JP2011003260A - Magnetic recording medium and magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium that can achieve high scratch resistance even when a carbon protective layer is thinned.SOLUTION: In the magnetic recording medium in which at least a vertical magnetic layer 4 in which an easy axis of magnetization is largely perpendicularly oriented to a nonmagnetic substrate 1, and a carbon protective layer 5 are superposed on the nonmagnetic substrate 1, an intermediate layer 9 including Ru and Co is provided between the vertical magnetic layer 4 and the carbon protective layer 5. This allows the surface of the magnetic recording medium to be protected without causing spacing loss as great as the carbon protective layer 5. Also it is possible to significantly increase scratch resistance of the magnetic recording medium by raising the coverage of the carbon protective layer 5 and firmly bonding the vertical magnetic layer 4 and the carbon protective layer 5.

Description

  The present invention relates to a magnetic recording medium and a magnetic recording / reproducing apparatus.

  The recording density of a hard disk drive (HDD), which is a kind of magnetic recording / reproducing device, is currently increasing at an annual rate of 50% or more, and it is said that this trend will continue in the future. Along with this, development of magnetic heads and magnetic recording media suitable for high recording density is underway.

  Currently, a magnetic recording medium mounted on a commercially available magnetic recording / reproducing apparatus is a so-called perpendicular magnetic recording medium in which an easy axis of magnetization in a magnetic film is oriented mainly vertically. Even when the recording density of the perpendicular magnetic recording medium is increased, the influence of the demagnetizing field in the boundary region between the recording bits is small and a clear bit boundary is formed, so that an increase in noise can be suppressed. In addition, since the recording bit volume decreases with the increase in recording density, the thermal fluctuation effect is strong. For this reason, in recent years, much attention has been paid and a medium structure suitable for perpendicular magnetic recording has been proposed.

  In order to meet the demand for higher recording density of magnetic recording media, it has been studied to use a single-pole head having excellent writing ability for the perpendicular magnetic layer. In order to deal with such a single magnetic pole head, a soft magnetic underlayer made of a soft magnetic material is provided between a perpendicular magnetic layer as a recording layer and a nonmagnetic substrate. A so-called two-layer magnetic recording medium has been proposed in which the efficiency of magnetic flux entry and exit between the two is improved.

  By the way, the HDD uses the magnetic head while rotating the magnetic recording medium at a high speed and using the air flow generated between the magnetic recording medium and the magnetic head to float the magnetic head on the surface of the magnetic recording medium. The information is recorded on and reproduced from the magnetic recording medium. Therefore, in the magnetic recording medium in a state where the rotation is stopped, such an air flow does not occur, and the magnetic head cannot fly.

  Also, in the HDD, the magnetic head is placed on the surface of the magnetic recording medium in order to prevent the magnetic head from damaging the surface of the magnetic recording medium until the magnetic head is levitated from the rotation stopped magnetic recording medium. A CSS (contact activation stop) method installed in the formed laser texture zone (retraction position of the magnetic head), a ramp loading method for completely retracting the magnetic head from the magnetic recording medium, or the like is employed.

  However, in the HDD, when an impact or the like is applied from the outside while the magnetic head is flying, the magnetic head may accidentally contact the surface of the magnetic recording medium and damage the surface of the magnetic recording medium. is there.

  As described above, the problem related to tribology between the magnetic head and the magnetic recording medium has become a fateful technical issue, and efforts have been made to improve the protective layer stacked on the magnetic layer of the magnetic recording medium. It has been continued. In addition, impact resistance (scratch resistance), wear resistance, and sliding resistance on the medium surface are major pillars for improving the reliability of magnetic recording media.

  Here, as a protective layer of a magnetic recording medium, materials made of various materials have been proposed, but a carbon film is mainly used from a comprehensive viewpoint such as film formability and durability. . The hardness, density, dynamic friction coefficient, etc. of the carbon film are very important because they are reflected in the CSS characteristics or corrosion resistance characteristics of the magnetic recording medium.

  On the other hand, in order to improve the recording density of the magnetic recording medium, it is preferable to reduce the flying height (flying height) of the magnetic head, increase the rotational speed of the medium, and the like. Accordingly, the protective layer formed on the surface of the magnetic recording medium is required to have higher sliding durability and flatness in order to cope with accidental contact of the magnetic head. In addition, in order to reduce the spacing loss between the magnetic recording medium and the magnetic head and increase the recording density, the thickness of the protective film should be as thin as possible, for example, 30 mm (3.0 nm) or less. There is a growing demand for thin, dense and tough protective films as well as smoothness.

  The carbon film used for the protective layer of the magnetic recording medium is formed by sputtering, CVD, ion beam evaporation or the like. Among these, the durability of the carbon film formed by the sputtering method may be insufficient when the film thickness is, for example, 100 mm (10.0 nm) or less. On the other hand, the carbon film formed by the CVD method has low surface smoothness, and when the film thickness is reduced, the coverage of the surface of the magnetic recording medium is lowered, and corrosion of the magnetic recording medium may occur. is there. On the other hand, the ion beam evaporation method can form a dense carbon film with higher hardness and higher smoothness than the above-described sputtering method and CVD method (see, for example, Patent Document 1).

JP 2000-226659 A

  As described above, in order to further improve the recording density of the magnetic recording medium, it is required to make the carbon film serving as the protective layer thinner than ever. However, since the carbon film and the magnetic layer have different crystal structures, thermal expansion coefficients, etc., if the carbon film is made extremely thin, the coverage of the carbon film, adhesion, etc. will decrease, and it will be extremely scratch resistant. This causes a problem of lowering.

  The present invention has been proposed in view of such conventional circumstances, and includes a magnetic recording medium capable of obtaining high scratch resistance even when the carbon protective layer is thinned, and such a magnetic recording medium. An object of the present invention is to provide a magnetic recording / reproducing apparatus.

  As a result of earnest research to solve the above problems, the present inventor has provided an intermediate layer containing Ru and Co between the perpendicular magnetic layer and the carbon protective layer, thereby reducing the spacing loss as much as the carbon protective layer. Protect the surface of the magnetic recording medium without causing it, increase the coverage of the carbon protective layer, and firmly bond the perpendicular magnetic layer and the carbon protective layer to significantly increase the scratch resistance of the magnetic recording medium As a result, the present invention has been completed.

That is, the present invention provides the following means.
(1) A magnetic recording medium comprising a carbon protective layer and a perpendicular magnetic layer in which an easy axis is oriented mainly perpendicularly to the nonmagnetic substrate on at least a nonmagnetic substrate,
A magnetic recording medium, wherein an intermediate layer containing Ru and Co is provided between the perpendicular magnetic layer and the carbon protective layer.
(2) The magnetic recording medium as described in (1) above, wherein the intermediate layer is a layer containing 30 atomic% or more of Ru and 30 atomic% or more of Co.
(3) The magnetic recording medium as described in (1) or (2) above, wherein the thickness of the intermediate layer is in the range of 0.2 to 0.8 nm.
(4) The magnetic recording medium according to any one of (1) to (3) above,
A magnetic recording / reproducing apparatus comprising: a magnetic head for recording / reproducing information with respect to the magnetic recording medium.

