JPH11265501A - Magnetic recording and reproducing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive magnetic recording and reproducing system used by high rotation capable of suppressing the generation of TA(thermal asperity), improving durability and performing high-density recording and reproduction by using the FD(floppy disk) of a flexible supporting body. SOLUTION: In this magnetic recording and reproducing system for performing recording by rotating a magnetic disk provided with at least a ferromagnetic metallic thin film formed by a vacuum film formation method on both surfaces of the flexible supporting body above 3000 rpm in the state of being housed in a cartridge in a rotatable state and performing reproduction by an MR(magneto-resistance) head, the total thickness (t) of the thin film formed on the flexible supporting body by the vacuum film formation method is 0.08-0.36 μm and the thickness (d) of the flexible supporting body is 30-100 μm. Further, (t<3> /d<3> ) is 3.5×10<-7> to 1×10<-9> and fine projections are provided on the surface of the ferromagnetic metallic thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-density floppy disk (FD) having a ferromagnetic metal thin film and a flexible support.
And a magnetic recording / reproducing system for performing reproduction using an MR (magnetoresistive) head.

[0002]

2. Description of the Related Art In a hard disk (HD), which is one of ultra-high-density recording disks, high-density recording is realized by using a ferromagnetic metal thin film formed by a sputtering method as a recording layer and using an MR head. I have. As a magnetic recording / reproducing system using an MR head, a head is floated on a medium having a magnetic layer of a ferromagnetic metal thin film on a synthetic substrate such as an aluminum plate or a glass plate so that the head does not come into direct contact with the magnetic layer. This is a method of rotating at a high speed of up to 7000 rotations. Such a recording / reproducing system realizes a high capacity and a high transfer rate, and is widely used as an external storage medium of a personal computer.

[0003] Although the MR head provides high sensitivity, that is, high output, when the head comes in contact with the medium, the output baseline increases as the temperature of the head increases, causing a reading error. Such a phenomenon is known as so-called thermal asperity (hereinafter abbreviated as TA). Therefore, in the HD, the head is separated from the medium so that this contact does not occur, and the contact between the head and the disk is prevented by stabilizing the disk by using a thick and highly rigid material for the substrate of the magnetic disk. However, the high rigidity of the substrate adversely affects the impact in the event of a collision, which causes the above-described large rise in the baseline. Furthermore, the result is that the head or the disk is damaged. HD is usually used in a fixed form to overcome the above difficulties and become practical. In addition, the problem with HD is that it is inevitably expensive to finish the substrate, and because the substrate is rigid, it is difficult to absorb external force such as impact, and the magnetic layer is damaged by the impact from the head or dust attached thereto. The magnetic layer is easily damaged by dust and dust.

It is desired that the magnetic recording medium is interchangeable like the FD, but in this case, an impact is inevitably caused to move the medium, and the chance of contact between the head and the medium increases. Therefore, a medium having a rigid substrate such as HD has a concern that it may be a fatal obstacle. HD also has the disadvantage of being expensive. Even after the MR head is put to practical use, the FD using the flexible substrate is about 0.1 Gbit / inch due to problems inherent to the MR head (the generation of TA, weak to static electricity, and weak to contact due to thin elements). ^At present, only a recording density of about ² has been practically used, and a magnetic recording / reproducing system with a higher density has been desired. The occurrence of TA is caused by the fact that the medium is flexible when the rotation speed is high, so that the frequency at which the MR head hits the magnetic layer surface is higher than HD. , And it takes time for the heat to return to its original state, during which time the output level changes more frequently. In addition, there is a problem that both are easily damaged due to the contact between the MR head and the magnetic recording disk and the durability is low.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a high-density recording / reproducing method which uses a flexible support FD to suppress the generation of TA and enhance the durability and is inexpensive and used at a high rotation speed is provided. It is an object of the present invention to provide a possible magnetic recording / reproducing system.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cartridge in which a magnetic disk having at least a ferromagnetic metal thin film formed on both surfaces of a flexible support by a vacuum film forming method is rotatable in a cartridge. In a magnetic recording / reproducing system in which recording is performed by rotating at 3000 rpm or more in a state where the recording medium is rotated and reproduction is performed using an MR (magnetoresistive) head, a total of thin films formed on the flexible support by a vacuum film forming method is used. Thickness (t)
Is 0.08 to 0.36 μm, the thickness (d) of the flexible support is 30 to 100 μm, and (t ³ /
d ³ ) is 3.5 × 10 ⁻⁷ to 1 × 10 ⁻⁹ , and the magnetic recording / reproducing system is characterized in that the ferromagnetic metal thin film has fine projections on its surface.

