JP2008176825A - Magnetic recording medium, magnetic recording and reproducing device, and magnetic recording medium manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high quality magnetic recording medium which is applicable to ramp loading and is excellent for stabilizing the flying of the magnetic head and superior in electromagnetic transducing, and also provide its manufacturing method, and a magnetic recording and reproducing device. <P>SOLUTION: The magnetic recording medium has at least a magnetic layer formed on a non-magnetic base plate 1. It has grooves 11 having circumferential components in the length direction by texturing and crossing one another with an angle α of 2-8° on the surface 1a of the non-magnetic base plate 1. It is used in combination with a flying magnetic head floating 10 nm high or lower. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium, a magnetic recording / reproducing apparatus, and a method of manufacturing a magnetic recording medium, and in particular, a magnetic recording medium and a magnetic recording / reproducing applicable to a ramp load method, which is a kind of information recording / reproducing method. The present invention relates to an apparatus and a method for manufacturing a magnetic recording medium.

  A hard disk device, which is a magnetic recording device used as a storage device of an information processing device, includes a magnetic head for reproduction recording and a magnetic disk that is a magnetic recording medium having a magnetic layer. In a magnetic disk, the magnetic layer is formed by depositing a ferromagnetic metal or an alloy thereof on a nonmagnetic substrate by sputtering, vapor deposition, electroless plating, or the like.

  In recent hard disk devices, a so-called ramp load system has been put to practical use as a method for recording and reproducing information. The ramp loading method is a method having a mechanism in which a head retreat location is prepared in the vicinity of the outer periphery of the disk, and the head is stored in this retreat location when the rotation of the disk is stopped. In this system, the head is not in contact with the disk when the disk is stationary, and it has been said that there is no concern about so-called stiction in the CSS system. However, in the ramp load system, it is necessary to improve the flight stability of the head in order to reduce the change in the behavior of the head when the head and the disk are inadvertently contacted.

  In order to improve the flight stability of the head in the ramp load system, it is preferable that the disk surface has a certain roughness called texture as in the case of CSS. Therefore, it has been studied to provide a concentric texture with respect to the rotation center of the magnetic disk.

  However, when processing a concentric texture, scratches are likely to occur. If a concentric texture is provided, a large number of concentric irregularities are formed on the magnetic disk. When the thickness is large, the depth of the uneven portion is partially increased. As described above, when the irregular shape becomes irregular or the depth becomes large, the air flow between the magnetic disk surface and the magnetic head becomes unstable, and the flight stability of the magnetic head may be reduced. there were.

Patent Document 1 listed below discloses a magnetic recording medium that is preferably used in a CSS system in which adjacent concentric textures are alternately crossed and the cross angle is defined in a range of 30 ° to 50 °. ing. According to the magnetic recording medium described in Patent Document 1, the occurrence of scratches at the time of texturing is small, and the uneven portions formed by texturing have a regular shape. It is said that the flow of air to and from the head becomes stable, and the flight stability of the magnetic head is expected to be improved.
JP-A-6-150304

However, when the cross angle is increased, scratches discovered by visual observation of the magnetic disk surface increase, and the quality of the magnetic disk may be deteriorated.
The present invention has been made in view of the above circumstances, and can be applied to a ramp load system. The magnetic recording medium has excellent flight stability of a magnetic head, high quality, and excellent electromagnetic conversion characteristics. It is an object to provide a method and a magnetic recording / reproducing apparatus.

In order to achieve the above object, the present invention employs the following configuration.
[1] A magnetic recording medium in which at least a magnetic layer is provided on a nonmagnetic substrate, and the surface of the nonmagnetic substrate has a circumferential component in the longitudinal direction and intersects each other by texturing. A plurality of grooves are formed, and a cross angle between the grooves is set in a range of 2 ° to 8 °. The groove is used in combination with a flying magnetic head, and the flying height of the flying magnetic head is 10 nm or less. A magnetic recording medium used under certain conditions.
[2] The magnetic recording medium according to [1], wherein the nonmagnetic substrate is made of glass or aluminum.
[3] The above item 1 or 2, wherein the non-magnetic substrate after the texturing process has a surface roughness Ra in the range of 0.2 nm (2.0 mm) to 0.25 nm (2.5 mm). 3. The magnetic recording medium according to item 2.
[4] A magnetic recording / reproducing apparatus including a magnetic recording medium and a floating head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium is any one of the preceding items 1 to 3. A magnetic recording / reproducing apparatus characterized by being a magnetic recording medium.
[5] A method of manufacturing a magnetic recording medium in which at least a magnetic layer is formed after a texturing process is performed on the surface of a nonmagnetic substrate, and the texturing process uses a slurry containing abrasive grains and a texture tape. The texture tape is swung along the radial direction of the non-magnetic substrate while rotating the non-magnetic substrate, thereby having a circumferential component in the longitudinal direction and a cross angle in the range of 2 ° to 8 °. A method for manufacturing a magnetic recording medium is used in combination with a floating magnetic head, which forms a plurality of grooves intersecting each other, and the flying height of the floating magnetic head is 10 nm or less.
[6] The method of manufacturing a magnetic recording medium as described in [5] above, wherein the nonmagnetic substrate is made of glass or aluminum.

