt relative to the total metal components, containing 2.0 vol% to 31.0 vol% of the non-magnetic oxide relative to the total volume, the lowest magnetic layer body of the plurality of magnetic layer body parts being formed on the non-magnetic initial intermediate layer, the non-magnetic intermediate layer being arranged between the magnetic layer body parts, and the adjacent magnetic layer body parts separated by the non-magnetic intermediate layer being ferromagnetically coupled, and the non-magnetic grain boundary material of the initial magnetic layer containing at least one of Zn oxide and Ta oxide.

[0028] A fourth aspect of the in-plane magnetized film multilayer structure according to the present invention is the in-plane magnetized film multilayer structure of the first or third aspect, wherein the non-magnetic initial intermediate layer is made of Ru or a Ru alloy.

[0029] A fifth aspect of the in-plane magnetized film multilayer structure according to the present invention is the in-plane magnetized film multilayer structure of the first or third aspect, wherein the thickness of the non-magnetic initial intermediate layer is 0.3 nm or more and 2 nm or less.

[0030] A sixth aspect of the in-plane magnetized film multilayer structure according to the present invention is the in-plane magnetized film multilayer structure of the second or third aspect, wherein the non-magnetic intermediate layer is made of Ru or a Ru alloy.

[0031] A seventh aspect of the in-plane magnetized film multilayer structure according to the present invention is an aspect of the in-plane magnetized film multilayer structure of the second or third aspect, wherein the thickness of the non-magnetic intermediate layer is 0.3 nm or more and 2 nm or less.

[0032] An eighth aspect of the in-plane magnetized film multilayer structure according to the present invention is an aspect of the in-plane magnetized film multilayer structure according to any of the first to seventh aspects, wherein the initial magnetic layer further contains metallic Fe, and the total amount of metallic Co and metallic Fe is 44 at% to 82 at% with respect to the total amount of metallic components, and metallic Pt is 18 at% to 56 at%.

[0033] A ninth aspect of the in-plane magnetized film multilayer structure according to the present invention is an aspect in which the non-magnetic oxide of the magnetic layer body contains boron oxide, in the in-plane magnetized film multilayer structure according to any of the first to eighth aspects.

[0034] A tenth embodiment of the in-plane magnetized film multilayer structure according to the present invention is an embodiment in which the initial magnetic layer is formed on a substrate having a surface roughness of 0.1 nm or more and 1.5 nm or less, in an in-plane magnetized film multilayer structure according to any of the first to ninth embodiments.

[0035] An eleventh aspect of the in-plane magnetized film multilayer structure according to the present invention is an aspect of the in-plane magnetized film multilayer structure according to the tenth aspect, wherein the underlying layer is an insulating layer.

[0036] A first embodiment of the hard bias layer according to the present invention is a hard bias layer characterized by having an in-plane magnetization film according to the fifth embodiment.

[0037] A second embodiment of the hard bias layer according to the present invention is a hard bias layer characterized by having the in-plane magnetized film multilayer structure of the eleventh embodiment.

[0038] A first embodiment of the magnetoresistive element according to the present invention is a magnetoresistive element characterized by having a hard bias layer according to the first embodiment.

[0039] A second embodiment of the magnetoresistive element according to the present invention is a magnetoresistive element characterized by having a hard bias layer according to the second embodiment.

[0040] An embodiment of the sputtering target according to the present invention is a sputtering target used when forming an in-plane magnetized film used as at least a part of the hard bias layer of a magnetoresistive element by room temperature deposition, and is characterized in that it contains metallic Co, metallic Pt and a non-magnetic grain boundary material, wherein the sputtering target contains 60 at% to 82 at% of metallic Co, 18 at% to 40 at% of metallic Pt, and the non-magnetic grain boundary material contains 6 vol% to 30 vol% of the entire sputtering target, and the non-magnetic grain boundary material contains at least one of Zn oxide and Ta oxide. [Effects of the Invention]

[0041] According to the present invention, the coercivity Hc is 2.00 kOe or more, and the remanent magnetization Mrt per unit area is 2.00 memu / cm². 2 It is possible to provide an in-plane magnetized film, an in-plane magnetized film multilayer structure, and a hard bias layer that can achieve the above magnetic performance without using a non-magnetic underlayer to promote in-plane orientation of the magnetic layer and without performing heat deposition. Furthermore, it is possible to provide a magnetoresistive effect element and a sputtering target related to the in-plane magnetized film, the in-plane magnetized film multilayer structure, or the hard bias layer. [Brief explanation of the drawing]

[0042] [Figure 1] This is a schematic cross-sectional view showing a magnetoresistive element 10, an in-plane magnetization film 12, and a hard bias layer 14 according to the first embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetization film 12 according to the first embodiment of the present invention applied to the hard bias layer 14 of the magnetoresistive element 10. [Figure 2]This is a schematic cross-sectional view showing a magnetoresistive element 200 in a conventional example. [Figure 3] This is a schematic cross-sectional view showing a magnetoresistive element 20, an in-plane magnetized film multilayer structure 22, and a hard bias layer 24 according to a second embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetized film multilayer structure 22 according to the second embodiment of the present invention applied to the hard bias layer 24 of the magnetoresistive element 20. [Figure 4] This is a schematic cross-sectional view showing a magnetoresistive element 30, an in-plane magnetized film multilayer structure 32, and a hard bias layer 34 according to a third embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetized film multilayer structure 32 according to the third embodiment of the present invention applied to the hard bias layer 34 of the magnetoresistive element 30. [Figure 5] This is a schematic cross-sectional view showing a magnetoresistive element 40, an in-plane magnetized film multilayer structure 42, and a hard bias layer 44 according to a fourth embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetized film multilayer structure 42 according to the fourth embodiment of the present invention applied to the hard bias layer 44 of the magnetoresistive element 40. [Figure 6] The bar graphs for the experimental results of Reference Examples 1-8 show the type of nonmagnetic grain boundary oxide on the horizontal axis and the coercivity Hc(kOe) on the vertical axis. [Figure 7] This is an observation image (cross-sectional TEM photograph) obtained by scanning a scanning transmission electron microscope (STEM) of a perpendicular cross-section (cross-section perpendicular to the in-plane direction of the CoPt in-plane magnetization film) of the CoPt in-plane magnetization film (initial magnetic layer) in Reference Example 8. [Figure 8] The graphs show the experimental results for Examples 1-6 and Comparative Example 1, with the thickness of the initial magnetic layer of the in-plane magnetized film on the horizontal axis and the coercivity Hc(kOe) on the vertical axis. [Figure 9] The graphs show the experimental results for Examples 4, 7-15 and Comparative Examples 2 and 3, with the ZnO content in the initial magnetic layer of the in-plane magnetized film on the horizontal axis and the coercivity Hc(kOe) on the vertical axis. [Figure 10] This graph shows the Pt content (at%) relative to the total Co and Pt metal components of the initial magnetic layer on the horizontal axis, and the coercivity Hc(kOe) on the vertical axis. [Modes for carrying out the invention]

[0043] Embodiments of the present invention will be described in detail below with reference to the drawings. Hereinafter, the description will focus on a tunnel-type magnetoresistive element as the magnetoresistive element according to the embodiment of the present invention, but the magnetoresistive element according to the present invention is not limited to a tunnel-type magnetoresistive element. Furthermore, the in-plane magnetization film and hard bias layer according to the present invention are not limited to application to the hard bias layer of a tunnel-type magnetoresistive element, but can also be applied to the hard bias layer of, for example, a giant magnetoresistive element or anisotropic magnetoresistive element.

[0044] (1) First Embodiment (1-1) Schematic configuration of the magnetoresistive element 10 according to the first embodiment Figure 1 is a schematic cross-sectional view showing a magnetoresistive element 10, an in-plane magnetization film 12, and a hard bias layer 14 according to a first embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetization film 12 according to the first embodiment of the present invention applied to the hard bias layer 14 of the magnetoresistive element 10. Figure 2 is a schematic cross-sectional view showing a conventional magnetoresistive element 200.

[0045] The magnetoresistive element 10 according to this first embodiment (here, a tunnel-type magnetoresistive element) comprises an in-plane magnetization film 12 (hard bias layer 14), a magnetic shield layer 50, a seed layer 52, an antiferromagnetic layer 54, a pin layer 56, a barrier layer 58, a free magnetic layer 60, a cap layer 62, and an insulating layer 70.

[0046] The pinned layer 56 and the free magnetic layer 60 are both ferromagnetic layers and are separated by a barrier layer 58, which is a very thin non-magnetic tunnel barrier layer. The magnetization direction of the pinned layer 56 is fixed by means of exchange coupling with the adjacent antiferromagnetic layer 54. The free magnetic layer 60 can rotate its magnetization direction freely relative to the magnetization direction of the pinned layer 56 in the presence of an external magnetic field. When the free magnetic layer 60 rotates relative to the magnetization direction of the pinned layer 56 due to an external magnetic field, its electrical resistance changes, and by detecting this change in electrical resistance, the external magnetic field can be detected. A seed layer 52 is provided on the magnetic shield layer 50, and an antiferromagnetic layer 54 is provided on the seed layer 52. A cap layer 62 is provided on the free magnetic layer 60.

[0047] The hard bias layer 14 has the role of applying a bias magnetic field to the free magnetic layer 60 and stabilizing the magnetization direction axis of the free magnetic layer 60. In the magnetoresistive element 10 according to this first embodiment, the in-plane magnetization film 12 constitutes the hard bias layer 14.

[0048] The insulating layer 70 is formed of an electrically insulating material and plays a role in suppressing the splitting of the sensor current flowing perpendicularly through the sensor laminate (free magnetic layer 60, barrier layer 58, pin layer 56, antiferromagnetic layer 54) into the hard bias layers 14 on both sides of the sensor laminate (free magnetic layer 60, barrier layer 58, pin layer 56, antiferromagnetic layer 54). Specifically, for example, silicon oxide or aluminum oxide can be used as the insulating layer 70.

[0049] (1-2) Schematic configuration of the in-plane magnetization film 12 and hard bias layer 14 according to the first embodiment As shown in Figure 1, in the magnetoresistive element 10 according to this first embodiment, the in-plane magnetization film 12 is used as a hard bias layer 14, and the in-plane magnetization film 12 applies a bias magnetic field to the free magnetic layer 60 that exhibits the magnetoresistive effect. The hard bias layer 14 is composed solely of the in-plane magnetization film 12 according to this first embodiment.

[0050] The in-plane magnetized film 12 according to this first embodiment is composed of an initial magnetic layer 12A and a magnetic layer main body 12B. Both the initial magnetic layer 12A and the magnetic layer main body 12B are in-plane magnetized films having a granular structure in which magnetic metal particles are separated by non-magnetic grain boundary materials.

[0051] The initial magnetic layer 12A is a layer directly laminated on the insulating layer 70. It promotes the growth of magnetic metal particles (hcp structure CoPt alloy particles) in the magnetic layer body 12B formed on the initial magnetic layer 12A, with their spontaneously oriented easy magnetization axis (c axis) in-plane. This facilitates the formation of a columnar granular layer in the magnetic layer body 12B having a hcp structure CoPt alloy with the c axis oriented in-plane. In addition, the initial magnetic layer 12A itself acts as part of the hard bias layer 14, applying a bias magnetic field to the free magnetic layer 60. In order for the initial magnetic layer 12A to perform these roles, it is important that the non-magnetic grain boundary material of the initial magnetic layer 12A contains at least one of Zn oxide and Ta oxide, as demonstrated later in the [Examples] section.

[0052] The magnetic layer body portion 12B is a magnetic layer formed on top of the initial magnetic layer 12A, and literally occupies most of the in-plane magnetization film 12 (hard bias layer 14), and plays the role of applying a bias magnetic field to the free magnetic layer 60.

[0053] The in-plane magnetization film 12 according to this first embodiment is composed of an initial magnetic layer 12A and a magnetic layer body portion 12B as described above. Therefore, when forming the in-plane magnetization film 12 according to this first embodiment, good magnetic properties can be achieved without forming a non-magnetic Ru underlayer 202 (see Figure 2) with a thickness of approximately 15 nm or more on the insulating layer 70, as in the conventional method, before forming the in-plane magnetization film 12. By forming the initial magnetic layer 12A, which is part of the in-plane magnetization film 12, directly on the insulating layer 70, and then forming the magnetic layer body portion 12B, which is the remaining part of the in-plane magnetization film 12, the in-plane magnetization film 12 exhibits good magnetic properties (coercivity Hc of 2.00 kOe or more, and remanent magnetization per unit area of ​​2.00 memu / cm²). 2 That's all. ) expresses.

