JP2015130220A - Perpendicular magnetic recording medium and method of manufacturing perpendicular magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a perpendicular magnetic recording medium capable of suppressing the particle diameter dispersion of magnetic particles, exhibiting excellent recording and reproducing characteristics, and achieving high density recording.SOLUTION: A perpendicular magnetic recording medium according to an embodiment comprises: a substrate; a foundation layer formed on the substrate; and a magnetic recording layer formed on the foundation layer and having an easy axis of magnetization in a direction perpendicular to a film surface. The foundation layer includes a plurality of convex portions arranged at intervals of 1 nm to 20 nm. The magnetic recording layer is an amorphous magnetic recording layer containing a plurality of magnetic particles each formed to spread from a convex surface of the foundation layer in a spatulate fashion, the magnetic particles at least in the convex portions being separated.

Description

  Embodiments described herein relate generally to a perpendicular magnetic recording medium and a method for manufacturing the perpendicular magnetic recording medium.

In the current magnetic recording medium in which the perpendicular magnetic recording method is used, it is essential to satisfy both the perpendicular orientation of the recording layer and the isolation of the magnetic particles. The prior art employs a granular structure in which vertically oriented ferromagnetic (CoPt alloy, FePt alloy, CoPd alloy, etc.) particles are arranged in a matrix of oxide (SiO _x , TiO _x , AlO _x, etc.). . However, due to the decrease in the number of particles per bit accompanying the increase in density, the particle size dispersion of magnetic particles has become a problem. This particle size dispersion mainly comes from the unevenness of the underlayer and the crystal grain size, and the present situation is that the dispersion cannot be reduced despite various attempts. The reason is that only a specific material such as Ru or MgO can satisfy the granular structure and the crystalline anisotropy at the same time, and the recording layer itself is also crystalline, and unique grain growth occurs. is there. On the other hand, the amorphous magnetic recording layer can be perpendicularly oriented regardless of the underlayer, and can easily trace the underlayer shape because it does not have its own grain growth. If an amorphous material is used for the magnetic recording layer, a structure with little particle size dispersion can be expected regardless of the underlayer material.

  For example, when the amorphous material is TbFeCo, a magnetic recording medium having a structure in which the domain wall of TbFeCo as a recording layer is pinned by bringing a material having a fine concavo-convex structure such as Al or TiN into the underlayer. It can be produced.

  Also, a magnetic recording medium in which irregularities (0.5 nm to 3 nm) are formed by plasma etching a matrix having carbon clusters, an amorphous recording layer is formed thereon, and a domain wall is pinned by the irregularities of the underlayer, or FePt There is a magnetic recording medium in which a TbFeCo amorphous recording layer is formed on a granular layer and the granular layer suppresses domain wall movement of the amorphous recording layer.

  However, in general, these fine irregularities and granular layers have been considered difficult to apply to magnetic recording media because it is difficult to fix magnetic domains when performing high-density recording.

Japanese Patent No. 3794995 JP 2008-159177 A

J. et al. Sato et al. , Jpn. J. et al. Appl. Phys. 47 (2008) 152 M.M. T. T. et al. Rahman et al. , J. et al. Magn. Magn. Mater. 303 (2006) e113

An embodiment of the present invention has been made in view of the above circumstances, and a perpendicular magnetic recording medium that suppresses particle size dispersion of magnetic particles, has good recording / reproducing characteristics, and enables high-density recording. The purpose is to provide.

According to the embodiment, a substrate, a base layer having a plurality of convex portions formed on the substrate and arranged at a distance of 1 nm to 20 nm, and a tip extending from the convex portion surface of the base layer, respectively. Provided is a perpendicular magnetic recording medium comprising an amorphous magnetic recording layer including a plurality of formed magnetic particles, the film surface vertical direction being an easy axis of magnetization, and at least the convex side magnetic particles are separated Is done.

It is sectional drawing which represents typically the structure of the magnetic recording medium concerning embodiment. It is a figure which represents typically a mode that the arrangement pattern of the convex part of a base layer was seen from the top. It is a figure which represents typically a mode that the arrangement pattern of the convex part of a base layer was seen from the top. It is a figure which represents typically a mode that the arrangement pattern of the convex part of a base layer was seen from the top. It is sectional drawing showing the example of the shape of the convex part of a base layer. It is sectional drawing showing the example of the shape of the convex part of a base layer. It is sectional drawing showing the example of the shape of the convex part of a base layer. It is sectional drawing showing the example of the shape of the convex part of a base layer. It is a figure showing an example of the manufacturing method of the magnetic-recording medium based on embodiment. It is a figure showing an example of the manufacturing method of the magnetic-recording medium based on embodiment. It is a figure showing an example of the manufacturing method of the magnetic-recording medium based on embodiment. It is a figure showing an example of the manufacturing method of the magnetic-recording medium based on embodiment. It is a figure showing an example of the manufacturing method of the magnetic-recording medium based on embodiment. It is a graph showing the magnetization curve made | formed of the perpendicular magnetic recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment. It is a figure showing another example of the manufacturing method of the magnetic-recording medium concerning embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

  The perpendicular magnetic recording medium according to the first embodiment includes a substrate, an underlayer formed on the substrate, and a magnetic recording layer having an axis of easy magnetization in the direction perpendicular to the film surface formed on the underlayer.

  The underlayer has a plurality of convex portions arranged at a distance of 1 nm to 20 nm.

  The magnetic recording layer is an amorphous magnetic recording layer including a plurality of magnetic particles each formed so as to spread from the surface of the convex portion of the underlayer, and at least the magnetic particles on the convex portion side are separated. According to the embodiment, a magnetic recording medium having a structure in which convex portions arranged at a predetermined distance on a substrate are formed and an amorphous recording layer is deposited thereon can be obtained. The amorphous recording layer has a columnar structure according to the convex portion, and the shape is deposited so that the tip extends from the surface of the convex portion, and can be continuous on the outermost layer. The magnetic recording medium having such a structure has not a domain wall motion type magnetization reversal mode like a normal amorphous recording layer but a simultaneous rotation type magnetization reversal mode like a granular structure. Since the domain wall is pinned and stabilized by the air gap, it can be used as a magnetic recording medium for high-density recording.

The method for manufacturing a perpendicular magnetic recording medium according to the second embodiment is an example of a process for manufacturing the perpendicular magnetic recording medium according to the first embodiment, and a processing underlayer is formed on a substrate.
A fine particle dispersion is applied onto the processing substrate to form a single particle layer, and the processing substrate is etched through the fine particles to form an underlayer having a convex portion, and the surface of the convex portion is amorphous. Depositing a magnetic recording layer.