  According to the present invention, it is possible to provide a magnetic recording medium that can be applied to a ramp load system, has excellent flight stability of a magnetic head, has high quality, and has excellent electromagnetic conversion characteristics, a manufacturing method thereof, and a magnetic recording / reproducing apparatus. Can do.

  Hereinafter, a magnetic recording medium, a manufacturing method thereof, and a magnetic recording / reproducing apparatus according to embodiments of the present invention will be described with reference to the drawings. The drawings referred to in the following description are for explaining the configuration of the magnetic recording medium and the like of the present embodiment, and the size, thickness, dimensions, etc. of each part shown in the drawings are the dimensions of the actual magnetic recording medium. The relationship may be different.

FIG. 1 is an enlarged schematic cross-sectional view showing an example of the magnetic recording medium of the present embodiment. The magnetic recording medium shown in FIG. 1 is configured such that an underlayer 2, an intermediate layer 3, a magnetic layer 4, and a protective film layer 5 are sequentially laminated on a nonmagnetic substrate 1, and a lubricant layer 6 is provided as the uppermost layer. ing.
In FIG. 1, the underlayer 2, the intermediate layer 3, the magnetic layer 4, and the protective film layer 5 are formed on one surface 1a of the nonmagnetic substrate 1. However, the present invention is not limited to this, and the nonmagnetic substrate 1 These layers may be formed on both sides.

  Nonmagnetic substrate 1 is made of a metal material such as aluminum or aluminum alloy, an inorganic material such as glass, ceramic, titanium, carbon or silicon, polyethylene terephthalate, polyimide, polyamide, polycarbonate, polysulfone, polyethylene naphthalate, or polyvinyl chloride. In addition, a polymer compound such as a cyclic hydrocarbon group-containing polyolefin can be used. Further, one or more kinds of films selected from NiP, NiP alloys, and other alloys can be deposited on the surfaces of these substrates by plating, sputtering, or the like.

In the non-magnetic substrate 1, the average surface roughness Ra is 0.25 nm (2.5 cm) or less, preferably 0.20 nm (2.0 cm) or more and 0.23 nm (2.3 cm) or less. However, this is desirable because it is suitable for high recording density recording that causes the magnetic head to fly low.
In addition, it is preferable that the fine waviness (Wa) on the surface of the nonmagnetic substrate 1 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 a low flying height of the magnetic head. .

  On one surface 1a of the nonmagnetic substrate 1 on the base layer 2 side, a plurality of grooves formed by texturing is provided. FIG. 2 is a schematic plan view in which a part of one surface 1a of the nonmagnetic substrate is partially enlarged. As shown in FIG. 2, a plurality of grooves 11 are formed in the nonmagnetic substrate 1 so as to cross each other. A line represented by reference numeral 11 in FIG. 2 corresponds to one groove 11. By forming the groove 11, a minute uneven pattern is formed on the one surface 1 a of the nonmagnetic substrate 1.

  As shown in FIG. 2, each groove 11 is formed so that the longitudinal direction thereof is substantially along the circumferential direction indicated by the arrow R of the nonmagnetic substrate 1. The longitudinal direction of each groove 11 may coincide with the circumferential direction R, and the longitudinal direction of each groove 11 may be a direction that intersects the circumferential direction R. The longitudinal direction of each groove 11 can be decomposed into a circumferential R component and a radial L component with respect to the base point O. The longitudinal direction of each groove 11 has at least a circumferential component R, and the circumferential component R is larger than the radial component L.