The present invention first provides a ferromagnetic metal thin film (hereinafter, referred to as a ferromagnetic metal thin film).
Small protrusions (hereinafter, referred to as "fine protrusions") for reducing the friction coefficient are formed on the surface of the "magnetic film" so that the influence of the head colliding is reduced. Further, according to the present invention, the thickness (d) of the flexible support and the total thickness (t) of the thin film formed on the support by the vacuum film formation method are described.
Is defined as a specific range, and (t ³ / d ³ ) is further specified to define the rigidity of the entire medium in the specific range, so that the impact of the MR head is moderately moderated and the medium is not blurred. Characterized by maintaining rigidity.

In the present invention, high output can be obtained by suitably selecting the spacing between the MR head and the magnetic disk by the above configuration. In addition, the MR head has weak points due to the small thickness of the element, so that it is weak to contact and mechanically weak to heat.However, according to the present invention, it is possible to avoid contact as much as possible and to reduce the TA level even when contact is made. In addition, since the magnetic recording disk does not strongly hit the MR head, the durability of both is improved.

Further, according to the present invention, it is possible to remove TA by signal processing up to about three times the normal output from the problem of saturation of the reproduction amplifier even in recording and reproduction. That is,
ADVANTAGE OF THE INVENTION This invention can reduce TA generation | occurrence | production and the rise of the level when it generate | occur | produces, can fully compensate the part by signal processing, and can ensure durability.

In the present invention, the total thickness (t) of the thin film means the total of all the arbitrary thin films provided on both surfaces of the flexible support by the vacuum film forming method, and includes at least the magnetic film. . t is in the range of 0.08 to 0.36 μm, preferably 0.06 to 0.15 μm / one side. The thin film is
Although only a magnetic film may be used, it is preferable to provide a base film, a magnetic film, and a protective film sequentially on a flexible support. Each of these thin films may be a single film or a multiple film having a different composition or crystal structure, and the order of forming these thin films may be arbitrarily selected as desired.

In the present invention, the thickness (d) of the flexible support is 30 to 100 μm, preferably 45 to 95 μm.
μm / one side. Further, the present invention provides (t ³ /
d ³ ) is from 3.5 × 10 ⁻⁷ to 1 × 10 ⁻⁹ , preferably 1 × 10 ⁻⁹
The range is 10 ^{-7 to} 2 × 10 ^-9 . In the present invention, t
Although the mechanism of the appropriate range of d and d as described above is not clear, it is speculated as follows.

In this system, since the head and the magnetic recording medium come into contact with each other, the strength of the thin film during high-speed rotation has an effect.
In addition, since the thin film has internal strain, if the thickness is too large, the effect will be significant, and it will not be a flat magnetic disk, but the impact strength when contacting the head is strong, and the head and the magnetic disk will be damaged. Is easy to enter. On the other hand, if the thickness t is too large, the internal strain of the film becomes large, and the film exceeds or approaches the adhesion at a certain film thickness or more. Therefore, when a small external force acts, the film is easily peeled. On the other hand, if t is too thin, the film strength of the vacuum film formation itself is not sufficient, and the film is likely to be damaged by contact with the head. In addition, surface blur is likely to occur.

On the other hand, the flexible support has elasticity.
This elasticity has the advantage of absorbing the internal strain of the thin film and the possibility that the flexible support shrinks at the time of contact with the head, thus producing a cushion effect. However, if d is too thick, the magnetic disk as a whole becomes hard and difficult to bend, so that the effect of flattening cannot be enjoyed due to the centrifugal force applied during rotation. For this reason, it is conceivable that the impact force once in contact with the head is strong, the relaxation effect is reduced, and a large TA is generated and the head and the magnetic film are damaged.

