Magnetic recording medium and magnetic storage device

Abstract

The purpose of the present invention is to provide a magnetic recording medium in which the surface recording density of the magnetic recording medium is further improved by suppressing oxygen atoms diffused into a magnetic layer, reducing the particle size of magnetic particles contained in the magnetic recording layer, and improving saturation magnetization. A magnetic recording medium according to the present invention has at least an underlayer and a magnetic recording layer in this order on a non-magnetic substrate, the magnetic recording layer including a first magnetic layer and a second magnetic layer from the non-magnetic substrate side, the first magnetic layer and the second magnetic layer having a granular structure, the first magnetic layer has a granular structure including magnetic particles having an L10-type structure and a grain boundary portion, the grain boundary portion of the first magnetic layer contains aluminum nitride, the grain boundary portion of the second magnetic layer contains hexagonal boron nitride, the content of the aluminum nitride in the first magnetic layer is in the range of 15-35 vol%, and the content of the hexagonal boron nitride in the second magnetic layer is in the range of 15-35 vol%. The spectral peak of B1s in the grain boundary portion of the second magnetic layer, as observed by X-ray photoelectron spectroscopy, is 191.6 eV or less.

Description

Technical Field

[0001] The present invention relates to a magnetic recording medium and a magnetic storage device. Background Art

[0002] In recent years, heat-assisted recording or microwave-assisted recording, which is a method of irradiating magnetic recording media with near-field light or microwaves to locally heat the medium and thereby reduce the coercivity, has become a popular method for achieving 2Tbit / inch. 2 The next generation recording method with a high surface recording density of about 10000 Å has attracted attention. When using a magnetic head with such an auxiliary recording method, it is easy to record on a magnetic recording medium with a coercive force of tens of kOe at room temperature. Therefore, as the magnetic particles contained in the magnetic layer, magnetic particles with a high crystal magnetic anisotropy constant (Ku) can be used, and as a result, the magnetic particles can be miniaturized while maintaining thermal stability.

[0003] As described above, the magnetic layer of the recording-assisted magnetic recording medium can use magnetic particles with high Ku. Magnetic particles with high Ku can be miniaturized while maintaining thermal stability, and the coercive force at room temperature can be increased.

[0004] As magnetic particles with high Ku, for example, Fe-Pt alloy particles (Ku: 7×10 6 J / m 3 ), Co-Pt alloy particles (Ku: maximum 5×10 6 J / m 3 ) and the like having an L10 type structure.

[0005] As a magnetic layer using magnetic grains having an L10 type structure, for example, Non-Patent Document 1 discloses a granular magnetic layer in which the periphery of FePt magnetic grains having an L10 type structure is covered with a layer of hexagonal boron nitride.

[0006] [Prior art literature]

[0007]

Non-patent literature

[0008] [Non-patent document 1] BSD Ch. S. Varaprasad et al., AIP Advances, 13, 035002 (2023) Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] Here, it is desired to further improve the surface recording density of the magnetic recording medium. In order to further improve the surface recording density of the magnetic recording medium, it is important to further reduce the particle size of the magnetic grains contained in the magnetic layer and further improve the anisotropy of the magnetic grains.

[0011] As such a magnetic layer, a magnetic layer having a granular structure of FePt magnetic grains oriented in the (001) direction with an L10 structure and a grain boundary portion with hexagonal boron nitride (hereinafter simply referred to as "FePt-hBN granular magnetic layer") has been proposed.

[0012] Hexagonal boron nitride has a layered structure with (001) planes stacked in parallel, but it is easy to form a structure where its (001) plane surrounds the side of the FePt magnetic particles, and can precipitate as a grain boundary between the FePt magnetic particles, thereby reducing the particle size of the FePt magnetic particles. In addition, hexagonal boron nitride has low reactivity with FePt magnetic particles, so it does not hinder the regularization of magnetic particles.

