Magnetic recording medium and magnetic recording device

Abstract

To provide a magnetic recording device that suppresses diffusion of oxygen atoms into a magnetic layer, reduces a grain size of magnetic particles, increases saturation magnetization, and further improves a surface recording density of a magnetic recording medium.SOLUTION: A magnetic recording medium 1 has at least an underlayer 20 and a magnetic recording layer 30 in this order on a non-magnetic substrate 10, in which the magnetic recording layer 30 includes a first magnetic layer 30A and a second magnetic layer 30B from the non-magnetic substrate side, 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, the grain boundary portion of the first magnetic layer 30A contains aluminum nitride, the grain boundary portion of the second magnetic layer 30B includes hexagonal boron nitride, the content amount of the aluminum nitride in the first magnetic layer 30A is within a range of 15 vol% to 35 vol%, and the peak of the B1s spectrum observed by X-ray photoelectron spectroscopy in the gain boundary portion of the second magnetic layer 30B is 191.6 eV or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In recent years, the thermally assisted recording method or microwave assisted recording method, in which near-field light or microwaves are irradiated onto a magnetic recording medium to locally heat it, thereby reducing the coercive force and recording, has achieved a data rate of 2 Tbit / inch. 2 This assisted recording method is attracting attention as a next-generation recording method that can realize a surface recording density as high as 1000 times higher. By using such a magnetic head of the assisted recording method, it is possible to easily record on a magnetic recording medium with a coercive force of several tens of kOe at room temperature. Therefore, magnetic particles with a high magnetocrystalline anisotropy constant (Ku) can be used as the magnetic particles contained in the magnetic layer, and as a result, the magnetic particles can be made fine while maintaining thermal stability.

[0003] As described above in

[0002] , magnetic particles with a high Ku can be used in the magnetic layer of a magnetic recording medium for an assisted recording system. Magnetic particles with a high Ku can be made fine while maintaining thermal stability, and can increase the coercive force at room temperature.

[0004] An example of a magnetic particle with a high Ku is an Fe-Pt alloy particle (Ku: up to 7×10 6 J / m 3 ), Co-Pt alloy particles (Ku: up to 5 × 10 6 J / m 3 Magnetic particles having an L10 type structure such as ZnO, ZnSe, and ZnO-based nanoparticles are known.

[0005] As an example of a magnetic layer using magnetic particles having an L10 type structure, Non-Patent Document 1 discloses a magnetic layer with a granular structure in which FePt magnetic particles having an L10 type structure are covered with layers of hexagonal boron nitride. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] BSD Ch. S. Varaprasad et al., AIP Advances, 13, 035002(2023) Summary of the Invention [Problem to be solved by the invention]

[0007] Here, it is desired to further improve the areal recording density of the magnetic recording medium. In order to further improve the areal recording density of the magnetic recording medium, it is important to further reduce the grain size of the magnetic particles contained in the magnetic layer and to further increase the anisotropy of the magnetic particles.

[0008] As such a magnetic layer, a granular-structure magnetic layer has been proposed, in which FePt magnetic grains with an L10 structure oriented in the (001) direction and their grain boundaries are made of hexagonal boron nitride (hereinafter referred to simply as an “FePt-hBN granular magnetic layer”).

[0009] Hexagonal boron nitride has a layered structure in which (001) planes are stacked in parallel, but the (001) planes are easily formed to surround the sides of FePt magnetic particles, and can precipitate as grain boundaries between FePt magnetic particles, making it possible to reduce the particle size of the FePt magnetic particles. In addition, hexagonal boron nitride has low reactivity with FePt magnetic particles, so it does not inhibit the ordering of the magnetic particles.

[0010] However, it was difficult to stably form such an FePt-hBN granular magnetic layer by the conventional method. That is, the FePt-hBN granular magnetic layer is formed by, for example, a sputtering method, but in order to crystallize boron nitride into a hexagonal crystal, a high substrate temperature and a plasma space with a high energy density are required. As a result of intensive research by the present inventors, it was found that when the magnetic layer is exposed to the high energy environment required for this hexagonal crystallization, oxygen atoms contained in the underlayer and the substrate diffuse into the FePt-hBN granular magnetic layer. The diffused oxygen atoms induce coarsening of FePt particles and deterioration of static magnetic properties such as saturation magnetization Ms, which results in a decrease in the electromagnetic conversion properties of the magnetic recording medium, especially the surface recording density.