  Furthermore, the method of manufacturing the perpendicular magnetic recording medium according to the third embodiment is another example of the manufacturing process of the perpendicular magnetic recording medium according to the first embodiment, and includes particles and grain boundaries on the substrate. Form an underlayer for processing using a metal compound having a eutectic structure, etch to leave particles of the eutectic structure, form an underlayer having convex portions, and deposit an amorphous magnetic recording layer on the convex surface Including.

  In addition, according to the magnetic recording medium according to the other embodiment, in the magnetic recording medium according to the first embodiment, the antioxidant layer can be provided between the base layer having the convex portion and the amorphous magnetic recording layer. .

  Furthermore, according to the method for manufacturing a magnetic recording medium according to another embodiment, in the method for manufacturing a magnetic recording medium according to the second and third embodiments, the oxidation layer is formed before the amorphous magnetic recording layer is deposited. The process of carrying out can be further included.

Amorphous materials have the advantage that they can easily trace irregularities during sputtering. However, many amorphous magnetic materials tend to oxidize because they contain rare earths. For example, when an amorphous magnetic material such as TbFeCo is laminated on the underlying layer SiO ₂ having a convex portion, Tb tends to oxidize by taking oxygen atoms from SiO ₂ and the magnetostatic characteristics may change. This can be prevented by changing SiO ₂ to a non-oxide such as SiN _x .

  Further, when the underlayer having a convex portion has an oxide or a hydroxyl group during the processing process, the same change in magnetic characteristics may occur. Even in such a case, an antioxidant layer can be sandwiched between the base layer having a convex portion and the amorphous magnetic recording layer. Various materials can be used for the anti-oxidation layer. For example, when crystalline Pd is used, crystal grains are generated, and it tends to be difficult to trace the shape of the uneven base on the recording layer. For this reason, an amorphous material can be used as an antioxidant layer. By using an amorphous material similar to that of the magnetic recording layer for the oxidation preventing layer, the underlying shape can be traced while preventing oxidation. A medium having such an antioxidant layer and a magnetic recording layer can reduce jitter noise due to low particle size dispersion, and can also have environmental stability.

<Amorphous recording layer material>
The amorphous magnetic recording layer can be formed using an amorphous rare earth element / transition metal (R-TM) alloy and an additive element.

  As the rare earth element, any of Nd, Sm, Gd, Tb, and Dy can be used.

  As the transition metal, Fe, Co, Ni, or the like can be used.

As an additive element, Pt, Au, Ag, In, Cr, Ti, Si, and Al can be contained.

  Specifically, there are alloys such as Gd—Co, Gd—Fe, Tb—Fe, Gd—Tb—Fe, Tb—Co, Tb—Fe—Co, Nd—Dy—Fe—Co, and Sm—Co.

  When the rare earth is a light rare earth (Nd or the like), it has a magnetization parallel to the transition metal, so that it becomes a ferromagnetic material. When the rare earth is heavy rare earth (Gd, Tb, Dy), it has a magnetization opposite to that of the transition metal, so that it becomes a ferrimagnetic material. When the ferrimagnetic material is used, the saturation magnetization Ms is lowered, so that the coercive force Hc can be increased. Examples of the transition metal include Fe, Co, and Ni. In the case of Ni, the Curie temperature Tc tends to be lower than room temperature.

  Oxidation of the magnetic material can be suppressed by mixing a small amount of easily oxidizable materials such as Cr, Si, Ti, Al, and In with these alloys. Moreover, even if it mixes a small amount of noble metals, such as Au, Pt, and Ag, the oxidation suppression effect is acquired. The additives as described above can be mixed in a composition ratio of preferably up to 30%, more preferably up to 10% of all elements. When there are too many additives, there exists a tendency for the fall of saturation magnetization Ms and the fall of perpendicular magnetic anisotropy Ku.

  In an embodiment, a TbCo alloy can be used.

  Among the TbCo alloys, it is possible to use TbCoCr which does not use Fe that is relatively easily oxidized but has a Tb content smaller than the compensation composition and a transition metal composition ratio increased.

  The amorphous recording layer can be deposited with a film thickness of 3 nm or more and 30 nm or less. If it is 3 nm or less, an effective perpendicular magnetization film cannot be obtained due to the influence of the initial layer, and the magnetic recording volume tends to be insufficient. If it exceeds 30 nm, the head magnetic field necessary for magnetization reversal tends to be insufficient.

<Amorphous recording layer shape>
FIG. 1 is a cross-sectional view schematically showing the configuration of the magnetic recording medium according to the embodiment.

  The amorphous recording layer 5 is deposited on a base layer 2 provided on the substrate 1 and has a columnar structure as shown in FIG. The recording layer 5 starts to be deposited in a state of being separated from each other by the convex portion 3 of the underlayer 2, but as the film thickness increases, the size of the magnetic particles increases, the area of the gap 4 becomes narrower, and finally the magnetic particles They tend to bond together. The magnetic particles may be bonded in the region of the outermost layer, or may be columnar grown without being bonded. However, for example, in the case where only the lowermost layer 2 nm of the film thickness of 20 nm is divided and the subsequent portion is a uniform amorphous film, it is difficult to obtain the effect of the embodiment. The regions separated from each other are preferably at least 1/3 of the film thickness. This separation state can be observed by a method such as a cross-sectional TEM (Transmission Electron Microscope).

  For example, when TbCoCr is grown on the underlayer, the structure of the underlayer is maintained up to a thickness of about 30 nm, but beyond this, a columnar structure composed of a plurality of particles bonded to each other is obtained. Therefore, it is preferable to form the recording layer with a film thickness of 30 nm or less.

  In addition, like the amorphous recording layer 5 in the embodiment of FIG. 1, a magnetic layer that is on the underlayer 2 and is completely or partially isolated may be expressed as “magnetic particle”. . Magnetic particles are also used to refer to granular parts of the granular structure. It is different from the fine particles used in the template.

<Magnetic properties of amorphous recording layer>
The magnetic recording medium of the embodiment can exhibit a magnetization rotation type magnetic characteristic. The magnetic characteristics can be measured with a vibrating sample magnetometer (VSM) or a Kerr effect measuring device.

  The coercive force Hc of the perpendicular magnetic recording layer can be 2 kOe or more. When the coercive force Hc is less than 2 kOe, it tends to be difficult to obtain a high surface recording density.

  The perpendicular squareness ratio of the perpendicular magnetic recording layer can be 0.9 or more. Here, the perpendicular squareness ratio is obtained by dividing the residual magnetization Mr by the saturation magnetization Ms. If the vertical squareness ratio is less than 0.9, the crystal orientation may be deteriorated, or a structure with partially reduced thermal stability may be formed.