[0013] However, it is difficult to form such a FePt-hBN granular magnetic layer stably using conventional methods. That is, the FePt-hBN granular magnetic layer is formed by, for example, sputtering, but in order to hexagonally crystallize boron nitride, a high substrate temperature and a high energy density plasma space are required. After careful research, the inventors of the present invention have learned that when the magnetic layer is exposed to the high energy environment required for the hexagonal crystallization, oxygen atoms contained in the base layer and the substrate diffuse into the FePt-hBN granular magnetic layer. The diffused oxygen atoms induce the coarsening of the FePt particles and the deterioration of the static magnetic properties such as the saturation magnetization Ms, which results in a decrease in the electromagnetic conversion properties of the magnetic recording medium, especially the surface recording density.

[0014] An object of one embodiment of the present invention is to provide a magnetic recording medium in which the surface recording density of the magnetic recording medium is further improved by reducing the particle size of magnetic grains included in the magnetic recording layer and improving the saturation magnetization by suppressing diffusion of oxygen atoms into the magnetic layer.

[0015]

Methods to solve the problem

[0016] The above object can be achieved as follows.

[0017] (1) A magnetic recording medium comprising at least an underlayer and a magnetic recording layer in this order on a non-magnetic substrate,

[0018] The magnetic recording layer includes a first magnetic layer and a second magnetic layer from the non-magnetic substrate side.

[0019] The first magnetic layer and the second magnetic layer have a granular structure including magnetic grains having an L10 type structure and a grain boundary portion.

[0020] The grain boundary portion of the first magnetic layer contains aluminum nitride,

[0021] The grain boundary portion of the second magnetic layer contains hexagonal boron nitride,

[0022] The content of the aluminum nitride in the first magnetic layer is in the range of 15 volume % to 35 volume %,

[0023] The B1s spectrum peak of the grain boundary portion of the second magnetic layer observed by X-ray photoelectron spectroscopy is 191.6 eV or less.

[0024] (2) The magnetic recording medium according to (1), wherein the thickness of the first magnetic layer is in the range of 0.25 nm to 0.7 nm.

[0025] (3) In the magnetic recording medium according to (1) or (2), the thickness of the second magnetic layer is in the range of 5 nm to 12 nm.

[0026] (4) The magnetic recording medium according to any one of (1) to (3), wherein the magnetic grains having the L10 type structure are FePt alloy grains.

[0027] (5) A magnetic storage device comprising the magnetic recording medium according to any one of (1) to (4).

[0028] [Effects of the invention]

[0029] According to one embodiment of the present invention, there is provided a magnetic recording medium in which the particle size of magnetic grains included in a magnetic recording layer is reduced, the saturation magnetization is increased, and the surface recording density is further increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0030]

Figure 1

[0031]

Figure 2

[0032]

Figure 3

[0033]

Figure 4

[0034]

Figure 5

[0035] The specific embodiments of the present invention are described below with reference to the accompanying drawings. In addition, the drawings used in the following descriptions may enlarge the features for convenience in order to facilitate understanding of the features, and the size ratios of the various structural elements may not be the same. In this specification, "to" indicating a numerical range, unless otherwise specified, means that the numerical values ​​recorded before and after it are included as the lower limit and upper limit.

[0036] [Magnetic recording media]

[0037] Figure 1 An example of the layer structure of the magnetic recording medium according to the embodiment of the present invention is shown.

[0038] like Figure 1 As shown, the magnetic recording medium 1 is characterized in that it has an underlayer 20, a first magnetic layer 30A, and a second magnetic layer 30B on a non-magnetic substrate 10.

[0039] The first magnetic layer 30A and the second magnetic layer 30B have a granular structure including magnetic grains having an L10 type structure and a grain boundary portion.

[0040] The grain boundary portion of the first magnetic layer 30A contains aluminum nitride.

[0041] The grain boundary of the second magnetic layer 30B contains hexagonal boron nitride.