[0054] The thickness of the initial magnetic layer 12A is such that the in-plane magnetization film 12 has good magnetic properties (coercivity Hc of 2.00 kOe or more, and remanent magnetization per unit area of ​​2.00 memu / cm²). 2 From the viewpoint of exhibiting the above, the standard is 1 nm to 32 nm, but from the viewpoint of achieving a large balance between coercivity Hc and remanent magnetization Mrt per unit area, the thickness of the initial magnetic layer 12A is preferably 2 nm to 30 nm, and more preferably 8 nm to 20 nm. The initial magnetic layer 12A has a granular structure in which magnetic metal is separated by non-magnetic grain boundary material and is part of the in-plane magnetization film 12, so even if the thickness of the initial magnetic layer 12A is thick, for example 30 nm, the distance between the free magnetic layer 60 and the in-plane magnetization film 12 is only the distance of the insulating layer 70 arranged between the free magnetic layer 60 and the in-plane magnetization film 12. Therefore, in the magnetoresistive element 10 according to this first embodiment, the attenuation of the bias magnetic field applied by the hard bias layer 14 to the free magnetic layer 60 is small.

[0055] On the other hand, as shown in Figure 2, the conventional magnetoresistive element 200 has a non-magnetic Ru underlayer 202 with a thickness of about 15 nm or more on top of the insulating layer 70, and an in-plane magnetized film 204 on top of the non-magnetic Ru underlayer 202. Therefore, in addition to the insulating layer 70, a non-magnetic Ru underlayer 202 with a thickness of about 15 nm or more exists between the free magnetic layer 60 and the in-plane magnetized film 204. The distance between the free magnetic layer 60 and the in-plane magnetized film 204 is separated by the distance due to the thickness of the insulating layer 70 as well as the distance due to the thickness of the non-magnetic Ru underlayer 202. Thus, the conventional magnetoresistive element 200 has a larger distance between the free magnetic layer 60 and the in-plane magnetized film 204 compared to the magnetoresistive element 10 according to the first embodiment, by the distance due to the thickness of the non-magnetic Ru underlayer 202. Therefore, in the conventional magnetoresistive element 200, the attenuation of the bias magnetic field applied by the hard bias layer 206 to the free magnetic layer 60 is greater than in the magnetoresistive element 10 according to the first embodiment.

[0056] (1-3) Components of the initial magnetic layer 12A As described above, the in-plane magnetized film 12 according to this first embodiment is composed of an initial magnetic layer 12A and a magnetic layer main body 12B, and both the initial magnetic layer 12A and the magnetic layer main body 12B are in-plane magnetized films having a granular structure in which magnetic metal particles are separated by non-magnetic grain boundary materials.

[0057] The initial magnetic layer 12A plays the role described above (promoting the growth of the magnetic metal particles (hcp structure CoPt alloy particles) in the magnetic layer body 12B with their easy magnetization axis (c axis) spontaneously oriented in plane, thereby enabling the formation of a columnar granular layer having an hcp structure CoPt alloy with the c axis oriented in plane in the magnetic layer body 12B, and also acting as part of the hard bias layer 14 to apply a bias magnetic field to the free magnetic layer 60). To fulfill these roles, the initial magnetic layer 12A contains at least one of Zn oxide and Ta oxide as a non-magnetic grain boundary material, and contains Co and Pt as metallic components.

[0058] Metallic Co and metallic Pt become constituent components of magnetic metal particles (tiny magnets) in the initial magnetic layer 12A of the in-plane magnetized film 12 formed by sputtering.

[0059] Co is a ferromagnetic metallic element and plays a central role in the formation of magnetic crystal grains (tiny magnets) in the initial magnetic layer 12A of the in-plane magnetization film 12.

[0060] From the viewpoint of increasing the magnetic anisotropy constant Ku of the CoPt alloy crystal grains (magnetic crystal grains) and maintaining the magnetism of the CoPt alloy crystal grains (magnetic crystal grains), the initial magnetic layer 12A contains Co in an amount of 44 at% to 82 at% relative to the total metallic components of the initial magnetic layer 12A. However, from the viewpoint of the above, a more desirable range for the Co content in the initial magnetic layer 12A is preferably 55 at% to 80 at% relative to the total metallic components of the initial magnetic layer 12A, and more preferably 65 at% to 75 at%.

[0061] Pt has the function of reducing the magnetic moment of the alloy by alloying with Co within a predetermined composition range, and plays a role in adjusting the magnetic strength of the magnetic crystal grains. On the other hand, it also has the function of increasing the magnetic anisotropy constant Ku of the CoPt alloy crystal grains (magnetic crystal grains) in the initial magnetic layer 12A of the in-plane magnetized film 12 obtained by sputtering, thereby increasing the coercivity of the initial magnetic layer 12A of the in-plane magnetized film 12.

[0062] From the viewpoint of increasing the coercivity of the initial magnetic layer 12A and adjusting the magnetic strength of the CoPt alloy crystal grains (magnetic crystal grains) in the initial magnetic layer 12A, the initial magnetic layer 12A contains Pt in an amount of 18 at% to 56 at% relative to the total metal components of the initial magnetic layer 12A. However, from the viewpoint of the above, a more desirable range for the Pt content in the initial magnetic layer 12A is preferably 20 at% to 45 at% relative to the total metal components of the initial magnetic layer 12A, and more preferably 25 at% to 35 at%.

[0063] Furthermore, in addition to Co and Pt, Fe may be included as a metallic component in the initial magnetic layer 12A of the in-plane magnetized film 12 according to this embodiment, in an amount of 0.5 at% to 1.5 at% relative to the total metallic components of the initial magnetic layer 12A.

[0064] In this first embodiment, the non-magnetic grain boundary material of the initial magnetic layer 12A of the in-plane magnetized film 12 contains at least one of Zn oxide and Ta oxide. Within the initial magnetic layer 12A, the CoPt alloy magnetic crystal grains are separated from each other by the non-magnetic grain boundary material containing at least one of Zn oxide and Ta oxide, forming a granular structure. That is, the granular structure of the initial magnetic layer 12A consists of CoPt alloy crystal grains and crystal grain boundaries surrounded thereby by the non-magnetic grain boundary material containing at least one of Zn oxide and Ta oxide.

[0065] Increasing the content of the non-magnetic grain boundary material in the initial magnetic layer 12A makes it easier to reliably partition the magnetic crystal grains and separate them. From this viewpoint, it is standard practice to set the content of the non-magnetic grain boundary material in the initial magnetic layer 12A of the in-plane magnetized film 12 according to this first embodiment to 2.0 vol% or more relative to the total volume of the initial magnetic layer 12A, preferably 3.0 vol% or more, and more preferably 4.0 vol% or more.

[0066] However, if the content of the non-magnetic grain boundary material in the initial magnetic layer 12A becomes too high, the non-magnetic grain boundary material may be mixed into the CoPt alloy crystal grains (magnetic crystal grains), adversely affecting the crystallinity of the CoPt alloy crystal grains (magnetic crystal grains), and there is a risk that the proportion of structures other than hcp in the CoPt alloy crystal grains (magnetic crystal grains) will increase. From this viewpoint, it is standard practice to set the content of the non-magnetic grain boundary material contained in the initial magnetic layer 12A of the in-plane magnetization film 12 according to this first embodiment to 31.0 vol% or less, preferably 15.0 vol% or less, and more preferably 10.0 vol% or less, relative to the total volume of the initial magnetic layer 12A.

[0067] Therefore, in this first embodiment, the content of the non-magnetic grain boundary material in the initial magnetic layer 12A is typically 2.0 vol% to 31.0 vol%, preferably 3.0 vol% to 15.0 vol%, and more preferably 4.0 vol% to 10.0 vol% relative to the total volume of the initial magnetic layer 12A.

[0068] The non-magnetic grain boundary material of the initial magnetic layer 12A of the in-plane magnetization film 12 according to this first embodiment contains at least one of Zn oxide and Ta oxide, and it is demonstrated in the [Examples] described later that this is important for improving the magnetic properties (coercivity Hc and remanent magnetization per unit area Mrt) of the in-plane magnetization film 12.

[0069] (1-4) Components of the magnetic layer body 12B As mentioned above, the magnetic layer body portion 12B is a magnetic layer formed on top of the initial magnetic layer 12A, and literally occupies most of the in-plane magnetization film 12 (hard bias layer 14), and plays the role of applying a bias magnetic field to the free magnetic layer 60. To fulfill this role, the magnetic layer body portion 12B contains Co and Pt as metallic components and oxides as non-magnetic grain boundary materials.

[0070] Metallic Co and metallic Pt become constituent components of magnetic metal particles (tiny magnets) in the magnetic layer body portion 12B of the in-plane magnetized film 12 formed by sputtering.

[0071] As mentioned above, Co is a ferromagnetic metallic element and plays a central role in the formation of magnetic crystal grains (tiny magnets) in the magnetic layer body portion 12B of the in-plane magnetization film 12.

[0072] In the magnetic layer body 12B, similar to the initial magnetic layer 12A, the magnetic layer body 12B contains Co at a concentration of 44 at% to 82 at% relative to the total metallic components of the magnetic layer body 12B, from the viewpoint of increasing the crystal magnetic anisotropy constant Ku of the CoPt alloy crystal grains (magnetic crystal grains) and maintaining the magnetism of the CoPt alloy crystal grains (magnetic crystal grains). However, from the above viewpoint, a more desirable range for the Co content in the magnetic layer body 12B is preferably 55 at% to 80 at% relative to the total metallic components of the initial magnetic layer 12A, and more preferably 65 at% to 75 at%.

[0073] As mentioned above, Pt has the function of reducing the magnetic moment of the alloy by alloying with Co within a predetermined composition range, and plays a role in adjusting the magnetic strength of the magnetic crystal grains. On the other hand, it also has the function of increasing the magnetic anisotropy constant Ku of the CoPt alloy crystal grains (magnetic crystal grains) in the magnetic layer body 12B of the in-plane magnetized film 12 obtained by sputtering, thereby increasing the coercivity of the magnetic layer body 12B of the in-plane magnetized film 12.

[0074] From the viewpoint of increasing the coercivity of the magnetic layer body 12B and adjusting the magnetic strength of the CoPt alloy crystal grains (magnetic crystal grains) in the magnetic layer body 12B, the magnetic layer body 12B contains Pt in an amount of 18 at% to 56 at% relative to the total metal components of the magnetic layer body 12B. However, from the viewpoint of the above, a more desirable range for the Pt content in the magnetic layer body 12B is preferably 20 at% to 45 at% relative to the total metal components of the magnetic layer body 12B, and more preferably 25 at% to 35 at%.

[0075] The magnetic layer body portion 12B of the in-plane magnetized film 12 according to this first embodiment contains an oxide as a non-magnetic grain boundary material. Within the magnetic layer body portion 12B, the CoPt alloy magnetic crystal grains are separated from each other by the oxide, which is the non-magnetic grain boundary material, forming a granular structure. That is, the granular structure of the magnetic layer body portion 12B consists of CoPt alloy crystal grains and crystal grain boundaries made of the oxide, which is the non-magnetic grain boundary material, surrounding them.

[0076] Increasing the content of oxides, which are non-magnetic grain boundary materials, in the magnetic layer body portion 12B makes it easier to reliably partition the spaces between magnetic crystal grains and to isolate them. From this viewpoint, it is standard practice to set the content of oxides, which are non-magnetic grain boundary materials, in the magnetic layer body portion 12B of the in-plane magnetized film 12 according to this first embodiment to 2.0 vol% or more relative to the total volume of the magnetic layer body portion 12B, preferably to 3.0 vol% or more, and more preferably to 4.0 vol% or more.

[0077] However, if the content of oxides, which are non-magnetic grain boundary materials, in the magnetic layer body portion 12B becomes too high, the oxides, which are non-magnetic grain boundary materials, may be mixed into the CoPt alloy crystal grains (magnetic crystal grains), adversely affecting the crystallinity of the CoPt alloy crystal grains (magnetic crystal grains), and there is a risk that the proportion of structures other than hcp in the CoPt alloy crystal grains (magnetic crystal grains) will increase. From this viewpoint, it is standard practice to set the content of oxides, which are non-magnetic grain boundary materials, in the magnetic layer body portion 12B of the in-plane magnetized film 12 according to this first embodiment to 31.0 vol% or less, preferably 15.0 vol% or less, and more preferably 10.0 vol% or less, relative to the total volume of the magnetic layer body portion 12B.

[0078] Therefore, in this first embodiment, it is standard practice to have an oxide content in the magnetic layer body 12B that is a non-magnetic grain boundary material of 2.0 vol% or more and 31.0 vol% or less relative to the total volume of the magnetic layer body 12B. Furthermore, it is preferable that the oxide content in the magnetic layer body 12B that is a non-magnetic grain boundary material of 3.0 vol% or more and 15.0 vol% or less is set to be 4.0 vol% or more and 10.0 vol% or less.

[0079] Furthermore, if boron oxide is included as the non-magnetic grain boundary material in the magnetic layer body 12B, the coercivity Hc of the magnetic layer body 12B increases, and the coercivity Hc of the in-plane magnetization film 12 increases. Therefore, it is preferable to include boron oxide as the oxide.