  As described above, according to the present invention, a high-hardness and dense carbon protective layer can be formed, and the thickness of the carbon protective layer can be reduced. Can be set narrow, and as a result, the recording density of the magnetic recording medium can be increased.

It is sectional drawing which shows an example of the magnetic recording medium to which this invention is applied. It is sectional drawing which expands and shows the laminated structure of the magnetic recording medium shown in FIG. It is a perspective view which shows an example of a magnetic recording / reproducing apparatus.

  Hereinafter, a magnetic recording medium and a magnetic recording / reproducing apparatus to which the present invention is applied will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Make it not exist.

(Magnetic recording medium)
A magnetic recording medium to which the present invention is applied is formed by laminating at least a nonmagnetic substrate, a perpendicular magnetic layer having an easy axis of magnetization oriented perpendicularly to the nonmagnetic substrate, and a carbon protective layer. An intermediate layer containing Ru and Co is provided between the perpendicular magnetic layer and the carbon protective layer.

  In the magnetic recording medium to which the present invention is applied, the scratch resistance and corrosion resistance of the magnetic recording medium can be enhanced by adopting such a configuration as compared with the case of using only the carbon protective layer. Usually, in order to increase the scratch resistance of the magnetic recording medium, it is conceivable to increase the thickness of the carbon protective layer. However, the carbon protective layer is made of a non-magnetic material. When the layer thickness is increased, the distance between the perpendicular magnetic layer and the magnetic head is increased (this is referred to as spacing loss), and the electromagnetic conversion characteristics of the magnetic recording medium are improved. It will get worse.

  On the other hand, the intermediate layer used in the present invention includes Ru and Co, which are nonmagnetic materials in terms of physical properties, and includes Co, which is a ferromagnetic material, although the hardness is lower than that of the carbon protective layer. The spacing loss is not as high as that of the carbon protective layer, while the hardness is higher than that of the perpendicular magnetic layer and the hcp structure is the same as that of the perpendicular magnetic layer. Also, lattice matching is high.

  As a result, in the magnetic recording medium to which the present invention is applied, it is possible to increase the coverage of the carbon protective layer on the medium surface, firmly bond the perpendicular magnetic layer and the carbon protective layer, and enhance the protective effect of the medium surface It is.

  In the magnetic recording medium to which the present invention is applied, the intermediate layer containing Ru and Co is preferably a layer containing Ru at least 30 atomic% and Co at least 30 atomic%. That is, by setting Ru to 30 atomic% or more, the hardness of this intermediate layer is increased, and by setting Co to 30 atomic% or more, the spacing loss due to the provision of this intermediate layer is reduced to the actual layer thickness. Can be reduced.

  In the magnetic recording medium to which the present invention is applied, the thickness of the intermediate layer containing Ru and Co is preferably in the range of 2 to 8 mm (0.2 nm to 0.8 nm). If the thickness of the intermediate layer is less than 2 mm, the effect of providing this intermediate layer is reduced. This is presumably because when the layer thickness is extremely thin, the entire surface of the perpendicular magnetic layer cannot be covered. On the other hand, if the thickness of the intermediate layer exceeds 8 mm, the spacing loss due to the intermediate layer increases, and the electromagnetic conversion characteristics of the magnetic recording medium deteriorate.

Hereinafter, a specific configuration example of a magnetic recording medium to which the present invention is applied will be described.
A magnetic recording medium to which the present invention is applied includes a soft magnetic underlayer 2, an orientation control layer 3, a perpendicular magnetic layer 4, a carbon protective layer 5 on a nonmagnetic substrate 1, as shown in FIG. , And a lubricating layer 6 are sequentially laminated.

  Among these, the soft magnetic underlayer 2 and the orientation control layer 3 constitute an underlayer. The soft magnetic underlayer 2 includes two soft magnetic layers 2a that are AFC (anti-ferro-coupled) coupled via a spacer layer 2b. The perpendicular magnetic layer 4 includes three layers of a lower magnetic layer 4a, an intermediate magnetic layer 4b, and an upper magnetic layer 4c, and the nonmagnetic layer 7a is formed between the magnetic layer 4a and the magnetic layer 4b. By sandwiching the nonmagnetic layer 7b between 4b and the magnetic layer 4c, the magnetic layers 4a to 4c and the nonmagnetic layers 7a and 7b are alternately stacked. A nonmagnetic underlayer 8 is provided between the orientation control layer 3 and the perpendicular magnetic layer 4. The magnetic recording medium to which the present invention is applied has a configuration in which an intermediate layer 9 containing Ru and Co is provided between the perpendicular magnetic layer 4 and the carbon protective layer 5.

  As the nonmagnetic substrate 1, for example, a metal substrate made of a metal material such as aluminum or an aluminum alloy may be used. For example, a nonmetal substrate made of a nonmetal material such as glass, ceramic, silicon, silicon carbide, or carbon. May be used. In addition, it is also possible to use a substrate in which a NiP layer or a NiP alloy layer is formed on the surface of the metal substrate or nonmetal substrate by using, for example, a plating method or a sputtering method.

  As the glass substrate, for example, amorphous glass or crystallized glass can be used, and as the amorphous glass, for example, general-purpose soda lime glass or aluminosilicate glass can be used. In addition, as the crystallized glass, for example, lithium-based crystallized glass can be used. As the ceramic substrate, for example, general-purpose aluminum oxide, a sintered body mainly composed of aluminum nitride, silicon nitride, or the like, or a fiber reinforced material thereof can be used.

  The nonmagnetic substrate 1 preferably has an average surface roughness (Ra) of 2 nm (20 mm) or less, preferably 1 nm or less from the viewpoint of suitable for high recording density recording with a magnetic head flying low. Further, it is preferable that the surface fine waviness (Wa) is 0.3 nm or less (more preferably 0.25 nm or less) from the viewpoint of being suitable for high recording density recording with the magnetic head flying low. In addition, it is possible to use a magnetic head having a chamfered portion at the end face and a surface average roughness (Ra) of at least one of the side surface portion of 10 nm or less (more preferably 9.5 nm or less). Preferred for stability. In addition, microwaviness (Wa) can be measured as surface average roughness in a measuring range of 80 μm, for example, using a surface roughness measuring device P-12 (manufactured by KLM-Tencor).

  Further, when the nonmagnetic substrate 1 is in contact with the soft magnetic underlayer 2 mainly composed of Co or Fe, there is a possibility that the corrosion progresses due to the adsorption gas on the surface, the influence of moisture, the diffusion of the substrate components, and the like. is there. In this case, it is preferable to provide an adhesion layer between the nonmagnetic substrate 1 and the soft magnetic underlayer 2, thereby suppressing these. In addition, as a material of the adhesion layer, for example, Cr, Cr alloy, Ti, Ti alloy, or the like can be selected as appropriate. The thickness of the adhesion layer is preferably 2 nm (30 mm) or more.

