WO2012164825A1 - 垂直磁気記録媒体およびその製造方法 - Google Patents
垂直磁気記録媒体およびその製造方法 Download PDFInfo
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- WO2012164825A1 WO2012164825A1 PCT/JP2012/002956 JP2012002956W WO2012164825A1 WO 2012164825 A1 WO2012164825 A1 WO 2012164825A1 JP 2012002956 W JP2012002956 W JP 2012002956W WO 2012164825 A1 WO2012164825 A1 WO 2012164825A1
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
- G11B5/7368—Non-polymeric layer under the lowermost magnetic recording layer
- G11B5/7369—Two or more non-magnetic underlayers, e.g. seed layers or barrier layers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/85—Coating a support with a magnetic layer by vapour deposition
-
- G—PHYSICS
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- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/851—Coating a support with a magnetic layer by sputtering
Definitions
- the present invention relates to a perpendicular magnetic recording medium mounted on various magnetic recording devices. More specifically, the present invention relates to a perpendicular magnetic recording medium that can be mounted on a hard disk drive used as an external storage device such as a computer or an AV device and can realize high-density magnetic recording.
- a magnetic recording medium used as a hard disk drive employs a perpendicular magnetic recording system as a technique for realizing higher density of magnetic recording.
- the layer structure is formed, for example, by sequentially laminating an underlayer, a magnetic recording layer, a protective film, and a liquid lubricating layer on a nonmagnetic substrate.
- the recording bit recorded on the perpendicular magnetic recording medium has an advantage that the magnitude of the residual magnetization becomes more stable as the recording density is higher due to the influence of the demagnetizing field of the adjacent recording bit.
- the perpendicular magnetic recording medium can also realize excellent thermal fluctuation resistance.
- a medium having a soft magnetic backing layer between an underlayer and a substrate is used.
- the soft magnetic underlayer steeply draws the magnetic field generated from the magnetic head, the magnetic field gradient is reduced and the influence of signal writing spread is reduced (for example, “perpendicular magnetic recording "The latest technology", supervised by Akihisa Nakamura, see CMC Publishing (2007), pages 127-131 (Non-Patent Document 1)).
- Japanese Patent Application Laid-Open No. 2008-34060 discloses a perpendicular recording medium including a soft magnetic backing layer, an orientation control underlayer having an fcc structure mainly composed of NiCr and NiCu, and a recording layer made of a perpendicular magnetization film having an hcp structure. Is disclosed (see Patent Document 1). Japanese Patent Laid-Open No. 2008-34060 discloses that at least one of Fe, Al, Rh, Pd, Ag, Pt, and Au is further added to the orientation control underlayer, Ta, W, Mo A non-magnetic amorphous layer mainly composed of one of the above is used below the orientation control underlayer, and further, a Ru alloy or Ti is used between the orientation control underlayer and the recording layer. The use of a single orientation control interlayer is disclosed.
- Japanese Patent Laid-Open No. 2010-44842 discloses a magnetic recording medium having at least a backing layer, an orientation control layer, a magnetic recording layer, and a protective layer on a substrate, and the orientation control layer is a laminated layer having at least a seed layer and an intermediate layer.
- a magnetic recording medium having a structure, in which a seed layer is disposed on the substrate side from an intermediate layer, and the seed layer has a Cu—Ti alloy layer mainly composed of Cu is disclosed (see Patent Document 2). ).
- the intermediate layer has an hcp structure mainly composed of an alloy material containing at least one of Ru, Re, or an alloy thereof. Furthermore, it discloses that making the intermediate layer into two layers achieves both crystal orientation and miniaturization.
- Japanese Patent Application Laid-Open No. 2002-358617 discloses a perpendicular magnetic recording medium having a base layer, a magnetic recording layer, a protective layer, and a liquid lubricating layer sequentially on a nonmagnetic substrate, wherein the base layer contains nonmagnetic NiFeCr. (See Patent Document 3). Further, it is described that an intermediate layer including any one of CoCr, CoCrB, Ru, and Pd nonmagnetic materials is included between the underlayer and the magnetic recording layer.
- Japanese Patent Application Laid-Open No. 2003-168207 discloses a perpendicular magnetic recording medium having a soft magnetic backing layer, an intermediate layer, a magnetic layer of a CoCr-based alloy layer, a protective layer, and a liquid lubricating layer in this order on a nonmagnetic substrate.
- a perpendicular magnetic recording medium in which a layer is composed of a first magnetic layer having a granular structure and a second magnetic layer having a non-granular structure is disclosed (see Patent Document 4).
- the intermediate layer is made of an alloy containing at least one metal of Ti, Re, Ru, and Os having an hcp structure.
- Japanese Patent Application Laid-Open No. 2005-196898 is a perpendicular magnetic recording medium in which a seed layer, an underlayer, a magnetic recording layer, and a coating layer are sequentially laminated on a nonmagnetic substrate, and the magnetic recording layers are made of different materials.
- a perpendicular magnetic recording medium having a structure in which magnetic layers are laminated is disclosed (see Patent Document 5).
- a seed layer a NiFe alloy or an alloy in which at least one of B, Si, Nb, and Mo is added to NiFe, or at least one of B, Si, Nb, Mo, Fe, and Ni is added to Co or Co.
- the alloy is further formed of a metal having an hcp structure such as Ti, Zr, Ru, Zn, Tc, and Re, or Cu, Rh, Pd, Ag, Ir, Pt, Au, Ni, Co, etc.
- a metal having an fcc structure is disclosed.
- JP-A-2006-277950 discloses a perpendicular magnetic recording medium in which a soft magnetic backing layer, an intermediate layer, a magnetic layer of a CoCr alloy layer, a protective layer, and a liquid lubricant layer are sequentially laminated on a nonmagnetic substrate.
- a perpendicular magnetic recording medium is disclosed in which a magnetic layer is composed of a first magnetic layer having a granular structure and a second magnetic layer having a non-granular structure (see Patent Document 6).
- the intermediate layer is made of a metal of any one of Ti, Re, Ru, and Os having an hcp crystal structure, or an alloy containing at least one metal of Ti, Re, Ru, and Os.