When d is thin, it has the advantage that it can be easily flattened by rotation, but it is difficult to create a flat shape before rotation because the tolerance for absorbing internal strain of the thin film is small. For this reason, a large internal distortion of the entire magnetic disk appears, and a so-called flutter (surface blur) occurs due to an uneven air flow during rotation. In addition, many TAs are generated. Since the thin film has no elasticity and is hard, it appears in a region where the film thickness effect is small. Since the flexible support has elasticity, it also has the advantage of being flexible and absorbing internal strain of the thin film. However, if it is too thick, the bending hardness of the entire magnetic disk becomes too high. For this reason, a balance between the two becomes essential. It is presumed that the relationship between the cube of the thickness of the vacuum film formation and the cube of the thickness of the polymer support was found due to the above mechanism.

Next, the fine projections provided on the surface of the magnetic film will be described. In the present invention, the term “microprojection” refers to a magnetic film surface having a height of 1 to 50 nm, preferably 5 to 40 nm, as observed by an AFM (atomic force microscope). The shape of the fine projection is not particularly limited, and is preferably circular when the surface is viewed from the vertical direction, but may be elliptical.

In the present invention, the object of the present invention can be effectively achieved by controlling the mode of existence of the fine projections, for example, the distribution of the fine projections, the density of the fine projections, and the like. For example, regarding the distribution of the fine projections, the density of the fine projections may be unevenly distributed in a certain direction to increase or decrease the density of the fine projections, and it may be used as a means for adjusting the internal stress of the thin film in addition to the effect of reducing the friction coefficient. The microprojection density is usually 0.05 to 10 / μm ² , preferably 0.1 to 1
It is adjusted to a range of 0 pieces / μm ² .

The means for adjusting the density of the microprojections is not particularly limited, but a means for adjusting the surface properties of the flexible support is preferred. As a specific method for adjusting the surface properties of the flexible support, a preferred embodiment is to provide an undercoat film made of a resin containing heat-resistant fine particles (filler) on a film base. In this case, it is preferable that the film base is sufficiently smooth. Otherwise, the undercoat film a containing only the resin containing no heat-resistant fine particles is provided, and the resin containing the filler is further provided on the undercoat film a. Undercoat film b
Is preferably provided.

The resin used for the undercoat film a and / or the undercoat film b is not particularly limited, but is preferably the same type of resin as that of the film base. These resins can be used in the form of a polymer, but are preferably used in the form of a resin monomer that can be polymerized on a film base. In the case of the undercoat film a, a coating obtained by dissolving the resin monomer in a solvent is used for undercoating. In the case of membrane b,
By preparing a resin monomer paint containing a filler and applying it on a film base, it can be formed on the film base.

For example, an undercoating film mainly composed of a polyimide resin, which is a polymer of an imide monomer having two or more terminal unsaturated groups in the molecule, can be used as an undercoating film, and the imide monomer is represented by the following chemical formula 1. Bisallyl nadimide can achieve more excellent properties.

[0020]

Embedded image In the formula, R ¹ and R ² are independently selected hydrogen or a methyl group, and R ³ is a divalent linking group such as an aliphatic or aromatic hydrocarbon group and is not particularly limited. Or an alkylene group and alkenylene group having a branched structure, a cycloalkylene group, a cycloalkylene group having an alkylene group, an aromatic group, an aromatic group having an alkylene group, a polyoxyalkylene group, a carbonyl group, an ether group, and the like.

The thickness of the undercoat film is usually in the range of 0 to 5 μm / one side, preferably 0.5 to 3 μm / one side. In the case where the base originally has fine projections and no coarse projections, the undercoat film may not be provided. Further, the undercoat film paint may contain components other than the resin monomer and the filler. For example, a curing agent for promoting polymerization, a coupling agent for improving adhesion, a rust inhibitor for preventing oxidation of the magnetic film, and the like can be contained.