  The soft magnetic underlayer 2 increases the component of the magnetic flux generated from the magnetic head in the direction perpendicular to the substrate surface, and further strengthens the direction of magnetization of the perpendicular magnetic layer 4 on which information is recorded to be perpendicular to the nonmagnetic substrate 1. It is provided to fix in any direction. This effect becomes more conspicuous particularly when a single pole head for perpendicular recording is used as a magnetic head for recording and reproduction.

  As the soft magnetic underlayer 2, for example, a soft magnetic material containing Fe, Ni, Co, or the like can be used. Specific examples of soft magnetic materials include CoFe alloys (CoFeTaZr, CoFeZrNb, etc.), FeCo alloys (FeCo, FeCoV, etc.), FeNi alloys (FeNi, FeNiMo, FeNiCr, FeNiSi, etc.), and FeAl alloys. Alloys (FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, FeAlO, etc.), FeCr alloys (FeCr, FeCrTi, FeCrCu, etc.), FeTa alloys (FeTa, FeTaC, FeTaN, etc.), FeMg alloys (FeMgO, etc.), Examples thereof include FeZr alloys (FeZrN, etc.), FeC alloys, FeN alloys, FeSi alloys, FeP alloys, FeNb alloys, FeHf alloys, FeB alloys, and the like.

  Further, the soft magnetic underlayer 2 has a microcrystalline structure such as FeAlO, FeMgO, FeTaN, FeZrN, etc. containing Fe of 60 at% (atomic%) or more, or a granular structure in which fine crystal particles are dispersed in a matrix. Materials can be used.

  In addition, as the soft magnetic underlayer 2, a Co alloy containing 80 at% or more of Co, containing at least one of Zr, Nb, Ta, Cr, Mo and the like and having an amorphous structure can be used. . Specific examples of the specific material include CoZr, CoZrNb, CoZrTa, CoZrCr, and CoZrMo-based alloys.

  The coercive force Hc of the soft magnetic underlayer 2 is preferably 100 Oe or less (preferably 20 Oe or less). 1 Oe is 79 A / m. When the coercive force Hc exceeds the above range, the soft magnetic characteristics are insufficient, and the reproduced waveform is changed from a so-called rectangular wave to a distorted waveform, which is not preferable.

  The saturation magnetic flux density Bs of the soft magnetic underlayer 2 is preferably 0.6 T or more (preferably 1 T or more). If this Bs is less than the above range, the reproduced waveform becomes a waveform having distortion from a so-called rectangular wave, which is not preferable.

  The product Bs · t (T · nm) of the saturation magnetic flux density Bs (T) of the soft magnetic underlayer 2 and the layer thickness t (nm) of the soft magnetic underlayer 2 is 15 T · nm or more (preferably 25 T · nm). nm or more). If this Bs · t is less than the above range, the reproduced waveform will be distorted and the OW (OverWrite) characteristic (recording characteristic) will be deteriorated.

  In the soft magnetic underlayer 2, a Ru film is provided as a spacer layer 2b between two soft magnetic layers 2a. Further, by adjusting the film thickness of the Ru film, the two soft magnetic layers 2a have an AFC structure. By adopting such an AFC structure, so-called spike noise can be suppressed. The soft magnetic underlayer 2 is preferably composed of at least two or more soft magnetic layers 2a, and a Ru film is preferably provided as a spacer layer 2b between the soft magnetic layers 2a.

  The outermost surface (surface on the orientation control layer 3 side) of the soft magnetic underlayer 2 is preferably formed by partially or completely oxidizing the material constituting the soft magnetic underlayer 2. For example, the material constituting the soft magnetic underlayer 2 is partially oxidized on the surface of the soft magnetic underlayer 2 (surface on the orientation control layer 3 side) and its vicinity, or an oxide of the above material is formed. Are preferably arranged. Thereby, since the magnetic fluctuation of the surface of the soft magnetic underlayer 2 can be suppressed, the noise caused by the magnetic fluctuation can be reduced and the recording / reproducing characteristics of the magnetic recording medium can be improved.

  The orientation control layer 3 can improve the recording / reproducing characteristics by refining the crystal grains of the perpendicular magnetic layer 4. Such a material is not particularly limited, but a material having an hcp structure, an fcc structure, or an amorphous structure is preferable. In particular, Ru-based alloys, Ni-based alloys, Co-based alloys, Pt-based alloys, and Cu-based alloys are preferable, and these alloys may be multilayered. For example, it is preferable to adopt a multilayer structure of Ni-based alloy and Ru-based alloy, a multilayer structure of Co-based alloy and Ru-based alloy, or a multilayer structure of Pt-based alloy and Ru-based alloy from the substrate side.

  For example, in the case of a Ni-based alloy, it is made of at least one material selected from NiW alloy, NiTa alloy, NiNb alloy, NiTi alloy, NiZr alloy, NiMn alloy and NiFe alloy containing 33 to 96 at% Ni. Is preferred. Further, it may be a nonmagnetic material containing 33 to 96 at% Ni and containing at least one or more of Sc, Y, Ti, Zr, Hf, Nb, Ta, and C. In this case, the Ni content is preferably in the range of 33 at% to 96 at% in order to maintain the effect as the orientation control layer 3 and to have a range without magnetism.

  The thickness of the orientation control layer 3 is preferably 5 to 40 nm, more preferably 8 to 30 nm, as the total thickness in the case of multiple layers. When the thickness of the orientation control layer 3 is within the above range, the perpendicular orientation of the perpendicular magnetic layer 4 is particularly high, and the distance between the magnetic head and the soft magnetic underlayer 2 during recording can be reduced. The recording / reproducing characteristics can be improved without reducing the signal resolution.

  On the other hand, when the thickness of the orientation control layer 3 is less than the above range, the perpendicular orientation in the perpendicular magnetic layer 4 is lowered, and the recording / reproducing characteristics and the thermal fluctuation resistance are degraded. On the other hand, if the thickness of the orientation control layer 3 exceeds the above range, the magnetic particle diameter of the perpendicular magnetic layer 4 is increased, and noise characteristics may be deteriorated. In addition, since the distance between the magnetic head and the soft magnetic underlayer 2 during recording increases, the resolution of the reproduction signal and the reproduction output decrease.

  Since the surface shape of the orientation control layer 3 affects the surface shape of the perpendicular magnetic layer 4 and the protective layer 5, the surface irregularities of the magnetic recording medium are reduced to reduce the flying height of the magnetic head during recording and reproduction. For this, the surface average roughness Ra of the orientation control layer 3 is preferably 2 nm or less. Thereby, the unevenness on the surface of the magnetic recording medium can be reduced, the flying height of the magnetic head during recording and reproduction can be sufficiently lowered, and the recording density can be increased.