- Japanese Patent Application Laid-Open No. 2008-84413 discloses a magnetic recording medium having a soft magnetic underlayer, a FeCoB seed layer, a crystal orientation control layer having an fcc structure, a nonmagnetic underlayer, and a magnetic recording layer on a substrate. It is disclosed that the orientation control layer is formed of an alloy containing at least one element selected from Ni, Fe, Co, Cu, Rh, Ir, Pd, Pt, Al, Au, and Ag (Patent Literature). 7). Japanese Patent No.
- 4224804 discloses a method of manufacturing a perpendicular magnetic recording medium in which at least an underlayer, a magnetic recording layer, a protective film, and a liquid lubricant layer are sequentially laminated on a nonmagnetic substrate, and Ru, RuW, RuTi. Also disclosed is a method of manufacturing a magnetic recording medium in which a seed layer made of a Ni-based alloy such as NiFe is further provided under a base layer made of an alloy containing at least Ru such as RuAl, RuCu, RuSi, RuC, RuB, and RuCoCr. (See Patent Document 8).
- a magnetic recording layer called a granular layer which is a structure in which a CoCrPt alloy is used as fine particles and an oxide such as SiO 2 and TiO 2 is segregated at the fine particle interface, is used.
- JP 2010-518536 A discloses a perpendicular magnetic recording medium including a seed layer containing amorphous Ta, a nonmagnetic fcc alloy underlayer containing Ni and W, a nonmagnetic hcp underlayer, and a magnetic layer. It is described that a RuCr 30 underlayer is used for the hcp underlayer (see Patent Document 9). Further, it is disclosed that noble metal elements such as Ru and Pt are desirably reduced as much as possible from the medium.
- JP 2008-34060 A JP 2010-44842 A JP 2002-358617 A JP 2003-168207 A JP 2005-196898 A JP 2006-277950 A JP 2008-84413 A Japanese Patent No. 4224804 Special table 2010-518536
- the seed layer or the intermediate layer has a function of controlling the crystallinity, orientation, crystal grain size, etc. of the magnetic recording layer formed thereon, and may affect the characteristics of the magnetic recording layer.
- the crystal grain size of the magnetic recording layer material it is effective to reduce the crystal grain size of the seed layer or the intermediate layer.
- the seed layer or intermediate layer thickness is decreased, the crystal orientation of the magnetic recording layer material is lowered and the magnetic separation between magnetic crystal grains is hindered, resulting in deterioration of the magnetic properties of the magnetic recording layer. Is also known. Therefore, considering these points, it is necessary to control the film thickness of the seed layer or the intermediate layer while maintaining or improving the magnetic characteristics of the magnetic recording layer.
- an object of the present invention is to reduce the orientation dispersion of the magnetic recording layer and to refine the crystal grain size, and at the same time to reduce the film thickness of the seed layer and the intermediate layer, thereby reducing the noise and performance such as the SN ratio. It is an object of the present invention to provide a perpendicular magnetic recording medium that can improve the above.
- the present inventors laminated a plurality of nonmagnetic intermediate layers made of a specific metal alloy so that each film thickness is greater than the film thickness when a single layer is used as the intermediate layer. It has been clarified that the particle size of the magnetic recording layer can be easily reduced without degrading the characteristics of the magnetic recording layer, and the following means have been achieved.
- the perpendicular magnetic recording medium according to the present invention is a perpendicular magnetic recording medium in which at least a first nonmagnetic intermediate layer, a second nonmagnetic intermediate layer, and a magnetic recording layer are sequentially laminated on a nonmagnetic substrate,
- the first nonmagnetic intermediate layer is formed of a CoCrRuW alloy
- the second nonmagnetic intermediate layer is formed of a Ru-based alloy.
- the CoCrRuW alloy has a Cr content of 14.5 at. % Or more, 25.5 at. % Or less, and the Ru amount is 4.5 at. % Or more, 20.5 at. %, And the W amount is 4.5 at. % Or more, 8.5 at. % Or less, and the balance is preferably Co.
- the film thickness of the first nonmagnetic intermediate layer is 5 to 14 nm, preferably 6 to 12 nm.
- the magnetic recording layer preferably includes a granular structure.
- the present invention also includes a method for manufacturing these perpendicular magnetic recording media.
- the present invention provides a perpendicular magnetic recording medium that is capable of realizing high density magnetic recording with improved performance such as noise reduction and SN ratio.
- FIG. 1 is a schematic cross-sectional view showing the layer structure of the perpendicular magnetic recording medium of the present invention.
- FIG. 2 is a plot of MFspi SNR values versus ROW in Example 1 and Comparative Example 1.
- FIG. 3 is a plot of Squash values versus ROW in Example 1 and Comparative Example 1.
- FIG. 4 is a plot of MFspi SNR values versus ROW in Example 2 and Comparative Example 1.
- FIG. 5 is a plot of Squash values versus ROW in Example 2 and Comparative Example 1.
- FIG. 6 is a plot of MFspi SNR values versus ROW in Example 3 and Comparative Example 1.
- FIG. 7 is a plot of Squash values versus ROW in Example 3 and Comparative Example 1.
- FIG. 8 is a plot of MFspi SNR values versus ROW in Example 4 and Comparative Example 1.
- FIG. 9 is a plot of Squash values versus ROW in Example 4 and Comparative Example 1.
- FIG. 10 is a plot of MFspi SNR values versus ROW in Example 5.
- FIG. 11 is a plot of Squash values versus ROW in Example 5.
- FIG. 12 is a plot of MFspi SNR values versus ROW in Example 6.
- FIG. 13 is a plot of Squash values versus ROW in Example 6.
- FIG. 1 is a cross-sectional view showing a perpendicular magnetic recording medium of the present invention.
- the perpendicular magnetic recording medium of the present invention includes a soft magnetic backing layer 103, a first nonmagnetic intermediate layer 108, a second nonmagnetic intermediate layer 109, and a magnetic recording layer 110 in this order on a nonmagnetic substrate 101.
- the perpendicular magnetic recording medium of the present invention optionally has a pre-seed layer 106 and a seed layer 107 between the soft magnetic backing layer 103 and the first nonmagnetic intermediate layer 108 as shown in FIG. Also good.
- the perpendicular magnetic recording medium of the present invention may optionally have a protective layer 114 formed on the magnetic recording layer 110 as shown in FIG.
- the lubricating layer 115 may be included.
