Sputtering target for magnetic recording medium

Abstract

To provide a sputtering target capable of depositing a granular thin film with an excellent magnetic separability, the granular film being a magnetic film composed of a CoPt-based alloy.SOLUTION: The present invention relates to a sputtering target for a magnetic recording medium including Co and Pt as a metal component and including at least one kind of oxide. In the present invention, the sputtering target contains a tungsten oxide and / or a molybdenum oxide as a mandatory oxide for improving a magnetic separability, and a content of the mandatory oxide is 15 vol.% or less. As an oxide in the sputtering target, another oxide such as B2O3 may be contained as an optional oxide. In this case, a total oxide content is preferably 20 vol.% or more and 50 vol.% or less. In the present invention, the toral oxide content can be suitably set while maintaining the magnetic separability by applying the mandatory oxide.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sputtering target for forming a thin film made of a CoPt-based alloy for use in a magnetic recording medium, and more particularly to a sputtering target for forming a thin film made of a CoPt-based alloy having a granular structure and exhibiting good magnetic separation between magnetic particles. [Background technology]

[0002] The recording density of magnetic recording media such as hard disk drives (HDDs) has been increasing rapidly, and the demand and trend for higher recording density is expected to continue in the future. In order to achieve higher recording density of magnetic recording media, a perpendicular magnetic recording method has been proposed. Furthermore, in order to improve the recording density under the optimization of such a recording method, it is considered preferable to reduce the interaction between particles while miniaturizing the magnetic particles of the magnetic thin film that constitutes the magnetic recording layer.

[0003] As a magnetic thin film that reduces the interparticle interaction of magnetic particles, a magnetic thin film having a structure called a granular structure has attracted attention (hereinafter, a magnetic thin film having a granular structure is referred to as a granular thin film). A granular thin film has a structure in which magnetic particles are dispersed in a matrix of a nonmagnetic material such as an oxide, and the interparticle interaction is reduced by the nonmagnetic grain boundaries of the oxide or the like. In a granular thin film, a plurality of magnetic particles constitute a recording bit. As oxides that constitute the nonmagnetic grain boundaries of a magnetic recording layer to which such a granular thin film is applied, SiO2, TiO2, B2O3, etc. are known (Patent Documents 1 and 2).

[0004] Usually, the magnetic thin film of a magnetic recording medium is often manufactured by a sputtering method. A granular thin film can also be manufactured by a sputtering method, and a sputtering target containing an oxide together with an alloy or metal such as Co or Pt constituting a magnetic material is applied (for example, Patent Documents 3 and 4). In addition, in the formation of a granular thin film, an underlayer made of Ru or a Ru-containing alloy, which has an effect of promoting the epitaxial growth of magnetic particles, is applied. Then, by sputtering the surface of the underlayer with a sputtering target containing the above-mentioned oxide, a two-phase precipitation of magnetic particles and an oxide (non-magnetic grain boundary) occurs, and a granular thin film is formed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-83411 A [Patent Document 2] JP 2001-43526 A [Patent Document 3] Patent No. 5032706 [Patent Document 4] Patent No. 6317636 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned at the beginning, miniaturization of magnetic particles is effective for increasing the recording density of magnetic recording media. The magnetic particles in the granular thin film can be miniaturized by increasing the oxide content in the sputtering target. Increasing the oxide content increases the thickness of the non-magnetic grain boundaries, making the boundaries clearer, and forming a granular thin film in which the magnetic particles are dispersed and separated.

[0007] However, an increase in recording density is achieved by miniaturizing the magnetic particles and improving the separation between recording bits composed of the magnetic particles. Here, separation means magnetic separation. By increasing the oxide content, the magnetic particles become finer and the non-magnetic grain boundaries become thicker, but this does not immediately lead to an improvement in the magnetic separation of the granular thin film. Considering that a recording bit is composed of multiple magnetic particles, it is necessary to consider not only the amount of oxide (non-magnetic grain boundaries) but also the effect of its composition in order to ensure magnetic separation throughout the thin film.

[0008] In addition, by increasing the amount of oxide in the granular thin film, the magnetic grains can be made finer, but the increase in the amount of oxide inevitably leads to a decrease in the volume ratio of the magnetic grains. The decrease in the volume ratio of the magnetic grains reduces the magnetization amount of the entire granular thin film, which can be a factor in the decrease in signal strength when reproducing from a recording medium. Although the oxide in the granular thin film can be said to be an essential component, its content cannot be unlimited.