If the magnetic field at the intersection of the tangent to the magnetization curve near Hc and the negative saturation value is the nucleation magnetic field Hn, Hn is smaller than Hc, but the reproduction output, thermal fluctuation resistance, information erasure resistance during adjacent track recording, etc. From the viewpoint, it is preferably as large as possible. However, increasing Hn means increasing the slope α of the magnetization curve in the vicinity of Hc, which is not preferable because the S / N ratio tends to decrease.

In general, the inclination α of the magnetization curve in the vicinity of the coercive force Hc is expressed as the following equation (1).

α = 4πdM / dH | H = Hc (1)
Here, M represents magnetization, and H represents an external magnetic field. In a granular-type perpendicular magnetic recording medium that is currently in practical use, α is about 2 because generally better recording / reproducing characteristics can be obtained by slightly increasing the interparticle coupling. However, basically, a weaker interparticle bond tends to obtain a higher S / N ratio at a higher linear recording density. In a granular type perpendicular magnetic recording medium, a strong particle whose α is larger than 3. Interbonding is not preferred. When α is 5 or more, the magnetic particles are not independent of magnetization reversal, but are more likely to be reversed by being pulled by the reversal of adjacent particles.

<Antioxidation layer>
An antioxidant layer can be further provided between the uneven base and the amorphous recording layer. The anti-oxidation layer plays a role of preventing movement of the surface contamination during the preparation of the uneven base to the amorphous recording layer which is easy to react. Examples of such surface stains include oxygen, oxides, hydroxides, and rarely nitrides, chlorides, fluorides, and the like. For this reason, it is preferable to use a material that does not react with the recording layer alone. Specific examples include noble metals such as Pd, Ru, Pt, Au, Cu, and Ag, and transition metals such as Ti, Cr, Fe, Co, Ni, Ta, and W. Furthermore, in order to improve the traceability of the shape, it is preferable that the material of the antioxidant layer does not have crystal grains. The materials listed above do not have very large crystal grains when deposited with a thickness on the order of several nm, but some of them already have crystal grains with a diameter of 5 to 6 nm at a thickness of about 10 nm. Since the crystal grains of the film are not one-to-one with the shape of the irregular base, the amorphous recording layer tends to grow along the crystal grains of the antioxidant layer. In order to solve this problem, it is preferable to make the material amorphous when the antioxidant layer is thickened. For example, Ni-Ta, Cr-Ti, Zr-Fe, etc. are typical amorphous materials. At least one metal selected from the first metal group consisting of Ti, Ta, Hf, Nb, and Zr, and a second metal consisting of Cr, Fe, Co, Ni, Cu, Mo, Rh, Pd, and Ir An amorphous film can be obtained by sputtering a combination with at least one metal selected from the group. The comparison of the shape with the uneven substrate can be confirmed by observation using a scanning electron microscope (SEM) or TEM of a plane / cross section.

  The amorphous material is preferably non-magnetic. If there is magnetism, the magnetic properties of the amorphous material tend to change due to oxidation, which leads to the magnetic properties of the continuously grown recording layer.

  The thickness of the antioxidant layer is preferably thicker from the viewpoint of preventing oxidation. For example, if the antioxidant layer is less than 1 nm, the film is not continuously deposited, and the effect of preventing oxidation tends to decrease. However, if it is too thick, the uneven shape tends to be flattened. For example, when the antioxidant layer exceeds 30 nm, the film is continuous, and the amorphous recording layer has a domain wall motion type magnetic characteristic. For the above reasons, the antioxidant layer is preferably in the range of 1 nm to 30 nm.

<Underlayer shape>
FIG. 2 to FIG. 4 are diagrams schematically showing the arrangement pattern of the convex portions of the underlayer as viewed from above.

  The arrangement pattern of the protrusions 3 of the underlayer is preferably regular. For example, when the arrangement pattern of the protrusions 3 of the underlayer is viewed from above, as shown in FIG. 2, a circular (or polygonal) pattern arranged at a close pitch of 4 to 20 nm, as shown in FIG. A pattern arranged in a square at the same pitch is preferable.

  If the arrangement pitch is wider than 20 nm, the recording density of the magnetic recording medium tends to decrease. If it is less than 4 nm, the recording tends to disappear due to the effect of thermal fluctuation.

  Here, the pitch of the convex portions in the array pattern is represented by the distance between the centers of the convex portions. These patterns may have, for example, a domain of several hundred nm or more, such as a region surrounded by the boundary lines 101 and 102 as shown in FIG. 4, that is, a collection of regularly arranged patterns. There is no need.

  The depth of the grooves of the convex array is preferably 3 nm or more and 30 nm or less. When the depth of the groove is less than 3 nm, the sputtered atoms enter the groove portion and prevent the isolated magnetic particles from being isolated. If it exceeds 30 nm, the distance from the soft magnetic backing layer becomes too large, and the recording density tends to decrease.

  The underlayer has a plurality of convex portions arranged at a distance of 1 nm to 20 nm. This means that the groove distance between the convex portions is 1 nm to 20 nm.

  When the distance of the groove between the convex portions is less than 1 nm, the deposited magnetic film is supported on the left and right without being divided by the groove, and tends to be continuously formed. For this reason, a pattern having a groove with a depth of less than 3 nm and a width of less than 1 nm tends to be substantially the same as a flat substrate.

  5 to 8 are cross-sectional views showing examples of the shape of the convex portions of the base layer.

  Examples of the uneven shape include a semicircular shape 21 as shown in FIG. 5, a trapezoid 22 as shown in FIG. 6, a cylindrical shape 23 as shown in FIG. 7, and a V-shaped groove 24 as shown in FIG. It is done. However, in the case of a trapezoid, when the angle θ of the trapezoidal side surface with respect to the direction parallel to the groove bottom of the underlayer is a so-called taper of less than 30 degrees, the trapezoidal surface tends to be oriented perpendicularly to the side surface and not a perpendicular magnetic film with respect to the substrate is there.

<Underlayer material>
Various materials in consideration of corrosivity and durability can be used for the underlayer.

  Examples of materials used for the underlayer include inorganic materials such as C and Si, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Ru, Rh, Pd, Examples thereof include metal materials such as Ag, In, Hf, Ta, W, Ir, Pt, Au, or alloys thereof (CrTi, NiW, etc.), oxides / nitrides, and the like. In particular, when a material such as C, Al, Ta, Fe, Pt, or Au is used, the ease of forming irregularities and the affinity for the amorphous material tend to be good.