  Further, oxygen, nitrogen, or the like may be introduced into the gas for forming the orientation control layer 3. For example, when a sputtering method is used as the film forming method, the process gas is a gas in which oxygen is mixed in an amount of 0.05 to 50% (preferably 0.1 to 20%) by volume with argon, and nitrogen is added to argon. Is preferably used in a volume ratio of 0.01 to 20% (preferably 0.02 to 10%).

Further, the orientation control layer 3 may have a structure in which metal particles are dispersed in an oxide, a metal nitride, or a metal carbide. In order to obtain such a structure, it is preferable to use an alloy material containing an oxide, a metal nitride, or a metal carbide. Specifically, as the oxide, for example, SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , Cr ₂ O ₃ , MgO, Y ₂ O ₃ , TiO _2, etc. As the metal nitride, for example, AlN, Si For example, TaC, BC, SiC, or the like can be used as the metal carbide such as ₃ N ₄ , TaN, or CrN. Furthermore, for example, NiTa—SiO ₂ , RuCo—Ta ₂ O ₅ , Ru—SiO ₂ , Pt—Si ₃ N ₄ , Pd—TaC, or the like can be used.

  The content of the oxide, metal nitride, or metal carbide in the orientation control layer 3 is preferably 1 mol% or more and 12 mol% or less with respect to the alloy. When the content of oxide, metal nitride, or metal carbide in the orientation control layer 3 exceeds the above range, the oxide, metal nitride, or metal carbide remains in the metal particles, and the crystallinity of the metal particles and In addition to impairing the orientation, the crystallinity and orientation of the magnetic layer formed on the orientation control layer 3 may be impaired. Moreover, when the content of the oxide, metal nitride, or metal carbide in the orientation control layer 3 is less than the above range, it is not preferable because the effect of addition of the oxide, metal nitride, or metal carbide cannot be obtained. .

  Here, in the initial part of the perpendicular magnetic layer 4 immediately above the orientation control layer 3, disorder of crystal growth is likely to occur, which causes noise. The occurrence of noise can be suppressed by replacing the disturbed portion of the initial portion with the nonmagnetic underlayer 8. For this reason, it is preferable to provide a nonmagnetic underlayer 8 between the orientation control layer 3 and the perpendicular magnetic layer 4.

The nonmagnetic underlayer 8 is preferably made of a material mainly containing Co and further containing an oxide. The Cr content is preferably 25 at% (atomic%) or more and 50 at% or less. As the oxide, for example, oxides such as Cr, Si, Ta, Al, Ti, Mg, and Co are preferably used, and among them, TiO ₂ , Cr ₂ O ₃ , SiO _{2, and the} like are preferably used. it can. The content of the oxide is preferably 3 mol% or more and 18 mol% or less with respect to the total amount of mol calculated as one compound, for example, an alloy such as Co, Cr, and Pt constituting the magnetic particles.

The nonmagnetic underlayer 8 is preferably made of a complex oxide to which two or more kinds of oxides are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used. Furthermore, CoCr—SiO ₂ , CoCr—TiO ₂ , CoCr—Cr ₂ O ₃ —SiO ₂ , CoCr—TiO ₂ —Cr ₂ O ₃ , CoCr—Cr ₂ O ₃ —TiO ₂ —SiO ₂ or the like is preferably used. Can do. Further, Pt may be added from the viewpoint of crystal growth.

  The thickness of the nonmagnetic underlayer 8 is preferably 0.2 nm or more and 3 nm or less. If the thickness exceeds 3 nm, Hc and Hn decrease, which is not preferable.

As shown in FIG. 2, the magnetic layer 4a is made of a material containing Co as a main component and an oxide 41. Examples of the oxide 41 include Cr, Si, Ta, Al, Ti, Mg, and Co. It is preferable to use an oxide such as Among _{them, TiO 2, Cr 2 O 3} , SiO ₂ or the like can be suitably used. The magnetic layer 4a is preferably made of a complex oxide to which two or more kinds of oxides are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used.

  In the magnetic layer 4a, it is preferable that magnetic particles (crystal grains having magnetism) 42 are dispersed in the layer. The magnetic particles 42 preferably have a columnar structure that vertically penetrates the magnetic layers 4a and 4b and further the magnetic layer 4c. By having such a structure, the orientation and crystallinity of the magnetic particles 42 of the magnetic layer 4a are improved, and as a result, a signal / noise ratio (S / N ratio) suitable for high-density recording can be obtained. .

  In order to obtain such a structure, the amount of the oxide 41 to be contained and the film formation conditions of the magnetic layer 4a are important. That is, the content of the oxide 41 is 3 mol% or more and 18 mol% or less with respect to the total mol amount of the magnetic particles 42, for example, an alloy such as Co, Cr, and Pt calculated as one compound. preferable. More preferably, it is 6 mol% or more and 13 mol% or less.

  The above range is preferable as the content of the oxide 41 in the magnetic layer 4a. When the magnetic layer 4a is formed, the oxide 41 is precipitated around the magnetic particles 42, and the magnetic particles 42 are isolated and refined. This is because it becomes possible. On the other hand, when the content of the oxide 41 exceeds the above range, the oxide 41 remains in the magnetic particle 42, impairs the orientation and crystallinity of the magnetic particle 42, and further above and below the magnetic particle 42. The oxide 41 is deposited, and as a result, a columnar structure in which the magnetic particles 42 penetrate through the magnetic layers 4a to 4c is not formed. In addition, when the content of the oxide 41 is less than the above range, separation and refinement of the magnetic particles 42 are insufficient, resulting in an increase in noise during recording and reproduction, and a signal / This is not preferable because the noise ratio (S / N ratio) cannot be obtained.

  The content of Cr in the magnetic layer 4a is preferably 4 at% or more and 19 at% or less (more preferably 6 at% or more and 17 at% or less). The reason why the Cr content is in the above range is that the magnetic anisotropy constant Ku of the magnetic particles 42 is not lowered too much, and high magnetization is maintained. As a result, recording / reproduction characteristics suitable for high-density recording and sufficient heat This is because fluctuation characteristics can be obtained.

  On the other hand, when the Cr content exceeds the above range, the magnetic anisotropy constant Ku of the magnetic particles 42 becomes small, so that the thermal fluctuation characteristics deteriorate, and the crystallinity and orientation of the magnetic particles 42 deteriorate. As a result, the recording / reproduction characteristics deteriorate, which is not preferable. Further, when the Cr content is less than the above range, the magnetic anisotropy constant Ku of the magnetic particles 42 is high, so that the perpendicular coercive force becomes too high and data is sufficiently written by a magnetic head when data is recorded. This is not preferable because the recording characteristics (OW) are unsuitable for high density recording.