[0009] The present invention has been made under the above background, and relates to a sputtering target for magnetic recording media for producing a magnetic thin film made of a CoPt-based alloy, which is one of the magnetic thin films most commonly used in magnetic recording media. The present invention also provides a sputtering target capable of depositing a granular thin film with good magnetic isolation. In order to achieve this goal, the inventors have set out to find a means for optimizing the oxide content while maintaining magnetic properties including magnetic isolation. [Means for solving the problem]

[0010] According to the studies conducted by the present inventors, the magnetic properties of a granular thin film change depending on the type of oxide that constitutes the non-magnetic grain boundaries. Since the magnetic properties include magnetic separation, it can be said that the magnetic separation differs depending on the type of oxide even if the oxide content is the same. In addition, various magnetic properties in a magnetic thin film may be in a contradictory relationship, and improving one property may result in a decrease in the other property.

[0011] The most basic evaluation method for magnetic recording media is the MH hysteresis loop. The saturation magnetization (M s ), perpendicular coercivity (H c ) can be grasped. The magnetic separation of granular thin films can also be determined from the MH hysteresis loop, and can be determined by the α value, which indicates the slope (4π × (dM / dH)) of the magnetization curve near the coercive force (near M = 0). The α value increases as the magnetic separation between recording bits decreases, and the closer the α value is to 1, the better the magnetic separation.

[0012] In order to solve the above problems, the present inventors have attempted to improve the magnetic isolation of granular thin films and to increase the saturation magnetization (M s As a result, it was found that oxides of W (tungsten) and Mo (molybdenum) can form magnetic thin films with low α values ​​and good magnetic separation properties even when the oxides contain relatively small amounts of W and Mo, and this led to the present invention.

[0013] That is, the present invention provides a sputtering target for a magnetic recording medium, which contains Co and Pt as metal components and at least one type of oxide, and is characterized in that it contains tungsten oxide and / or molybdenum oxide as essential oxides, and the content of the essential oxides is 15 vol% or less.

[0014] The configuration and manufacturing method of the sputtering target for a magnetic recording medium according to the present invention will be described below.

[0015] A. Configuration of a sputtering target for a magnetic recording medium according to the present invention (i) Metal component As described above, the sputtering target for magnetic recording media according to the present invention contains Co and Pt as essential metal components. Co is a ferromagnetic metal, and is the main component of CoPt-based alloy particles that become magnetic particles of the granular thin film that constitutes the magnetic recording layer. Pt is a paramagnetic metal, but has a large spin-orbit interaction, and improves magnetic anisotropy by alloying with Co, which is a ferromagnetic material. Pt is also a metal that is an essential component of CoPt-based alloy particles that become magnetic particles.

[0016] The preferred composition of the CoPt-based alloy particles constituting the magnetic recording layer is u For the reason of optimizing the above, the Co content is 60 atomic % or more and 95 atomic % or less. Therefore, in the sputtering target for magnetic recording media according to the present invention, the Co content with respect to the entire metal components is preferably 60 atomic % or more and 95 atomic % or less. The metal components refer to Co and Pt, and in the case where other metal components are included as described below, the other metals. Metal components of oxides are not included. The Co content with respect to the entire metal components is more preferably 70 atomic % or more and 90 atomic % or less.

[0017] The magnetic grains constituting the magnetic recording layer are CoPt-based alloys, with Co and Pt as essential metals, but may contain other metals. Examples of other metals include Cr, Ru, and B. These metal elements have a saturation magnetization M s These metals can be added because they have the effect of adjusting the amount of Pt and improving the magnetic separation of the magnetic particles. The CoPt-based alloy, which is the magnetic particles of the magnetic recording layer, can contain 20 atomic % or less of these metals. Therefore, the sputtering target according to the present invention can contain 20 atomic % or less of other metals with respect to the entire metal component. The content of Pt in the metal component is the remainder of the content of Co and the other metals.

[0018] In the sputtering target for magnetic recording media according to the present invention, the metal components may be metallic Co and metallic Pt in a single metal state, or may be in the form of an alloy (CoPt-based alloy). The same applies to other metal components such as Cr.