The grooves 11 intersect each other, and the cross angle α at the intersecting portion is set in a range of 2 ° to 8 °. When the cross angle α is less than 2 °, scratches may be formed in the texturing process, the irregular pattern on the surface 1a becomes irregular due to the occurrence of scratches, and the scratch depth by the scratches is large. In this case, the depth of the unevenness is partially increased, and the air flow between the magnetic recording medium and the magnetic head becomes unstable, so that the flight stability is lowered. The texture also has the effect of enhancing the magnetic orientation in the circumferential direction. However, when the cross angle is less than 2 °, the magnetic orientation in the circumferential direction is weakened, and the electromagnetic conversion characteristics at the time of recording / reproducing magnetic recording information by the magnetic head are reduced. Since it falls, it is not preferable.
On the other hand, if the cross angle α exceeds 8 °, scratches discovered by visual observation of the magnetic disk surface increase, and the quality of the magnetic disk may be deteriorated, which is not preferable.

Next, the material of the underlayer 2 is a Cr alloy composed of one or more selected from Ti, Mo, Al, Ta, W, Ni, B, Si, Mn and V and Cr, or Cr. Can be configured.
When the underlayer 2 is a nonmagnetic underlayer having a multilayer structure, at least one of the constituent layers constituting the nonmagnetic underlayer can be made of the Cr alloy or Cr.
The nonmagnetic underlayer is made of NiAl alloy, RuAl alloy, or Cr alloy (one or more selected from Ti, Mo, Al, Ta, W, Ni, B, Si, and V and Cr). Alloy).
When the nonmagnetic underlayer has a multilayer structure, at least one of the constituent layers constituting the nonmagnetic underlayer can be made of a NiAl alloy, a RuAl alloy, or the Cr alloy.

  As the material of the intermediate layer 3, for the purpose of promoting the epitaxial growth of the Co alloy, it is preferable to use a Co alloy containing Co as a main material and a non-magnetic material having an hcp structure. For example, it is preferable to include any one selected from Co—Cr, Co—Cr—Ru, Co—Cr—Ta, and Co—Cr—Zr alloys.

  The material of the magnetic layer 4 is preferably a Co alloy containing Co as a main material and having a hcp structure. For example, any of Co—Cr—Ta, Co—Cr—Pt, Co—Cr—Pt—Ta, Co—Cr—Pt—B, and Co—Cr—Pt—B—Cu alloys It is preferable to include one kind.

  As the protective film layer 5, a carbon-based material such as CVD carbon, amorphous carbon, hydrogen-containing carbon, nitrogen-containing carbon, or fluorine-containing carbon formed by a plasma CVD method, or a ceramic-based material such as silica or zirconia is used. Can do. Among these, hard and dense CVD carbon is preferably used not only from the viewpoint of durability but also from the viewpoint of economy and productivity. When the thickness of the protective film layer 5 is thin, the durability is lowered, and when it is thick, the loss during recording / reproduction increases. Therefore, the thickness is set to 10 to 150 mm (1 to 15 nm), preferably 20 to 60 mm (2 to 6 nm). Is done.

  The uppermost lubricant layer 6 includes a polymer of a polymerizable unsaturated group-containing perfluoropolyether compound. Examples of the polymerizable unsaturated group-containing perfluoropolyether compound include compounds in which an organic group having a polymerizable unsaturated bond is bonded to at least one end of the main chain perfluoropolyether. When a lubricant having a polymerizable group is used, a photopolymerization initiator such as a commercially available azo polymerization initiator, perester polymerization initiator, peralcohol polymerization initiator, or benzophenone is used as necessary. It is also possible to add a photosensitizer.

  In the magnetic recording medium of the present embodiment, the underlayer 2, the intermediate layer 3, the magnetic layer 4, and the protective film layer 5 are sequentially laminated on the nonmagnetic substrate 1, and the lubricant layer 6 is provided as the uppermost layer. In this magnetic recording medium, since the surface of the nonmagnetic substrate 1 is textured, a plurality of grooves having circumferential components in the longitudinal direction and intersecting with each other are formed. The magnetic recording medium is capable of recording / reproducing density information.

  In the magnetic recording medium of this embodiment, the texturing process is performed on the nonmagnetic substrate 1, and then the underlayer 2, the intermediate layer 3, the magnetic layer 4, and the protective film layer 5 are sequentially stacked, and further the lubricant layer 6. It is manufactured by forming.