[0042] The content of aluminum nitride in the first magnetic layer 30A is in the range of 10 volume % to 45 volume %.

[0043] The B1s spectrum peak of the grain boundary portion of the second magnetic layer 30B based on X-ray photoelectron spectroscopy is 191.6 eV or less.

[0044] By adopting such a structure, the magnetic grains are prevented from being coarsened, and the magnetic properties of the magnetic recording medium, particularly the saturation magnetization Ms, are prevented from being reduced.

[0045] Examples of magnetic grains having an L10 type structure constituting the first magnetic layer 30A and the second magnetic layer 30B include FePt alloy grains and CoPt alloy grains, and FePt alloy grains are preferably used.

[0046] Furthermore, the magnetic grains included in the first magnetic layer 30A and the second magnetic layer 30B preferably have a high c-axis orientation, that is, (001) plane orientation, with respect to the nonmagnetic substrate 10 . The first magnetic layer 30A and the second magnetic layer 30B are preferably formed by sputtering.

[0047] As a method of orienting the magnetic grains included in the second magnetic layer 30B in the c-axis direction with respect to the nonmagnetic substrate 10 , for example, there is a method of epitaxially growing a magnetic layer in the c-axis direction using the base layer 20 .

[0048] The content of aluminum nitride in the grain boundary of the first magnetic layer 30A is 15 to 35 volume %. The content of aluminum nitride is preferably 15 volume % or more, more preferably 20 volume % or more, and preferably 35 volume % or less, more preferably 25 volume % or less.

[0049] As described above, to form a granular magnetic layer containing hexagonal boron nitride in the grain boundary, a high substrate temperature and a high energy density plasma space are required. Under such conditions, oxygen atoms contained in the base layer and the substrate diffuse into the second magnetic layer 30B. As a result, the magnetic particles are coarsened and the saturation magnetization Ms is greatly reduced. Therefore, in this embodiment, the first magnetic layer 30A is provided between the base layer 20 and the second magnetic layer 30B, and the grain boundary of the first magnetic layer 30A contains aluminum nitride, thereby suppressing the diffusion of oxygen atoms into the second magnetic layer 30B.

[0050] That is, aluminum has a larger absolute value of Gibbs free energy of oxidation reaction than B, Fe, and Pt contained in the first magnetic layer 30A and the second magnetic layer 30B, and is easily oxidized. Therefore, aluminum reacts efficiently with oxygen diffused from the non-magnetic substrate 10 or the base layer 20, which can suppress diffusion into the second magnetic layer 30B.

[0051] Therefore, the aluminum nitride contained in the grain boundary portion of the first magnetic layer 30A captures the aforementioned oxygen, and is represented by, for example, AlN x O 1-x The composition ratio.

[0052] According to the research of the present inventors, if the content of aluminum nitride in the first magnetic layer 30A is within the range of 10 volume % to 30 volume %, about 30 atomic % (X=0.7) of the aluminum nitride is used for oxygen capture. It is believed that the oxygen captured by the aluminum nitride is captured as Al2O3, AlON, amorphous, etc. in the grain boundary of the first magnetic layer 30A.

[0053] The grain boundary portion of the first magnetic layer 30A may contain not only aluminum nitride but also BN, C, SiO 2 , etc. In this case, the grain boundary portion of the first magnetic layer 30A preferably has a concentration of 25 volume % to 50 volume %.

[0054] The oxidation state of the boron nitride contained in the grain boundary of the second magnetic layer 30B can be estimated from the peak position of the B1s spectrum given by X-ray photoelectron spectroscopy. In addition, the B1s spectrum peak observed by XPS refers to the peak top of the XPS spectrum of the B1s electron from the boron contained in the magnetic layer, which reflects the chemical state of the boron contained in the magnetic layer. When it is below 191.6eV, the oxidation of the boron nitride is suppressed to less than about 30%, thereby preventing the coarsening of the magnetic grains of the second magnetic layer 30B and the reduction of the electromagnetic conversion characteristics of the magnetic recording medium. In addition, if the peak of the B1s spectrum reaches 192.0eV, the oxidation of the boron nitride is about 50%, and the coarsening of the magnetic grains in the second magnetic layer 30B and the reduction of the electromagnetic conversion characteristics of the magnetic recording medium are significant.