[0019] (ii) Oxides (mandatory and optional) The sputtering target for magnetic recording media according to the present invention contains at least one oxide to form non-magnetic grain boundaries in the granular thin film. In the present invention, tungsten oxide and / or molybdenum oxide are contained as essential oxides. The granular thin film formed by the sputtering target containing tungsten oxide and / or molybdenum oxide has a low α value and good magnetic separation even with a relatively small oxide content. In this case, the saturation magnetization M s The reason why the magnetic separation property (α value) of the granular thin film containing tungsten oxide and molybdenum oxide is good is unclear, and is based on the results of screening by the present inventors, which will be described later.

[0020] In a magnetic thin film made of a CoPt-based alloy, the essential oxides tungsten oxide and molybdenum oxide can significantly reduce the α value even when added in very small amounts (more than 0 vol%). As the content of the essential oxides increases, the α value decreases and approaches 1. However, when the content of the essential oxides exceeds 15 vol%, the effect of reducing the α value decreases. For this reason, in the present invention, the content of the essential oxides is set to 15 vol% or less with respect to the total volume of the target. The upper limit of the content of the essential oxides may be 13 vol% or less, 10 vol% or less, or 8 vol% or less. The lower limit of the content of the essential oxides is preferably 0.5 vol% or more, more preferably 1.0 vol% or more, and even more preferably 2.0 vol% or more.

[0021] The sputtering target of the present invention may contain either one of tungsten oxide and molybdenum oxide, which are essential oxides. It may also contain both tungsten oxide and molybdenum oxide. When both tungsten oxide and molybdenum oxide are contained, the total content thereof may be 15 vol% or less.

[0022] In the present invention, the tungsten oxide contained in the sputtering target is WO3 and / or WO2, and the molybdenum oxide is MoO3 and / or MoO2. For example, even if a sputtering target is produced using WO3 as a raw material, a part of it may be reduced to WO2, and in such a case, WO3 and WO2 may be contained in the sputtering target. The tungsten oxide and molybdenum oxide contained in the present invention also include cases in which oxides of tungsten and molybdenum with different valences are mixed.

[0023] The sputtering target for magnetic recording media according to the present invention essentially contains tungsten oxide and / or molybdenum oxide, and may contain other oxides different from these as optional oxides. Specific examples of the optional oxides include B2O3, SiO2, TiO2, Cr2O3, CoO, and Co3O4. These optional oxides form non-magnetic grain boundaries by combining with the essential oxides.

[0024] Among the above optional oxides, the oxide that is preferably added together with the essential oxide is B2O3. A granular thin film containing B2O3 in the nonmagnetic grain boundaries has a uniaxial anisotropy constant K u This tends to lead to an increase in the uniaxial anisotropy constant K u is related to the resistance of a magnetic thin film to thermal fluctuations (thermal stability). Such thermal stability depends on the uniaxial anisotropy constant K u and activation volume V a (or the volume V of the magnetization reversal unit). u Since an increase in increases the value of the above product, the addition of B2O3 to the granular thin film leads to an improvement in thermal fluctuation resistance.

[0025] As for the optional oxides other than B2O3, SiO2 has the effect of amorphizing non-magnetic grain boundaries. TiO2 has the effect of preventing segregation to magnetic grains due to oxygen deficiency, since Ti has a large valence. Cr2O3, CoO, and Co3O4 have the effect of compensating for oxygen deficiency at grain boundaries. Which of these optional oxides the sputtering target according to the present invention contains can be appropriately selected according to the properties required for the magnetic thin film to be formed.

[0026] The sputtering target for magnetic recording media according to the present invention is made up of essential oxides (tungsten oxide and / or molybdenum oxide) and optional oxides (B2O3, SiO2, TiO2, Cr2O 3、 When the magnetic material contains oxides such as CoO, Co3O4, etc., the total content of the essential oxides and the optional oxides (total oxide content) is preferably 20 vol% or more and 50 vol% or less. This is to form a granular structure that ensures magnetic separation and to ensure signal strength when reproducing the recording medium. In addition, when the magnetic material contains optional oxides, the content of the essential oxides is preferably 15 vol% or less.