  The texturing process is for forming a plurality of grooves on the upper surface of the non-magnetic substrate 1, and using a polishing liquid containing diamond abrasive grains or alumina abrasive grains, a disk-like non-magnetic rotating at low speed A plurality of grooves are formed on the upper surface of the nonmagnetic substrate 1 by pressing the texturing tape against the surface of the substrate 1 and reciprocating (vibrating) the texturing tape in the radial direction of the nonmagnetic substrate 1 while dripping the polishing liquid. Is a process of forming

As the polishing liquid used here, for example, aqueous diamond slurry or the like can be used, and polyester-based ultrafine fiber woven fabric or the like can be used as the texturing tape. In order to set the cross angle α between the grooves in the range of 2 ° to 8 °, the relationship between the rotation speed of the substrate and the reciprocating speed of the texturing tape may be set as appropriate. The rotational speed and the reciprocating speed vary depending on the diameter of the magnetic recording medium. For example, the rotational speed of the substrate 1 when manufacturing a magnetic recording medium having a diameter of 1.89 to 3.5 inches is about 150 to 800 rpm. The reciprocating period of the texturing tape can be about 3 to 20 Hz. The reciprocating amplitude of the texturing tape may be about 1.0 mm to 2.0 mm, for example.
If the rotational speed of the nonmagnetic substrate 1 is increased too much, there is a possibility that radial texture grooves cannot be formed uniformly on the surface of the disk-shaped nonmagnetic substrate 1, and the cross angle α between the grooves becomes less than 2 °. Since it may be, it is not preferable. On the other hand, if the rotational speed of the nonmagnetic substrate 1 is reduced, the cross angle α between the grooves may exceed 8 °, which is not preferable.
If the moving period of the texturing tape is too slow, the textured grooves may not be formed uniformly, and the cross angle α between the grooves may exceed 8 °, which is not preferable. On the other hand, if the moving period of the texturing tape is made too fast, the cross angle α between the grooves may be less than 2 °, which is not preferable.

  Further, the average surface roughness Ra of the surface of the non-magnetic substrate 1 after texturing is preferably 0.15 nm (1.5 以上) or more and 0.3 nm (3.0 Å) or less, and 0.2 nm ( It is more preferable that the thickness be 2.0 mm or more and 0.25 nm (2.5 mm) or less, and it is more preferable that the thickness be 0.2 nm (2.0 mm) or more and 0.23 nm (2.3 mm) or less. When the average surface roughness Ra of the surface is less than 0.15 nm (1.5 mm), the effect of the textured groove becomes insufficient, and the magnetic anisotropy of the backing layer deviates from the direction of the textured groove. Therefore, it is not preferable. If the average surface roughness Ra of the surface exceeds 0.3 nm (3.0 mm), it is not preferable because the flying height of the magnetic head cannot be made sufficiently small. Further, it is not preferable because the SNR is lowered due to the deterioration of the orientation of the perpendicular magnetic recording film 6.

  By the above texturing process, a plurality of grooves having a circumferential component in the longitudinal direction and intersecting each other with a cross angle in the range of 2 ° to 8 ° can be formed. Thereafter, the underlayer 2, the intermediate layer 3, the magnetic layer 4 and the protective film layer 5 are sequentially laminated, and the lubricant layer 6 is further formed, whereby the magnetic recording medium of this embodiment can be manufactured.

Next, an example in which the magnetic recording / reproducing apparatus according to the present embodiment is applied to a hard disk drive (hereinafter referred to as HDD) will be described with reference to FIG.
The HDD shown in FIG. 3 operates by a so-called ramp load method (load / unload method), and has a rectangular box-like case 12 having an upper surface opened and a top end opening of the case screwed to the case by a plurality of screws. And a top cover (not shown) that closes.

  In the case 12, there are two magnetic disks 10 (only one is shown) as a magnetic recording medium according to the present invention, a spindle motor 18 as a drive unit for supporting and rotating the magnetic disk, and information on the magnetic disk 10. A plurality of floating magnetic heads 40 that perform recording and reproduction, a carriage assembly 22 that supports these floating magnetic heads 40 movably with respect to the magnetic disk 10, and a voice coil motor that rotates and positions the carriage assembly 22 ( (Hereinafter referred to as VCM) 24, when the floating magnetic head 40 moves to the outermost periphery of the magnetic disk 10, the ramp load mechanism 25 that holds the floating magnetic head 40 in the retracted position separated from the magnetic disk 10 and the recording / reproducing signal A substrate unit 21 having a read / write amplifier as a processing circuit is provided. It has been paid.