A buffer layer may be sandwiched between the underlayer and the amorphous magnetic material. For example, when an amorphous recording layer such as TbFeCo is directly deposited on a material such as Ag, Ag may diffuse and erase the perpendicular magnetization. On the other hand, when the buffer layer is provided, the reaction between the underlayer and the amorphous magnetic layer can be suppressed. Further, when an amorphous recording layer such as TbFeCo is directly deposited on Au processed by the RIE process using CF ₄ gas, the same reaction occurs because the surface of the Au base is contaminated by fluorine. If the amorphous magnetic layer is laminated thickly, this problem may be solved, but if the distance from the soft magnetic backing layer is extended, the distance from the soft magnetic backing layer will be too wide, which tends to cause a decrease in recording density. is there.

  In such a case, by forming a buffer layer material such as Ta, Al, or NiTa with a thickness of several nanometers, diffusion can be suppressed and a perpendicular magnetization film can be obtained.

<Processing method of underlayer>
The underlayer can be processed by various methods.

  For example, by arranging fine particles having a diameter of several nanometers to several tens of nanometers uniformly on a substrate, it is possible to form a ground layer with unevenness. By using fine particles having a small particle size dispersion, the particle size dispersion of the underlayer can also be lowered. Similar effects can be obtained by using self-organizing materials such as diblock copolymers, alumina nanoholes, mesoporous materials, and the like.

  When anodized alumina is used as a template, a regular nanohole can be obtained by applying an electric field in an acidic solution after depositing an Al thin film in advance on a substrate to produce an electrode.

  The mesoporous material will be described using an example of mesoporous silica. TEOS (Tetraethoxysilane), triblock copolymer, HCl, ethanol, and water are mixed, diluted to a concentration to form a single layer, and applied to a substrate by a spin coating method. By removing the block copolymer by baking, a regular pattern with pores of several nm size can be obtained. In both cases, the planar image is the same pattern as in FIG. 2 except that the concave and convex portions are reversed and the reference numeral 3 is concave as in the case of fine particles and diblock copolymers. It is possible to embed a metal material in the recess by electroforming or sputtering and to reverse the unevenness by an etching process.

  A eutectic structure such as AlSi or AgGe can also be applied. Since there is no unevenness in the eutectic structure, it is necessary to provide unevenness by an etching process.

  The listed materials can be applied to a substrate on which an underlayer material such as C (carbon) is deposited, and the surface can be roughened by an etching process such as RIE to form an underlayer. When transferring to a substrate, the hardness and adhesion are superior to using fine particles or organic materials directly for the underlayer.

Various dry etching processes can be used for patterning the underlayer as required. For example, when using C, etching with O ₂ plasma is preferable. In the case of Si, Ge, Ti, Fe, Co, Cr, Ta, W, Mo, etc., etching using a halogen gas such as CF ₄ , CF ₄ / O ₂ , CHF ₃ , SF ₆ , or Cl ₂ may be used. it can. For noble metals that are difficult to etch with O ₂ or halogen, a technique such as ion milling using a rare gas is used. When a halogen gas process is used, it is necessary to thoroughly wash with water after the process.

  For patterning the underlayer, not only dry etching but also wet etching can be used. By using wet etching, a large amount of substrates can be processed at a time, and productivity is improved. For example, hydrofluoric acid or an alkaline etching solution can be used to remove the grain boundaries of eutectic Si or Ge.

<Fine particles>
The size of the fine particles used for processing the underlayer can be about 1 nm to several tens of μm in particle size. Most of the shapes are spherical, but other than the spherical shape, for example, a tetrahedron, a rectangular parallelepiped, an octahedron, a triangular prism, a hexagonal prism, a cylindrical shape, and the like can be given. When considering the regular arrangement, the symmetry of the shape can be increased. The fine particles preferably have a small particle size dispersion in order to improve the alignment during coating. For example, when used for an HDD medium, the particle size dispersion is preferably 20% or less, more preferably 15% or less. When the particle size dispersion is small, the jitter noise of the HDD medium can be reduced. If the dispersion exceeds 20%, jitter noise increases and the medium S / N tends to decrease.

The material of the fine particles is preferably a metal, an inorganic material, or a compound thereof. Specific examples include Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Sn, Mo, Ta, and W. These oxides, nitrides, borides, carbides, sulfides, and the like can also be used. The fine particles can be either crystalline or amorphous. For example, core-shell type particles may be used, such as a structure in which Fe is surrounded by FeO _x (x = 1 to 1.5). In the case of the core-shell type, materials having different compositions such that SiO ₂ covers the periphery of Fe ₃ O ₄ may be used. Further, the surface of a metal core shell type such as Co / Fe may be oxidized to have a structure of three or more layers such as Co / Fe / FeO _x . If the main component is as mentioned above, a compound with a noble metal such as Pt or Ag can be used, for example, Fe ₅₀ Pt ₅₀ .

  Since the fine particles are arranged in a solution system, the fine particles are used in a state where a protective group is attached and stably dispersed in the solution. For application to the substrate, the solvent boiling point is preferably 200 ° C. or lower, more preferably 160 ° C. or lower. Aromatic hydrocarbon, alcohol, ester, ether, ketone, glycol ether, alicyclic hydrocarbon, aliphatic hydrocarbon and the like can be mentioned. From the viewpoints of boiling point and coatability, specifically, hexane, toluene, xylene, cyclohexane, cyclohexanone, propylene glycol monomethyl ether acetate (PGMEA), diglyme, ethyl lactate, methyl lactate, tetrahydrofuran (THF) and the like are used. The fine particles are dispersed in these solvents and applied to the substrate as a single layer by a spin coating method, a dip coating method, an LB (Langmuir-Blodgett) method, or the like.

<Eutectic>
The eutectic structure is produced by vapor deposition or sputtering of two or more elements. A typical example is an eutectic structure of Al—Ge or Ag—Ge. For example, if Ag—Ge in which Ag is arranged in a cylinder shape is used, the desired uneven structure can be obtained. At this time, the composition ratio of the target is preferably about Ag ₂₀ Ge _{80 to} Ag ₅₀ Ge ₅₀ . By immersing Ag-Ge in hydrofluoric acid having a concentration of 10% for several minutes, it is possible to dissolve Ge and selectively leave only Ag.

<Embedding process>
The medium of the embodiment can be subjected to a process of flattening by embedding. For embedding, sputtering using an embedding material as a target is used because of its simplicity, but other methods such as plating, ion beam evaporation, chemical vapor deposition (CVD), and atomic layer deposition (ALD) are also used. You can also. If CVD or ALD is used, the film can be formed at a high rate on the side wall of the high taper magnetic recording layer. Also, by applying a bias to the substrate during the embedded film formation, even a high aspect pattern can be embedded without a gap. A so-called resist such as SOG (Spin-On-Glass) or SOC (Spin-On-Carbon) may be spin-coated and cured by heat treatment.