[0011] One aspect of the present invention aims to provide a magnetic recording medium in which the particle size of the magnetic particles contained in the magnetic recording layer is reduced by suppressing the diffusion of oxygen atoms into the magnetic layer, thereby increasing the saturation magnetization and further improving the areal recording density of the magnetic recording medium. [Means for solving the problem]

[0012] The above objectives can be achieved by: (1) A magnetic recording medium having at least an underlayer and a magnetic recording layer in this order on a non-magnetic substrate, the magnetic recording layer includes, from the non-magnetic substrate side, a first magnetic layer and a second magnetic layer, the first magnetic layer and the second magnetic layer have a granular structure including magnetic grains having an L10 structure and grain boundaries, 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 within a range of 15 volume % to 35 volume %; A magnetic recording medium, wherein the grain boundary portion of the second magnetic layer has a B1s spectrum peak of 191.6 eV or less when observed by X-ray photoelectron spectroscopy. (2) The magnetic recording medium according to (1), wherein the first magnetic layer has a thickness within a range of 0.25 nm to 0.7 nm. (3) The magnetic recording medium according to (1) or (2), wherein the second magnetic layer has a thickness within a range of 5 nm to 12 nm. (4) The magnetic recording medium according to any one of (1) to (3), wherein the magnetic particles having an L10 structure are FePt alloy particles. (5) A magnetic storage device having the magnetic recording medium according to any one of (1) to (4). Effect of the Invention

[0013] According to one aspect of the present invention, it is possible to provide a magnetic recording medium in which the particle size of the magnetic particles contained in the magnetic recording layer is reduced, the saturation magnetization is increased, and the areal recording density is further improved. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing an example of a layer structure of a magnetic recording medium according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a perspective view showing an example of a magnetic storage device according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing the magnetic head of FIG. 2. [Figure 4] 13 is a spectrum of B1s of the second magnetic layer observed by X-ray photoelectron spectroscopy in Example 3. [Diagram 5] 13 is a spectrum of B1s of the second magnetic layer of Comparative Example 4 observed by X-ray photoelectron spectroscopy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described with reference to the drawings. Note that the drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not necessarily be the same. In this specification, "~" indicating a numerical range means that the numerical values ​​before and after it are included as the lower and upper limits, unless otherwise specified.

[0016] [Magnetic recording media] FIG. 1 shows an example of the layer structure of a magnetic recording medium according to an embodiment of the present invention. As shown in FIG. 1, the magnetic recording medium 1 has an underlayer 20, a first magnetic layer 30A, and a second magnetic layer 30B on a non-magnetic substrate 10. The first magnetic layer 30A and the second magnetic layer 30B have a granular structure including magnetic grains having an L10 structure and grain boundaries, The grain boundary portion of the first magnetic layer 30A contains aluminum nitride, The grain boundary portion of the second magnetic layer 30B contains hexagonal boron nitride, The content of aluminum nitride in the first magnetic layer 30A is within a range of 10 volume % to 45 volume %; The grain boundary portion of the second magnetic layer 30B is characterized in that the peak of the B1s spectrum by X-ray photoelectron spectroscopy is 191.6 eV or less.

[0017] By employing such a configuration, the magnetic particles are prevented from becoming coarse, and the magnetic properties of the magnetic recording medium, particularly the saturation magnetization Ms, are prevented from decreasing.

[0018] Examples of magnetic particles having an L10 type structure that form the first magnetic layer 30A and the second magnetic layer 30B include FePt alloy particles and CoPt alloy particles, and it is preferable to use FePt alloy particles.

[0019] In addition, it is preferable that the magnetic particles contained in the first magnetic layer 30A and the second magnetic layer 30B have a high c-axis orientation, i.e., (001) plane orientation, relative to the non-magnetic substrate 10, and the first magnetic layer 30A and the second magnetic layer 30B are preferably formed by a sputtering method.