  The content of Pt in the magnetic layer 4a is preferably 8 at% or more and 20 at% or less. The reason why the Pt content is within the above range is that the magnetic anisotropy constant Ku required for the perpendicular magnetic layer 4 is low when it is less than 8 at%. On the other hand, if it exceeds 20 at%, a stacking fault occurs inside the magnetic particle 42, and as a result, the magnetic anisotropy constant Ku decreases. Therefore, in order to obtain thermal fluctuation characteristics and recording / reproduction characteristics suitable for high-density recording, the Pt content is preferably set in the above range.

  In addition, when the Pt content exceeds the above range, an fcc structure layer is formed in the magnetic particles 42, and the crystallinity and orientation may be impaired. On the other hand, if the Pt content is less than the above range, the magnetic anisotropy constant Ku for obtaining thermal fluctuation characteristics suitable for high-density recording cannot be obtained.

  In addition to Co, Cr, Pt and oxide 41, the magnetic layer 4a contains one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re. Can be included. By including the above elements, the miniaturization of the magnetic particles 42 can be promoted or the crystallinity and orientation can be improved, and recording / reproduction characteristics and thermal fluctuation characteristics suitable for higher density recording can be obtained.

  Further, the total content of the above elements is preferably 8 at% or less. If it exceeds 8 at%, a phase other than the hcp phase is formed in the magnetic particles 42, so that the crystallinity and orientation of the magnetic particles 42 are disturbed, resulting in recording / reproducing characteristics and thermal fluctuation characteristics suitable for high-density recording. Is not preferred because it cannot be obtained.

As a material suitable for the magnetic layer 4a, for example, 90 (Co14Cr18Pt) -10 (SiO ₂ ) {Cr content 14at%, Pt content 18at%, molar concentration calculated as one compound with magnetic particles composed of the remaining Co. Is 90 mol%, the oxide composition of SiO ₂ is 10 mol%}, 92 (Co10Cr16Pt) -8 (SiO ₂ ), 94 (Co8Cr14Pt4Nb) -6 (Cr ₂ O ₃ ), and (CoCrPt)-(Ta ₂ O _{5), (CoCrPt) - (} Cr 2 O 3) - (TiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO 2) _{- (TiO 2), (CoCrPtMo} ) - (TiO), (CoCrPtW) - (TiO 2), (CoCrPtB) - (Al 2 O ₃ ), (CoCrPtTaNd) — (MgO), (CoCrPtBCu) — (Y ₂ O ₃ ), (CoCrPtRu) — (SiO ₂ ), and the like.

As shown in FIG. 2, the magnetic layer 4 b is preferably made of a material containing Co as a main component and further containing an oxide 41. The oxide 41 is preferably an oxide of Cr, Si, Ta, Al, Ti, Mg, and Co. Of these, TiO ₂ , Cr ₂ O ₃ , and SiO ₂ can be preferably used. The magnetic layer 4b is preferably made of a composite oxide to which two or more types of oxides 41 are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used.

  In the magnetic layer 4b, it is preferable that magnetic particles (crystal particles having magnetism) 42 are dispersed in the layer. The magnetic particles 42 preferably form a columnar structure that vertically penetrates the magnetic layers 4a and 4b and further the magnetic layer 4c. By forming such a structure, the orientation and crystallinity of the magnetic particles 42 of the magnetic layer 4b are improved, and as a result, a signal / noise ratio (S / N ratio) suitable for high-density recording can be obtained. it can.

  The content of the oxide 41 in the magnetic layer 4b is preferably 3 mol% or more and 18 mol% or less with respect to the total amount of compounds such as Co, Cr, and Pt constituting the magnetic particles 42. More preferably, it is 6 mol% or more and 13 mol% or less.

  The above range is preferable as the content of the oxide 41 in the magnetic layer 4b. When the magnetic layer 4b is formed, the oxide 41 is precipitated around the magnetic particles 42, and the magnetic particles 42 are isolated and refined. This is because it becomes possible. On the other hand, when the content of the oxide 41 exceeds the above range, the oxide 41 remains in the magnetic particle 42, impairs the orientation and crystallinity of the magnetic particle 42, and further above and below the magnetic particle 42. The oxide 41 is deposited, and as a result, a columnar structure in which the magnetic particles 42 penetrate through the magnetic layers 4a to 4c is not formed. Further, when the content of the oxide 41 is less than the above range, separation and refinement of the magnetic particles 42 are insufficient, resulting in an increase in noise during recording / reproduction, and a signal / This is not preferable because the noise ratio (S / N ratio) cannot be obtained.

  The content of Cr in the magnetic layer 4b is preferably 4 at% or more and 18 at% or less (more preferably 8 at% or more and 15 at% or less). The reason why the Cr content is in the above range is that the magnetic anisotropy constant Ku of the magnetic particles 42 is not lowered too much, and high magnetization is maintained, resulting in recording / reproduction characteristics suitable for high-density recording and sufficient heat. This is because fluctuation characteristics can be obtained.

  On the other hand, when the Cr content exceeds the above range, the magnetic anisotropy constant Ku of the magnetic particles 42 becomes small, so that the thermal fluctuation characteristics deteriorate, and the crystallinity and orientation of the magnetic particles 42 deteriorate. As a result, the recording / reproduction characteristics deteriorate, which is not preferable. Further, when the Cr content is less than the above range, the magnetic anisotropy constant Ku of the magnetic particles 42 is high, so that the perpendicular coercive force becomes too high and data is sufficiently written by a magnetic head when data is recorded. This is not preferable because the recording characteristics (OW) are unsuitable for high density recording.

  The Pt content in the magnetic layer 4b is preferably 10 at% or more and 22 at% or less. The content of Pt in the above range is less than 10 at% because the magnetic anisotropy constant Ku required for the perpendicular magnetic layer 4 is not preferable. On the other hand, if it exceeds 22 at%, a stacking fault occurs inside the magnetic particle 42, and as a result, the magnetic anisotropy constant Ku becomes low, which is not preferable. In order to obtain thermal fluctuation characteristics and recording / reproduction characteristics suitable for high-density recording, the Pt content is preferably set in the above range.

  In addition, when the Pt content exceeds the above range, an fcc structure layer is formed in the magnetic particles 42, and the crystallinity and orientation may be impaired. On the other hand, if the Pt content is less than the above range, the magnetic anisotropy constant Ku for obtaining thermal fluctuation characteristics suitable for high-density recording cannot be obtained.

  The magnetic layer 4b includes one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and the oxide 41. Can be included. By including the above elements, the miniaturization of the magnetic particles 42 can be promoted or the crystallinity and orientation can be improved, and recording / reproduction characteristics and thermal fluctuation characteristics suitable for higher density recording can be obtained.

  Further, the total content of the above elements is preferably 8 at% or less. If it exceeds 8 at%, a phase other than the hcp phase is formed in the magnetic particles 42, so that the crystallinity and orientation of the magnetic particles 42 are disturbed, resulting in recording / reproducing characteristics and thermal fluctuation characteristics suitable for high-density recording. Is not preferred because it cannot be obtained.