  A printed circuit board (not shown) that controls the operations of the spindle motor 18, the VCM 24, and the floating magnetic head 40 via the board unit 21 is screwed to the outer surface of the bottom wall of the case 12.

  Each magnetic disk 10 has a magnetic layer on the upper surface and the lower surface. The two magnetic disks 10 are fitted on the outer periphery of a hub (not shown) of the spindle motor 18 and are fixedly supported on the hub by a clamp spring 17. As a result, the two magnetic disks 10 are coaxially stacked with a predetermined gap. Then, by driving the spindle motor 18, the two magnetic disks 10 are integrally rotated in the arrow B direction at a predetermined speed, for example, 4200 rpm.

  The carriage assembly 22 includes a bearing portion 26 fixed on the bottom wall of the case 12 and a plurality of arms 32 extending from the bearing portion 26. These arms 32 are positioned parallel to the surface of the magnetic disk 10 and at a predetermined distance from each other, and extend from the bearing portion 26 in the same direction. The carriage assembly 22 is provided with an elongated plate-like suspension 38 that can be elastically deformed. The suspension 38 is configured by a leaf spring, and the base end thereof is fixed to the distal end of the arm 32 by spot welding or adhesion, and extends from the arm 32. Each suspension 38 may be formed integrally with the corresponding arm 32. The arm 32 and the suspension 38 constitute a head suspension, and the head suspension and the floating magnetic head 40 constitute a head suspension assembly.

  Each floating magnetic head 40 is composed of a slider and a recording / reproducing head portion formed on the end face of the slider, and is fixed to a gimbal spring (not shown) provided at the tip of the suspension 38. Each magnetic head 40 is applied with a head load L toward the surface of the magnetic disk 10 due to the elasticity of the suspension 38. During operation, the flying height of the magnetic head 40 relative to the magnetic disk 10 is set to 10 nm or less.

  The carriage assembly 22 has a support frame 45 extending from the bearing portion 26 in the direction opposite to the arm 32, and the voice coil 47 constituting a part of the VCM 24 is supported by the support frame 45. The support frame 45 is integrally formed on the outer periphery of the voice coil 47 with synthetic resin. The voice coil 47 is positioned between a pair of yokes 49 fixed on the case 12, and constitutes the VCM 24 together with these yokes and a magnet (not shown) fixed to one of the yokes. When the voice coil 47 is energized, the carriage assembly 22 rotates around the bearing portion 26, and the magnetic head 40 is moved and positioned on a desired track of the magnetic disk 10.

  The ramp loading mechanism 25 includes a ramp 51 provided on the bottom wall of the case 12 and disposed outside the magnetic disk 10, and a tab 53 extending from the tip of each suspension 38. When the carriage assembly 22 rotates to the retracted position outside the magnetic disk 10, each tab 53 engages with the ramp surface formed on the ramp 51, and then is lifted by the inclination of the ramp surface and floated magnetically. The head 40 is unloaded.

As described above, according to the above magnetic recording medium, a plurality of grooves 11 having a circumferential component in the longitudinal direction and intersecting each other are formed on the nonmagnetic substrate 1, and the cross angle between the grooves 11. Is set in the range of 2 ° to 8 °, there is no possibility of forming a scratch in the texturing process, the air flow between the magnetic recording medium and the floating magnetic head becomes stable, and the floating type The flight stability of the magnetic head can be improved. Further, the occurrence of scratches found by visual observation of the magnetic recording medium surface is reduced, and the quality of the magnetic recording medium can be improved.
Furthermore, by setting the cross angle in the above range, the magnetic orientation in the circumferential direction is strengthened, and the electromagnetic conversion characteristics at the time of recording / reproducing magnetic recording information by the floating magnetic head can be enhanced.

  In particular, in the above magnetic recording medium, information is recorded and reproduced by a so-called ramp load method in which the floating magnetic head does not contact the magnetic recording medium during operation, and the flying height of the floating magnetic head is 10 nm or less. It is suitably used for a certain magnetic recording / reproducing apparatus. That is, unlike the CSS method, the floating magnetic head does not have an opportunity to contact the magnetic recording medium, so there is no need to consider the adsorption phenomenon between the floating magnetic head and the magnetic recording medium, compared with the conventional magnetic recording medium. Thus, the cross angle of the grooves formed by the texturing process can be greatly reduced. Since the cross angle can be reduced, the flying stability of the flying magnetic head can be increased, whereby the flying height can be further reduced and the recording density can be increased.