[0020] As a method for orienting the magnetic grains contained in the second magnetic layer 30B in the c-axis direction with respect to the non-magnetic substrate 10, for example, there is a method in which the magnetic layer is epitaxially grown in the c-axis direction using the underlayer 20, or the like.

[0021] The aluminum nitride content in the grain boundary portion of the first magnetic layer 30A is 15 volume % to 35 volume %. The aluminum nitride content is preferably 15 volume % or more, and more preferably 20 volume % or more. The aluminum nitride content is preferably 35 volume % or less, and more preferably 25 volume % or less.

[0022] As described above in

[0010] , in order to form a granular magnetic layer containing hexagonal boron nitride in the grain boundary portion, a high substrate temperature and a plasma space with a high energy density are required. Under such conditions, the oxygen atoms contained in the underlayer and the substrate diffuse into the second magnetic layer 30B. As a result, the magnetic grains become coarse and the saturation magnetization Ms is greatly reduced. Therefore, in this embodiment, the first magnetic layer 30A is provided between the underlayer 20 and the second magnetic layer 30B, and aluminum nitride is contained in the grain boundary portion of the first magnetic layer 30A, thereby suppressing the diffusion of oxygen atoms into the second magnetic layer 30B.

[0023] That is, aluminum has a larger absolute value of Gibbs free energy of oxidation reaction and is more easily oxidized than B, Fe, and Pt contained in the first magnetic layer 30A and the second magnetic layer 30B. Therefore, aluminum efficiently reacts with oxygen diffusing from the nonmagnetic substrate 10 or the underlayer 20, and can suppress the oxygen from diffusing into the second magnetic layer 30B.

[0024] Therefore, the aluminum nitride contained in the grain boundary portion of the first magnetic layer 30A is, for example, AlN x O 1―x The oxygen is captured as described above in the composition ratio.

[0025] According to the inventor's study, if the content of aluminum nitride in the first magnetic layer 30A is within the range of 10% to 30% by volume, about 30 atomic % (X=0.7) of the aluminum nitride is used to capture oxygen. It is considered 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.

[0026] The grain boundary portion of the first magnetic layer 30A may contain not only aluminum nitride but also BN, C, SiO2, etc. In this case, the grain boundary portion of the first magnetic layer 30A preferably has a content in the range of 25 volume % to 50 volume %.

[0027] The state of oxidation of boron nitride contained in the grain boundary part of the second magnetic layer 30B can be estimated from the peak position of the B1s spectrum by X-ray photoelectron spectroscopy. The peak of the B1s spectrum observed by XPS is the peak top of the XPS spectrum derived from the B1s electron of boron contained in the magnetic layer, and reflects the chemical state of boron contained in the magnetic layer. When this is 191.6 eV or less, the oxidation of boron nitride is suppressed to about 30% or less, thereby preventing the magnetic particles of the second magnetic layer 30B from coarsening and the deterioration of the electromagnetic conversion characteristics of the magnetic recording medium. When the peak of the B1s spectrum reaches 192.0 eV, the oxidation of boron nitride is about 50%, and the magnetic particles in the second magnetic layer 30B become coarse and the electromagnetic conversion characteristics of the magnetic recording medium become significantly deteriorated.

[0028] The non-magnetic substrate 10 may be a substrate generally used for the magnetic recording medium 1. Since the non-magnetic substrate 10 may be heated to a temperature of 500° C. or higher during the manufacture of the magnetic recording medium 1, it is preferable to use, for example, a heat-resistant glass substrate having a softening temperature of 500° C. or higher, preferably 600° C. or higher, as the non-magnetic substrate 10. If the softening temperature of the non-magnetic substrate 10 is 500° C. or higher, the 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.

[0029] The material constituting the underlayer 20 is not particularly limited as long as it can orient the magnetic grains having the L10 type structure contained in the first magnetic layer 30A and the second magnetic layer 30B in the (001) plane.

[0030] The underlayer 20 may have a multi-layer structure.

[0031] The underlayer 20 preferably comprises a NaCl type compound.

[0032] Examples of NaCl type compounds include MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, TiC, etc. These may be used alone or in combination of two or more.