- the non-magnetic substrate 101 used in the present invention is a non-magnetic material, and one that can withstand the conditions (solvent, temperature, etc.) used for forming each layer described later is used, and is a surface used for a normal magnetic recording medium.
- Various substrates can be used that are smooth. Specifically, a substrate made of a material such as an Al alloy plated with NiP, tempered glass, crystallized glass, or silicon can be used.
- the non-magnetic substrate 101 is preferably cleaned before forming the other components 102 to 115. Cleaning can be performed by a scrub method using a brush or a sponge, a high-pressure water jet method, an immersion method in an alkaline detergent, or the like. Further, after cleaning by these methods, ultraviolet irradiation can be further performed.
- the nonmagnetic substrate 101 of the present invention may optionally be provided with an adhesion layer 102 thereon.
- the adhesion layer 102 is used to enhance adhesion between the soft magnetic backing layer 103 formed thereon and the nonmagnetic substrate 101.
- a material for the adhesion layer 102 a material having good adhesion to a substrate material such as glass, such as a CrTi alloy, can be used.
- the soft magnetic backing layer 103 is formed on the nonmagnetic substrate 101 or the adhesion layer 102, and plays a role of ensuring a sufficient vertical magnetic field in order to prevent the spread of magnetic flux generated from the magnetic head during information recording. Is an element.
- a material of the soft magnetic backing layer 103 Ni alloy, Fe alloy, and Co alloy can be used.
- good electromagnetic conversion characteristics can be obtained by using amorphous CoZrNb, CoTaZr, CoTaZrNb, CoFeZrNb, CoFeNiZrNb, CoFeTaZrNb, CoFeTaZr, CoFeZrTaTiNb, FeCoTaB, and the like.
- the soft magnetic backing layer 103 can also be configured as a single layer film having a specific composition.
- the soft magnetic underlayer 103 of the present invention reduces the noise of the recording medium.
- a laminated film in which a plurality of magnetic films are ferromagnetically or antiferromagnetically coupled may be used.
- the soft magnetic backing layer 103 includes a lower soft magnetic backing layer 103a and an upper soft magnetic backing layer 103b.
- the total film thickness of the lower soft magnetic backing layer 103a and the upper soft magnetic backing layer 103b can be appropriately changed according to the structure and / or characteristics of the magnetic head used for recording information, In consideration, it is preferable to use a film thickness of 10 to 100 nm. By setting the thickness to 10 nm or more, a sufficient vertical magnetic field can be secured, while by setting the thickness to 100 nm or less, productivity can be improved.
- the soft magnetic backing layer 103 includes a Ru layer 104 that cuts the RKKY coupling of the soft magnetic backing layer between the lower soft magnetic backing layer 103a and the upper soft magnetic backing layer 103b.
- the Ru layer 104 is used for the purpose of deriving antiferromagnetic coupling between the upper and lower soft magnetic underlayers.
- a nonmagnetic alloy containing Cr, Cu, Ag, or the like as a main component may be used instead of the Ru layer 104.
- the present invention may optionally form the pre-seed layer 106 and the seed layer 107 or the seed layer 107 alone on the soft magnetic backing layer 103.
- the pre-seed layer 106 suitably controls the orientation and grain size of the seed layer 107 formed in contact with the layer.
- the seed layer 107 suitably controls the orientation and grain size of the first nonmagnetic intermediate layer 108 formed thereon, and further suitably controls the orientation and grain size of the second nonmagnetic intermediate layer 109.
- the magnetic recording layer 110 is a component that is disposed in order to suitably realize good perpendicular orientation and grain size.
- an amorphous alloy such as Ta, Ti, or W that shows a broad diffraction line in XRD or the like and does not have a specific crystal structure, or an intermetallic compound can be used.
- a Ni-based alloy having an fcc structure can be used as a material for the seed layer 107. Further, a refractory metal typified by Mo, Ti, Ta, W, or the like may be added to the seed layer 107.
- the film thicknesses of the pre-seed layer 106 and the seed layer 107 are not particularly limited as long as the orientation and grain size of the layer formed thereon can be controlled, but are 1 to 20 nm and 3 to 8.5 nm, respectively. Is preferred. More preferably, the pre-seed layer 106 has a thickness of 1 to 9.5 nm, and the seed layer 107 has a thickness of 3.5 to 6.5 nm.
- the nonmagnetic intermediate layer used in the present invention includes a first nonmagnetic intermediate layer 108 made of a material made of a CoCrRuW alloy and a second nonmagnetic intermediate layer 109 made of a Ru-based alloy.
- the nonmagnetic intermediate layer is a component having a function of controlling the crystallinity, orientation, crystal grain size, and the like of the magnetic recording layer 110 formed thereon. Therefore, in order to reduce the crystal grain size of the magnetic recording layer material, it is effective to reduce the crystal grain size of the nonmagnetic intermediate layer.
- each film thickness can be made thinner than that when a Ru single layer is used as the nonmagnetic intermediate layer. Further, it is possible to provide an effect that the magnetic recording layer can be easily miniaturized without degrading the characteristics of the magnetic recording layer 110.
- the total film thickness of the first nonmagnetic intermediate layer 108 and the second nonmagnetic intermediate layer 109 is preferably 10 to 30 nm. By setting the thickness to 10 nm or more, good crystallinity is obtained in each of the first nonmagnetic intermediate layer 108 and the second nonmagnetic intermediate layer 109, and excellent orientation can be realized. Therefore, even in the magnetic recording layer 110 disposed on the first nonmagnetic intermediate layer 108 and the second nonmagnetic intermediate layer 109, excellent orientation and excellent crystal grain separation are obtained.
- the total thickness of the first nonmagnetic intermediate layer 108 and the second nonmagnetic intermediate layer 109 is set to 30 nm or less, enlargement of the particle size of the nonmagnetic intermediate layer is suppressed, and the magnetic recording layer 110 is reduced. As a result, an excellent SN ratio resulting from noise reduction of the magnetic recording layer 110 can be obtained. The space between the magnetic recording layer 110 and the soft magnetic backing layer 103 can be reduced, and the write property can be maintained high.
- the film thicknesses of the first nonmagnetic intermediate layer 108 and the second nonmagnetic intermediate layer 109 are preferably 4 to 20 nm, respectively.
- the film thickness of the first nonmagnetic intermediate layer 108 is preferably 5 to 14 nm, more preferably 6 to 12 nm.