  As shown in FIG. 2, the magnetic layer 4c is preferably made of a material containing Co as a main component and not containing the oxide 41, and the magnetic particles 42 in the layer are columnar from the magnetic particles 42 in the magnetic layer 4a. Preferably, the structure is epitaxially grown. In this case, the magnetic particles 42 of the magnetic layers 4a to 4c are preferably epitaxially grown in a columnar shape in a one-to-one correspondence in each layer. Further, the magnetic particles 42 of the magnetic layer 4b are epitaxially grown from the magnetic particles 42 in the magnetic layer 4a, so that the magnetic particles 42 of the magnetic layer 4b are miniaturized and the crystallinity and orientation are further improved. Become.

  The content of Cr in the magnetic layer 4c is preferably 10 at% or more and 24 at% or less. By setting the Cr content in the above range, a sufficient output during data reproduction can be ensured, and even better thermal fluctuation characteristics can be obtained. On the other hand, when the content of Cr exceeds the above range, the magnetization of the magnetic layer 4c becomes too small, which is not preferable. When the Cr content is less than the above range, the magnetic particles 42 are not sufficiently separated and refined, noise during recording / reproduction increases, and a signal / noise ratio (S) suitable for high-density recording (S / N ratio) is not obtained.

  The magnetic layer 4c may be made of a material containing Pt in addition to Co and Cr. The content of Pt in the magnetic layer 4c is preferably 8 at% or more and 20 at% or less. When the Pt content is in the above range, a sufficient coercive force suitable for high recording density can be obtained, and a high reproduction output during recording and reproduction can be maintained, resulting in recording suitable for high density recording. Reproduction characteristics and thermal fluctuation characteristics can be obtained.

  On the other hand, when the content of Pt exceeds the above range, an fcc-structured phase is formed in the magnetic layer 4c, which is not preferable because the crystallinity and orientation may be impaired. On the other hand, if the Pt content is less than the above range, the magnetic anisotropy constant Ku for obtaining thermal fluctuation characteristics suitable for high-density recording cannot be obtained.

  The magnetic layer 4c contains one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn in addition to Co, Cr, and Pt. Can do. By including the above elements, it is possible to promote miniaturization of the magnetic particles 42 or improve crystallinity and orientation, and to obtain recording / reproducing characteristics and thermal fluctuation characteristics suitable for higher density recording.

  The total content of the above elements is preferably 16 at% or less. On the other hand, if it exceeds 16 at%, a phase other than the hcp phase is formed in the magnetic particles 42, so that the crystallinity and orientation of the magnetic particles 42 are disturbed, resulting in recording / reproduction characteristics suitable for high-density recording. This is not preferable because thermal fluctuation characteristics cannot be obtained.

  Examples of suitable materials for the magnetic layer 4c include CoCrPt and CoCrPtB. In the case of the CoCrPtB system, the total content of Cr and B is preferably 18 at% or more and 28 at% or less.

  Suitable materials for the magnetic layer 4c include, for example, Co14-24Cr8-22Pt {Cr content 14-24at%, Pt content 8-22at%, balance Co} in CoCrPt series, Co10-24Cr8 ~ in CoCrPtB series. 22Pt0-16B {Cr content: 10-24at%, Pt content: 8-22at%, B content: 0-16at%, balance Co} is preferable. In other systems, Co10-24Cr8-22Pt1-5Ta {Cr content 10-24at%, Pt content 8-22at%, Ta content 1-5at%, balance Co} in CoCrPtTa system, Co10 in CoCrPtTaB system In addition to -24Cr8-22Pt1-5Ta1-10B {Cr content 10-24at%, Pt content 8-22at%, Ta content 1-5at%, B content 1-10at%, balance Co}, CoCrPtBNd Examples thereof include materials such as a CoCrPtTaNd system, a CoCrPtNb system, a CoCrPtBW system, a CoCrPtMo system, a CoCrPtCuRu system, and a CoCrPtRe system.

  The perpendicular coercive force (Hc) of the perpendicular magnetic layer 4 is preferably 3000 [Oe] or more. When the coercive force is less than 3000 [Oe], the recording / reproducing characteristics, particularly the frequency characteristics, are deteriorated, and the thermal fluctuation characteristics are also deteriorated, which is not preferable as a high-density recording medium.

  The reverse magnetic domain nucleation magnetic field (-Hn) of the perpendicular magnetic layer 4 is preferably 1500 [Oe] or more. When the reverse domain nucleation magnetic field (-Hn) is less than 1500 [Oe], the thermal fluctuation resistance is poor, which is not preferable.

  The perpendicular magnetic layer 4 preferably has an average particle diameter of magnetic particles of 3 to 12 nm. This average particle diameter can be obtained, for example, by observing the perpendicular magnetic layer 4 with a TEM (transmission electron microscope) and image-processing the observed image.

  The thickness of the perpendicular magnetic layer 4 is preferably 5 to 20 nm. If the thickness of the perpendicular magnetic layer 4 is less than the above, sufficient reproduction output cannot be obtained, and the thermal fluctuation characteristics also deteriorate. When the thickness of the perpendicular magnetic layer 4 exceeds the above range, the magnetic particles in the perpendicular magnetic layer 4 are enlarged, increasing noise during recording and reproduction, and a signal / noise ratio (S / N). Ratio) and recording / reproducing characteristics represented by recording characteristics (OW) are not preferable.

As the nonmagnetic layers 7a and 7b provided between the magnetic layers 4a, 4b and 4c constituting the perpendicular magnetic layer 4, it is preferable to use a material having an hcp structure. Specifically, for example, Ru, Ru alloy, CoCr alloy, CoCrX ₁ alloy _{(X 1} is, Pt, Ta, Zr, Re , Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W , Mo, Ti, V, Zr, or B represents at least one element or two or more elements). Further, as an alloy having an hcp structure, an alloy such as Ru, Re, Ti, Y, Hf, or Zn can be used other than Ru.

  In the case where a CoCr alloy is used as the nonmagnetic layers 7a and 7b, the Co content is preferably in the range of 30 to 80 at%. This is because within this range, the coupling between the magnetic layers 4a, 4b, and 4c can be adjusted to be small.

Further, as the nonmagnetic layers 7a and 7b, metals or alloys having other structures may be used as long as the crystallinity and orientation of the upper and lower magnetic layers 4a, 4b and 4c are not impaired. Specifically, for example, Pd, Pt, Cu, Ag, Au, Ir, Mo, W, Ta, Nb, V, Bi, Sn, Si, Al, C, B, Cr, or an alloy thereof is used. it can. In particular, as a Cr alloy, CrX ₂ (X ₂ represents at least one element selected from Ti, W, Mo, Nb, Ta, Si, Al, B, C, and Zr. ) And the like can be preferably used. In this case, the Cr content is preferably 60 at% or more.