[0080] In current in-plane magnetized films, elemental elements such as Cr, W, Ta, and B are used as grain boundary materials to separate the CoPt alloy crystal grains (magnetic crystal grains). Therefore, it is thought that these grain boundary materials are dissolved in the CoPt alloy to some extent. Consequently, the CoPt alloy crystal grains (magnetic crystal grains) in current in-plane magnetized films are thought to be negatively affected by their crystallinity, resulting in reduced saturation magnetization and remanent magnetization. As a result, the values ​​of coercivity Hc and remanent magnetization in current in-plane magnetized films are negatively impacted.

[0081] On the other hand, in the magnetic layer body portion 12B of the in-plane magnetized film 12 according to this first embodiment, since the grain boundary material is an oxide, the grain boundary material is less likely to solid dissolve in the CoPt alloy compared to the case where the grain boundary material is an elemental element such as Cr, W, Ta, or B. As a result, the saturation magnetization and remanent magnetization of the magnetic layer body portion 12B of the in-plane magnetized film 12 according to this first embodiment become larger, and the coercivity Hc and remanent magnetization of the in-plane magnetized film 12 according to this first embodiment become larger.

[0082] (1-5) Thickness of the in-plane magnetization film 12 (initial magnetic layer 12A and magnetic layer main body 12B) As mentioned above, the "remanent magnetization per unit area" of an in-plane magnetization film is the value obtained by multiplying the remanent magnetization per unit volume of the in-plane magnetization film by the thickness of the in-plane magnetization film. Therefore, reducing the thickness of the in-plane magnetization film tends to decrease the remanent magnetization per unit area (Mrt). Also, increasing the thickness of the in-plane magnetization film tends to decrease the coercivity (Hc) of the in-plane magnetization film due to the shape magnetic anisotropy effect. These characteristics apply to both the initial magnetic layer 12A and the magnetic layer body 12B.

[0083] As mentioned above, the thickness of the initial magnetic layer 12A is typically between 1 nm and 32 nm. However, from the viewpoint of achieving a good balance between coercivity Hc and remanent magnetization Mrt per unit area, the thickness of the initial magnetic layer 12A is preferably between 2 nm and 30 nm, and more preferably between 8 nm and 20 nm.

[0084] While the thickness of the magnetic layer body 12B is typically 15 nm to 80 nm, from the viewpoint of achieving a good balance between coercivity Hc and remanent magnetization Mrt per unit area, the thickness of the magnetic layer body 12B is preferably 20 nm to 60 nm, and more preferably 25 nm to 50 nm.

[0085] (1-6) Base layer As mentioned above, in conventional technology, a non-magnetic underlayer (Cr, Ti, Cr alloy, Ti alloy, etc.) that promotes the in-plane orientation of the c axis of the hcp structure CoPt alloy is used as the underlayer of the Co-Pt in-plane magnetization film (paragraph 0028 of Patent Document 2 listed in the [Prior Art Documents] section). Also, as mentioned above, in other conventional technologies, a non-magnetic Ru underlayer is formed by using a high gas pressure during film formation, and a Co-Pt in-plane magnetization film is formed on top of this non-magnetic Ru underlayer, which is made thicker than about 15 nm, thereby improving the coercivity Hc of the Co-Pt in-plane magnetization film (paragraph 0016 of Patent Document 3 and Non-Patent Document 1 listed in the [Prior Art Documents] section). However, since all of these techniques use a non-magnetic underlayer, even if an in-plane magnetized film is formed as a hard bias layer using these techniques, the distance between the magnetoresistive element and the hard bias layer increases by the thickness of the non-magnetic underlayer, causing the magnetic field applied to the magnetoresistive element of the hard bias layer to decrease.

[0086] On the other hand, in the in-plane magnetization film 12 and the hard bias layer 14 consisting of the in-plane magnetization film 12 according to this first embodiment, no non-magnetic underlayer is used to improve the magnetic properties of the formed in-plane magnetization film. Instead, an initial magnetic layer 12A, which is part of the in-plane magnetization film 12 (hard bias layer 14), is formed directly on the insulating layer 70. In other words, the insulating layer 70 serves as the underlayer for the in-plane magnetization film 12 (hard bias layer 14). As a result, the hard bias layer 14 consisting of the in-plane magnetization film 12 according to this first embodiment is close to the free magnetic layer 60 of the magnetoresistive element, and the decrease in the magnetic field applied to the free magnetic layer 60 is suppressed. Furthermore, even if the in-plane magnetization film 12 according to this first embodiment is formed directly on the insulating layer 70, it is demonstrated in the [Examples] described later that a good coercivity Hc can be obtained by using a predetermined initial magnetic layer 12A.

[0087] Furthermore, as demonstrated later in the [Examples] section, the in-plane magnetized film 12 according to this first embodiment can obtain a good coercivity Hc even when the surface roughness of the insulating layer 70 that serves as the base for formation is extremely small, between 0.1 nm and 1.5 nm. Generally, it is believed that a certain degree of surface roughness in the non-magnetic base layer used as the base for formation promotes the magnetic isolation of Co-Pt alloy crystal grains, making it easier to increase the coercivity Hc.

[0088] Furthermore, in this first embodiment, since the surface roughness of the insulating layer 70 that serves as the base for the formation of the in-plane magnetized film 12 is extremely small, between 0.1 nm and 1.5 nm, it is possible to obtain the effect of reducing the surface irregularities of the formed in-plane magnetized film 12. When the surface irregularities of the formed in-plane magnetized film 12 are reduced, the effort required to commercialize it as a magnetoresistive element 10 is reduced, and subsequent processes become easier.

[0089] In the in-plane magnetization film 12 according to this first embodiment, the reason why the above-mentioned effects (good coercivity Hc can be obtained even when the in-plane magnetization film 12 according to this first embodiment is formed directly on an insulating layer 70 with an extremely small surface roughness of 0.1 nm to 1.5 nm) is that the in-plane magnetization film 12 is composed of an initial magnetic layer 12A and a magnetic layer main body 12B, and the non-magnetic grain boundary material of the initial magnetic layer 12A is configured to contain at least one of Zn oxide and Ta oxide, which is demonstrated in the [Examples] described later. However, the theoretical reason why the above-mentioned effects can be obtained by configuring the non-magnetic grain boundary material of the initial magnetic layer 12A to contain at least one of Zn oxide and Ta oxide is currently unknown.

[0090] (1-7) Sputtering targets The sputtering target used to form the initial magnetic layer 12A of the in-plane magnetized film 12 according to this first embodiment by room temperature deposition contains metallic Co, metallic Pt, and a non-magnetic grain boundary material. The sputtering target contains 60 at% to 82 at% metallic Co, 18 at% to 40 at% metallic Pt, and 6 vol% to 30 vol% of the non-magnetic grain boundary material relative to the total metallic components of the sputtering target, and the non-magnetic grain boundary material contains at least one of Zn oxide and Ta oxide. As described in the [Examples] below, there is a discrepancy between the actual composition of the fabricated CoPt-oxide system in-plane magnetized film (composition obtained by compositional analysis) and the composition of the sputtering target used to fabricate the CoPt-oxide system in-plane magnetized film. Therefore, the composition range of each element contained in the sputtering target described above does not coincide with the composition range of each element contained in the initial magnetic layer 12A of the in-plane magnetized film 12 according to this first embodiment.

[0091] (1-8) Method for forming the initial magnetic layer 12A The initial magnetic layer 12A of the in-plane magnetization film 12 according to this first embodiment is formed by sputtering using the sputtering target described in "(1-7) Sputtering Target" above, and depositing the film on the insulating layer 70. Heating is not required during the film formation process of this initial magnetic layer 12A, and the film is formed at room temperature. Furthermore, heating is not required during sputtering when forming the magnetic layer body portion 12B, and the in-plane magnetization film 12 according to this first embodiment can be formed by film formation at room temperature.

[0092] Furthermore, as described in "(1-6) Underlying Layer" above, in the formation of the in-plane magnetization film 12 according to this first embodiment, a non-magnetic underlying layer is not used to improve the magnetic properties of the in-plane magnetization film 12 to be formed. Instead, an initial magnetic layer 12A is formed directly on the insulating layer 70 by sputtering, and the magnetic layer body portion 12B is formed on the formed initial magnetic layer 12A by sputtering to form the in-plane magnetization film 12.

[0093] (2) Second Embodiment Figure 3 is a schematic cross-sectional view showing a magnetoresistive element 20, an in-plane magnetized film multilayer structure 22, and a hard bias layer 24 according to a second embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetized film multilayer structure 22 according to the second embodiment of the present invention applied to the hard bias layer 24 of the magnetoresistive element 20.

[0094] The in-plane magnetized film multilayer structure 22 according to this second embodiment will be described below, but the same reference numerals will be used for components identical to those in the first embodiment, and their descriptions will be omitted in principle.

[0095] As shown in Figure 3, the in-plane magnetized film multilayer structure 22 according to the second embodiment of the present invention has a structure in which an initial magnetic layer 22A is formed on an insulating layer 70, a non-magnetic initial intermediate layer 22C is formed on the initial magnetic layer 22A, and a magnetic layer main body 22B is formed on the non-magnetic initial intermediate layer 22C. Here, the constituent components and thickness of the initial magnetic layer 22A and the magnetic layer main body 22B are the same as those of the initial magnetic layer 12A and the magnetic layer main body 12B of the in-plane magnetized film 12 according to the first embodiment, so their explanation will be omitted in principle.

[0096] The in-plane magnetized film multilayer structure 22 according to this second embodiment can be used as a hard bias layer 24 of a magnetoresistive element 20, and a bias magnetic field can be applied to the free magnetic layer 60 that exhibits a magnetoresistive effect.

[0097] The non-magnetic initial intermediate layer 22C is a layer that separates the initial magnetic layer 22A and the magnetic layer main body 22B in the thickness direction and multilayers them, thereby reducing the thickness of each individual magnetic layer while maintaining the total thickness of the magnetic layers. This layer plays a role in further improving the coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area.

[0098] The initial magnetic layer 22A and the magnetic layer main body 22B, separated by the interposition of the non-magnetic initial intermediate layer 22C, are arranged so that their spins are parallel (same direction). By arranging them in this way, the initial magnetic layer 22A and the magnetic layer main body 22B, separated by the interposition of the non-magnetic initial intermediate layer 22C, form a ferromagnetic coupling. As a result, the in-plane magnetized film multilayer structure 22 can improve its coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area, thereby exhibiting a good coercivity Hc.

[0099] The metal used for the non-magnetic initial intermediate layer 22C is one that has the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic crystal grains, in order to avoid damaging the crystal structure of the CoPt alloy magnetic crystal grains. Specifically, as the non-magnetic initial intermediate layer 22C, metal Ru or Ru alloy having the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic crystal grains in the initial magnetic layer 22A and the magnetic layer body portion 22B can be suitably used.

[0100] When the metal used for the non-magnetic initial intermediate layer 22C is a Ru alloy, specific elements such as Cr, Pt, and Co can be used as additives, and the range of amounts of these metals added should be such that the Ru alloy forms a hexagonal close-packed structure (hcp).

[0101] Bulk samples of Ru alloy were prepared by arc melting, and X-ray diffraction peak analysis was performed using an X-ray diffractometer (XRD: SmartLab, Rigaku Corporation). In the RuCr alloy, when the amount of Cr added was 50 at%, a multiphase structure of hexagonal close-packed structure (hcp) and RuCr2 was confirmed. Therefore, when using RuCr alloy for the non-magnetic initial intermediate layer 22C, it is appropriate to add less than 50 at%, preferably less than 40 at%, and more preferably less than 30 at% Cr. In the RuPt alloy, when the amount of Pt added was 15 at%, a multiphase structure of hexagonal close-packed structure (hcp) and face-centered cubic structure (fcc) derived from Pt was confirmed. Therefore, when using RuPt alloy for the non-magnetic initial intermediate layer 22C, it is appropriate to add less than 15 at%, preferably less than 12.5 at%, and more preferably less than 10 at% Pt. Furthermore, in RuCo alloys, a hexagonal close-packed structure (hcp) is formed regardless of the amount of Co added. However, if more than 40 at% of Co is added, the alloy becomes magnetic. Therefore, it is appropriate to add less than 40 at% of Co, preferably less than 30 at%, and more preferably less than 20 at%.

[0102] Regarding the thickness of the non-magnetic initial intermediate layer 22C, if the thickness of the non-magnetic initial intermediate layer 22C is too thin, it may not be able to perform the aforementioned role (the role of further improving the coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area by separating the initial magnetic layer 22A and the magnetic layer main body portion 22B in the thickness direction and multilayering them, thereby reducing the thickness of the magnetic layer as a single layer while maintaining the total thickness of the magnetic layer). Therefore, the thickness of the non-magnetic initial intermediate layer 22C is typically 0.3 nm or more, preferably 0.5 nm or more, and more preferably 0.7 nm or more.

[0103] On the other hand, the thinner the non-magnetic initial intermediate layer 22C is, the closer the distance between the magnetic layer body 22B and the free magnetic layer 60 becomes, and the reduction in the magnetic field applied to the free magnetic layer 60 by the hard bias layer 24, which is made up of an in-plane magnetized film multilayer structure 22, is suppressed. Therefore, the thickness of the non-magnetic initial intermediate layer 22C is typically 2 nm or less, preferably 1.5 nm or less, and more preferably 1.2 nm or less.