- the thickness of the second nonmagnetic intermediate layer 109 is preferably 6 to 11 nm, and more preferably 7 to 9 nm.
- the first nonmagnetic intermediate layer 108 of the present invention is made of a CoCrRuW alloy having an hcp structure.
- the CoCrRuW alloy has a Cr content of 14.5 at. % Or more, 25.5 at. % Or less, and the Ru content is 4.5 at. % Or more, 20.5 at. % Or less and the W content is 4.5 at. % Or more, 8.5 at. %, And the balance is Co as the main element. More preferably, the Cr content is 15 at. % Or more, 25 at. % Or less, and the Ru content is 5 at. % Or more, 15 at. %, And the W content is 5 at. % Or more, 10 at. % Or less, and the balance is Co.
- Addition of refractory metals typified by Mo, Ti, Ta, W, etc. to thin film alloy materials is expected to promote the refinement of crystal grains, and among them, W, which is the metal with the highest melting point The most effective is expected. However, for Co, 24 at. When more than 1% or more of Mo, Ti, Ta, or W metal is added, an intermetallic compound such as CoW 3 is formed, resulting in an undesirable crystal structure.
- the second nonmagnetic intermediate layer 109 of the present invention can be formed of Ru alone or a Ru-based alloy having an hcp structure. Since Ru has a large atomic radius, W or Ta having a larger atomic radius may be added to the second nonmagnetic intermediate layer 109.
- the Ru-based alloy has a Ru content of 5 at. % Or more, preferably 70 at. % Or more, more preferably 95 at. % Ru or more is included.
- the magnetic recording layer 110 is a component disposed for recording information.
- the easy axis of magnetization needs to be oriented in a direction perpendicular to the substrate surface.
- the hcp (0002) plane is preferably oriented parallel to the substrate surface.
- the magnetic recording layer 110 preferably has a so-called granular structure in which ferromagnetic crystal grains made of a Co-based alloy are surrounded by nonmagnetic crystal grains mainly composed of oxide.
- the electromagnetic conversion characteristics of the magnetic recording layer 110 can be sufficiently secured, and an excellent SN ratio resulting from noise reduction of the magnetic recording medium can be obtained.
- “mainly composed of oxide” means that it does not preclude containing a small amount of other components, and the oxide is present in a ratio of approximately 90 mol% or more of the nonmagnetic crystal grains. Means that.
- Co-based alloy constituting the ferromagnetic crystal grains examples include CoPt-based alloys such as CoPtCr, CoPt, CoPtSi, and CoPtCrB, and CoCr-based alloys such as CoCr, CoCrTa, and CoCrTaPt.
- CoPt-based alloys such as CoPtCr, CoPt, CoPtSi, and CoPtCrB
- CoCr-based alloys such as CoCr, CoCrTa, and CoCrTaPt.
- a CoPt-based alloy is preferable in that the magnetic anisotropy energy (Ku) can be set high.
- Examples of the oxide constituting the nonmagnetic crystal grains include SiO 2 , Cr 2 O 3 , ZrO 2 , and Al 2 O 3 which have high performance for magnetically separating the ferromagnetic crystal grains of the Co-based alloy. It is done. Among these, SiO 2 is preferable in that it has excellent performance for magnetically separating ferromagnetic crystal grains made of the Co-based alloy.
- the magnetic recording layer 110 may be a single layer or a laminate (not shown) composed of a plurality of layers.
- the magnetic recording layer 110 is a stacked body formed of a plurality of layers, and includes a plurality of magnetic recording layers.
- the magnetic recording medium of the present invention may be provided with an exchange coupling force control layer 111 between the magnetic recording layer and the magnetic recording layer.
- the exchange coupling force control layer 111 is provided between the first granular magnetic recording layer 110a and the second granular magnetic recording layer 110b to weaken the exchange coupling energy, thereby reducing the switching magnetic field with almost no deterioration in thermal stability. This layer improves the writing characteristics.
- the film thickness of the exchange coupling force control layer 111 is preferably in the range of 0.07 to 0.8 nm, although the optimum film thickness varies depending on the material used.
- the thickness is smaller than 0.07 nm, the first granular magnetic recording layer 110a and the second granular magnetic recording layer 110b are ferromagnetically coupled, and the write characteristics are deteriorated.
- the thickness is greater than 0.8 nm, the magnetic coupling between the first granular magnetic recording layer 110a and the second granular magnetic recording layer 110b is broken, so that the thermal stability is deteriorated.
- the perpendicular magnetic recording medium of the present invention may further include a non-granular magnetic recording layer 110c (not shown).
- the non-granular magnetic recording layer 110c secures excellent durability of the magnetic recording medium, and the exchange coupling force control layer 111 or the second magnetic recording layer 110c in order to suitably control the magnetic characteristics of the entire granular magnetic recording layers 110a and 110b. 2 is a component disposed on the granular magnetic recording layer 110b.
- the non-granular magnetic recording layer 110c has a structure including ferromagnetic crystal grains made of a Co-based alloy and metal non-magnetic crystal grains not containing metal oxides and nitrides.
- the non-granular magnetic recording layer 110c realizes excellent durability of the magnetic recording medium by blocking Co atoms eluted from the non-magnetic crystal grain boundaries of the first granular magnetic recording layer 110a and the second granular magnetic recording layer 110b.
- the magnetic properties of the first granular magnetic recording layer 110a and the second granular magnetic recording layer 110b can be controlled to a preferable state.
- Examples of the metal material constituting the nonmagnetic crystal grain boundary of the non-granular magnetic recording layer 110c include at least one of Ta, Pt, B, Si, Nb, Cu, and Ti.
- B is preferable in that the performance of magnetically separating the ferromagnetic crystal grains made of the Co-based alloy is particularly excellent.
- the film thickness of the non-granular magnetic recording layer 110c can take any value as long as it does not interfere with the performance of the perpendicular recording medium of the present invention, but is preferably 1 nm to 5 nm, more preferably 3 nm to 4 nm. is there.
- the magnetic recording layer 110 of the perpendicular recording medium of the present invention is obtained by using the granular magnetic recording layers 110a and / or 110b, the exchange coupling force control layer 111, and the non-granular magnetic recording layer 110c in order to obtain sufficient magnetic recording performance. Can be laminated and formed optionally in combination. In one embodiment, the second granular layer may be omitted, and the non-granular magnetic recording layer 110c may be formed directly on the exchange coupling force control layer 111.