[0027] In addition, the effect of reducing the α value of the essential oxides is not hindered by the optional oxides. In the present invention, when the optional oxides are included, the content of the essential oxides can be 10 vol% or less, and can also be 8 vol% or less, or 5 vol% or less, within the above-mentioned range of the total oxide content. This shows that the essential oxides, tungsten oxide and / or molybdenum oxide, are useful for the purpose of reducing the total oxide content and ensuring the proportion of magnetic components. In this case, the lower limit of the content of the essential oxides is preferably 0.5 vol% or more, more preferably 1.0 vol% or more, and even more preferably 2.0 vol% or more.

[0028] B. Method for producing a sputtering target for a magnetic recording medium according to the present invention The sputtering target according to the present invention is composed of a metal phase (CoPt-based alloy phase, or metallic Co phase and metallic Pt phase) made of the above-mentioned metal components, and an oxide phase (essential oxide phase and optional oxide phase). As a method for producing such a sputtering target, it is preferable to apply a powder metallurgy method in order to uniformly disperse the oxide phase in the metal phase. In the powder metallurgy method, a metal powder and an oxide powder that will become the metal phase are mixed, appropriately molded, and then pressure sintered to produce a sputtering target.

[0029] The metal powder may be an alloy powder made of a CoPt-based alloy, or a metal Co powder and a metal Pt powder. The alloy powder may be produced by an atomization method such as gas atomization from a molten CoPt-based alloy having the above-mentioned composition. When using metal Co powder and metal Pt powder, commercially available powders of each metal may be used, and it is preferable to use high-purity products. Then, in the mixing step described below, the metal Co powder and metal Pt powder are mixed to obtain the above-mentioned composition. In the production of the sputtering target according to the present invention, the particle size of the metal powder is preferably 100 μm or less.

[0030] The above metal powder and oxide powder are thoroughly mixed before sintering to obtain a mixed powder. For the mixing, a mixing and dispersing means such as a ball mill, a bead mill, a rocking mill, etc. may be used. The mixed powder obtained by these mixing means may be preformed before the next step of pressure sintering.

[0031] The mixed powder is then appropriately molded and then pressure-sintered to obtain the sputtering target according to the present invention. The sintering method may be hot pressing (HP), hot isostatic sintering (HIP), spark plasma sintering (SPS), or the like. The sintering temperature during pressure sintering is preferably 600°C or higher and 1500°C or lower, and the pressure is preferably 10 MPa or higher and 200 MPa or lower. The heating atmosphere is preferably a vacuum or a non-oxidizing atmosphere. Effect of the Invention

[0032] As described above, the sputtering target according to the present invention can form a magnetic thin film having a granular structure with excellent magnetic separation while maintaining saturation magnetization. In the present invention, tungsten oxide and / or molybdenum oxide are used as essential oxides that form the non-magnetic grain boundaries of the granular thin film, from the viewpoint of magnetic separation. Furthermore, the sputtering target according to the present invention is allowed to contain optional oxides such as B2O3 other than the essential oxides. This allows the uniaxial anisotropy constant K u It is possible to set a suitable oxide content while balancing the improvement of magnetic properties such as the above with magnetic separation. Optimizing the oxide content leads to optimizing the ratio of the magnetic component in the magnetic thin film and ensuring the amount of magnetization. [Brief description of the drawings]

[0033] [Figure 1] 4 is a graph showing the measurement results of the α value and Ms depending on the oxide content of a magnetic film made of a sputtering target (75 atomic % Co-25 atomic % Pt+oxide) manufactured in the first embodiment. [Diagram 2] 13 is a graph showing the measurement results of the α value and Ms depending on the oxide content of a magnetic film using a sputtering target (80 atomic % Co-20 atomic % Pt / 20 vol % B 2 O 3 +Oxide) manufactured in the second embodiment. [Diagram 3] 13 is a graph showing the measurement results of the α value and Ms depending on the oxide content of a magnetic film using a sputtering target (80 atomic % Co-20 atomic % Pt / 30 vol % B 2 O 3 +Oxide) manufactured in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] First embodimentThe following describes an embodiment of the present invention. In this embodiment, sputtering targets were manufactured by adding various oxides (WO3, MoO3, B2O3, SiO2, TiO2, Cr2O3) to a CoPt alloy (75 atomic % Co-25 atomic % Pt). Then, magnetic thin films were formed using these sputtering targets, and the MH hysteresis loops were measured to determine the saturation magnetization M s and the magnetic separation ability α value were evaluated.