[0104] Therefore, the thickness of the non-magnetic initial intermediate layer 22C is typically 0.3 nm to 2 nm, preferably 0.5 nm to 1.5 nm, and more preferably 0.7 nm to 1.2 nm.

[0105] (3) Third Embodiment Figure 4 is a schematic cross-sectional view showing a magnetoresistive element 30, an in-plane magnetized film multilayer structure 32, and a hard bias layer 34 according to a third embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetized film multilayer structure 32 according to the third embodiment of the present invention applied to the hard bias layer 34 of the magnetoresistive element 30.

[0106] The in-plane magnetized film multilayer structure 32 according to this third embodiment will be described below, but the same reference numerals will be used for components identical to those in the first embodiment, and their descriptions will be omitted in principle.

[0107] As shown in Figure 4, the in-plane magnetized film multilayer structure 32 according to the third embodiment of the present invention has a structure in which an initial magnetic layer 32A is formed on an insulating layer 70, a first magnetic layer main body 32B is formed on the initial magnetic layer 32A, a non-magnetic intermediate layer 32D is formed on the first magnetic layer main body 32B, and a second magnetic layer main body 32C is formed on the non-magnetic intermediate layer 32D, so that the magnetic layer main body is separated into the first magnetic layer main body 32B and the second magnetic layer main body 32C by the non-magnetic intermediate layer 32D. Here, the constituent components and thickness of the initial magnetic layer 32A are the same as the constituent components and thickness of the initial magnetic layer 12A of the in-plane magnetized film 12 according to the first embodiment, so the explanation will be omitted in principle. Also, the constituent components of the first magnetic layer main body 32B and the second magnetic layer main body 32C are the same as the constituent components of the magnetic layer main body 12B of the in-plane magnetized film 12 according to the first embodiment, so the explanation will be omitted in principle.

[0108] The in-plane magnetized film multilayer structure 32 according to this third embodiment can be used as a hard bias layer 34 of a magnetoresistive element 30, and a bias magnetic field can be applied to the free magnetic layer 60 that exhibits a magnetoresistive effect.

[0109] The non-magnetic intermediate layer 32D is formed by separating the main body of the magnetic layer in the thickness direction into a first magnetic layer main body 32B and a second magnetic layer main body 32C, and then layering them. This reduces the thickness of each individual magnetic layer while maintaining the total thickness of the magnetic layers, thereby further improving the coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area.

[0110] The first magnetic layer body 32B and the second magnetic layer body 32C, separated by the interposed non-magnetic intermediate layer 32D, are arranged so that their spins are parallel (same direction). By arranging them in this way, the first magnetic layer body 32B and the second magnetic layer body 32C, separated by the interposed non-magnetic intermediate layer 32D, form a ferromagnetic coupling. As a result, the in-plane magnetized film multilayer structure 32 can improve its coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area, thereby exhibiting a good coercivity Hc.

[0111] The thickness of the first magnetic layer body 32B and the second magnetic layer body 32C can be considered as their combined thickness. Typically, the combined thickness of the first magnetic layer body 32B and the second magnetic layer body 32C is between 15 nm and 80 nm. However, from the viewpoint of achieving a good balance between coercivity Hc and remanent magnetization Mrt per unit area, the combined thickness of the first magnetic layer body 32B and the second magnetic layer body 32C is preferably between 20 nm and 60 nm, and more preferably between 25 nm and 50 nm.

[0112] The metal used for the non-magnetic intermediate layer 32D is one that has the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic crystal grains, in order to avoid damaging the crystal structure of the CoPt alloy magnetic crystal grains. Specifically, as the non-magnetic intermediate layer 32D, metal Ru or a Ru alloy having the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic crystal grains in the in-plane magnetization film 12 can be suitably used.

[0113] When the metal used for the non-magnetic intermediate layer 32D is a Ru alloy, specific elements such as Cr, Pt, and Co can be used as additives, and the range of amounts of these metals added should be such that the Ru alloy forms a hexagonal close-packed structure (hcp).

[0114] Bulk samples of Ru alloy were prepared by arc melting, and peak analysis of X-ray diffraction was performed using an X-ray diffractometer (XRD: SmartLab, Rigaku Corporation). In the RuCr alloy, when the amount of Cr added was 50 at%, a multiphase structure of hexagonal close-packed structure (hcp) and RuCr2 was confirmed. Therefore, when using RuCr alloy for the non-magnetic intermediate layer 32D, it is appropriate to add less than 50 at%, preferably less than 40 at%, and more preferably less than 30 at% Cr. In the RuPt alloy, when the amount of Pt added was 15 at%, a multiphase structure of hexagonal close-packed structure (hcp) and face-centered cubic structure (fcc) derived from Pt was confirmed. Therefore, when using RuPt alloy for the non-magnetic intermediate layer 32D, it is appropriate to add less than 15 at%, preferably less than 12.5 at%, and more preferably less than 10 at% Pt. Furthermore, in RuCo alloys, a hexagonal close-packed structure (hcp) is formed regardless of the amount of Co added. However, if more than 40 at% of Co is added, the alloy becomes magnetic. Therefore, it is appropriate to add less than 40 at% of Co, preferably less than 30 at%, and more preferably less than 20 at%.

[0115] Regarding the thickness of the non-magnetic intermediate layer 32D, if the thickness of the non-magnetic intermediate layer 32D is too thin, it may not be able to perform the aforementioned role (separating the main body of the magnetic layer in the thickness direction, separating it into the first main body of the magnetic layer 32B and the second main body of the magnetic layer 32C, and multilayering it, thereby reducing the thickness of the magnetic layer as a single layer while maintaining the total thickness of the magnetic layer, thereby further improving the coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area). Therefore, the thickness of the non-magnetic intermediate layer 32D is typically 0.3 nm or more, preferably 0.5 nm or more, and more preferably 0.7 nm or more.

[0116] On the other hand, the thinner the non-magnetic intermediate layer 32D, the larger the proportion of the in-plane magnetized film (initial magnetic layer 32A and magnetic layer main body portions 32B, 32C) in the in-plane magnetized film multilayer structure 32 becomes, and the magnetic field applied to the free magnetic layer 60 by the hard bias layer 34 consisting of the in-plane magnetized film multilayer structure 32 becomes larger. Therefore, the thickness of the non-magnetic intermediate layer 32D is typically 2 nm or less, preferably 1.5 nm or less, and more preferably 1.2 nm or less.

[0117] Therefore, the thickness of the non-magnetic intermediate layer 32D is typically 0.3 nm to 2 nm, preferably 0.5 nm to 1.5 nm, and more preferably 0.7 nm to 1.2 nm.

[0118] (4) Fourth Embodiment Figure 5 is a schematic cross-sectional view showing a magnetoresistive element 40, an in-plane magnetized film multilayer structure 42, and a hard bias layer 44 according to the fourth embodiment of the present invention, and is a schematic cross-sectional view showing the in-plane magnetized film multilayer structure 42 according to the fourth embodiment of the present invention applied to the hard bias layer 44 of the magnetoresistive element 40.

[0119] The in-plane magnetized film multilayer structure 42 according to this fourth embodiment will be described below, but the same reference numerals will be used for components identical to those in the first embodiment, and their descriptions will be omitted in principle.

[0120] As shown in Figure 5, the in-plane magnetized film multilayer structure 42 according to the fourth embodiment of the present invention has a structure in which an initial magnetic layer 42A is formed on an insulating layer 70, a non-magnetic initial intermediate layer 42D is formed on the initial magnetic layer 42A, a first magnetic layer main body 42B is formed on the non-magnetic initial intermediate layer 42D, a non-magnetic intermediate layer 42E is formed on the first magnetic layer main body 42B, and a second magnetic layer main body 42C is formed on the non-magnetic intermediate layer 42E. The initial magnetic layer 42A is separated from the magnetic layer main bodies 42B and 42C by the non-magnetic initial intermediate layer 42D, and the magnetic layer main body is separated into the first magnetic layer main body 42B and the second magnetic layer main body 42C by the non-magnetic intermediate layer 42E. Here, the constituent components and thicknesses of the initial magnetic layer 42A, the first magnetic layer main body 42B, and the second magnetic layer main body 42C are the same as those of the initial magnetic layer 32A, the first magnetic layer main body 32B, and the second magnetic layer main body 32C of the in-plane magnetized film multilayer structure 32 according to the third embodiment, so their explanation will be omitted in principle.

[0121] The in-plane magnetized film multilayer structure 42 according to this fourth embodiment can be used as a hard bias layer 44 of a magnetoresistive element 40, and a bias magnetic field can be applied to the free magnetic layer 60 that exhibits a magnetoresistive effect.

[0122] The non-magnetic initial intermediate layer 42D is a layer that separates the initial magnetic layer 42A and the main body portion 42B of the first magnetic layer in the thickness direction and multilayers them, thereby reducing the thickness of each individual magnetic layer while maintaining the total thickness of the magnetic layers. This layer plays a role in further improving the coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area.

[0123] The initial magnetic layer 42A and the main body portion 42B of the first magnetic layer, separated by the interposition of the non-magnetic initial intermediate layer 42D, are arranged so that their spins are parallel (same direction). By arranging them in this way, the initial magnetic layer 42A and the main body portion 42B of the first magnetic layer, separated by the interposition of the non-magnetic initial intermediate layer 42D, form a ferromagnetic coupling. As a result, the in-plane magnetized film multilayer structure 42 can improve its coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area, thereby exhibiting a good coercivity Hc.

[0124] The metal used for the non-magnetic initial intermediate layer 42D is the same as the metal used for the non-magnetic initial intermediate layer 22C of the in-plane magnetized film multilayer structure 22 according to the second embodiment, and the thickness of the non-magnetic initial intermediate layer 42D is the same as the thickness of the non-magnetic initial intermediate layer 22C of the in-plane magnetized film multilayer structure 22 according to the second embodiment.

[0125] The non-magnetic intermediate layer 42E is formed by separating the main body of the magnetic layer in the thickness direction into a first magnetic layer main body 42B and a second magnetic layer main body 42C, and then layering them. This reduces the thickness of each individual magnetic layer while maintaining the total thickness of the magnetic layers, thereby further improving the coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area.

[0126] The first magnetic layer body 42B and the second magnetic layer body 42C, separated by the interposed non-magnetic intermediate layer 42E, are arranged so that their spins are parallel (same direction). By arranging them in this way, the first magnetic layer body 42B and the second magnetic layer body 42C, separated by the interposed non-magnetic intermediate layer 42E, form a ferromagnetic coupling. As a result, the in-plane magnetized film multilayer structure 42 can improve its coercivity Hc while maintaining the value of the remanent magnetization Mrt per unit area, thereby exhibiting a good coercivity Hc.

[0127] The metal used for the non-magnetic intermediate layer 42E is the same as the metal used for the non-magnetic intermediate layer 32D of the in-plane magnetized film multilayer structure 32 according to the third embodiment, and the thickness of the non-magnetic intermediate layer 42E is the same as the thickness of the non-magnetic intermediate layer 32D of the in-plane magnetized film multilayer structure 32 according to the third embodiment. [Examples]

[0128] The following describes examples, comparative examples, and reference examples that support the present invention.

[0129] In (A) below, the influence of the type of non-magnetic grain boundary oxide in the initial magnetic layer of an in-plane magnetized film on the coercivity Hc and remanent magnetization per unit area Mrt in a single-layer structure of in-plane magnetized films made of CoPt-non-magnetic oxides is investigated. In (B) below, in a multilayer structure of in-plane magnetized films made of CoPt-non-magnetic oxides (initial magnetic layer: CoPt-ZnO in-plane magnetized film, magnetic layer body: CoPt-B2O3 in-plane magnetized film), the influence of the thickness of the initial magnetic layer of the in-plane magnetized film on the coercivity Hc and remanent magnetization per unit area Mrt is investigated. The effect on the remanent magnetization Mrt per unit area is being investigated. In (C) below, in a CoPt-nonmagnetic oxide in-plane magnetization film multilayer structure (initial magnetic layer: CoPt-ZnO in-plane magnetization film, magnetic layer body: CoPt-B2O3 in-plane magnetization film), the effect of the oxide (ZnO) content (volume fraction) in the initial magnetic layer of the in-plane magnetization film on the coercivity Hc and remanent magnetization Mrt per unit area is being investigated. In (D) below, the CoPt-nonmagnetic oxide in-plane magnetization film multilayer structure In a multilayer structure of in-plane magnetized films (initial magnetic layer: CoPt-ZnO in-plane magnetized film, magnetic layer body: CoPt-B2O3 in-plane magnetized film), the influence of the composition ratio of Co and Pt, which are metallic components in the initial magnetic layer of the in-plane magnetized film, on the coercivity Hc and the remanent magnetization Mrt per unit area was investigated. In (E) below, in a multilayer structure of in-plane magnetized films of CoPt-nonmagnetic oxide (initial magnetic layer: CoPt in-plane magnetized film, magnetic layer body: CoPt-B2O3 in-plane magnetized film), the influence of the initial magnetic layer of the in-plane magnetized film on the remanent magnetization Mrt was investigated. We are investigating the effects of using Ta2O5 as the magnetic grain boundary material on coercivity Hc and remanent magnetization Mrt per unit area. In (F) below, we are investigating the effects of adding Fe as a metallic component in the initial magnetic layer of the in-plane magnetized film in a CoPt-nonmagnetic oxide multilayer structure (initial magnetic layer: CoPt-ZnO in-plane magnetized film, magnetic layer body: CoPt-B2O3 in-plane magnetized film).