- the protective layer 114 protects each of the layers 102 to 110c positioned below the layer 114 in the cross-sectional view of the magnetic recording medium of the present invention shown in FIG. 1, and in particular, the lower soft magnetic backing layer 103 and the upper soft magnetic backing layer.
- 105 is a component disposed to prevent the elution of Co from 105.
- a material usually used for a perpendicular magnetic recording medium can be used.
- a protective layer mainly composed of carbon such as diamond-like carbon (DLC) or amorphous carbon (preferably diamond-like carbon) or various thin-layer materials known to be used as a protective layer for magnetic recording media is used. it can.
- As the film thickness of the protective layer 114 a film thickness normally used as a component of the perpendicular magnetic recording medium can be applied.
- the lubricating layer 115 is an optional component, but for the purpose of reducing the frictional force generated between the protective layer 114 and a magnetic head (not shown) and obtaining excellent durability and reliability of the magnetic recording medium. Liquid component to be disposed.
- a material of the lubricating layer 115 a material usually used for a magnetic recording medium can be used.
- a perfluoropolyether lubricant can be used.
- the film thickness of the lubricating layer 115 a film thickness normally used as a component of the perpendicular magnetic recording medium can be applied.
- Each layer laminated on the nonmagnetic substrate 101 can be formed by various film forming techniques that are usually used in the field of magnetic recording media.
- a sputtering method including a DC magnetron sputtering method, an RF magnetron sputtering method, etc.
- a vacuum evaporation method or the like can be used.
- a CVD method or the like can be used in addition to the above method.
- the lubricating layer 115 can be formed using any coating method known in the art, such as a dip coating method or a spin coating method.
- Example 1 As the nonmagnetic substrate 101, an Al substrate having a diameter of 95 mm was used.
- the Al substrate had an AFM roughness of 1.2 ⁇ (angstrom) or less in a 10 ⁇ m ⁇ 10 ⁇ m measurement region.
- the protective layer and the lubricating layer were removed, and each layer was formed by a sputtering method to produce a magnetic recording medium having the configuration shown in Table 1.
- the sputtering method in a present Example was implemented using the direct-current magnetron sputtering apparatus unless otherwise indicated.
- a 13 nm thick CrTi adhesion layer 102 was formed on a nonmagnetic substrate 101.
- a first soft magnetic backing layer 103a made of a FeCoTaB alloy having a thickness of 13 nm, a Ru layer 104 having a thickness of 1.2 nm, and a second soft magnetic backing layer 103b made of an FeCoTaB alloy having a thickness of 12 nm are sequentially formed.
- the magnetic backing layer 103 was used.
- a pre-seed layer 106 made of CrTi alloy having an amorphous structure was formed with a thickness of 9 nm, and a seed layer 107 made of NiFeCrWTi alloy was formed with a thickness of 6 nm.
- the first nonmagnetic intermediate layer 108 is composed of Co25Cr5Ru5W (25 at.% C, 5 at.% Ru, and the remaining Co, based on all atoms, and so on).
- a second nonmagnetic intermediate layer 109 was formed by sputtering using an alloy target with a thickness of 12 nm, and a Ru single layer with a thickness of 8 nm.
- a first magnetic recording layer 110a and a second magnetic recording layer 110b made of a Co-based alloy are formed as a coupling control layer 111 with a Ru single layer interposed therebetween.
- the magnetic recording layer 110 was fabricated by forming the third magnetic recording layer 110c made of a CoPt alloy on the two magnetic recording layers 110b.
- the first magnetic recording layer 110a and the second magnetic recording layer 110b are granular magnetic recording layers
- the third magnetic recording layer 110c is a non-granular magnetic recording layer
- their film thicknesses are as shown in Table 1. Met.
- a carbon protective layer 114 with a thickness of 2.0 nm was formed on the magnetic recording layer by a CVD method, and a lubricating layer 115 made of perfluoropolyether was formed with a thickness of 9 nm to produce a magnetic recording medium.
- the MFSpiSNR is an SN ratio at a frequency that is 1 ⁇ 2 of the maximum recording frequency, and a higher value enables higher density recording.
- S reproduction signal output
- Nt total size
- SqzSNR indicates the ratio between the signal output S 1 remaining in the center track and the total noise (Nt) when the signal of the adjacent track is erased after writing to the center track, and is expressed by the following equation.
- SqzSNR log (S 1 / Nt)
- Squash indicates the ratio of signal output remaining when the signal of the adjacent track is erased after writing to the center track.
- ROW is the ratio between the original recording signal intensity and the unerased signal intensity when a low-density recording is overwritten on a high-density recording, and a linear recording density of 108 kfci is applied to a signal having a linear recording density of 815 kfci. The value at the time of overwriting the signal was measured.
- Comparative Example 1 As the first nonmagnetic intermediate layer 108, a two-layer film of 10 nm thick Co25Cr5Mo5Ru and 3 nm thick Co24Cr4W was used to produce a magnetic recording medium.
- the FeCoZrTaTiNb alloy is used as the material of the first soft magnetic backing layer 103a and the second soft magnetic backing layer 103b, and the film of the preseed layer 106
- the thickness was 14 nm and the thickness of the first nonmagnetic intermediate layer 108 was different from that of Example 1, these differences other than the material of the first nonmagnetic intermediate layer 108 were the electromagnetic conversion characteristics.
- the MFSpiSNR value for the same ROW was generally within about 0.1 dB.
- Example 1 For Comparative Example 1, as in Example 1, the electromagnetic conversion characteristics of the obtained magnetic recording medium were evaluated. The results are shown in Table 2 and FIGS. Compared to Comparative Examples 1-1 and 1-2, in Examples 1-1 and 1-2 in which a Co25Cr5Ru5W alloy having a thickness of 12 nm was used for the first nonmagnetic intermediate layer 108, the MFSpiSNR was about 0.4 dB higher. Further, SqzSNR and Squash were equal or higher, and Example 1 was better than Comparative Example 1.