[0035] In the manufacture of the sputtering target, first, metallic Co and metallic Pt were weighed and melted at 1500°C or higher to prepare a molten alloy of CoPt alloy (75 atomic % Co-25 atomic % Pt). Then, alloy powder was produced from this molten alloy by gas atomization. After that, classification was performed to obtain CoPt alloy powder (75 atomic % Co-25 atomic % Pt alloy powder) with an average particle size of 100 μm or less.

[0036] The CoPt alloy powder obtained above was mixed with various oxide powders (WO3, MoO3, B2O3, SiO2, TiO2, Cr2O3). The CoPt alloy powder and the oxide powder were mixed in a ball mill (grinding medium: ceramic balls).

[0037] The mixed powder obtained above was pressure-sintered to prepare a sputtering target. The pressure-sintering was carried out by hot pressing at a sintering temperature of 920° C., a pressure of 24.5 MPa, and a pressure-sintering time of 30 min in an atmosphere of 5×10 -2 The vacuum conditions were set to be equal to or less than Pa. The manufactured sputtering target had a diameter of 180 mm and a thickness of 5 mm, and had a relative density in the range of 95% to 100%.

[0038] In this embodiment, a sputtering target containing WO3, MoO3, B2O3, SiO2, TiO2, and Cr2O3 as oxides and with an oxide content of 2.5 vol% to 40 vol% was manufactured, and the characteristics of the magnetic thin film were evaluated according to the type and content of the oxide.

[0039] Next, magnetic thin films (granular thin films) were formed using the various sputtering targets produced. The substrate for the magnetic thin film was a glass substrate with a layer structure of Ni-Ta (60 nm) / 90Ni-10W alloy (6 nm) / Ru (25 nm) / CoCrRu-TiO2 (2 nm). The magnetic thin film was formed using a sputtering device (Ar gas pressure 1-5 Pa, room temperature to 250°C), with the target film thickness set to 4-16 nm. After the magnetic thin film was formed, a C thin film (7 nm) was sputtered as a protective layer for the magnetic thin film to prepare a sample for magnetic property evaluation.

[0040] The magnetic properties of each magnetic thin film were evaluated by measuring the MH hysteresis loop using a vibrating magnetometer (VSM). The saturation magnetization M s was calculated, and the slope α value near M=0 was also calculated.

[0041] The magnetic thin film formed from the 75 atomic % Co-25 atomic % Pt alloy target containing various oxides (WO3, MoO3, B2O3, SiO2, TiO2, Cr2O3) produced in this embodiment has a magnetic separation property α value and a saturation magnetization M s The measurement results are shown in Figure 1. In Figure 1, the value for the magnetic thin film (75 atomic % Co-25 atomic % Pt) that does not contain any oxide (X=0 vol%) is shown by the dotted line.

[0042] As can be seen from FIG. 1, the α value basically decreases and approaches 1 with increasing content for any oxide. However, the magnetic thin film containing WO3 and MoO3 as oxides shows a remarkable effect of reducing the α value even at the minimum content (2.5 vol%) examined in this embodiment. It can be said that tungsten oxide and molybdenum oxide are effective as essential oxides for reducing the α value of granular thin films even when added in small amounts. Furthermore, the saturation magnetization M, which tends to decrease with increasing oxide content, s Taking this into consideration, it is confirmed that the content of these essential oxides is preferably 15 vol % or less.

[0043] Second embodiment In this embodiment, a sputtering target was manufactured for forming a magnetic thin film made of a CoPt alloy (80 atomic % Co-20 atomic % Pt) and B2O3 to which various oxides were added. That is, this embodiment is intended to examine the magnetic separation properties when oxides are added to a granular thin film formed in advance by adding B2O3.

[0044] The manufacturing method of the sputtering target was basically the same as that of the first embodiment. CoPt alloy powder was produced from a molten CoPt alloy (80 atomic % Co-20 atomic % Pt alloy) by gas atomization, and this CoPt alloy powder was mixed with B2O3 powder and oxide powders of various oxides (WO3, MoO3, B2O3, SiO2, TiO2, Cr2O3) in a ball mill. The mixed powder was then hot pressed and pressure sintered to produce a sputtering target with a relative density in the range of 95% to 100%.