[0130] Since there was a discrepancy between the actual composition of the fabricated CoPt-nonmagnetic oxide in-plane magnetized film (composition obtained by compositional analysis) and the composition of the sputtering target used to fabricate the CoPt-nonmagnetic oxide in-plane magnetized film, the actual composition of several of the fabricated CoPt-nonmagnetic oxide in-plane magnetized films was obtained by compositional analysis. Based on these results, calculations were performed to correct for the compositional discrepancy in all the examples, comparative examples, and reference examples described below, and the corrected compositions were used as the compositions of the in-plane magnetized films in all the examples, comparative examples, and reference examples.

[0131] In the compositional analysis of the in-plane magnetized film, energy-dispersive X-ray spectroscopy (EDX) was employed as the elemental analysis method, and the EMAXEvolution instrument manufactured by Horiba, Ltd. was used. However, since boron (B) is a light element with a smaller atomic number than oxygen (O), it cannot be detected by EDX analysis, and therefore the exact value of the B2O3 content in the in-plane magnetized film is currently unknown. For this reason, the B2O3 content values ​​in the in-plane magnetized film compositions described below in the examples, comparative examples, and reference examples are based on the B2O3 content in the target composition, and may deviate from the actual value.

[0132] The compositions of the CoPt-nonmagnetic oxide in-plane magnetized films in the examples, comparative examples, and reference examples described in (A) to (F) below were calculated by applying a calculation that corrects for compositional deviations to the composition of the sputtering target used for fabrication. However, for B2O3, as mentioned above, the value of the B2O3 content in the target composition is given.

[0133] <(A) In a CoPt-nonmagnetic oxide monolayer structure, the type of nonmagnetic oxide in the initial magnetic layer of the in-plane magnetization film has an effect on coercivity Hc and remanent magnetization Mrt per unit area (Reference Examples 1-8)> In Reference Examples 1 to 8, experimental data was obtained by varying the type of nonmagnetic grain boundary oxide used in the in-plane magnetized film single-layer structure of CoPt-nonmagnetic oxide formed on a silicon substrate. The nonmagnetic grain boundary oxides used in Reference Examples 1 to 8 were, in order from Reference Example 1 to Reference Example 8, Al2O3, B2O3, Ga2O3, MgO, MnO, Nb2O5, Ta2O5, and ZnO. In all cases, the in-plane magnetized film of the formed CoPt-nonmagnetic oxide was a single layer, and no nonmagnetic intermediate layer was provided.

[0134] The silicon substrate used has a surface that has been oxidized to a thickness of approximately 100 nm, and the surface is composed of an insulating layer of silicon oxide (SiOx). Furthermore, the surface of the silicon substrate is mirror-finished, and its surface roughness Ra (arithmetic mean roughness) is 0.1 nm. In other words, the surface roughness Ra (arithmetic mean roughness) of the silicon oxide (SiOx, the insulating layer on the surface of the silicon substrate) that forms the underlayer of the in-plane magnetization film is 0.1 nm. Hereafter, this silicon substrate will be referred to as the surface-oxidized silicon substrate.

[0135] On surface-oxidized silicon substrates, single-layer in-plane magnetized films of CoPt-nonmagnetic oxides, each representing a different type of oxide (Reference Examples 1-8), were formed to a thickness of 15 nm using sputtering with an ES-3100W sputtering machine manufactured by Eiko Engineering Co., Ltd. No substrate heating was performed during this deposition process; the deposition was carried out at room temperature. In the examples, comparative examples, and reference examples of this application, the sputtering machine used for sample preparation was the ES-3100W manufactured by Eiko Engineering Co., Ltd.; however, the name of the machine will be omitted below.

[0136] Specifically, samples were prepared and experimental data obtained to investigate the types of nonmagnetic grain boundary oxides in the initial magnetic layer, as described below.

[0137] In Reference Example 1, a 15 nm thick (Co-26.12Pt)-5.11 vol%Al2O3 in-plane magnetized film single layer structure was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Reference Example 2, a 15 nm thick (Co-26.12Pt)-10 vol%B2O3 in-plane magnetized film single layer structure was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Reference Example 3, In Reference Example 4, a 15 nm thick (Co-26.12Pt)-4.89 vol%Ga2O3 in-plane magnetized film single layer structure was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating underlayer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Reference Example 5, a 15 nm thick (Co-26.12Pt)-4.28 vol%MgO in-plane magnetized film single layer structure was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating underlayer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. Using a (Co-25Pt)-10vol%MnO sputtering target, a 15nm thick (Co-26.12Pt)-4.72vol%MnO in-plane magnetized film single-layer structure was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating underlayer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1nm. In Reference Example 6, a (Co-25Pt)-10vol%Nb2O5 sputtering target was used, and a 15nm thick (Co-26.12Pt)-4.72vol%MnO film single-layer structure was formed on a surface-oxidized silicon substrate, that is, on an insulating underlayer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1nm.A single-layer structure of an in-plane magnetization film with 57 vol% Nb2O5 was formed by sputtering. In Reference Example 7, using a (Co-25Pt)-10 vol% Ta2O5 sputtering target, on a surface-oxidized silicon substrate, that is, on an insulating layer serving as a base layer which is a silicon oxide layer with an extremely smooth surface roughness Ra (arithmetic mean roughness) of 0.1 nm, a single-layer structure of an in-plane magnetization film with a thickness of 15 nm and a composition of (Co-26.12Pt)-4.32 vol% Ta2O5 was formed by sputtering. In Reference Example 8, using a (Co-25Pt)-10 vol% ZnO sputtering target, on a surface-oxidized silicon substrate, that is, on an insulating layer serving as a base layer which is a silicon oxide layer with an extremely smooth surface roughness Ra (arithmetic mean roughness) of 0.1 nm, a single-layer structure of an in-plane magnetization film with a thickness of 15 nm and a composition of (Co-26.12Pt)-4.44 vol% ZnO was formed by sputtering.

[0138] On the single-layer structures of the in-plane magnetization films of Reference Examples 1 to 8 formed as described above, a carbon cap layer was formed by sputtering respectively to fabricate samples for magnetic property measurement.

[0139] In each of the film formation processes in Reference Examples 1 to 8, substrate heating was not performed and film formation was carried out at room temperature.

[0140] The hysteresis loops of the single-layer structures of the in-plane magnetization films (initial magnetic layers) of Reference Examples 1 to 8 fabricated were measured by a vibrating sample magnetometer (VSM: TM-VSM211483-HGC type manufactured by Tamagawa Seisakusho Co., Ltd.) (hereinafter referred to as the vibrating sample magnetometer). From the measured hysteresis loops, the coercive force Hc (kOe), the residual magnetization Mr (memu / cm 3 ) and the saturation magnetization Ms (memu / cm 3 ) were read. Then, the residual magnetization Mr (memu / cm ) read was multiplied by the thickness of the fabricated CoPt in-plane magnetization film (initial magnetic layer) to calculate the residual magnetization Mrt (memu / cm 3 ) per unit area of the fabricated single-layer structure of the in-plane magnetization film (initial magnetic layer), and the saturation magnetization Ms (memu / cm 2 ) read 3Multiplying this by the thickness of the fabricated CoPt in-plane magnetization film (initial magnetic layer) gives the saturation magnetization Mst (memu / cm²) per unit area of ​​the fabricated in-plane magnetization film (initial magnetic layer) single-layer structure. 2 ) was calculated.

[0141] The experimental results for Reference Examples 1 to 8 are shown in Table 1. Furthermore, Figure 6 shows bar graphs for the experimental results of Reference Examples 1 to 8, with the type of nonmagnetic grain boundary oxide on the horizontal axis and the coercivity Hc(kOe) on the vertical axis.

[0142] Furthermore, for the CoPt in-plane magnetization film (initial magnetic layer) of Reference Example 8, whose composition is (Co-26.12Pt)-4.44vol%ZnO, its perpendicular cross-section (cross-section perpendicular to the in-plane direction of the CoPt in-plane magnetization film) was observed using a scanning transmission electron microscope (Hitachi High-Technologies Corporation H-9500), and the observed image (cross-sectional TEM image) was acquired. The observed image (cross-sectional TEM image) is shown in Figure 7.

[0143] [Table 1]

[0144] As is clear from Table 1 and Figure 6, the coercivity Hc of Reference Example 7, which uses Ta2O5 as the nonmagnetic grain boundary oxide for the in-plane magnetization film (initial magnetic layer), and Reference Example 8, which uses ZnO, were 2.09 kOe and 3.13 kOe, respectively, which are above 2.00 kOe. Compared to Reference Examples 1-6, which use other nonmagnetic grain boundary oxides, significantly better coercivity Hc was obtained.

[0145] The excellent coercivity Hc in Reference Examples 7 and 8 is groundbreaking because it is an experimental result obtained by directly depositing an in-plane magnetized film (initial magnetic layer) on an extremely smooth silicon oxide layer (a surface oxidation treatment layer on a surface oxidation treatment silicon substrate, which serves as the underlying insulating layer) with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. As shown in the cross-sectional TEM image in Figure 7, the initial magnetic layer of (Co-26.12Pt)-4.44vol%ZnO in Reference Example 8 is formed directly on an extremely smooth silicon oxide layer (a surface oxidation treatment layer on a surface oxidation treatment silicon substrate, which serves as the underlying insulating layer) with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, yet the Co-26.12Pt alloy particles are clearly formed in columnar shapes. Regarding the initial magnetic layer of (Co-26.12Pt)-4.32vol%Ta2O5 in Reference Example 7, we have not yet observed its vertical cross-section with an electron microscope. However, although the coercivity Hc (2.09kOe) of Reference Example 7 is above 2.00kOe, it is smaller than the coercivity Hc (3.13kOe) of Reference Example 8. Therefore, it is thought that the initial magnetic layer of Reference Example 7 is not formed in a columnar shape with clearly separated Co-26.12Pt alloy particles to the same extent as the initial magnetic layer of Reference Example 8. Although we have not yet observed the vertical cross-sections of the initial magnetic layers in Reference Examples 1-6 using an electron microscope, the coercivity Hc of Reference Examples 1-6 ranges from 0.14kOe to 1.21kOe, indicating that a good coercivity Hc was not obtained. Therefore, in the initial magnetic layers of Reference Examples 1-6, as previously known, it is thought that CoPt alloy particles were hardly formed in a columnar shape on the amorphous silicon oxide layer (the insulating layer that serves as the underlying layer, which is the surface oxidation treatment layer of the surface oxidation treatment silicon substrate), resulting in poor magnetic separation between the CoPt alloy particles.

[0146] As mentioned above, in conventional technology, a non-magnetic underlayer (Cr, Ti, Cr alloy, Ti alloy, etc.) that promotes the in-plane orientation of the c axis of the hcp structure CoPt alloy is used as the underlayer of the Co-Pt in-plane magnetization film (paragraph 0028 of Patent Document 2 listed in the [Prior Art Documents] section). Also, as mentioned above, in other conventional technologies, a non-magnetic Ru underlayer is formed by using a high gas pressure during film formation, and a Co-Pt in-plane magnetization film is formed on top of this non-magnetic Ru underlayer, which is made thicker than about 15 nm, thereby improving the coercivity Hc of the Co-Pt in-plane magnetization film (paragraph 0016 of Patent Document 3 and Non-Patent Document 1 listed in the [Prior Art Documents] section). In conventional technology, it was impossible to directly deposit an in-plane magnetization film onto an extremely smooth silicon oxide layer (a surface oxidation treatment layer on a surface oxidation treatment silicon substrate, which serves as the underlying insulating layer) with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, thereby obtaining a good coercivity Hc.

[0147] Based on the experimental results for coercivity Hc in Reference Examples 7 and 8, the present invention has adopted a non-magnetic grain boundary oxide containing at least one of Zn oxide and Ta oxide for the in-plane magnetization film (initial magnetic layer) directly formed on a substrate of silicon oxide layer (surface oxidation treatment layer of a surface oxidation treatment silicon substrate, which is an insulating layer that serves as the underlying layer) having an extremely smooth surface roughness Ra (arithmetic mean roughness) of 0.1 nm.

[0148] In the following studies (B) to (D) and (F), the in-plane magnetized film of Reference Example 8 (an in-plane magnetized film using ZnO as a non-magnetic grain boundary oxide), which yielded the best results, was adopted as the initial magnetic layer for the investigation.