- Example 2 The point that the soft magnetic backing layer 103 is formed from an FeCoZrTiNb alloy, the point that the thickness of the Ru single layer 104 between the first soft magnetic backing layer 103a and the second soft magnetic backing layer 103b is 0.4 nm, A magnetic recording medium was produced in the same manner as in Example 1 except that the material and film thickness of the magnetic intermediate layer 108 were changed as shown in Table 3. Further, the electromagnetic conversion characteristics of the obtained magnetic recording medium were evaluated in the same manner as in Example 1. The results are shown in Table 4 and FIGS.
- Example 2 For comparison of Example 2, the same Comparative Example 1 as in Example 1 was used.
- the thickness of the Ru single layer 104 in the soft magnetic underlayer 103 is set to 0.4 nm
- the thickness of the pre-seed layer 106 is set to 14 nm
- the film thickness of the first nonmagnetic intermediate layer 108 was different from that of Comparative Example 1, but the effects of these differences other than the material of the first nonmagnetic intermediate layer 108 on the electromagnetic conversion characteristics were the same.
- the value of MFSpiSNR for ROW was generally within about 0.2 dB.
- Example 2-1 to 2-9 Compared with Comparative Examples 1-1 and 1-2, in Examples 2-1 to 2-9, the MFspi SNR was higher than the same ROW by about 0.3 dB or more. Further, in Examples 2-4 to 2-6 in which the film thickness of the first nonmagnetic intermediate layer 108 was set to 10 nm as in Comparative Examples 1-1 and 1-2, compared with Comparative Examples 1-1 and 1-2. Thus, MFSpiSNR was increased by about 0.4 dB or more. SqzSNR and Squash were also equal or higher, and Example 2 was better than Comparative Example 1.
- the magnetic recording medium using the Co25Cr5Ru5W alloy for the first nonmagnetic intermediate layer 108 is superior to the magnetic recording medium using the laminated intermediate layer made of the Co25Cr5Mo5Ru alloy having a thickness of 10 nm and the Co24Cr4W alloy having a thickness of 3 nm. It was found to show characteristics.
- Example 3 The magnetic recording medium was the same as in Example 1 except that the soft magnetic backing layer 103 was formed from an FeCoZrTiNb alloy and the material and film thickness of the first nonmagnetic intermediate layer 108 were changed as shown in Table 5, respectively. Was made. Further, the electromagnetic conversion characteristics of the obtained magnetic recording medium were evaluated in the same manner as in Example 1. The results are shown in Table 6 and FIGS.
- Example 3 differs from Example 1 in that the thickness of the pre-seed layer 106 is 14 nm and the film thickness of the first nonmagnetic intermediate layer 108 in addition to the material of the first nonmagnetic intermediate layer 108.
- the influence of these differences other than the material of the first nonmagnetic intermediate layer 108 on the electromagnetic conversion characteristics was generally within about 0.1 dB in terms of the MFpiSNR value for the same ROW.
- the MFspi SNR was about 0.2 to 0.3 dB higher than the same ROW.
- the MFSpiSNR was 0.1 to 0.2 dB higher than the same ROW. SqzSNR and Squash were equal or higher, and Example 3 was generally better than Comparative Example 1.
- the magnetic recording medium using the Co25Cr5W5Ru alloy or the Co20Cr5W5Ru alloy for the first nonmagnetic intermediate layer 108 is similarly magnetic using a laminated intermediate layer made of a Co25Cr5Mo5Ru alloy having a thickness of 10 nm and a Co24Cr4W alloy having a thickness of 3 nm. It was found that the electromagnetic conversion characteristics were superior to those of the recording medium.
- Example 4 The film thickness of the Ru single layer 104 between the first soft magnetic backing layer 103a and the second soft magnetic backing layer 103b is 0.25 nm in that a 65 mm diameter glass substrate (HOYA model number N5) is used as the nonmagnetic substrate 101.
- a 65 mm diameter glass substrate HOYA model number N5
- the thickness of the pre-seed layer 106 is 3 nm
- the material and film thickness of the first nonmagnetic intermediate layer 108 are changed as shown in Table 7, respectively.
- a magnetic recording medium was produced.
- Example 5 A point in which a glass substrate having a diameter of 65 mm is used as the nonmagnetic substrate 101, a point that the thickness of the Ru single layer 104 between the first soft magnetic backing layer 103a and the second soft magnetic backing layer 103b is 0.25 nm, a pre-seed layer A magnetic recording medium was manufactured in the same manner as in Example 1 except that the thickness of 106 was 3 nm and the material and film thickness of the first nonmagnetic intermediate layer 108 were changed as shown in Table 9, respectively. .
- Example 5 The electromagnetic conversion characteristics of the magnetic recording medium obtained in Example 5 are the same as those in the evaluation test 1 in the measurement conditions of the linear recording density of about 2000 kfci and the track pitch of 400 ktpi at the position of the radius of 29.0 mm, MFSpiSNR, Evaluated by SqzSNR, Squash, and ROW. The results are shown in Table 10 and FIGS. For the ROW, a value when a signal having a linear recording density of 926 kfci was overwritten with a signal having a linear recording density of 123 kfci was used.
- Example 6 A point in which a glass substrate having a diameter of 65 mm is used as the nonmagnetic substrate 101, a point that the thickness of the Ru single layer 104 between the first soft magnetic backing layer 103a and the second soft magnetic backing layer 103b is 0.25 nm, a pre-seed layer A magnetic recording medium was manufactured in the same manner as in Example 1 except that the thickness of 106 was 6 nm and the material and film thickness of the first nonmagnetic intermediate layer 108 were changed as shown in Table 11, respectively. .
- the electromagnetic conversion characteristics of the obtained magnetic recording medium were evaluated under the same conditions as in Example 5. The results are shown in Table 12 and FIGS. As shown in FIGS. 12 and 13, it was confirmed that Examples 6-1 to 6-10 all had good electromagnetic conversion characteristics. Further, as the first nonmagnetic intermediate layer 108, the Co15Cr15Ru5W alloy film having a thickness of 6 nm showed better characteristics than the Co10Cr15Ru5W alloy film having a thickness of 6 nm. *
- Example 7 Similar to Example 1, except that a CoTi layer was used as the pre-seed layer 106, an adhesion layer 102, a first soft magnetic backing layer 103a, a Ru layer 104, a second layer on a nonmagnetic substrate 101 made of an Al substrate having a diameter of 95 mm.