[0033] Among NaCl type compounds, it is particularly preferable to use MgO having a (100) plane orientation as the material constituting the underlayer 20. MgO having a (100) plane orientation has high lattice matching with L10 alloys such as FePt, and is more preferably introduced into the uppermost surface of the underlayer 20. In this embodiment, the diffusion of oxygen atoms from the underlayer 20 to the first magnetic layer 30A and the second magnetic layer 30B is effectively prevented, so that the degree of freedom in designing the underlayer 20 can be increased.

[0034] The magnetic recording medium 1 preferably further comprises a protective layer on the second magnetic layer 30B.

[0035] The protective layer may be, for example, a hard carbon film.

[0036] Methods for forming the protective layer include, for example, RF-CVD (Radio Frequency-Chemical Vapor Deposition) method, in which a film is formed by decomposing a hydrocarbon gas (raw material gas) using high frequency plasma, IBD (Ion Beam Deposition) method, in which a film is formed by ionizing a raw material gas using electrons emitted from a filament, and FCVA (Filtered Cathodic Vacuum Arc) method, in which a film is formed by using a solid carbon target without using a raw material gas.

[0037] 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 improved, and if it is 6.0 nm or less, the magnetic spacing is small, and the SNR (signal / noise ratio (S / N ratio)) of the magnetic recording medium 1 is improved.

[0038] The magnetic recording medium 1 may further have a lubricant layer on the protective layer.

[0039] The lubricant layer can be formed by using a liquid lubricant layer. The liquid lubricant is preferably one that is chemically stable, has low friction, and has low adsorption. As the wetting agent, for example, fluororesin-based lubricants such as perfluoropolyether-based lubricants containing a compound having a perfluoropolyether structure can be mentioned.

[0040] The thickness of the lubricant layer is not particularly limited, but may be, for example, 1 nm to 3 nm.

[0041] In addition, the magnetic recording medium 1 may include any layer as appropriate, in addition to the protective layer and the lubricant layer. For example, the magnetic recording medium 1 may include an adhesion layer, a soft magnetic underlayer, an orientation control layer, etc., between any of the non-magnetic substrate 10, the underlayer 20, and the first magnetic layer 30A, as necessary. The soft magnetic underlayer may include, 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 may be two or more layers (for example, a first orientation control layer, a second orientation control layer, etc.). Materials for forming the adhesion layer, the soft magnetic underlayer, the orientation control layer, etc. may be general materials used for magnetic recording media.

[0042] Thus, the magnetic recording medium 1 has a non-magnetic substrate 10, an underlayer 20, a first magnetic layer 30A, and a second magnetic layer 30B in this order, and the first magnetic layer 30A and the second magnetic layer 30B have a granular structure including magnetic grains having an L10 type structure and grain boundaries, the grain boundaries of the first magnetic layer 30A include aluminum nitride, and the grain boundaries of the second magnetic layer 30B include hexagonal boron nitride. By having the above-mentioned configuration, the magnetic recording medium 1 can reduce the grain size of the magnetic grains included in the second magnetic layer 30B, increase the saturation magnetization Ms, and further improve the electromagnetic conversion characteristics and areal recording density.

[0043] Since the magnetic recording medium 1 has the above-mentioned characteristics, even if a thermally 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 have high recording density, so that magnetic information can be sufficiently recorded on the first magnetic layer 30A and the second magnetic layer 30B by the recording magnetic field of a magnetic head. Therefore, the magnetic recording medium 1 can be suitably used in a magnetic storage device having an even higher recording capacity.

[0044] [Magnetic storage device] A magnetic storage device including the magnetic recording medium according to the present embodiment will be described. The magnetic storage device according to the present embodiment is not particularly limited in form as long as it has the magnetic recording medium according to the present embodiment. Here, the magnetic storage device will be described as recording magnetic information on the magnetic recording medium using a thermally assisted recording method.

[0045] The magnetic storage device of this embodiment may include, for example, a magnetic recording medium drive unit that drives and rotates the magnetic recording medium of this embodiment, a thermally assisted recording magnetic head having a near-field light generating element at its tip, a magnetic head drive unit that drives and moves the magnetic head, and a recording / playback signal processing system.

[0046] A thermally assisted recording magnetic head has, for example, a laser light generating unit that generates laser light to heat a magnetic recording medium, and a waveguide that guides the laser light generated from the laser light generating unit to a near-field light generating element.