[0055] The non-magnetic substrate 10 may be a substrate generally used for the magnetic recording medium 1. The non-magnetic substrate 10 may be heated to a temperature of 500° C. or higher when manufacturing the magnetic recording medium 1, and therefore, for example, a heat-resistant glass substrate having a softening temperature of 500° C. or higher, preferably 600° C. or higher is preferably used as the non-magnetic substrate 10. If the softening temperature of the non-magnetic substrate 10 is 500° C. or higher, diffusion of oxygen atoms from the non-magnetic substrate 10 to the first magnetic layer 30A and the second magnetic layer 30B can be effectively suppressed, thereby increasing the degree of freedom in designing the non-magnetic substrate 10.

[0056] The material constituting the base layer 20 is not particularly limited as long as it can orient the magnetic grains having the L10 type structure included in the first magnetic layer 30A and the second magnetic layer 30B in the (001) plane.

[0057] The base layer 20 may have a multi-layer structure.

[0058] The base layer 20 preferably contains a NaCl type compound.

[0059] Examples of the NaCl type compound include MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, and TiC, etc. These may be used alone or in combination of two or more.

[0060] Among NaCl-type compounds, MgO having a (100) plane orientation is particularly preferably used as a material constituting the base layer 20. MgO having a (100) plane orientation has high lattice consistency with an L10 alloy such as FePt, and is more preferably introduced to the top surface of the base layer 20. In this embodiment, diffusion of oxygen atoms from the base layer 20 to the first magnetic layer 30A and the second magnetic layer 30B is effectively prevented, thereby increasing the degree of freedom in designing the base layer 20.

[0061] The magnetic recording medium 1 preferably further includes a protective layer on the second magnetic layer 30B.

[0062] As the protective layer, a hard carbon film or the like can be mentioned, for example.

[0063] As methods for forming a protective layer, for example, there can be cited the RF-CVD (radio frequency chemical vapor deposition) method of decomposing hydrocarbon gas (raw gas) by high-frequency plasma to form a film, the IBD (ion beam deposition) method of ionizing the raw gas by electrons emitted from a filament to form a film, and the FCVA (filtered cathode vacuum arc) method of forming a film by using a solid carbon target without using a raw gas.

[0064] The thickness of the protective layer is preferably 1.0 nm to 6.0 nm. If the thickness of the protective layer is 1 nm or more, the floating characteristics of the magnetic head are good, and if it is 6.0 nm or less, the magnetic pitch is small and the SNR (signal / noise ratio (S / N ratio)) of the magnetic recording medium 1 is improved.

[0065] The magnetic recording medium 1 may further include a lubricant layer on the protective layer.

[0066] The lubricant layer can be formed by a liquid lubricant layer. Liquid lubricants are preferably chemically stable, low-friction, and low-adsorbent. Examples of wetting agents include fluororesin lubricants such as perfluoropolyether lubricants containing compounds having a perfluoropolyether structure.

[0067] The thickness of the lubricant layer is not particularly limited, and may be, for example, 1 nm to 3 nm.

[0068] In addition, the magnetic recording medium 1 may contain any layer in addition to the protective layer and the lubricant layer. For example, the magnetic recording medium 1 may have an adhesive layer, a soft magnetic base layer, an orientation control layer, etc. between any layers of the non-magnetic substrate 10, the base layer 20, and the first magnetic layer 30A as needed. The soft magnetic base layer may be composed of, for example, a first soft magnetic layer, an intermediate layer, and a second soft magnetic layer. The orientation control layer may be one layer or two layers (for example, a first orientation control layer, a second orientation control layer, etc.). The materials forming the adhesive layer, the soft magnetic base layer, the orientation control layer, etc. may be general materials used in magnetic recording media.