- the soft magnetic backing layer 103b, the pre-seed layer 106, the seed layer 107, the first nonmagnetic intermediate layer 108, the Ru single layer, the second nonmagnetic intermediate layer 109, and the first magnetic recording layer 110a are sequentially formed and protected thereon.
- the layer 114 was formed to produce a measurement sample for XRD crystal structure analysis.
- Example 2 A measurement sample for XRD crystal structure analysis was prepared in the same manner as in Example 7 except that the first nonmagnetic intermediate layer 108 was formed using a Co25Cr5Mo5Ru5Mn alloy.
- Example 7 using the Co25Cr5Ru5W alloy film for the first nonmagnetic intermediate layer 108 corresponds to the hcp (002) plane of the sample as compared with Comparative Example 2 using the Co25Cr5Mo5Ru5Mn alloy for the first nonmagnetic intermediate layer 108.
- the full width at half maximum (FWHM) at 42.2 deg and 42.6 deg showed a decreasing tendency, and the c-axis orientation was good.
- nonmagnetic substrate 101 nonmagnetic substrate 103 soft magnetic backing layer 106 pre-seed layer 107 seed layer 108 first nonmagnetic intermediate layer 109 second nonmagnetic intermediate layer 110 magnetic recording layer 114 protective layer 115 lubricating layer
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Abstract
Description
本発明において用いる非磁性基板101は、非磁性体であり、また、後述する各層の形成に用いられる条件(溶媒、温度など)に耐えるものが用いられ、通常の磁気記録媒体に用いられる、表面が平滑である様々な基板を利用することができる。詳細には、NiPメッキを施したAl合金、強化ガラス、結晶化ガラス、およびシリコンなどの材料からなる基板を用いることができる。
軟磁性裏打ち層103は、非磁性基板101または密着層102上に形成され、情報の記録時に磁気ヘッドから発生する磁束の広がりを防止すべく、垂直方向の磁界を十分に確保する役割を担う構成要素である。軟磁性裏打ち層103の材料としては、Ni合金、Fe合金、Co合金を用いることができる。特に、非晶質のCoZrNb、CoTaZr、CoTaZrNb、CoFeZrNb、CoFeNiZrNb、CoFeTaZrNb、CoFeTaZr、CoFeZrTaTiNb、FeCoTaBなどを用いることにより、良好な電磁変換特性を得ることができる。
本願発明は、任意選択的にプレシード層106およびシード層107を、またはシード層107単独で、軟磁性裏打ち層103の上に形成してもよい。プレシード層106は、当該層に接して形成されるシード層107の配向性および粒径を好適に制御する。また、シード層107は、その上に形成される第1非磁性中間層108の配向性および粒径を好適に制御し、さらに第2非磁性中間層109の配向性および粒径を好適に制御し、その結果として磁気記録層110の良好な垂直配向性および粒径を好適に実現するために配設する構成要素である。
本発明において用いる非磁性中間層は、CoCrRuW合金からなる材料からなる第1非磁性中間層108とRu基合金からなる第2非磁性中間層109とを含む。非磁性中間層は、その上に形成される磁気記録層110の結晶性、配向性および結晶粒径等を制御する機能を有する構成要素である。したがって、磁気記録層材料の結晶粒径を低減させるためには、非磁性中間層の結晶粒径を縮小することが有効である。
磁気記録層110は、情報を記録するために配設する構成要素である。磁気記録層110は、垂直磁気記録媒体の構成要素として用いる場合、磁化容易軸が基板面に対して垂直方向に配向している必要がある。具体的には、hcp(0002)面が基板面に平行に配向していることが好ましい。
保護層114は、図1の本発明の磁気記録媒体の断面図において、当該層114の下方に位置する各層102~110cを保護するとともに、特に、下軟磁性裏打ち層103、上軟磁性裏打ち層105からのCoの溶出を防止するために配設する構成要素である。保護層114には、垂直磁気記録媒体に通常使用される材料を用いることができる。例えば、ダイヤモンド状カーボン(DLC)もしくはアモルファスカーボンなどのカーボンを主体とする保護層(好ましくはダイヤモンド状カーボン)、または磁気記録媒体の保護層として用いることが知られている種々の薄層材料を利用できる。保護層114の膜厚は、垂直磁気記録媒体の構成要素として通常用いられる膜厚を適用することができる。
非磁性基板101の上に積層される各層は、磁気記録媒体の分野で通常用いられる様々な成膜技術によって形成することができる。密着層102から保護層114に至る各層の形成には、例えば、スパッタ法(DCマグネトロンスパッタ法、RFマグネトロンスパッタ法などを含む)、真空蒸着法などを用いることができる。また、保護層114の形成においては、前記の方法に加えてCVD法などを用いることもできる。一方、潤滑層115は、たとえば、ディップコート法、スピンコート法などの当該技術分野において知られている任意の塗布方法を用いて形成することができる。
非磁性基板101として、直径95mmのAl基板を用いた。Al基板は、10μm×10μmの測定領域におけるAFMでの粗さが1.2Å(オングストローム)以下であった。この基板上に、保護層および潤滑層を除き、スパッタリング法にて各層の成膜を行い、表1に記載の構成を有する磁気記録媒体を作製した。なお、本実施例におけるスパッタリング法は、特に示さない限り直流マグネトロンスパッタリング装置を用いて実施した。