SiO ₂ can be used as the embedding material, but the embedding material is not limited to this, and materials as long as hardness and flatness allow are usable. For example, amorphous metals such as NiTa and NiNbTi are easy to flatten and can be used as an embedding material. When a material containing C as a main component, for example, CN _x , CH _x or the like is used, the hardness is increased and the adhesion to DLC can be improved. Oxides and nitrides such as SiO ₂ , SiN _x , TiO _x , and TaO _x can also be used as the filling material. In the above compounds, 0 <x ≦ 3. However, when a reaction product is formed with the magnetic recording layer in contact with the magnetic recording layer, one protective layer can be sandwiched between the buried layer and the magnetic recording layer. Examples of such a protective layer include non-oxides of protective layers such as Si, Ti, and Ta.

<Protection film formation and post-treatment>
The carbon protective film can be formed by a CVD method in order to improve the coverage to the unevenness. Alternatively, the film can be formed by sputtering or vacuum evaporation. According to the CVD method, a DLC film containing a large amount of sp ³ bonded carbon is formed. If the film thickness is 2 nm or less, the coverage is poor, and if it is 10 nm or more, the magnetic spacing between the recording / reproducing head and the medium increases and the SNR decreases, which is not preferable. A lubricant can be applied on the protective film. As the lubricant, for example, perfluoropolyether, fluorinated alcohol, fluorinated carboxylic acid and the like can be used.

<Soft magnetic backing layer>
The soft magnetic underlayer (SUL) has a part of the function of the magnetic head for passing a recording magnetic field from a single pole head for magnetizing the perpendicular magnetic recording layer in the horizontal direction and returning it to the magnetic head side. The recording layer has a function of applying a steep and sufficient vertical magnetic field to improve the recording / reproducing efficiency.

  For the soft magnetic underlayer, a material containing Fe, Ni, or Co can be used. Examples of such materials include FeCo alloys such as FeCo and FeCoV, FeNi alloys such as FeNi, FeNiMo, FeNiCr, and FeNiSi, FeAl alloys, FeSi alloys such as FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, and FeAlO. Examples thereof include FeTa, FeTaC, and FeTaN, and FeZr alloys such as FeZrN. It is also possible to use a material having a fine crystal structure such as FeAlO, FeMgO, FeTaN, FeZrN or the like having a granular structure in which fine crystal particles are dispersed in a matrix and containing 60 at% or more of Fe.

  As another material of the soft magnetic backing layer, a Co alloy containing Co and at least one of Zr, Hf, Nb, Ta, Ti, and Y can also be used. The Co alloy preferably contains 80 at% or more of Co. In such a Co alloy, an amorphous layer is easily formed when the film is formed by sputtering. Since the amorphous soft magnetic material does not have magnetocrystalline anisotropy, crystal defects, and grain boundaries, it exhibits very excellent soft magnetism and can reduce the noise of the medium. Examples of the amorphous soft magnetic material include CoZr, CoZrNb, and CoZrTa alloys.

  An underlayer can be further provided under the soft magnetic backing layer in order to improve the crystallinity of the soft magnetic backing layer or the adhesion to the substrate. Examples of the material for such an underlayer include Ti, Ta, W, Cr, Pt, alloys containing these, and oxides or nitrides thereof.

  In order to prevent spike noise, the soft magnetic backing layer can be divided into a plurality of layers and antiferromagnetically coupled by inserting Ru of 0.5 to 1.5 nm. In addition, a hard magnetic film having in-plane anisotropy such as CoCrPt, SmCo, and FePt, or a pinned layer made of an antiferromagnetic material such as IrMn and PtMn, and a soft magnetic layer can be exchange-coupled. In order to control the exchange coupling force, a magnetic film (for example, Co) or a nonmagnetic film (for example, Pt) can be stacked on and under the Ru layer.

Example 1
9A to 9E are views showing an example of a method for manufacturing a magnetic recording medium according to the embodiment.

First, as shown in FIG. 9A, a 50 nm thick soft magnetic backing layer 7 made of CoZrNb and a 20 nm thick processing base layer 2 made of C were formed on a glass substrate 1. Thereon to FeO _x particles 8 dispersed diameter 7nm in PGMEA solvent with an acrylic monomer FeO _x particles 8. The coating is a single layer, FeO _x particles 8 acrylic resin layer thereof provided around 9 The FeO _x fine particle coating layer 11 containing Further, polystyrene having a molecular weight of 1000 was attached to the fine particles 8 as a protective group, and was arranged on the substrate 1 at a pitch of 10 nm. After the arrangement, a hexagonal close-packed pattern as shown in FIG. 2 was obtained.

As shown in FIG. 9B, by dry etching, the C underlayer 2 is etched together with the acrylic resin layer 9 around the fine particles 8 using the FeO _x fine particles 8 as a mask to obtain a C underlayer 2 made of convex portions on the substrate 1. It was. In this step, for example, by using an inductively coupled plasma (ICP) RIE apparatus, O ₂ gas is used as a process gas, the chamber pressure is 0.1 Pa, the coil RF power and the platen RF power are 40 W and 40 W, respectively, and the etching time For 40 seconds. By this process, the C underlayer 2 was etched, and the C underlayer 2 composed of convex portions having a height of 15 nm was formed on the substrate 1 and the soft magnetic layer 7.

As shown in FIG. 9C, the FeO _x fine particles 8 were removed from the substrate 1. By immersing the substrate 1 in hydrochloric acid having a concentration of 1 wt% for 10 minutes, the FeO _x fine particles 8 were dissolved in hydrochloric acid and removed from the substrate 1. The substrate 1 was washed with pure water to prevent corrosion due to residual hydrochloric acid.

As shown in FIG. 9D, an amorphous recording layer was deposited on the C underlayer 2 on the substrate 1. First, Ta, which is a buffer layer (not shown), was deposited with a thickness of 2 nm, and then a Tb ₁₅ Co ₈₁ Cr ₄ amorphous recording layer 5 was deposited with a thickness of 20 nm.

  As shown in FIG. 9E, the target magnetic recording medium 20 is obtained by depositing the C protective film 6 with a film thickness of 4 nm on the recording layer 5 by CVD (chemical vapor deposition) and applying a lubricant (not shown). It was.

  The magnetic recording medium thus obtained was evaluated using a Kerr effect measuring device.

  FIG. 10 is a graph showing a magnetization curve measured by the Kerr effect measuring apparatus.

  In the figure, reference 103 shows the magnetization curve of Example 1.

  As shown in the figure, it was confirmed that the squareness ratio 1 and Hc were 4 kOe, Hn = 2 kOe, and Hs = 8 kOe. Further, the slope α of the loop near the coercive force Hc was 1.9. From the magnetization curve, it is estimated that it is not a domain wall motion type, but a reversal mode in which magnetically isolated magnetic particles rotate and rotate. When a magnetic recording medium was incorporated into a spin stand and writing was performed at a recording density of 500 kFCI, a clear reproduction waveform was confirmed.