[0069] Thus, the magnetic recording medium 1 has the non-magnetic substrate 10, the base layer 20, the first magnetic layer 30A and the second magnetic layer 30B in this order, the first magnetic layer 30A and the second magnetic layer 30B have a granular structure, the granular structure includes magnetic grains having an L10 type structure and a grain boundary portion, the grain boundary portion of the first magnetic layer 30A contains aluminum nitride, and the grain boundary portion of the second magnetic layer 30B contains hexagonal boron nitride. By having such a structure, the magnetic recording medium 1 can reduce the particle size of the magnetic grains contained in the second magnetic layer 30B, increase the saturation magnetization Ms, and further improve the electromagnetic conversion characteristics and the surface recording density.

[0070] The magnetic recording medium 1 has the above-mentioned characteristics, and even when a heat-assisted recording method or a microwave-assisted recording method is used as a recording method, the first magnetic layer 30A and the second magnetic layer 30B also have a high recording density, and the first magnetic layer 30A and the second magnetic layer 30B can fully record magnetic information through the recording magnetic field of the magnetic head. Therefore, the magnetic recording medium 1 can be appropriately used in a magnetic storage device with a higher recording capacity.

[0071] [Magnetic storage device]

[0072] A magnetic storage device having a magnetic recording medium according to the present embodiment is described. The magnetic storage device according to the present embodiment has no particular limitation on form as long as it has the magnetic recording medium according to the present embodiment. In addition, the following case is described here, in which the magnetic storage device records magnetic information on the magnetic recording medium using a thermally assisted recording method.

[0073] The magnetic storage device involved in this embodiment has, for example, a magnetic recording medium driving unit that drives the magnetic recording medium involved in this embodiment to rotate, a magnetic head of a thermally assisted recording method with a near-field light generating element provided at the front end, a magnetic head driving unit that drives the magnetic head to move, and a recording and reproducing signal processing system.

[0074] The magnetic head of the heat-assisted recording method includes, for example, a laser generating unit that generates laser light to heat the magnetic recording medium and a waveguide that guides the laser light generated by the laser generating unit to the near-field light generating element.

[0075] Figure 2 A perspective view showing an example of a magnetic storage device using the magnetic recording medium according to this embodiment. Figure 2 As shown, the magnetic storage device 100 may include a magnetic recording medium 101, a magnetic recording medium driving unit 102 for rotating the magnetic recording medium 101, a magnetic head 103 of a thermally assisted recording method having a near-field light generating element at the front end, a magnetic head driving unit 104 for moving the magnetic head 103 of the thermally assisted recording method, and a recording and reproducing signal processing system 105. The magnetic recording medium 101 uses the magnetic recording medium 1 described above.

[0076] Figure 3 An example of a magnetic head 103 of a thermally assisted recording method is schematically shown. Figure 3 As shown, the magnetic head 103 includes a recording head 110 and a reproducing head 120 .

[0077] The recording head 110 has a main magnetic pole 111 , an auxiliary magnetic pole 112 , a coil 113 for generating a magnetic field, a laser diode (LD) 114 for generating laser light, and a waveguide 116 for guiding the laser light L generated by the LD 114 to a near-field light generating element 115 .

[0078] The reproducing head 120 includes a reproducing element 1222 sandwiched between shutters 121 .

[0079] like Figure 2 As shown, in the magnetic storage device 100, the center portion of the magnetic recording medium 101 is installed on the rotating axis of the spindle motor. On the surface of the magnetic recording medium 101 driven by the spindle motor, the head 103 floats and operates while writing or reading information to the magnetic recording medium 101.