  Hereinafter, an example is shown and the operation effect of the present invention is clarified. However, the present invention is not limited to the following examples.

(Example 1)
Texturing processing was performed on the glass substrate (Ohara Corporation crystallized substrate TS10-SX, diameter 2.5 inches) in the substrate radial direction.
In the texturing process, an aqueous diamond slurry containing diamond abrasive grains having an average particle diameter of 0.1 μm was used as the polishing liquid, and a polyester ultrafine fiber woven fabric was used as the texturing tape. The rotation speed of the substrate 1 was 550 rpm, the reciprocation period of the texturing tape was 3.5 Hz, and the amplitude width was 2 mm. In this way, a plurality of grooves having a cross angle of 2.7 ° at a radial position of 15 mm were formed on the surface of the glass substrate. Further, the surface roughness Ra of the glass substrate after the texturing treatment was 1.19 nm.

After the texturing process, the surface of the substrate is cleaned, and after the surface of the substrate is cleaned, the substrate is accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3010 manufactured by Anerva Co., Ltd.) The inside of the deposition chamber was evacuated until the ^pressure reached 2.7 × 10 ⁻⁵ Pa (2 × 10 ⁻⁷ Torr). Thereafter, the substrate was heated to 250 ° C.
After heating, a nonmagnetic underlayer was laminated using a Cr target to a thickness of 5 nm. Further, a nonmagnetic underlayer was laminated from a Cr—Mo alloy (Cr: 80 at%, Mo: 20 at%) to a thickness of 5 nm using a target.
Next, as a nonmagnetic intermediate layer, a target made of a Co—Cr alloy (Co: 65 at%, Cr: 35 at%) was used so as to have a thickness of 2 nm.
Next, a CoCrPtB alloy layer as a magnetic layer is formed using a target made of a Co—Cr—Pt—B alloy (Co: 60 at%, Cr: 22 at%, Pt: 12 at%, B: 6 at%) as a magnetic layer. The film was formed to a thickness of 20 nm, and a protective film made of CVD carbon was laminated to a thickness of 5 nm using a plasma CVD apparatus.
Then, a lubricant made of perfluoropolyether is adjusted to 0.05% by weight on the protective film and applied at a lifting speed of 3 mm / sec by the dipping method to obtain the perpendicular magnetic recording medium of Example 1. It was.

(Example 2)
A perpendicular magnetic recording medium of Example 2 was manufactured in the same manner as in Example 1 except that the rotation speed of the substrate 1 was 550 rpm and the reciprocation period of the texturing tape was 7 Hz. In this example, a plurality of grooves having a cross angle of 5.4 ° were formed on the surface of the glass substrate at a radial position of 15 mm. Further, the surface roughness Ra of the glass substrate after the texturing treatment was 1.21 nm.

(Example 3)
A perpendicular magnetic recording medium of Example 3 was manufactured in the same manner as in Example 1 except that the rotation speed of the substrate 1 was 550 rpm and the reciprocation period of the texturing tape was 9 Hz. In this example, a plurality of grooves having a cross angle of 7.2 ° were formed on the surface of the glass substrate at a radial position of 15 mm. Further, the surface roughness Ra of the glass substrate after the texturing treatment was 1.24 nm.

(Comparative Example 1)
A perpendicular magnetic recording medium of Comparative Example 1 was manufactured in the same manner as in Example 1 except that the rotation speed of the substrate 1 was 550 rpm and the reciprocation period of the texturing tape was 11 Hz. In this comparative example, a plurality of grooves having a cross angle of 9.0 ° were formed on the surface of the glass substrate at a radial position of 15 mm. Further, the surface roughness Ra of the glass substrate after the texturing treatment was 1.22 nm.

The recording / reproducing characteristics of each of the perpendicular magnetic recording media of Examples 1 to 3 and Comparative Example 1 were evaluated.
The recording / reproduction characteristics were evaluated using a read / write analyzer RWA1632 manufactured by GUZIK, USA, and a spin stand S1701MP.