[0149] As shown in the cross-sectional TEM image in Figure 7, the initial magnetic layer of (Co-26.12Pt)-4.44vol%ZnO in Reference Example 8 has a granular structure in which the Co-26.12Pt alloy particles are clearly separated and formed in columnar shapes. The in-plane magnetized film (Co-26.12Pt)-10vol%B2O3, which is the main body of the magnetic layer used in the following studies (B) to (F), is also thought to have a similar granular structure. Therefore, the experimental data on the content of non-magnetic grain boundary material (oxide) and the composition of metal components (Co, Pt, Fe) in the CoPt-ZnO in-plane magnetized film (initial magnetic layer) can be used in the study of the numerical range of the content of non-magnetic grain boundary material (oxide) and the numerical range of the composition of metal components (Co, Pt, Fe) in the main body of the magnetic layer.

[0150] <(B) In a multilayer structure of in-plane magnetized films of CoPt-nonmagnetic oxides (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer portion: CoPt-B2O3 in-plane magnetized film), investigation of the effect of the thickness of the initial magnetic layer of the in-plane magnetized film on coercivity Hc and remanent magnetization per unit area Mrt (Examples 1-6, Comparative Example 1)> In Examples 1 to 6, an initial magnetic layer, a (Co-26.12Pt)-4.44vol%ZnO in-plane magnetized film, was formed on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, using a (Co-25Pt)-10vol%ZnO sputtering target. The thickness of the film was varied to 2 nm (Example 1), 5 nm (Example 2), 10 nm (Example 3), 15 nm (Example 4), 20 nm (Example 5), and 30 nm (Example 6) by sputtering.

[0151] Then, a 1 nm thick Ru non-magnetic initial intermediate layer was formed on the formed (Co-26.12Pt)-4.44 vol% ZnO in-plane magnetization film (initial magnetic layer) by sputtering, a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic initial intermediate layer by sputtering, a 1 nm thick Ru non-magnetic intermediate layer was formed on the formed 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film, which is the main body of the first magnetic layer, by sputtering, and a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film, which is the main body of the second magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, thereby forming an in-plane magnetization film multilayer structure.

[0152] In Comparative Example 1, without forming an initial magnetic layer, a (Co-26.12Pt)-4.44vol%ZnO in-plane magnetization film, on the surface-oxidized silicon substrate, a surface roughness Ra was formed on the surface-oxidized silicon substrate. A silicon oxide layer with an extremely smooth (arithmetic mean roughness) of 0.1 nm was used as the underlying insulating layer. On this layer, a 15 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed by sputtering. On this 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, a 1 nm thick Ru non-magnetic intermediate layer was formed by sputtering. On this 1 nm thick Ru non-magnetic intermediate layer, a 15 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the second magnetic layer, was formed by sputtering to form a multilayer in-plane magnetized film structure.

[0153] A carbon cap layer was formed on the in-plane magnetized film multilayer structures of Examples 1-6 and Comparative Example 1, which were formed as described above, by sputtering, and samples for magnetic property measurement were prepared.

[0154] In all of the above film deposition processes in Examples 1-6 and Comparative Example 1, the substrate was not heated, and the films were deposited at room temperature.

[0155] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 1-6 were measured using a vibrating magnetometer. From the measured hysteresis loops, the coercivity Hc(kOe) and remanent magnetization Mr(memu / cm) were determined. 3 ) and saturation magnetization Ms(memu / cm 3 The remanent magnetization Mr (memu / cm) was read. 3 Multiply this by the total thickness of the fabricated CoPt in-plane magnetized film to obtain the remanent magnetization Mrt (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film single-layer structure. 2 ) is calculated and the saturation magnetization Ms (memu / cm) is read. 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film gives the saturation magnetization Mst (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film multilayer structure. 2 ) was calculated.

[0156] The experimental results for Examples 1-6 and Comparative Example 1 are shown in Table 2. Furthermore, Figure 8 shows a graph of the experimental results for Examples 1-6 and Comparative Example 1, with the thickness of the initial magnetic layer of the in-plane magnetization film on the horizontal axis and the coercivity Hc(kOe) on the vertical axis.

[0157] [Table 2]

[0158] As is clear from Table 2 and Figure 8, when the initial magnetic layer using ZnO as the non-magnetic oxide grain boundary material has a thickness of 15 nm (Example 4), the coercivity Hc is largest at 3.15 kOe. On the other hand, when the initial magnetic layer using ZnO as the non-magnetic oxide grain boundary material has a thickness greater than 15 nm, the coercivity Hc decreases as the thickness increases to 20 nm (Example 5) and 30 nm (Example 6). Therefore, it is considered preferable to use the initial magnetic layer using ZnO as the non-magnetic oxide grain boundary material only in a limited range from the surface of the surface-oxidized silicon substrate (for example, within about 30 nm from the surface of the surface-oxidized silicon substrate), and to use an in-plane magnetized film (CoPt-B2O3) using B2O3 as the non-magnetic oxide grain boundary material, which has been conventionally used as an in-plane magnetized film, as the main body of the magnetic layer.

[0159] The results shown in Table 2 and Figure 8 indicate that the initial magnetic layer thickness is important for achieving good magnetic properties in an in-plane magnetized film single-layer structure (coercivity Hc of 2.00 kOe or higher, and remanent magnetization per unit area of ​​2.00 memu / cm²). 2 The above.) From the viewpoint of exhibiting the above, it is generally preferable to have a thickness of 1 nm to 32 nm, and from the viewpoint of achieving a good balance between coercivity Hc and remanent magnetization Mrt per unit area, the thickness of the initial magnetic layer is preferably 2 nm to 30 nm, and more preferably 8 nm to 20 nm.

[0160] Comparative Example 1 does not have an initial magnetic layer using ZnO as a non-magnetic oxide grain boundary material, and instead forms an in-plane magnetized film (CoPt-B2O3) using B2O3 as a non-magnetic oxide grain boundary material directly on a surface-oxidized silicon substrate, and is therefore not within the scope of the present invention. Although Comparative Example 1's coercivity Hc was 2.48 kOe, exceeding 2.00 kOe, its remanent magnetization Mrt per unit area was 1.83 memu / cm². 2 Therefore, the remanent magnetization Mrt per unit area is 2.00 memu / cm². 2 The result was less than [amount missing].

[0161] <(C) In a multilayer structure of in-plane magnetized films of non-magnetic oxides (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film), the effect of oxide (ZnO) content (volume fraction) in the initial magnetic layer of the in-plane magnetized film on coercivity Hc and remanent magnetization Mrt per unit area was investigated (Examples 4, 7-15, Comparative Examples 2, 3)> In Examples 4, 7-15, and Comparative Examples 2 and 3, a 15 nm thick initial magnetic layer containing CoPt was formed on a surface-oxidized silicon substrate, that is, on an insulating layer which was an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, by sputtering, with the ZnO content varying from 0 vol% to 30.10 vol%.

[0162] Specifically, in Comparative Example 2, a Co-26.12Pt initial magnetic layer with a thickness of 15 nm was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Comparative Example 3, a (Co-25Pt)-4vol%ZnO initial magnetic layer with a thickness of 15 nm was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 7, a (Co-25Pt)-6vol%ZnO sputtering target was used to form a (Co-25Pt)-6vol%ZnO initial magnetic layer on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra In Example 8, a 15 nm thick (Co-26.12Pt)-2.30 vol%ZnO initial magnetic layer was formed by sputtering on an extremely smooth silicon oxide layer with an arithmetic mean roughness (Ra) of 0.1 nm, which serves as the underlying insulating layer. In Example 4, a 15 nm thick (Co-26.12Pt)-3.25 vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the underlying insulating layer. An initial magnetic layer of (Co-26.12Pt)-4.44vol%ZnO was formed by sputtering in Example 9. Using a (Co-25Pt)-12vol%ZnO sputtering target, a 15nm thick layer of (Co-26.12Pt)-5.44vol%ZnO was formed on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1nm, and which serves as the underlying layer.In Example 10, an 89 vol% ZnO initial magnetic layer was formed by sputtering using a (Co-25Pt)-14 vol% ZnO sputtering target. This was done on a surface-oxidized silicon substrate, specifically on an insulating underlayer consisting of an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 11, a 15 nm thick (Co-26.12Pt)-9.53 vol% ZnO initial magnetic layer was formed by sputtering using a (Co-25Pt)-16 vol% ZnO sputtering target. This was done on a surface-oxidized silicon substrate, specifically on an insulating underlayer consisting of an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 12, In Example 13, a 15 nm thick (Co-26.12Pt)-11.72 vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 14, a 15 nm thick (Co-26.12Pt)-14.16 vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. An extremely smooth silicon oxide layer with an arithmetic mean roughness (Ra) of 0.1 nm is used as the underlying insulating layer. On this layer, a 15 nm thick (Co-26.12Pt)-21.35 vol% ZnO initial magnetic layer is formed by sputtering. In Example 15, a (Co-25Pt)-30 vol% ZnO sputtering target is used to form a 15 nm thick (Co-26.12Pt)-21.35 vol% ZnO initial magnetic layer on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which is the underlying insulating layer.An initial magnetic layer of 12Pt)-30.10vol%ZnO was formed by sputtering.

[0163] Then, a 1 nm thick Ru non-magnetic initial intermediate layer was formed on the formed initial magnetic layer by sputtering, a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic initial intermediate layer by sputtering, a 1 nm thick Ru non-magnetic intermediate layer was formed on the formed 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, and a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the second magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, thereby forming an in-plane magnetized film multilayer structure.

[0164] As described above, carbon cap layers were formed on the in-plane magnetized film multilayer structures of Examples 4, 7-15 and Comparative Examples 2 and 3 by sputtering, and samples for magnetic property measurement were prepared.

[0165] In all of the above film deposition processes in Examples 4, 7-15, and Comparative Examples 2 and 3, the substrate was not heated, and the films were deposited at room temperature.

[0166] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 4, 7-15, and Comparative Examples 2 and 3 were measured using a vibrating magnetometer. From the measured hysteresis loops, the coercivity Hc (kOe) and remanent magnetization Mr (memu / cm) were determined. 3 ) and saturation magnetization Ms(memu / cm 3 The remanent magnetization Mr (memu / cm) was read. 3 Multiply this by the total thickness of the fabricated CoPt in-plane magnetized film to obtain the remanent magnetization Mrt (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film single-layer structure. 2 ) is calculated and the saturation magnetization Ms (memu / cm) is read. 3Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film gives the saturation magnetization Mst (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film multilayer structure. 2 ) was calculated.

[0167] The experimental results for Examples 4, 7-15, and Comparative Examples 2 and 3 are shown in Table 3. Furthermore, Figure 9 shows a graph of the experimental results for Examples 4, 7-15, and Comparative Examples 2 and 3, with the ZnO content in the initial magnetic layer of the in-plane magnetized film on the horizontal axis and the coercivity Hc(kOe) on the vertical axis.

[0168] [Table 3]

[0169] As is clear from Table 3 and Figure 9, when the ZnO content in the initial magnetic layer using ZnO as a non-magnetic oxide grain boundary material was 5.89 vol% (Example 9), the coercivity Hc was highest at 3.25 kOe. When the ZnO content in the initial magnetic layer using ZnO as a non-magnetic oxide grain boundary material was greater than 5.89 vol%, the coercivity Hc decreased as the ZnO content in the initial magnetic layer increased. However, even when the ZnO content in the initial magnetic layer was as high as 30.10 vol%, the coercivity Hc remained at 2.10 kOe, maintaining a coercivity of 2.00 kOe or higher. Furthermore, while the coercivity Hc of Comparative Example 3, which has a ZnO content of 1.60 vol% in the initial magnetic layer, is 0.84 kOe, the coercivity Hc of Example 7, which has a ZnO content of 2.30 vol%, is 2.97 kOe, showing a sharp increase. This indicates that the coercivity Hc of the in-plane magnetized film multilayer structure increases sharply when the ZnO content in the initial magnetic layer changes from 1.60 vol% to 2.30 vol%.

[0170] The results shown in Table 3 and Figure 9 indicate that the ZnO content in the initial magnetic layer is important for achieving good magnetic properties in the in-plane magnetized film multilayer structure (coercivity Hc of 2.00 kOe or higher, and remanent magnetization per unit area of ​​2.00 memu / cm²). 2From the viewpoint of exhibiting the above, it is preferable to set the initial magnetic layer to 2.0 vol% to 31.0 vol% of the total volume of the initial magnetic layer, and from the viewpoint of achieving a good balance between coercivity Hc and remanent magnetization Mrt per unit area, it is preferable to set it to 3.0 vol% to 15.0 vol%, and more preferably to 4.0 vol% to 10.0 vol%.

[0171] Comparative Examples 2 and 3, which are outside the scope of the present invention because the ZnO content in the initial magnetic layer was 0 vol% and 1.60 vol%, respectively, and the ZnO content in the initial magnetic layer was less than 2.0 vol%, had low coercivity of 0.41 kOe and 0.84 kOe, respectively, and were below 2.00 kOe.

[0172] The remanent magnetization (Mrt) per unit area was 3.00 memu / cm² in all of Examples 4, 7-15, and Comparative Examples 2 and 3. 2 This was a good result, exceeding the previous average.