Comparative Example 1
A magnetic recording medium was produced in the same manner as in Example 1 except that an Al layer was formed to a thickness of 2 nm instead of applying the FeO _x fine particles 8. The roughness of the Al layer was 3 nm in Rmax and 0.36 nm in Ra. Here, Rmax is the maximum value of the unevenness when the surface unevenness is measured using an atomic force microscope (AFM) at 10 μm square. Ra is the average of the absolute values of the irregularities.

Tb ₁₅ Co ₈₁ Cr ₄ was deposited to a thickness of 20 nm on Al, and a C protective film was deposited in the same manner as in Example 1. The magnetic recording medium thus obtained was evaluated using the Kerr effect measuring apparatus in the same manner as in Example 1. FIG. 10 similarly shows a graph showing the magnetization curve measured by the Kerr effect measuring apparatus.

  In the figure, reference 104 shows the magnetization curve of Comparative Example 1.

  As shown in the figure, it was confirmed that the squareness ratio 1 and Hc were 4 kOe as in Example 1. However, it was found that the inclination of the Kerr loop in Hc is very large and is a magnetization reversal due to domain wall movement.

  When this magnetic recording medium was incorporated into a spin stand and writing was performed at a recording density of 500 kFCI, a reproduced waveform was not confirmed. The reason is considered that the surface unevenness formed of Al has a poor force for pinning the domain wall and recording could not be performed.

  From the above results, it was found that the medium manufactured by the manufacturing method of the embodiment has sufficient performance as a magnetic recording medium.

Example 2
FIG. 11A to FIG. 11D are diagrams each showing another example of the method of manufacturing the magnetic recording medium according to the embodiment.

As shown in FIG. 11A, a 50 nm-thick soft magnetic backing layer 7 made of CoZrNb and a 10 nm-thickness processing base layer 14 made of Ag ₃₀ Ge ₇₀ were formed on a glass substrate 1. The underlayer 14 for processing AgGe has a eutectic structure, and Ag particles 12 are arranged in the Ge grain boundaries 13 at a pitch of 8 nm.

  As shown in FIG. 11B, the Ge grain boundaries 13 were removed by wet etching with hydrofluoric acid, and convex portions made of Ag particles 12 were formed on the substrate. By immersing in hydrofluoric acid having a concentration of 1% for 1 minute, Ge is removed, and a convex portion having a height of 10 nm is formed on the substrate.

As shown in FIG. 11C, an amorphous recording layer is deposited on the substrate. First, Al, which is a buffer layer (not shown), was deposited with a film thickness of 2 nm, and then a Tb ₂₄ Fe ₅₂ Co ₂₄ layer 5 was deposited with a film thickness of 15 nm.

  As shown in FIG. 11D, the magnetic recording medium 30 was obtained by depositing the C protective film 6 with a film thickness of 4 nm on the recording layer by CVD (chemical vapor deposition) and applying a lubricant (not shown).

  The magnetic recording medium thus obtained was evaluated by a Kerr effect measuring apparatus, and it was confirmed that the squareness ratio 1 and Hc were 3 kOe. The loop inclination α was 2.5. When a magnetic recording medium was incorporated into a spin stand and writing was performed at a recording density of 500 kFCI, a clear reproduction waveform was confirmed.

Examples 3-1, 3-2, 3-3
The amorphous recording layer is formed in the same manner as in Example 1 except that the RIE processing process conditions of the underlayer are changed and the groove widths that are the distances between the convex portions are 5 nm, 2 nm, 1 nm, and 0.5 nm. A patterned medium having the following characteristics was prepared.

  Here, after the medium was AC demagnetized, the minor loop was measured to determine the magnetic domain size.

  The magnetic domain size is a method for estimating the magnetization reversal volume from a minor loop. A granular medium having a particle diameter of 9 nm is about 20 to 30 nm. It is important that this value is the same as that of the granular material because it is often not the actual size of one magnetic particle. As a result, the MH loop had an inclination until the groove width was 1 nm, but the domain size could not be measured when the groove width was 0.5 nm. This is because the magnetic characteristics of the domain wall motion type are 0.5 nm.

Further, a cross-sectional TEM was measured to examine how much the particles were divided with respect to the total film thickness. When the groove width was 1 nm or more, it was observed that the particles were divided along the underlayer, but when the groove width was 0.5 nm, the particles grew as a flat film.

  From the above results, it was found that a magnetic recording medium having a groove width of 1 nm or more, a divided film thickness of 30% or more of the total film thickness, and an appropriate domain size can be obtained.

Examples 4-1, 4-2, 4-3, 4-4
Implemented except changing the conditions of the RIE processing process of the underlayer and producing semicircular, trapezoidal, cylindrical, and V-shaped grooves as in Examples 4-1 to 4-4 in Table 2 below. A patterned medium having an amorphous recording layer was produced in the same manner as in Example 1. The groove width and groove depth measured by the cross-sectional TEM are as shown in Table 2 below. It was judged by measuring the inclination α of the magnetization curve with VSM whether or not the particles were sufficiently divided. α ≧ 5 is x, 5>α> 3 is Δ, and 3 ≧ α is o. It was confirmed that the particles were divided in all the underlayers.

  From this result, it was found that the target amorphous recording layer was obtained by using the underlayer of Example 4.

Examples 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5-8, 5-9 In the same manner as in Example 1, an amorphous recording layer was formed. A patterned medium having the same was produced. However, the material of the amorphous recording layer was changed to have a composition as shown in Table 3. It was judged by measuring the inclination α of the loop with VSM whether or not the particle division was sufficiently advanced. α ≧ 5 is x, 5>α> 3 is Δ, and 3 ≧ α is o.

  From the above results, it was possible to obtain a medium in which desired particles were divided even in the case where various materials were added to the amorphous recording layer.

Examples 6-1, 6-2, 6-3, 6-4
Table 1 shows the results obtained by depositing the amorphous recording layer of the embodiment on various underlayers and examining α. The amorphous recording layer was Tb ₁₅ Co ₈₁ Cr ₄ with a thickness of 20 nm, and was deposited on the Ta buffer layer with a thickness of 2 nm. The protective layer was 6 nm CN.

  In Example 6-1 and Example 6-2, the C underlayer was etched using Fe particles having a diameter of 8 nm as a template, and the particles were peeled off. The irregularities are 5 nm and 10 nm, respectively. In Example 6-3, an AlSi eutectic was deposited to 10 nm by sputtering, and only Si was removed by wet etching, leaving Al. In Example 6-4, Au fine particles were applied as a single layer on a substrate, and an amorphous recording layer was deposited thereon. As a comparative example, a base layer was not processed and Ta and Au were each deposited to 2 nm. The irregularities are 1.5 nm and 2 nm in Rmax, respectively.