[0080] The magnetic storage device 100 according to the present embodiment can improve the surface recording density of the magnetic recording medium 101 by using the magnetic recording medium 1 in the magnetic recording medium 101 , and thus can improve the recording capacity of the magnetic recording medium 101 .

[0081] Furthermore, the magnetic storage device 100 may use a magnetic head of a microwave-assisted recording method in addition to a magnetic head of a thermally-assisted recording method.

[0082] As described above, the embodiments are described, but the above embodiments are given as examples, and the present invention is not limited by the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, changes, etc. can be made without departing from the scope of the gist of the invention. These embodiments and their variations belong to the scope and gist of the invention, and also belong to the invention recorded in the claims and their equivalents.

[0083] [Example]

[0084] Hereinafter, the embodiment will be described in more detail with reference to Examples and Comparative Examples, but the embodiment is not limited to these Examples and Comparative Examples.

[0085] <Manufacturing of magnetic recording media>

[0086] (Example 1)

[0087] On a glass substrate, as a base layer, a Co-27at%Fe-5at%Zr-5at%B alloy layer with a thickness of 30nm and a Cr-50at%Ti alloy layer with a thickness of 100nm are formed in sequence by sputtering. Next, after the glass substrate is heated to 250°C, a Cr layer with a thickness of 10nm and a MgO layer with a thickness of 5nm are formed in sequence by sputtering. Next, after the glass substrate is heated to 450°C, a FePt-20vol%AlN-8vol%C-6vol%BN layer with a thickness of 0.25nm is formed by sputtering (first magnetic layer 30A). Then, a FePt-38vol%hBN layer with a thickness of 6nm is formed in sequence by sputtering (second magnetic layer 30B). In order to crystallize BN, a high-frequency bias of 7W is applied to the substrate when the second magnetic layer 30B is formed. Next, a carbon film with a thickness of 3nm is formed as a protective layer as a magnetic recording medium.

[0088] (Examples 2 to 11, Comparative Examples 1 to 11)

[0089] A magnetic recording medium was produced in the same manner as in Example 1 except that the film forming conditions of the first magnetic layer and the second magnetic layer were changed as shown in Table 1.

[0090] Table 1 shows the composition and thickness of the first magnetic layer, the composition and thickness of the second magnetic layer, and the high-frequency bias when the second magnetic layer is formed in each of the examples and comparative examples.

[0091] <Evaluation of Magnetic Recording Media>

[0092] The magnetic recording media produced in each example and each comparative example were measured by XPS observation of the spectral peak position of B1s of the second magnetic layer, the inter-grain distance of magnetic grains contained in the second magnetic layer, and the saturation magnetization Ms of the magnetic recording medium. These measurement results are shown in Table 1.

[0093] (Measurement of the Peak Position of B1s Spectrum of the Second Magnetic Layer Observed by XPS)

[0094] The surface of the magnetic recording medium was subjected to argon etching for 1 minute to remove the carbon protective film on the surface of the magnetic recording medium. Then, the XPS measurement of the second magnetic layer was performed using the following XPS measurement conditions, the B1s spectrum of the second magnetic layer observed by XPS was measured, and the binding energy of the peak position of the B1s spectrum was measured. The chemical state of BN contained in the grain boundary portion of the second magnetic layer was evaluated based on the measured binding energy of the peak position of the B1s spectrum. In addition, the measurement results of the B1s spectrum of the second magnetic layer observed by XPS in Example 4 and Comparative Example 7 are as follows: Figure 4 and Figure 5 shown.