The nonmagnetic layers 7a and 7b preferably have a structure in which metal particles of the above alloy are dispersed in an oxide, metal nitride, or metal carbide. Furthermore, it is more preferable that the metal particles have a columnar structure that vertically penetrates the nonmagnetic layers 7a and 7b. In order to obtain such a structure, it is preferable to use an alloy material containing an oxide, a metal nitride, or a metal carbide. Specifically, as the oxide, for example, SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , Cr ₂ O ₃ , MgO, Y ₂ O ₃ , TiO _2, etc. As the metal nitride, for example, AlN, Si For example, TaC, BC, SiC, or the like can be used as the metal carbide such as ₃ N ₄ , TaN, or CrN. Furthermore, for example, CoCr—SiO ₂ , CoCr—TiO ₂ , CoCr—Cr ₂ O ₃ , CoCrPt—Ta ₂ O ₅ , Ru—SiO ₂ , Ru—Si ₃ N ₄ , Pd—TaC, and the like can be used.

  The content of the oxide, metal nitride, or metal carbide in the nonmagnetic layer 7 is preferably a content that does not impair the crystal growth and crystal orientation of the perpendicular magnetic film. In addition, the content of oxide, metal nitride, or metal carbide is preferably 4 mol% or more and 30 mol% or less with respect to the alloy.

  When the content of the oxide, metal nitride, or metal carbide in the nonmagnetic layer 7 exceeds the above range, the oxide, metal nitride, or metal carbide remains in the metal particle, and the metal particle In addition to impairing crystallinity and orientation, oxides, metal nitrides, or metal carbides are also deposited on the top and bottom of the metal particles, making it difficult for the metal particles to have a columnar structure that vertically penetrates the nonmagnetic layer 7. This is not preferable because the crystallinity and orientation of the magnetic layer formed on the magnetic layer 7 may be impaired. On the other hand, when the content of the oxide, metal nitride, or metal carbide in the nonmagnetic layer 7 is less than the above range, the effect of adding the oxide, metal nitride, or metal carbide cannot be obtained. Therefore, it is not preferable.

  By providing the nonmagnetic layers 7a and 7b with an appropriate thickness, magnetization reversal of individual films can be facilitated, and dispersion of magnetization reversal of the entire magnetic particles can be reduced. As a result, the S / N ratio can be further improved.

  That is, the thickness of the nonmagnetic layers 7a and 7b is within a range in which the magnetostatic coupling of the magnetic layers 4a, 4b, and 4c constituting the perpendicular magnetic layer 4 is not completely cut, specifically, 0.1 nm to 2 nm (more Preferably, the thickness is 0.1 to 0.8 nm.

  The intermediate layer 9 containing Ru and Co provided between the perpendicular magnetic layer 4 (magnetic layer 4c) and the carbon protective film 5 has a RuCo alloy (the first main component is Ru and the second main component is Co). Or CoRu alloy (the first main component is Co and the second main component is Ru) or the like can be used. Since the RuCo alloy and the CoRu alloy are generally harder than the perpendicular magnetic layer 4, providing the RuCo alloy or the CoRu alloy on the perpendicular magnetic layer 4 has an effect of protecting the perpendicular magnetic layer 4. In addition, these alloys generally have the same crystal structure as that of the perpendicular magnetic layer 4 and have a close interstitial distance between crystals. Therefore, such an intermediate layer 9 containing Ru and Co has high coverage (adhesiveness) with respect to the perpendicular magnetic layer 4, and covers the entire surface of the perpendicular magnetic layer 4 densely, thereby strengthening the perpendicular magnetic layer 4. Will protect.

  Further, the reason why the intermediate layer 9 containing Ru and Co exhibits an effect as a protective layer is that, unlike a carbon film generally used as a protective layer, there is not much spacing loss. Although the reason for this is not necessarily clear, for example, RuCo alloys and CoRu alloys contain a large amount of Co, which is a ferromagnetic material, and therefore have the effect of drawing the magnetic field from the magnetic head into the perpendicular magnetic layer, which reduces the spacing loss. It is thought that.

  Moreover, although it is preferable that the intermediate layer 9 is a layer containing 30 atomic% or more of Ru and 30 atomic% or more of Co as described above, other elements are added within a range in which the above effects are exhibited. It is also possible. Examples of the additive element include a substance that increases the effect of drawing the magnetic field from the magnetic head into the perpendicular magnetic layer 4 without significantly reducing the hardness of the RuCo alloy or CoRu alloy, or the effect of increasing the hardness by refining the crystal structure. Substances having the following are preferred. Examples of such additive elements include one or more elements selected from Cr, Pt, B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn. Can do.

  Further, although the layer thickness of the intermediate layer 9 is preferably in the range of 2 to 8 mm as described above, the optimum film thickness is within this thickness range from the scratch resistance and electromagnetic conversion characteristics of the magnetic recording medium. It is selected appropriately.

  The carbon protective layer 5 prevents corrosion of the perpendicular magnetic layer 4 and prevents damage to the surface of the medium when the magnetic head comes into contact with the medium. For example, the carbon protective layer 5 is formed by sputtering, CVD, ion beam evaporation, or the like. It is formed. The thickness of the carbon protective layer 5 is preferably 1 to 10 nm from the viewpoint of high recording density because the distance between the head and the medium can be reduced.

  For the lubricating layer 6, it is preferable to use a lubricant such as perfluoropolyether, fluorinated alcohol, fluorinated carboxylic acid, or the like.

FIG. 3 shows an example of a magnetic recording / reproducing apparatus to which the present invention is applied.
This magnetic recording / reproducing apparatus includes a magnetic recording medium 50 having the configuration shown in FIG. 2, a medium driving unit 51 that rotationally drives the magnetic recording medium 50, a magnetic head 52 that records and reproduces information on the magnetic recording medium 50, A head driving unit 53 that moves the magnetic head 52 relative to the magnetic recording medium 50 and a recording / reproducing signal processing system 54 are provided. Further, the recording / reproducing signal processing system 54 can process data input from the outside and send a recording signal to the magnetic head 52, process a reproducing signal from the magnetic head 52, and send the data to the outside. ing. Further, as the magnetic head 52 used in the magnetic recording / reproducing apparatus to which the present invention is applied, a magnetic head suitable for a higher recording density having a GMR element utilizing a giant magnetoresistance effect (GMR) as a reproducing element is used. be able to.

  According to the magnetic recording / reproducing apparatus, by adopting the magnetic recording medium to which the present invention is applied as the magnetic recording medium 50, miniaturization of magnetic particles and magnetic isolation are promoted, and the S / N during reproduction is increased. Ratio can be greatly improved, thermal fluctuation characteristics can be improved, and a medium having excellent recording characteristics (OW) can be obtained. A recording / reproducing apparatus can be obtained.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

Example 1
In Example 1, first, a cleaned glass substrate (manufactured by Konica Minolta Co., Ltd., 2.5 inches in outer diameter) is accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3040 made by Anelva Co., Ltd.), and the ultimate vacuum is achieved. After the inside of the film formation chamber was evacuated to 1 × 10 ⁻⁵ Pa, an adhesion layer having a layer thickness of 10 nm was formed on the glass substrate using a Cr target. Further, on this adhesion layer, a layer thickness of 25 nm is obtained at a substrate temperature of 100 ° C. or lower using a target of 55Fe-30Co-15Ta {Fe content 55 at%, Co content 30 at%, Ta content 15 at%}. A soft magnetic layer is formed, and a Ru layer is formed thereon with a thickness of 1.6 nm. Then, a Co-20Fe-5Zr-5Ta soft magnetic layer is further formed with a thickness of 25 nm. An underlayer was used.