得られた磁気記録媒体の電磁変換特性を、MFSpiSNR、SqzSNR、Squash、およびROWにより評価した。半径31.37mmの位置で、最大で、線記録密度約2000kfci、トラックピッチ400ktpiの測定条件で、電磁変換特性を評価した結果を表2に示す。
MFSpiSNR=20×log(S/Nt)
SqzSNR=log(S1/Nt)
第1非磁性中間層108として、厚さ10nmのCo25Cr5Mo5Ruと厚さ3nmのCo24Cr4Wとの2層膜を用い、磁気記録媒体を作製した。また、比較例1では、第1非磁性中間層108の材料のほか、第1軟磁性裏打ち層103aおよび第2軟磁性裏打ち層103bの材料にFeCoZrTaTiNb合金を用いている点、プレシード層106の膜厚を14nmとしている点、ならびに第1非磁性中間層108の膜厚の点で実施例1と相違していたが、第1非磁性中間層108の材料以外のこれらの相違点が電磁変換特性に及ぼす影響は、同一のROWに対するMFSpiSNRの値で、総じておよそ0.1dB以内であった。
軟磁性裏打ち層103をFeCoZrTiNb合金から形成した点、第1軟磁性裏打ち層103aおよび第2軟磁性裏打ち層103bの間のRu単体層104の膜厚を0.4nmとした点、ならびに第1非磁性中間層108の材料および膜厚をそれぞれ表3に記載したとおりに変更した点以外は、実施例1と同様に磁気記録媒体を作製した。また、得られた磁気記録媒体について、実施例1と同様に電磁変換特性を評価した。その結果を表4ならびに図4および図5に示す。
軟磁性裏打ち層103をFeCoZrTiNb合金から形成した点、ならびに第1非磁性中間層108の材料および膜厚をそれぞれ表5に記載したとおりに変更した点以外は、実施例1と同様に磁気記録媒体を作製した。また、得られた磁気記録媒体について、実施例1と同様に電磁変換特性を評価した。その結果を表6ならびに図6および図7に示す。
非磁性基板101として直径65mmのガラス基板(HOYA製型番N5)を用いた点、第1軟磁性裏打ち層103aおよび第2軟磁性裏打ち層103bの間のRu単体層104の膜厚を0.25nmとした点、プレシード層106の厚さを3nmとしている点、ならびに第1非磁性中間層108の材料および膜厚をそれぞれ表7に記載したとおりに変更した点以外は、実施例1と同様に磁気記録媒体を作製した。
実施例4で得られた磁気記録媒体の電磁変換特性を、半径22.3mmの位置で、最大で、線記録密度約2000kfci、トラックピッチ400ktpiの測定条件で、評価試験1と同様に、MFSpiSNR、SqzSNR、Squash、およびROWにより評価した。結果を表8ならびに図8および9に示す。ROWは、997kfciの線記録密度を有する信号上に、133kfciの線記録密度を有する信号を上書きした時の値を用いた。
非磁性基板101として直径65mmのガラス基板を用いた点、第1軟磁性裏打ち層103aおよび第2軟磁性裏打ち層103bの間のRu単体層104の膜厚を0.25nmとした点、プレシード層106の厚さを3nmとしている点、ならびに第1非磁性中間層108の材料および膜厚をそれぞれ表9に記載したとおりに変更した点以外は、実施例1と同様に磁気記録媒体を作製した。
実施例5で得られた磁気記録媒体の電磁変換特性を、半径29.0mmの位置で、最大で、線記録密度約2000kfci、トラックピッチ400ktpiの測定条件で、評価試験1と同様に、MFSpiSNR、SqzSNR、Squash、およびROWにより評価した。結果を表10ならびに図10および図11に示す。ROWは、926kfciの線記録密度を有する信号上に、123kfciの線記録密度を有する信号を上書きした時の値を用いた。
非磁性基板101として直径65mmのガラス基板を用いた点、第1軟磁性裏打ち層103aおよび第2軟磁性裏打ち層103bの間のRu単体層104の膜厚を0.25nmとした点、プレシード層106の厚さを6nmとしている点、ならびに第1非磁性中間層108の材料および膜厚をそれぞれ表11に記載したとおりに変更した点以外は、実施例1と同様に磁気記録媒体を作製した。
プレシード層106にCoTi層を用いた以外は実施例1と同様に、直径95mmのAl基板からなる非磁性基板101上に、密着層102、第1軟磁性裏打ち層103a、Ru層104、第2軟磁性裏打ち層103b、プレシード層106、シード層107、第1非磁性中間層108、Ru単体層、第2非磁性中間層109、および第1磁気記録層110aを順次形成し、その上に保護層114を形成してXRD結晶構造解析用測定試料を作製した。
第1非磁性中間層108をCo25Cr5Mo5Ru5Mn合金を用いて形成した点以外は実施例7と同様に、XRD結晶構造解析用測定試料を作製した。
実施例7および比較例2で作製した測定試料について、X線回折装置(型番Rint-Ultima III、(株)リガク製)を用いて、XRD結晶構造解析を行った。表13に層構成及びXRDによる結晶構造解析結果を示す。第1非磁性中間層108にCo25Cr5Ru5W合金膜を用いた実施例7は、第1非磁性中間層108にCo25Cr5Mo5Ru5Mn合金を用いた比較例2と比較して、試料のhcp(002)面に対応する42.2degおよび42.6degにおける半値幅(FWHM)が低下傾向を示し、c軸配向性が良好となった。
103 軟磁性裏打ち層
106 プレシード層
107 シード層
108 第1非磁性中間層
109 第2非磁性中間層
110 磁気記録層
114 保護層
115 潤滑層
Claims (7)
- 非磁性基板上に少なくとも、第1非磁性中間層、第2非磁性中間層、および磁気記録層が順次積層された垂直磁気記録媒体であって、
前記第1非磁性中間層がCoCrRuW合金から形成され、かつ前記第2非磁性中間層がRu基合金から形成されることを特徴とする垂直磁気記録媒体。 - 前記CoCrRuW合金は、Cr量が14.5at.%以上、25.5at.%以下であり、Ru量が4.5at.%以上、20.5at.%以下であり、W量が 4.5at.%以上、8.5at.%以下であり、かつ残部がCoであることを特徴とする請求項1に記載の垂直磁気記録媒体。
- 前記磁気記録層がグラニュラー構造を含むことを特徴とする請求項1に記載の垂直磁気記録媒体。
- 前記第1非磁性中間層が膜厚5~14nmであることを特徴とする請求項1に記載の垂直磁気記録媒体。
- 非磁性基板上に少なくとも第1非磁性中間層、第2非磁性中間層、および磁気記録層を順次積層させる工程を含み、
前記第1非磁性中間層がCoCrRuW合金から形成され、かつ前記第2非磁性中間層がRu基合金から形成されることを特徴とする垂直磁気記録媒体の製造方法。 - 前記CoCrRuW合金は、Cr量が14.5at.%以上、25.5at.%以下であり、Ru量が4.5at.%以上、20.5at.%以下であり、W量が 4.5at.%以上、8.5at.%以下であり、かつ残部がCoであることを特徴とする請求項5に記載の製造方法。
- 前記磁気記録層がグラニュラー構造を含むことを特徴とする請求項5に記載の製造方法。
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