For the evaluation of the recording / reproducing characteristics, the recording frequency condition was measured at a linear recording density of 800 kFCI by using a magnetic head using a single pole magnetic pole for writing and a GMR element for the reproducing part.
In the SpSNR measurement, a base-Peak value of 450 kFCI output was used as a signal. SpSNR is 20 Log (450 kFCI signal / noise when writing 450 kFCI signal).
Further, Mrt-OR measurement was performed using an Mrt measuring device manufactured by ORM. Mrt-OR is the ratio of Mrt (the product of Mr (residual magnetization) and t (magnetic layer thickness of the medium)) in the radial direction to the circumferential direction, and the higher the ratio in the circumferential direction, the higher the electromagnetic conversion characteristics. It shows that.
“Floating point fixed” in Table 1 means that the floating magnetic head is fixed on the same radius and floated for a long time to evaluate damage to the magnetic recording medium and the floating magnetic head. “OK” means that the lubricant is not wound up by the magnetic head even during the 21-day operation, and the damage to the magnetic recording medium is small.
Furthermore, “Visual” in Table 1 is to visually check the surface of the magnetic recording medium under a halogen lamp light. “Visual” is “OK” when there is no unevenness on the surface and no scratches (small scratches), and “Visual” when “NG” is when unevenness or scratches are observed on the surface. .
The evaluation results are shown in Table 1 below and FIG.

As shown in Table 1 and FIG. 4, it can be seen that Mrt-OR and SpSNR show good values when the cross angle is in the range of 2.7 to 7.2 °.
Further, it is understood that the fixed point flying is stable for 21 days, and the flying magnetic head is excellent in flight stability.
On the other hand, in Comparative Example 1, Mrt-OR and SpSNR show the same values as in Examples 1 to 3, but the evaluation when the scratch on the surface of the magnetic recording medium was visually confirmed (Visual) under halogen lamp light was NG. Thus, it can be seen that the quality of the magnetic recording medium is inferior.

FIG. 1 is a schematic partial cross-sectional view showing a magnetic recording medium according to an embodiment of the present invention. FIG. 2 is an enlarged schematic plan view showing the main part of the magnetic recording medium according to the embodiment of the present invention. FIG. 3 is a schematic plan view showing an example of the internal structure of the magnetic recording / reproducing apparatus according to the embodiment of the present invention. FIG. 4 is a graph showing the relationship between the cross angle and the Mrt-OR and SpSNR.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic board | substrate, 1a ... One surface (surface of a nonmagnetic board | substrate), 2 ... 1st soft magnetic film (magnetic layer), 3 ... Intermediate | middle layer (magnetic layer), 4 ... 2nd soft magnetic film (magnetic layer), 5 ... orientation control layer (magnetic layer), 6 ... perpendicular magnetic recording film (magnetic layer), 11 ... groove, α ... cross angle, 40 ... floating magnetic head

Claims (6)

A magnetic recording medium comprising at least a magnetic layer on a nonmagnetic substrate,
A plurality of grooves having a circumferential component in the longitudinal direction and intersecting each other are formed by texturing on the surface of the nonmagnetic substrate, and the cross angle between the grooves is set in a range of 2 ° to 8 °. Has been
A magnetic recording medium used in combination with a floating magnetic head, wherein the flying magnetic head is used under a flying height of 10 nm or less.   The magnetic recording medium according to claim 1, wherein the nonmagnetic substrate is made of glass or aluminum.   The magnetic recording medium according to claim 1, wherein a surface roughness Ra of the non-magnetic substrate after the texturing process is in a range of 0.20 nm to 0.25 nm.   4. A magnetic recording / reproducing apparatus comprising a magnetic recording medium and a floating head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium is according to claim 1. A magnetic recording / reproducing apparatus which is a magnetic recording medium. A method of manufacturing a magnetic recording medium in which at least a magnetic layer is formed after texturing a surface of a nonmagnetic substrate,
In the texturing process, a slurry containing abrasive grains and a texture tape are used, and the texture tape is swung along the radial direction of the nonmagnetic substrate while rotating the nonmagnetic substrate. A plurality of grooves having a circumferential component and intersecting each other with a cross angle in a range of 2 ° to 8 °;
A method for manufacturing a magnetic recording medium, which is used in combination with a floating magnetic head and used under the condition that the flying height of the floating magnetic head is 10 nm or less.   6. The method of manufacturing a magnetic recording medium according to claim 5, wherein the nonmagnetic substrate is made of glass or aluminum.

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