All the MH loops were measured with a Kerr effect measuring device, and the slope α was calculated. Those using the processed underlayer have a small α and are all less than 5. This indicates a magnetization rotation type characteristic. On the other hand, in the case of the non-working underlayer, all α were 5 or more, indicating domain wall motion type characteristics.

Example 7
12A to 12F are views showing still another example of the method for manufacturing the magnetic recording medium according to the embodiment.

First, as shown in FIG. 12A, a 50 nm thick soft magnetic backing layer 7 made of CoZrNb and a 20 nm thick processing base layer 2 made of C were formed on a glass substrate 1. Thereon to FeO _x particles 8 dispersed diameter 7nm in PGMEA solvent with an acrylic monomer FeO _x particles 8. The coating is a single layer, FeO _x particles 8 acrylic resin layer thereof provided around 9 The FeO _x fine particle coating layer 11 containing Further, polystyrene having a molecular weight of 1000 was attached to the fine particles 8 as a protective group, and was arranged on the substrate 1 at a pitch of 10 nm. After the arrangement, a hexagonal close-packed pattern as shown in FIG. 2 was obtained.

As shown in FIG. 12B, by dry etching, the C underlayer 2 together with the polystyrene around the fine particles 8 was etched using the FeO _x fine particles 8 as a mask to obtain a C underlayer 2 composed of convex portions on the substrate 1. In this step, for example, using an ICP-RIE apparatus, O ₂ gas is used as the process gas, the chamber pressure is 0.1 Pa, the coil RF power and the platen RF power are 40 W and 40 W, respectively, and the etching time is 40 seconds. It was conducted. By this process, the C underlayer 2 was etched, and the C underlayer 2 composed of convex portions having a height of 15 nm was formed on the substrate 1 and the soft magnetic layer 7.

As shown in FIG. 12C, the FeO _x fine particles 8 were removed from the substrate 1. By immersing the substrate 1 in hydrochloric acid having a concentration of 1 wt% for 10 minutes, the FeO _x fine particles 8 were dissolved in hydrochloric acid and removed from the substrate 1. The substrate 1 was washed with pure water to prevent corrosion due to residual hydrochloric acid.

As shown in FIG. 12D, amorphous Ni ₅₀ Ta ₅₀ (hereinafter referred to as NiTa) was deposited on the C underlayer 2 as the anti-oxidation layer 15 of the uneven underlayer. The antioxidant layer 15 was deposited without filling the gaps between the irregularities while tracing the irregularities of the C underlayer 2.

As shown in FIG. 12E, an amorphous recording layer was deposited on the antioxidant layer 15 on the C underlayer 2. Thereafter, a Tb ₁₅ Co ₈₁ Cr ₄ amorphous recording layer 5 was deposited to a thickness of 20 nm.

  As shown in FIG. 12F, the target magnetic recording medium 40 is obtained by depositing a C protective film 6 with a film thickness of 4 nm on the recording layer 5 by CVD (chemical vapor deposition) and applying a lubricant (not shown). It was.

  When the magnetic recording medium thus obtained was evaluated by the Kerr effect measuring apparatus, the squareness ratio 1, Hc was 9 kOe, and the loop inclination α in the vicinity of the coercive force Hc was 2.5. From the magnetization curve, it is estimated that it is not a domain wall motion type, but a reversal mode in which magnetically isolated magnetic particles rotate and rotate. When a magnetic recording medium was incorporated into a spin stand and writing was performed at a recording density of 500 kFCI, a clear reproduction waveform was confirmed.

Examples 8-1, 8-2, 8-3, 8-4, 8-5, 8-6, 8-7, 8-8, 8-9
A magnetic recording medium was produced in the same manner as in Example 7. However, as an oxidation preventing layer, in addition to NiTa (Example 7), Zr ₅₀ Mo ₅₀ (Example 8-1), Ti ₇₅ Cu ₂₅ (Example 8-2), Hf ₆₀ Ni ₄₀ (Example 8- 3), Nb ₄₀ Ir ₆₀ (Example 8-4), Zr ₂₅ Rh ₇₅ (Example 8-5), Pd ₂₅ Zr ₇₅ (Example 8-6), Fe ₃₀ Zr ₇₀ (Example 8-7) Co ₃₀ Zr ₇₀ (Example 8-8) and Cr ₅₀ Ti ₅₀ (Example 8-9) were used. Writing was performed at a recording density of 500 kFCI, and the SNR of the waveform was measured using the same recording / reproducing head. The results are shown in Table 5. The evaluation results were ◎ for 17 dB or more, ○ for 10 dB or more, Δ for 5 dB or more, and × for less than 0 dB. The amorphous recording layer grown on the concavo-convex base showed a good Signal / Noise ratio, and in particular, provided an anti-oxidation layer made of an amorphous material and showed good characteristics.

Examples 9-1, 9-2, 9-3, 9-4, 9-5, 9-6, 9-7, 9-8
A magnetic recording medium was produced in the same manner as in Example 7. However, the NiTa film thickness is 0.5 nm (Example 9-1), 1 nm (Example 9-2), 2 nm (Example 9-3), 5 nm (Example 9-4), 10 nm (Example 9- 5), 20 nm (Example 9-6), 30 nm (Example 9-7), and 50 nm (Example 9-8). Writing was performed at a recording density of 500 kFCI, and the SNR of the waveform was measured using the same recording / reproducing head. The results are shown in Table 6 below. The evaluation results were ◎ for 17 dB or more, ○ for 10 dB or more, Δ for 5 dB or more, and × for less than 0 dB. A medium provided with an anti-oxidation layer made of an amorphous material showed a good Signal / Noise ratio, and in particular, an anti-oxidation layer having a thickness of 1 to 30 nm showed good characteristics.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Underlayer, 3 ... Convex part 3 ... Air gap, 5 ... Amorphous recording layer, 6 ... Protective layer, 7 ... Soft magnetic backing layer, 8 ... Fine particle, 9 ... Resin, 11 ... Fine particle layer, 12 ... Particles, 13 ... grain boundaries, 14 ... eutectic film, 10, 20, 30, 40 ... perpendicular magnetic recording medium,