[0045] In this embodiment, two types of reference configurations for sputtering targets were set. The first reference configuration was a target made of a CoPt alloy (80 atomic % Co-20 atomic % Pt) and 20 vol% B2O3, and the second reference configuration was a target made of a CoPt alloy (80 atomic % Co-20 atomic % Pt) and 30 vol% B2O3. In this embodiment, multiple sputtering targets were manufactured by adding WO3, MoO3, B2O3, SiO2, TiO2, and Cr2O3 to these two basic configurations while changing the content.

[0046] Thereafter, magnetic thin films were formed using various sputtering targets obtained in the same manner as in embodiment 1. The substrate configuration and film formation conditions were the same as in embodiment 1. In addition, the measurement of the MH hysteresis loop, which is an evaluation method for the created magnetic thin film samples, was also the same as in embodiment 1.

[0047] The results of this evaluation are shown in Figure 2, which shows the α value and M when various oxides were added to the first reference structure of 80 atomic % Co-20 atomic % Pt / 20 vol% B2O3. sIn addition, Fig. 3 shows the α value and M when various oxides are added to the second reference structure, 80 atomic % Co-20 atomic % Pt / 30 vol% B2O3. s These figures also show the values ​​of the magnetic thin film (80 atomic % Co-20 atomic % Pt / 20 vol% and 30 vol% B2O3) before adding various oxides (X=0 vol%).

[0048] 2 and 3, it can be seen that the α value of the CoPt alloy magnetic film containing the optional oxide (B2O3) considered in this embodiment is significantly reduced by including WO3 or MoO3. In this embodiment, the results are evaluation results when WO3 or MoO3 or different oxides are added to a sputtering target containing B2O3 as an optional oxide. WO3 and MoO3 are more effective at improving magnetic separation than other oxides. This tendency is similar to the tendency shown in the first embodiment.

[0049] It is also confirmed that even in a sputtering target containing optional oxides such as B2O3, small amounts of tungsten oxide and molybdenum oxide can exhibit the effect of reducing the α value. Furthermore, from this embodiment, it is also confirmed that the sputtering target according to the present invention can have a total content of essential oxides and optional oxides (total oxide content) of 20 vol% or more and 50 vol% or less.

[0050] As mentioned above, B2O3 forms nonmagnetic grain boundaries in granular thin films and has a uniaxial anisotropy constant K u Therefore, it is expected that sputtering targets will require the addition of optional oxides such as B2O3, and as a result, the oxide content in the magnetic thin film (sputtering target) may be relatively high. For such magnetic thin films (sputtering targets), tungsten oxide and molybdenum oxide are both considered to be useful additives that improve magnetic separation when mixed in small amounts. [Industrial Applicability]

[0051] As described above, the sputtering target according to the present invention is effective for forming a magnetic thin film having excellent magnetic separation properties when forming a magnetic thin film having a granular structure. The sputtering target according to the present invention can contain optional oxides such as B2O3 together with tungsten oxide and / or molybdenum oxide, which are essential oxides. In this case, the essential oxides tungsten oxide and molybdenum oxide can function as small amounts of additives to the optional oxides such as B2O3. This makes it possible to optimize the oxide content in the sputtering target and thus the magnetic thin film, and ensure the magnetization amount of the magnetic thin film. The sputtering target according to the present invention is particularly suitable for forming a magnetic thin film for a perpendicular recording method, which requires a significantly high density.

Claims

1. A sputtering target for a magnetic recording medium comprising Co and Pt as metal components and at least one oxide, Contains tungsten oxide and / or molybdenum oxide as essential oxides; A sputtering target for a magnetic recording medium, wherein the content of the essential oxide is 15 vol % or less.

2. 2. The sputtering target for a magnetic recording medium according to claim 1, further comprising an oxide different from the essential oxide as an optional oxide in addition to the essential oxide.

3. The optional oxide is B ２ O ３ , SiO ２ , TiO ２ , Cr ２ O ３ , CoO, Co ３ O ４ 3. The sputtering target for a magnetic recording medium according to claim 2, wherein

4. The total oxide content, which is the sum of the content of essential oxides and the content of optional oxides, is 20 vol.% or more and 50 vol.% or less, 4. The sputtering target for a magnetic recording medium according to claim 2, wherein the content of the essential oxide is 15 vol % or less.

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