[0095] (XPS measurement conditions)

[0096] Measurement device: X-ray photoelectron spectrometer (Quantera SXM, manufactured by ULVAC-PHI)

[0097] X-ray source: AlKα line (1486.6eV)

[0098] X-ray output: 25W, 15kV

[0099] Detection field:

[0100] Detection location: Surface of the second magnetic layer

[0101] Detection depth: 3nm (take-off angle 45°)

[0102] Measurement spectrum: B1s

[0103] (Inter-grain distance of magnetic grains included in the second magnetic layer)

[0104] The value of the center distance between particles calculated from the surface observation image given by a scanning electron microscope (TEM HD-2300, manufactured by Hitachi High-Technologies Corporation) is measured as the distance between the particles of the magnetic particles contained in the second magnetic layer. In addition, the center distance between magnetic particles refers to the distance between the centers of gravity of adjacent magnetic particles. The smaller the distance between particles, the smaller the particle size of the magnetic particles can be evaluated.

[0105] (Saturation magnetization Ms of magnetic recording medium)

[0106] The saturation magnetization of the magnetic recording medium was calculated using a Squid-VSM measuring device (MPMS, manufactured by Quantum Design Co., Ltd.) The saturation magnetization was measured for the first magnetic layer and the second magnetic layer, excluding the soft magnetic underlayer and the like.

[0107]

Table 1

[0108]

[0109] As shown in Table 1, in the magnetic recording media of each example, the binding energy of the peak position of the spectrum of B1s of the second magnetic layer observed by XPS appears below 191.6 eV, and the saturation magnetization Ms is 688.7 emu / cm 3 On the other hand, it is confirmed that the magnetic recording medium of each comparative example has any two or more of the following: the binding energy of the spectral peak position of B1s of the second magnetic layer observed by XPS is above 192 eV, the interparticle distance is above 8.0 nm, and the saturation magnetization Ms is less than 700 emu / cm 3 .

[0110] In addition, if Figure 4 As shown, the binding energy of the peak position of the spectrum of B1s of the second magnetic layer observed by XPS in Example 4 is around 191.0 eV, but as shown in FIG. Figure 5 As shown, the binding energy of the peak position of the B1s spectrum of the second magnetic layer of Comparative Example 7 observed by XPS is near 192.2 eV, which confirms that the magnetic grains included in the second magnetic layer of Comparative Example 7 are in a more oxidized state.

[0111] Therefore, it is confirmed that if the chemical state of the boron nitride BN in the grain boundary portion of the second magnetic layer is good, the particle size of the magnetic grains contained in the second magnetic layer is small, and the saturation magnetization Ms of the magnetic recording medium is improved. Therefore, the magnetic recording medium of each embodiment has a high surface recording density, and thus by using it in a magnetic storage device, the magnetic storage device can have a high recording capacity.

[0112] [Description of Reference Numerals]

[0113] 1,101 Magnetic Recording Media

[0114] 10 Non-magnetic substrate

[0115] 20 Basal layer

[0116] 30A 1st magnetic layer

[0117] 30B 2nd magnetic layer

[0118] 100 Magnetic storage device

Claims

1. A magnetic recording medium comprising at least a base layer and a magnetic recording layer in this order on a non-magnetic substrate, The magnetic recording layer includes a first magnetic layer and a second magnetic layer from the non-magnetic substrate side. The first magnetic layer and the second magnetic layer have a granular structure including magnetic grains having an L10 type structure and a grain boundary portion. The grain boundary portion of the first magnetic layer contains aluminum nitride, The grain boundary portion of the second magnetic layer contains hexagonal boron nitride, The content of the aluminum nitride in the first magnetic layer is in the range of 15 volume % to 35 volume %, The B1s spectrum peak of the grain boundary portion of the second magnetic layer observed by X-ray photoelectron spectroscopy is 191.6 eV or less. 2 . The magnetic recording medium according to claim 1 , wherein the thickness of the first magnetic layer is in the range of 0.25 nm to 0.7 nm. 3 . The magnetic recording medium according to claim 1 , wherein the thickness of the second magnetic layer is in the range of 5 nm to 12 nm. 4 . The magnetic recording medium according to claim 1 , wherein the magnetic particles having the L10 type structure are FePt alloy particles.

5. A magnetic storage device comprising the magnetic recording medium according to claim 1 or 2.

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