[0173] <(D) In ​​a multilayer structure of in-plane magnetized films of CoPt-nonmagnetic oxide (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film), the influence of the composition ratio of Co and Pt, which are metallic components in the initial magnetic layer of the in-plane magnetized film, on the coercivity Hc and remanent magnetization Mrt per unit area was investigated (Examples 4, 16-19, Comparative Examples 4, 5)> In Examples 4, 16-19, and Comparative Examples 4 and 5, a 15 nm thick initial magnetic layer (CoPt-ZnO) using ZnO as a non-magnetic oxide grain boundary material was formed on a surface-oxidized silicon substrate, that is, on an insulating layer which was an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, by sputtering, while varying the composition of Co and Pt, which are the metallic components of the initial magnetic layer. Specifically, experimental data was obtained by varying the total amount of Co and Pt in the initial magnetic layer from 83.97 at% to 31.04 at% and the amount of Pt from 16.03 at% to 68.96 at%.

[0174] In Comparative Example 4, a 15 nm thick (Co-16.03Pt)-4.44 vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 16, a 15 nm thick (Co-20.13Pt)-4.44 vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 4, a (Co-25Pt)-10 vol%ZnO sputtering target was used to form a (Co-25Pt)-4.44 vol%ZnO initial magnetic layer on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra In Example 17, a 15 nm thick (Co-26.12Pt)-4.44 vol%ZnO initial magnetic layer was formed by sputtering on an extremely smooth silicon oxide layer with an arithmetic mean roughness (Ra) of 0.1 nm, which serves as the underlying insulating layer. In Example 18, a 15 nm thick (Co-34.00Pt)-4.44 vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the underlying insulating layer. An initial magnetic layer of (Co-43.77Pt)-4.44vol%ZnO was formed by sputtering, and in Example 19, a (Co-40Pt)-10vol%ZnO sputtering target was used to form a 15nm thick layer of (Co-55.42Pt)-4.44vol%ZnO on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1nm.In Comparative Example 5, a 44-vol%ZnO initial magnetic layer was formed by sputtering using a (Co-45Pt)-10-vol%ZnO sputtering target. Specifically, a 15 nm thick (Co-68.96Pt)-4.44-vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which served as the underlying insulating layer.

[0175] Then, a 1 nm thick Ru non-magnetic initial intermediate layer was formed on the formed initial magnetic layer by sputtering, a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic initial intermediate layer by sputtering, a 1 nm thick Ru non-magnetic intermediate layer was formed on the formed 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, and a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the second magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, thereby forming an in-plane magnetized film multilayer structure.

[0176] As described above, carbon cap layers were formed on the in-plane magnetized film multilayer structures of Examples 4, 16-19 and Comparative Examples 4 and 5 by sputtering, and samples for magnetic property measurement were prepared.

[0177] In all of the above film deposition processes in Examples 4, 16-19, and Comparative Examples 4 and 5, the substrate was not heated, and the films were deposited at room temperature.

[0178] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 4, 16-19, and Comparative Examples 4 and 5 were measured using a vibrating magnetometer. From the measured hysteresis loops, the coercivity Hc (kOe) and remanent magnetization Mr (memu / cm²) were determined. 3 ) and saturation magnetization Ms(memu / cm 3 The remanent magnetization Mr (memu / cm) was read. 3Multiply this by the total thickness of the fabricated CoPt in-plane magnetized film to obtain the remanent magnetization Mrt (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film single-layer structure. 2 ) is calculated and the saturation magnetization Ms (memu / cm) is read. 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film gives the saturation magnetization Mst (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film multilayer structure. 2 ) was calculated.

[0179] The experimental results for Examples 4, 16-19, and Comparative Examples 4 and 5 are shown in Table 4. Figure 10 shows a graph with the Pt content (at%) relative to the total Co and Pt metal components of the initial magnetic layer on the x-axis and the coercivity Hc(kOe) on the y-axis.

[0180] [Table 4]

[0181] As is clear from Table 4 and Figure 10, the Co content of the initial CoPt-ZnO magnetic layer (in-plane magnetization film) relative to the total metal components (Co, Pt) is 44 at% to 82 at%, the Pt content is 18 at% to 56 at%, the volume ratio of ZnO to the total CoPt-ZnO in-plane magnetization film is 4.44 vol%, and the thickness is 15 nm. Examples 4, 16-19, which are included in the scope of the present invention, have a coercivity Hc of 2.00 kOe or more and a remanent magnetization Mrt per unit area of ​​2.00 memu / cm². 2 This magnetic performance, which is described above, is achieved through room-temperature film deposition without heating the substrate.

[0182] The results shown in Table 4 and Figure 10 indicate that the Pt content in the initial magnetic layer provides good magnetic properties for the in-plane magnetized film multilayer structure (coercivity Hc of 2.00 kOe or higher and remanent magnetization per unit area of ​​2.00 memu / cm²). 2From the viewpoint of exhibiting the above, it is preferable to have a Co content of 18 at% to 56 at% relative to the total metallic components of the initial magnetic layer, and from the viewpoint of achieving a good balance between coercivity Hc and remanent magnetization Mrt per unit area, it is preferable to have a Co content of 20 at% to 45 at% relative to the total metallic components of the initial magnetic layer, and more preferably 25 at% to 35 at%. In terms of the Co content in the initial magnetic layer, the Co content in the initial magnetic layer is preferable for the in-plane magnetized film multilayer structure to have good magnetic properties (coercivity Hc of 2.00 kOe or more and remanent magnetization per unit area of ​​2.00 memu / cm²). 2 From the viewpoint of exhibiting the above, it is preferable to have 44 at% to 82 at% of the total metal components of the initial magnetic layer, and from the viewpoint of achieving a large balance between coercivity Hc and remanent magnetization Mrt per unit area, it is preferable to have 55 at% to 80 at% of the total metal components of the initial magnetic layer, and more preferably 65 at% to 75 at%.

[0183] On the other hand, Comparative Example 4, which is not included in the scope of the present invention, has a Co content of 83.97 at% and a Pt content of 16.03 at% relative to the total metal components (Co, Pt) of the CoPt-ZnO initial magnetic layer (in-plane magnetization film), and a coercivity Hc of 1.68 kOe, which is less than 2.00 kOe. Furthermore, Comparative Example 5, which is not included in the scope of the present invention, has a Co content of 31.04 at% and a Pt content of 68.96 at% relative to the total metal components (Co, Pt) of the CoPt-ZnO initial magnetic layer (in-plane magnetization film), and a coercivity Hc of 1.55 kOe, which is less than 2.00 kOe, and a remanent magnetization Mrt per unit area of ​​1.79 memu / cm². 2 Therefore, the remanent magnetization Mrt per unit area is 2.00 memu / cm². 2 It is less than.

[0184] <(E) In a multilayer structure of in-plane magnetized films of CoPt-nonmagnetic oxide (initial magnetic layer: CoPt in-plane magnetized film, magnetic layer body: CoPt-B2O3 in-plane magnetized film), the effect of using Ta2O5 as the nonmagnetic grain boundary material in the initial magnetic layer of the in-plane magnetized film on coercivity Hc and remanent magnetization Mrt per unit area was investigated (Examples 4 and 20)> In Example 20, an initial magnetic layer with Ta2O5 as the non-magnetic grain boundary material was formed by sputtering, and a sample for magnetic property measurement was prepared and experimental data was obtained.

[0185] Specifically, a 15 nm thick (Co-26.12Pt)-4.32 vol%Ta2O5 initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm.

[0186] Then, a 1 nm thick Ru non-magnetic initial intermediate layer was formed on the formed initial magnetic layer by sputtering, a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic initial intermediate layer by sputtering, a 1 nm thick Ru non-magnetic intermediate layer was formed on the formed 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, and a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the second magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, thereby forming an in-plane magnetized film multilayer structure.

[0187] A carbon cap layer was formed on the in-plane magnetized film multilayer structure of Example 20, which was formed as described above, by sputtering, and a sample for magnetic property measurement was prepared.

[0188] In each of the film deposition processes in Example 20, the substrate was not heated, and the films were deposited at room temperature.

[0189] The hysteresis loop of the in-plane magnetized film multilayer structure of Example 20 was measured using a vibrating magnetometer. From the measured hysteresis loop, the coercivity Hc(kOe) and remanent magnetization Mr(memu / cm) were determined. 3 ) and saturation magnetization Ms(memu / cm 3 The remanent magnetization Mr (memu / cm) was read. 3 Multiply this by the total thickness of the fabricated CoPt in-plane magnetized film to obtain the remanent magnetization Mrt (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film single-layer structure. 2 ) is calculated and the saturation magnetization Ms (memu / cm) is read. 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film gives the saturation magnetization Mst (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film multilayer structure. 2 ) was calculated.

[0190] The experimental results for Example 20, along with the experimental results for Example 4, are shown in Table 5.

[0191] [Table 5]

[0192] As is clear from Table 5, even in Example 20, where the non-magnetic grain boundary material of the initial magnetic layer is Ta2O5, the coercivity Hc is 3.01 kOe and the remanent magnetization Mrt per unit area is 3.16 memu / cm². 2 Good magnetic properties were obtained. However, in Example 4, where the non-magnetic grain boundary material of the initial magnetic layer is ZnO, both the coercivity Hc and the remanent magnetization Mrt per unit area are slightly better than in Example 20, where the non-magnetic grain boundary material of the initial magnetic layer is Ta2O5.

[0193] <(F) In a multilayer structure of in-plane magnetized films of non-magnetic oxides (initial magnetic layer: CoPt-ZnO in-plane magnetized film, magnetic layer body: CoPt-B2O3 in-plane magnetized film), the effect of adding Fe as a metallic component in the initial magnetic layer of the in-plane magnetized film on the coercivity Hc and remanent magnetization Mrt per unit area was investigated (Examples 4 and 21)> In Example 21, an initial CoPtFe-ZnO magnetic layer was formed by sputtering, and a sample for magnetic property measurement was prepared to obtain experimental data.

[0194] Specifically, a 15 nm thick (Co-26.11Pt-0.78Fe)-4.44 vol%ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, that is, on an insulating layer which is an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm.

[0195] Then, a 1 nm thick Ru non-magnetic initial intermediate layer was formed on the formed initial magnetic layer by sputtering, a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic initial intermediate layer by sputtering, a 1 nm thick Ru non-magnetic intermediate layer was formed on the formed 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the first magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, and a 1 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which is the main body of the second magnetic layer, was formed on the formed 1 nm thick Ru non-magnetic intermediate layer by sputtering, thereby forming an in-plane magnetized film multilayer structure.

[0196] A carbon cap layer was formed on the in-plane magnetized film multilayer structure of Example 21, which was formed as described above, by sputtering, and a sample for magnetic property measurement was prepared.

[0197] In each of the film deposition processes in Example 21, the substrate was not heated, and the film deposition was carried out at room temperature.

[0198] The hysteresis loop of the in-plane magnetized film multilayer structure of Example 21 was measured using a vibrating magnetometer. From the measured hysteresis loop, the coercivity Hc(kOe) and remanent magnetization Mr(memu / cm) were determined. 3 ) and saturation magnetization Ms(memu / cm 3 The remanent magnetization Mr (memu / cm) was read. 3 Multiply this by the total thickness of the fabricated CoPt in-plane magnetized film to obtain the remanent magnetization Mrt (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film single-layer structure. 2 ) is calculated and the saturation magnetization Ms (memu / cm) is read. 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film gives the saturation magnetization Mst (memu / cm²) per unit area of ​​the fabricated in-plane magnetized film multilayer structure. 2 ) was calculated.

[0199] The experimental results for Example 21, along with the experimental results for Examples 4 and 20, are shown in Table 6.

[0200] [Table 6]

[0201] As is clear from Table 6, even in Example 21, where the metallic components of the initial magnetic layer of the in-plane magnetization film are Co, Pt, and Fe, the coercivity Hc is 2.98 kOe and 2.00 kOe or higher, and the remanent magnetization Mrt per unit area is 3.31 memu / cm². 2 and 2.00 memu / cm 2 The above results demonstrate that good magnetic properties were obtained. [Industrial applicability]

[0202] The in-plane magnetized film and in-plane magnetized film multilayer structure according to the present invention have a coercivity Hc of 2.00 kOe or more and a remanent magnetization Mrt per unit area of ​​2.00 memu / cm². 2The magnetic performance described above can be achieved without heat deposition, making it industrially applicable. Furthermore, the hard bias layer according to the present invention comprises an in-plane magnetized film or an in-plane magnetized film multilayer structure according to the present invention, has good magnetic performance, and is industrially applicable. Furthermore, the magnetoresistive element according to the present invention comprises a hard bias layer according to the present invention having good magnetic performance, and is industrially applicable. Moreover, by using the sputtering target according to the present invention, an initial magnetic layer of the in-plane magnetized film according to the present invention with good magnetic performance can be formed by deposition at room temperature, making it industrially applicable. [Explanation of Symbols]

[0203] 10, 20, 30, 40, 200... Magnetoresistive elements 12, 204...In-plane magnetization film 12A, 22A, 32A, 42A...Initial magnetic layer 12B, 22B...Magnetic layer main body part 14, 24, 34, 44, 206… Hard bias layer 22, 32, 42...In-plane magnetized film multilayer structure 22C, 42D…Nonmagnetic initial intermediate layer 32B, 42B...first magnetic layer main body part 32C, 42C...Second magnetic layer main body part 32D, 42E...Nonmagnetic intermediate layer 50…Magnetic shielding layer 52… Seed layer 54...antiferromagnetic layer 56... Pin layer 58… Barrier layer 60...Free magnetic layer 62...Cap layer 70…Insulating layer 202...Ru base layer

Claims

1. An in-plane magnetization film used as a hard bias layer for a magnetoresistive element, An initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm. A magnetic layer body is formed on the initial magnetic layer and contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co being 44 at% to 82 at% and metallic Pt being 18 at% to 56 at% based on the total volume, and the non-magnetic oxide being 2.0 vol% to 31.0 vol% based on the total volume. It has, The in-plane magnetized film is characterized in that the non-magnetic grain boundary material of the initial magnetic layer contains Zn oxide.