  Next, on the soft magnetic underlayer, Ni-6W {W content 6 at%, remaining Ni} target and Ru target were sequentially formed with a layer thickness of 5 nm and 20 nm, respectively, and this was subjected to orientation control. Layered.

Then, on the orientation control _{layer, (Co15Cr16Pt) 91- (SiO 2} ) 6- (TiO 2) 3 {Cr content 15 at%, Pt content of 18 at%, the alloy of the balance Co 91 mol%, of SiO ₂ A magnetic layer having a composition of 6 mol% of an oxide, 3 mol% of an oxide of Cr ₂ O ₃ , and 3 mol% of an oxide of TiO ₂ is formed at a sputtering pressure of 2 Pa and a layer thickness of 3 nm. In this magnetic layer, Ku was 2.2 × 10 ⁶ (erg / cc) and Ms was 500 (emu / cc).

Next, on the magnetic layer was deposited at a layer thickness of 0.3nm nonmagnetic layer composed of _{(Co30Cr) 88- (TiO 2)} 12.

Next, on the non-magnetic layer was formed by _(Co11Cr18Pt) 92- thickness 4nm and (SiO 2) 5-magnetic layer made of _(TiO 2) 3 as a sputtering pressure 2 Pa.

Next, a nonmagnetic layer made of Ru was formed with a layer thickness of 0.3 nm on the magnetic layer. In this magnetic layer, Ku was 4 × 10 ⁶ (erg / cc) and Ms was 600 (emu / cc).

Next, a magnetic layer is formed on the nonmagnetic layer using a target composed of Co20Cr14Pt3B {Cr content 20 at%, Pt content 14 at%, B content 3 at%, balance Co} and a sputtering pressure of 0.6 Pa. The film was formed with a layer thickness of 4 nm. In this magnetic layer, Ku was 1.5 × 10 ⁶ (erg / cc), and Ms was 400 (emu / cc).

  Next, on the magnetic layer, using a target made of 52.5 Ru 47.5 Co {Ru content 52.5 atomic%, Co content 47.5 atomic%}, the sputtering pressure is 0.6 Pa, and the same as the target A RuCo layer having a composition was formed with a layer thickness of 0.5 nm (5 mm).

  Next, a carbon protective layer having a thickness of 3.0 nm was formed by a CVD method, and then a lubricating layer made of perfluoropolyether was formed by a dipping method to obtain a magnetic recording medium of Example 1.

(Examples 2 to 7)
In Examples 2 to 7, as shown in Table 1 below, magnetic recording media were produced under the same conditions as in Example 1 except that the composition and layer thickness of the RuCo layer were changed.

(Comparative Example 1)
In Comparative Example 1, as shown in Table 1 below, a magnetic recording medium was manufactured under the same conditions as in Example 1 except that the RuCo layer was not provided.

<Evaluation of electromagnetic conversion characteristics of magnetic recording media>
The magnetic recording media of Examples 1 to 7 and Comparative Example 1 were recorded using the read / write analyzer RWA1632 and spin stand S1701MP manufactured by GUZIK, USA, and their recording / reproduction characteristics, that is, S / N ratio, recording characteristics (OW). ) And thermal fluctuation characteristics were evaluated. The evaluation results are shown in Table 1.

As the magnetic head, a head using a single pole magnetic pole on the writing side and a TMR element on the reading side was used.
The S / N ratio was measured as a recording density of 750 kFCI.
On the other hand, as for the recording characteristics (OW), first, a 750 kFCI signal was written, then a 100 kFCI signal was overwritten, a high frequency component was taken out by a frequency filter, and the data writing ability was evaluated by the residual ratio.
On the other hand, with respect to thermal fluctuation characteristics, after writing at a recording density of 50 kFCI under the condition of 70 ° C., the output attenuation rate with respect to the playback output one second after writing is (So−S) × 100 / (So). Calculated based on In this equation, So represents a reproduction output when 1 second has elapsed after writing, and S represents a reproduction output after 10,000 seconds.

<Scratch resistance evaluation of magnetic recording media>
Further, the magnetic recording media of Examples 1 to 7 and Comparative Example 1 were subjected to a scratch test for evaluating scratch resistance. The scratch test was performed using a SAF tester manufactured by Kubota. As test conditions, the magnetic recording medium was rotated at 12000 rpm, and the seek operation was repeated on the disk surface at a speed of 5 inches / second for 2 hours using a PP6 head, and then the presence or absence of scratches was confirmed with an optical microscope. Then, such a scratch test was performed on each of the 20 magnetic recording media of Examples 1 to 7 and Comparative Example 1, and the scratch generation rate (%) was obtained. The evaluation results are shown in Table 1.

  From the evaluation results shown in Table 1, the magnetic recording media of Examples 1 to 7, which are the scope of the present invention, are superior in electromagnetic conversion characteristics and scratch resistance than the magnetic recording medium of Comparative Example 1, which is outside the scope of the present invention. You can see that

1 ... Non-magnetic substrate
2. Soft magnetic underlayer
2a: Soft magnetic layer
2b ... Spacer layer
3 ... Orientation control layer
4 ... perpendicular magnetic layer
4a, 4b, 4c ... magnetic layer
5. Carbon protective layer
6 ... Lubrication layer
7a, 7b ... nonmagnetic layer
8 ... Nonmagnetic underlayer
9: Intermediate layer containing Ru and Co
41 ... Oxides
42 ... Magnetic particles (nonmagnetic particles in the nonmagnetic layers 7a and 7b)
50. Magnetic recording medium
51. Medium drive unit
52. Magnetic head
53. Head drive unit
54. Recording / reproducing signal processing system

Claims (4)

A magnetic recording medium comprising a carbon protective layer and a perpendicular magnetic layer having an easy axis of magnetization oriented perpendicularly to the nonmagnetic substrate at least on a nonmagnetic substrate,
A magnetic recording medium, wherein an intermediate layer containing Ru and Co is provided between the perpendicular magnetic layer and the carbon protective layer.   The magnetic recording medium according to claim 1, wherein the intermediate layer is a layer containing 30 atomic% or more of Ru and 30 atomic% or more of Co.   3. The magnetic recording medium according to claim 1, wherein a thickness of the intermediate layer is in a range of 0.2 to 0.8 nm. The magnetic recording medium according to any one of claims 1 to 3,
A magnetic recording / reproducing apparatus comprising: a magnetic head for recording / reproducing information with respect to the magnetic recording medium.

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