Claims (34)

substrate,
An underlayer having a plurality of protrusions formed on the substrate and arranged at a distance of 1 nm to 20 nm, and a plurality of magnetic particles each formed so as to spread from the surface of the protrusions of the underlayer And a perpendicular magnetic recording medium comprising an amorphous magnetic recording layer in which the perpendicular direction of the film surface is an easy axis of magnetization and at least the magnetic particles on the convex portion side are separated.   2. The perpendicular magnetic recording medium according to claim 1, wherein tips of the plurality of magnetic particles are in contact with each other, and the magnetic particles on the convex side are separated by 1/3 or more in the film thickness direction.   The perpendicular magnetic recording medium according to claim 1, wherein the pitch distribution of the convex portions is 20% or less. 4. The perpendicular magnetic recording medium according to claim 1, wherein the convex portion has one of a semicircular shape and a trapezoidal cross-sectional shape. 5.   The amorphous magnetic recording layer is formed using a rare earth element-transition metal alloy, and the rare earth element is at least one selected from the group consisting of samarium, gadolinium, terbium, and dysprosium, The perpendicular magnetic recording medium according to claim 1, wherein the perpendicular magnetic recording medium is at least one of iron and cobalt.   The perpendicular magnetic recording medium according to claim 5, wherein the amorphous magnetic recording layer is made of a terbium-cobalt alloy.   The perpendicular magnetic according to claim 5 or 6, wherein the amorphous magnetic recording layer further includes at least one additive element selected from the group consisting of platinum, gold, silver, indium, chromium, titanium, silicon, and aluminum. recoding media.   The perpendicular magnetic recording medium according to claim 7, wherein the additive element is added in an amount of 30 at% or less.   The base layer having the convex portions is carbon, silicon, aluminum, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, hafnium. The perpendicular magnetic recording medium according to claim 1, comprising at least one selected from the group consisting of tantalum, tantalum, tungsten, iridium, platinum, and iron, alloys thereof, and compounds thereof.   The perpendicular magnetic recording medium according to claim 1, wherein the amorphous magnetic recording layer has a thickness of 3 nm to 30 nm.   The perpendicular magnetic recording medium according to claim 1, wherein the convex portion has a height of 3 nm to 20 nm.   The perpendicular magnetic recording medium according to claim 1, wherein the convex portions are arranged at a pitch of 4 nm to 20 nm.   The perpendicular magnetic recording medium according to claim 1, further comprising an antioxidant layer between the underlayer having the convex portion and the amorphous magnetic recording layer.   The perpendicular magnetic recording medium according to claim 13, wherein the antioxidant layer has an amorphous structure.   The antioxidant layer is made of at least one metal selected from the group consisting of titanium, tantalum, hafnium, niobium, and zirconium, and chromium, iron, cobalt, nickel, copper, molybdenum, rhodium, palladium, and iridium. The perpendicular magnetic recording medium according to claim 13, comprising at least one metal selected from the group.   The perpendicular magnetic recording medium according to claim 13, wherein the antioxidant layer has a thickness of 1 nm to 30 nm. The perpendicular magnetic recording medium according to any one of claims 1 to 16, wherein an inclination α of a magnetization curve in the vicinity of a coercive force Hc represented by the following formula (1) is less than 5.
α = 4πdM / dH | H = Hc (1)
In the above formula, M represents magnetization, H represents magnetic field, and Hc represents coercive force. Form an underlayer for processing on the substrate,
A fine particle dispersion is applied on the processing substrate to form a single particle layer,
Etching the processing base through the fine particles to form the base layer having the convex portions,
A method of manufacturing a perpendicular magnetic recording medium, comprising depositing an amorphous magnetic recording layer on a surface of the convex portion. On the substrate, a base layer for processing is formed using a metal compound having a eutectic structure composed of particles and grain boundaries,
Etching so as to leave particles of the eutectic structure, forming a base layer having a convex portion,
A method of manufacturing a perpendicular magnetic recording medium, comprising depositing an amorphous magnetic recording layer on a surface of the convex portion.   20. The method of manufacturing a perpendicular magnetic recording medium according to claim 18, wherein the pitch distribution of the convex portions is 20% or less.   21. The method of manufacturing a perpendicular magnetic recording medium according to claim 18, wherein the convex portion has one of a semicircular shape and a trapezoidal cross-sectional shape.   The amorphous magnetic recording layer is formed using a rare earth element-transition metal alloy, and the rare earth element is at least one selected from the group consisting of samarium, gadolinium, terbium, and dysprosium, The method for manufacturing a perpendicular magnetic recording medium according to any one of claims 18 to 21, wherein the method is at least one of iron and cobalt.   23. The method of manufacturing a perpendicular magnetic recording medium according to claim 22, wherein the amorphous magnetic recording layer is made of a terbium-cobalt alloy.   The perpendicular magnetic according to claim 22 or 23, wherein the amorphous magnetic recording layer further includes an additive element that is at least one selected from the group consisting of platinum, gold, silver, indium, chromium, titanium, silicon, and aluminum. A method for manufacturing a recording medium.   25. The method of manufacturing a perpendicular magnetic recording medium according to claim 24, wherein the additive element is added in an amount of 30 at% or less.   The base layer having the convex portions is carbon, silicon, aluminum, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, hafnium. 26. The method of manufacturing a perpendicular magnetic recording medium according to claim 18, comprising at least one selected from the group consisting of tantalum, tantalum, tungsten, iridium, platinum, iron, alloys thereof, and compounds thereof. .   27. The method of manufacturing a perpendicular magnetic recording medium according to claim 18, wherein the amorphous magnetic recording layer has a thickness of 3 nm to 30 nm.   28. The method of manufacturing a perpendicular magnetic recording medium according to claim 18, wherein the convex portion has a height of 3 nm to 20 nm.   The method for manufacturing a perpendicular magnetic recording medium according to any one of claims 18 to 28, wherein the convex portions are arranged at a pitch of 4 nm to 20 nm.   30. The perpendicular magnetism according to any one of claims 18 to 29, further comprising a step of forming an antioxidant layer on the underlayer having the protrusions before depositing the amorphous magnetic recording layer on the surface of the protrusions. A method for manufacturing a recording medium.   The method for manufacturing a perpendicular magnetic recording medium according to claim 30, wherein the antioxidant layer has an amorphous structure.   The antioxidant layer is made of at least one metal selected from the group consisting of titanium, tantalum, hafnium, niobium, and zirconium, and chromium, iron, cobalt, nickel, copper, molybdenum, rhodium, palladium, and iridium. 32. The method of manufacturing a perpendicular magnetic recording medium according to claim 30, comprising at least one metal selected from the group.   The method for manufacturing a perpendicular magnetic recording medium according to any one of claims 30 to 32, wherein the antioxidant layer has a thickness of 1 nm to 30 nm. 34. The method of manufacturing a perpendicular magnetic recording medium according to claim 18, wherein the slope [alpha] of the magnetization curve in the vicinity of the coercive force Hc represented by the following formula (1) is less than 5.
α = 4πdM / dH | H = Hc (1)
In the above formula, M represents magnetization, H represents magnetic field, and Hc represents coercive force.

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