2. An in-plane magnetization film used as a hard bias layer for a magnetoresistive element, An initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm. A magnetic layer body is formed on the initial magnetic layer and contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co being 44 at% to 82 at% and metallic Pt being 18 at% to 56 at% based on the total volume, and the non-magnetic oxide being 2.0 vol% to 31.0 vol% based on the total volume. It has, The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer further contains metal Fe, and is characterized by containing 44 at% to 82 at% of the total amount of metal Co and metal Fe relative to the total amount of metal components, and containing 18 at% to 56 at% of metal Pt.

3. An in-plane magnetization film used as a hard bias layer for a magnetoresistive element, An initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm. A magnetic layer body is formed on the initial magnetic layer and contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co being 44 at% to 82 at% and metallic Pt being 18 at% to 56 at% based on the total volume, and the non-magnetic oxide being 2.0 vol% to 31.0 vol% based on the total volume. It has, The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The in-plane magnetization film is characterized in that the initial magnetic layer is formed directly on top of the insulating layer.

4. The in-plane magnetized film according to any one of claims 1 to 3, characterized in that the non-magnetic oxide in the magnetic layer body contains boron oxide.

5. The in-plane magnetized film according to any one of claims 1 to 3, characterized in that the initial magnetic layer is formed on a substrate having a surface roughness of 0.1 nm or more and 1.5 nm or less.

6. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, An initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm. A non-magnetic initial intermediate layer formed on the initial magnetic layer, A magnetic layer body is formed on the aforementioned non-magnetic initial intermediate layer and contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co being 44 at% to 82 at% and metallic Pt being 18 at% to 56 at% of the total metal components, and the non-magnetic oxide being 2.0 vol% to 31.0 vol% of the total volume. It has, The in-plane magnetized film multilayer structure is characterized in that the non-magnetic grain boundary material of the initial magnetic layer contains Zn oxide.

7. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, Initial magnetic layer, Multiple magnetic layer body parts, Non-magnetic intermediate layer, It has, The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material, with metallic Co present in an amount of 44 at% to 82 at% and metallic Pt present in an amount of 18 at% to 56 at% relative to the total metallic components, and the non-magnetic grain boundary material present in an amount of 2.0 vol% to 31.0 vol% relative to the total volume, and a thickness of 1 nm to 32 nm. Each of the aforementioned plurality of magnetic layer bodies contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co present in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt present in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic oxide present in an amount of 2.0 vol% to 31.0 vol% of the total volume. The lowest magnetic layer body of the plurality of magnetic layer body parts is formed on the initial magnetic layer, The non-magnetic intermediate layer is disposed between the main magnetic layer portions, and the adjacent main magnetic layer portions separated by the non-magnetic intermediate layer are ferromagnetically coupled. The in-plane magnetized film multilayer structure is characterized in that the non-magnetic grain boundary material of the initial magnetic layer contains Zn oxide.

8. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, Initial magnetic layer, A non-magnetic initial intermediate layer formed on the initial magnetic layer, Multiple magnetic layer body parts, Non-magnetic intermediate layer, It has, The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material, with metallic Co present in an amount of 44 at% to 82 at% and metallic Pt present in an amount of 18 at% to 56 at% relative to the total metallic components, and the non-magnetic grain boundary material present in an amount of 2.0 vol% to 31.0 vol% relative to the total volume, and a thickness of 1 nm to 32 nm. Each of the aforementioned plurality of magnetic layer bodies contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co present in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt present in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic oxide present in an amount of 2.0 vol% to 31.0 vol% of the total volume. The lowest magnetic layer body of the plurality of magnetic layer body parts is formed on the non-magnetic initial intermediate layer, The non-magnetic intermediate layer is disposed between the main magnetic layer portions, and the adjacent main magnetic layer portions separated by the non-magnetic intermediate layer are ferromagnetically coupled. The in-plane magnetized film multilayer structure is characterized in that the non-magnetic grain boundary material of the initial magnetic layer contains Zn oxide.

9. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, An initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm. A non-magnetic initial intermediate layer formed on the initial magnetic layer, A magnetic layer body is formed on the aforementioned non-magnetic initial intermediate layer and contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co being 44 at% to 82 at% and metallic Pt being 18 at% to 56 at% of the total metal components, and the non-magnetic oxide being 2.0 vol% to 31.0 vol% of the total volume. It has, The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer further contains metallic Fe, and is characterized by containing 44 at% to 82 at% of the total amount of metallic Co and metallic Fe relative to the total amount of metallic components, and containing 18 at% to 56 at% of metallic Pt.

10. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, Initial magnetic layer, Multiple magnetic layer body parts, Non-magnetic intermediate layer, It has, The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material, with metallic Co present in an amount of 44 at% to 82 at% and metallic Pt present in an amount of 18 at% to 56 at% relative to the total metallic components, and the non-magnetic grain boundary material present in an amount of 2.0 vol% to 31.0 vol% relative to the total volume, and a thickness of 1 nm to 32 nm. Each of the aforementioned plurality of magnetic layer bodies contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co present in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt present in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic oxide present in an amount of 2.0 vol% to 31.0 vol% of the total volume. The lowest magnetic layer body of the plurality of magnetic layer body parts is formed on the initial magnetic layer, The non-magnetic intermediate layer is disposed between the main magnetic layer portions, and the adjacent main magnetic layer portions separated by the non-magnetic intermediate layer are ferromagnetically coupled. The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer further contains metallic Fe, and is characterized by containing 44 at% to 82 at% of the total amount of metallic Co and metallic Fe relative to the total amount of metallic components, and containing 18 at% to 56 at% of metallic Pt.

11. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, Initial magnetic layer, A non-magnetic initial intermediate layer formed on the initial magnetic layer, Multiple magnetic layer body parts, Non-magnetic intermediate layer, It has, The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material, with metallic Co present in an amount of 44 at% to 82 at% and metallic Pt present in an amount of 18 at% to 56 at% relative to the total metallic components, and the non-magnetic grain boundary material present in an amount of 2.0 vol% to 31.0 vol% relative to the total volume, and a thickness of 1 nm to 32 nm. Each of the aforementioned plurality of magnetic layer bodies contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co present in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt present in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic oxide present in an amount of 2.0 vol% to 31.0 vol% of the total volume. The lowest magnetic layer body of the plurality of magnetic layer body parts is formed on the non-magnetic initial intermediate layer, The non-magnetic intermediate layer is disposed between the main magnetic layer portions, and the adjacent main magnetic layer portions separated by the non-magnetic intermediate layer are ferromagnetically coupled. The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer further contains metallic Fe, and is characterized by containing 44 at% to 82 at% of the total amount of metallic Co and metallic Fe relative to the total amount of metallic components, and containing 18 at% to 56 at% of metallic Pt.

12. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, An initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material, wherein the initial magnetic layer contains metallic Co in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic grain boundary material in an amount of 2.0 vol% to 31.0 vol% of the total volume, and has a thickness of 1 nm to 32 nm. A non-magnetic initial intermediate layer formed on the initial magnetic layer, A magnetic layer body is formed on the aforementioned non-magnetic initial intermediate layer and contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co being 44 at% to 82 at% and metallic Pt being 18 at% to 56 at% of the total metal components, and the non-magnetic oxide being 2.0 vol% to 31.0 vol% of the total volume. It has, The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The in-plane magnetized film multilayer structure is characterized by the initial magnetic layer being formed directly on top of the insulating layer.

13. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, Initial magnetic layer, Multiple magnetic layer body parts, Non-magnetic intermediate layer, It has, The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material, with metallic Co present in an amount of 44 at% to 82 at% and metallic Pt present in an amount of 18 at% to 56 at% relative to the total metallic components, and the non-magnetic grain boundary material present in an amount of 2.0 vol% to 31.0 vol% relative to the total volume, and a thickness of 1 nm to 32 nm. Each of the aforementioned plurality of magnetic layer bodies contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co present in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt present in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic oxide present in an amount of 2.0 vol% to 31.0 vol% of the total volume. The lowest magnetic layer body of the plurality of magnetic layer body parts is formed on the initial magnetic layer, The non-magnetic intermediate layer is disposed between the main magnetic layer portions, and the adjacent main magnetic layer portions separated by the non-magnetic intermediate layer are ferromagnetically coupled. The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The in-plane magnetized film multilayer structure is characterized in that the initial magnetic layer is formed directly on top of the insulating layer.

14. A multilayer in-plane magnetized film structure used as a hard bias layer for a magnetoresistive element, Initial magnetic layer, A non-magnetic initial intermediate layer formed on the initial magnetic layer, Multiple magnetic layer body parts, Non-magnetic intermediate layer, It has, The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material, with metallic Co present in an amount of 44 at% to 82 at% and metallic Pt present in an amount of 18 at% to 56 at% relative to the total metallic components, and the non-magnetic grain boundary material present in an amount of 2.0 vol% to 31.0 vol% relative to the total volume, and a thickness of 1 nm to 32 nm. Each of the aforementioned plurality of magnetic layer bodies contains metallic Co, metallic Pt, and a non-magnetic oxide, with metallic Co present in an amount of 44 at% to 82 at% of the total metallic components, metallic Pt present in an amount of 18 at% to 56 at% of the total metallic components, and the non-magnetic oxide present in an amount of 2.0 vol% to 31.0 vol% of the total volume. The lowest magnetic layer body of the plurality of magnetic layer body parts is formed on the non-magnetic initial intermediate layer, The non-magnetic intermediate layer is disposed between the main magnetic layer portions, and the adjacent main magnetic layer portions separated by the non-magnetic intermediate layer are ferromagnetically coupled. The non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The in-plane magnetized film multilayer structure is characterized in that the initial magnetic layer is formed directly on top of the insulating layer.

15. The in-plane magnetized film multilayer structure according to any one of 6, 8, 9, 11, 12, or 14, characterized in that the non-magnetic initial intermediate layer is made of Ru or a Ru alloy.

16. The in-plane magnetized film multilayer structure according to any one of 6, 8, 9, 11, 12, or 14, characterized in that the thickness of the non-magnetic initial intermediate layer is 0.3 nm or more and 2 nm or less.

17. The in-plane magnetized film multilayer structure according to any one of 7, 8, 10, 11, 13, or 14, characterized in that the non-magnetic intermediate layer is made of Ru or a Ru alloy.

18. The in-plane magnetized film multilayer structure according to any one of 7, 8, 10, 11, 13, or 14, characterized in that the thickness of the non-magnetic intermediate layer is 0.3 nm or more and 2 nm or less.

19. The in-plane magnetized film multilayer structure according to any one of 6 to 14, characterized in that the non-magnetic oxide in the magnetic layer body contains boron oxide.

20. The in-plane magnetized film multilayer structure according to any one of 6 to 14, characterized in that the initial magnetic layer is formed on a substrate having a surface roughness of 0.1 nm or more and 1.5 nm or less.

21. A hard bias layer characterized by having an in-plane magnetization film as described in claim 5.

22. A hard bias layer characterized by having the in-plane magnetized film multilayer structure described in claim 20.

23. A magnetoresistive element characterized by having the hard bias layer described in claim 21.

24. A magnetoresistive element characterized by having the hard bias layer described in claim 22.

25. A sputtering target used when forming an in-plane magnetization film, which is used as at least a part of the hard bias layer of a magnetoresistive element, by room temperature deposition, It contains metallic Co, metallic Pt, and a non-magnetic grain boundary material. The sputtering target contains 60 at% to 82 at% of metallic Co and 18 at% to 40 at% of metallic Pt, based on the total amount of metallic components. The sputtering target contains 6 vol% to 30 vol% of the nonmagnetic grain boundary material in its entirety. The sputtering target is characterized in that the non-magnetic grain boundary material contains Zn oxide.

26. A single sputtering target, A sputtering target that can be used when forming the initial magnetic layer of the in-plane magnetization film described in claim 2.

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