[0047] Fig. 2 shows a perspective view of an example of a magnetic storage device using the magnetic recording medium according to this embodiment. As shown in Fig. 2, the magnetic storage device 100 can have a magnetic recording medium 101, a magnetic recording medium driving unit 102 for rotating the magnetic recording medium 101, a thermally assisted recording magnetic head 103 having a near-field light generating element at its tip, a magnetic head driving unit 104 for moving the thermally assisted recording magnetic head 103, and a recording / reproducing signal processing system 105. The magnetic recording medium 1 described above is used as the magnetic recording medium 101.

[0048] 3 is a schematic diagram of an example of a thermally assisted recording magnetic head 103. As shown in FIG.

[0049] The recording head 110 has a main magnetic pole 111, an auxiliary magnetic pole 112, a coil 113 that generates a magnetic field, a laser diode (LD) 114 that generates laser light, and a waveguide 116 that guides the laser light L generated from the LD 114 to a near-field light generating element 115.

[0050] The read head 120 has a read element 1222 sandwiched between a shield 121 .

[0051] As shown in FIG. 2, in the magnetic storage device 100, the center of a magnetic recording medium 101 is attached to the rotating shaft of a spindle motor, and information is written to or read from the magnetic recording medium 101 while a magnetic head 103 floats and runs above the surface of the magnetic recording medium 101, which is rotated by the spindle motor.

[0052] In the magnetic storage device 100 according to this embodiment, by using the magnetic recording medium 1 as the magnetic recording medium 101, the surface recording density of the magnetic recording medium 101 can be increased, and therefore the recording capacity of the magnetic recording medium 101 can be increased.

[0053] The magnetic storage device 100 may use a magnetic head of a microwave assisted recording type instead of the magnetic head of a thermal assisted recording type.

[0054] Although the embodiment has been described above, the above embodiment is presented as an example, and the present invention is not limited to the above embodiment. The above embodiment can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. EXAMPLES

[0055] The embodiments will be described in more detail below with reference to examples and comparative examples, but the embodiments are not limited to these examples and comparative examples.

[0056] <Manufacture of magnetic recording media> Example 1 On the glass substrate, a 30 nm thick Co-27 at% Fe-5 at% Zr-5 at% B alloy layer and a 100 nm thick Cr-50 at% Ti alloy layer were sequentially formed as underlayers by sputtering. Next, the glass substrate was heated to 250°C, and then a 10 nm thick Cr layer and a 5 nm thick MgO layer were sequentially formed by sputtering. Next, the glass substrate was heated to 450°C, and then a 0.25 nm thick FePt-20 vol% AlN-8 vol% C-6 vol% BN layer (first magnetic layer 30A) was formed by sputtering. Then, a 6 nm thick FePt-38 vol% hBN layer (second magnetic layer 30B) was sequentially formed by sputtering. In order to crystallize BN, a high frequency bias of 7 W was applied to the substrate when forming the second magnetic layer 30B. Next, a 3 nm thick carbon film was formed as a protective layer to complete the magnetic recording medium.

[0057] (Examples 2 to 11, Comparative Examples 1 to 11) A magnetic recording medium was produced in the same manner as in Example 1, except that the film formation conditions for the first magnetic layer and the second magnetic layer were changed to those shown in Table 1.

[0058] Table 1 shows the composition and thickness of the first magnetic layer, and the composition and thickness of the second magnetic layer, as well as the high frequency bias during deposition of the second magnetic layer, for each of the examples and comparative examples.

[0059] <Evaluation of magnetic recording media> The peak position of the B1s spectrum of the second magnetic layer observed by XPS of the magnetic recording media manufactured in each Example and Comparative Example, the interparticle distance of the magnetic particles contained in the second magnetic layer, and the saturation magnetization Ms of the magnetic recording media were measured. The measurement results are shown in Table 1.

[0060] (Measurement of the peak position of the B1s spectrum of the second magnetic layer observed by XPS) The surface of the magnetic recording medium was subjected to argon etching treatment for 1 minute to remove the carbon protective film on the surface of the magnetic recording medium. Then, XPS measurement of the second magnetic layer was performed under the following XPS measurement conditions to measure the B1s spectrum of the second magnetic layer observed by XPS, and the binding energy at 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 from the binding energy at the peak position of the measured B1s spectrum. The measurement results of the B1s spectrum of the second magnetic layer observed by XPS in Example 4 and Comparative Example 7 are shown in Figures 4 and 5. (XPS measurement conditions) Measurement equipment: X-ray photoelectron spectrometer (Quantera SXM, manufactured by ULVAC-PHI, Inc.) X-ray source: AlKα ray (1486.6eV) X-ray output: 25W, 15kV Detection area: 100μmφ Detection location: Surface of the second magnetic layer Detection depth: 3 nm (take-off angle 45°) Measurement spectrum: B1s

[0061] (Interparticle distance of magnetic particles contained in the second magnetic layer) The interparticle center distance calculated from the surface observation image by a scanning electron microscope (Hitachi High-Technologies Corporation) was measured as the interparticle distance of the magnetic particles contained in the second magnetic layer. The interparticle center distance refers to the distance between the centers of gravity of adjacent magnetic particles, and it can be evaluated that the smaller the interparticle distance, the smaller the particle size of the magnetic particles.

[0062] (Saturation magnetization Ms of magnetic recording media) The saturation magnetization of the magnetic recording medium was calculated using a Squid-VSM measuring device (manufactured by Quantum Design, Inc.) Note that this saturation magnetization was measured for the first magnetic layer and the second magnetic layer, and does not include the magnetization of the soft magnetic backing layer or other portions.

[0063] [Table 1]

[0064] From Table 1, in the magnetic recording media of each embodiment, the binding energy of the peak position of the B1s spectrum of the second magnetic layer observed by XPS appears at 191.6 eV or less, and the saturation magnetization Ms is 688.7 emu / cm 3 On the other hand, it was confirmed that the magnetic recording media of the comparative examples had a binding energy of 192 eV or more at the peak position of the B1s spectrum of the second magnetic layer observed by XPS, an interparticle distance of 8.0 nm or more, or a saturation magnetization Ms of 700 emu / cm 3 It was confirmed that any two or more of the following were less than

[0065] Furthermore, as shown in Figure 4, the binding energy at the peak position of the B1s spectrum of the second magnetic layer observed by XPS in Example 4 was near 191.0 eV, while as shown in Figure 5, the binding energy at the peak position of the B1s spectrum of the second magnetic layer observed by XPS in Comparative Example 7 was near 192.2 eV, confirming that the magnetic particles contained in the second magnetic layer of Comparative Example 7 can be said to be in a more oxidized state.

[0066] Therefore, it is confirmed that if the chemical state of the boron nitride BN of the grain boundary of the second magnetic layer is good, the grain size of the magnetic grains contained in the second magnetic layer is small, and the saturation magnetization Ms of the magnetic recording medium can be increased.Therefore, the magnetic recording medium of each embodiment has high surface recording density, and by using it in a magnetic storage device, the magnetic storage device can have high recording capacity. [Explanation of symbols]

[0067] 1, 101 Magnetic recording media 10 Non-magnetic substrate 20 Base layer 30A First Magnetic Layer 30B Second magnetic layer 100 Magnetic storage device

Claims

1. A magnetic recording medium having at least an underlayer and a magnetic recording layer in this order on a non-magnetic substrate, the magnetic recording layer includes, from the non-magnetic substrate side, a first magnetic layer and a second magnetic layer, The first magnetic layer and the second magnetic layer are L1 ０ The magnetic particles have a granular structure including 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 within a range of 15 volume % to 35 volume %; A magnetic recording medium, wherein the grain boundary portion of the second magnetic layer has a B1s spectrum peak of 191.6 eV or less when observed by X-ray photoelectron spectroscopy.

2. 2. The magnetic recording medium according to claim 1, wherein the thickness of the first magnetic layer is within a range of 0.25 nm to 0.7 nm.

3. 3. The magnetic recording medium according to claim 1, wherein the second magnetic layer has a thickness in the range of 5 nm to 12 nm.

4. The L1 ０ 3. The magnetic recording medium according to claim 1, wherein the magnetic particles having a type structure are FePt alloy particles.

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

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