As a curing agent, p-toluenesulfonic acid,
p-xylene sulfonic acid, methyl toluene sulfonate,
Pyridinium p-toluenesulfonate, pyridinium m-nitrobenzenesulfonate, methylhydrazine sulfate and the like can be used. In addition, as a filler for providing fine projections on the surface of the flexible support, silica, alumina,
Examples include inorganic oxides such as titania and zirconia, and high molecular organic compounds such as calcium carbonate, carbon, and resin. The shape is preferably monodisperse and spherical. The particle diameter is appropriately selected according to the size of the fine projections.

Examples of the film base include materials such as polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polyamide imide, and polybenzoxazole. It is desirable that there be few. Since the magnetic film is preferably kept at a high temperature during film formation, a heat-resistant polymer is desirable. Therefore among the above polyimide,
Polyamides are preferred.

The system of the present invention can be used for recording and reproducing even if a magnetic head (inductive head) based on the principle of electromagnetic induction for recording and an MR head for reproduction are integrated, that is, a merge type MR head is used. Although another head may be used for reproduction, it is preferable to use the merge type from the viewpoint of recording / reproduction stability and price. In addition, the MR type includes an AMR having a normal configuration and a GMR such as a spin valve, but either type may be used. As another structural form, a yoke type MR in which a magnetic flux path is provided on the magnetic disk side of the MR element.
However, a dual stripe type MR that takes in two MR elements at different phases may be used.

In general, the higher the rotation speed of the magnetic disk,
A high speed is desirable because the transfer speed increases. Further, since the magnetic disk is also flattened by the flow of the wind due to the rotation, the rotation speed is set to 3000 rpm or more. If it is too high, the surface of the magnetic disk may fluctuate.
000-7000 rpm is preferred. Next, the configuration of the magnetic disk used in the present invention will be described.

In order to obtain a high recording density and to control the orientation of the magnetic film, it is desirable that there is a base film between the magnetic film and the flexible support. Cr, C
r alloys such as alloys with the following metals, Ti, Mo, V, T
a, B, Si, Mo, or an alloy of Mo with the above elements is preferable.

The thickness of the underlayer is usually 0.01 to 0.15 μm, preferably 0.03 to 0.15 μm on one side of the magnetic disk.
0.10 μm. Further, in order to enhance the crystallinity of the magnetic film provided thereon, it is preferable to provide CoCr containing more than 30 atomic% of nonmagnetic Cr as a further underlayer as a multi-layer structure. Al, NiAl, N
Even if iP or the like is used at the lowermost portion (on the flexible support) of the base film, it is useful for making the magnetic film finer.

As the magnetic film material, a CoCr alloy, particularly Pt, Ta, Ni, Si, B, Ni, Nb, W, Ti,
Alloy with O, especially Co-Cr-Pt, Co-Cr-P
t-Ta and Co-Cr-Pt-Ta-Nb are preferred.
If necessary, further improve the properties by using SiO ₂
A nonmagnetic material and a ferromagnetic material such as Co and Co may be sputtered together.

The thickness of the magnetic film on one side of the magnetic disk is preferably 0.01 to 0.10 μm, particularly preferably 0.015 to 0.030 μm. It is preferable that both the base film and the magnetic film are provided by a vacuum film forming method. Examples of the vacuum film formation method include a vacuum deposition method and sputtering. Sputtering is particularly preferable because a film can be formed without changing the composition of many elements.

When a magnetic film is formed by a sputtering method, it is preferable to form the film while the support is heated, and the temperature at that time is preferably 100 ° C. to 250 ° C. Further, the magnetic film of the present invention may have a multilayer structure in order to improve electromagnetic conversion characteristics. Further, it is preferable to provide a protective film as a thin film on the magnetic film. Silica as a protective film,
From oxides such as alumina, titania, zirconia, cobalt oxide and nickel oxide, nitrides such as titanium nitride, silicon nitride and boron nitride, carbides such as silicon carbide, chromium carbide and boron carbide, and carbon such as graphite and amorphous carbon Protective film.

The carbon protective film is formed by a plasma CVD method,
Amorphous and graphite created by the sputtering method, etc.
Or diamond structures, or a mixture of these.
Carbon film, particularly preferably a diamond film.
It is a hard carbon film called dry carbon. This
Hard carbon film has a Vickers hardness of 1000 kg / mm ^Two
Above, preferably 2000 kg / mm^TwoHard charcoal over
It is a base film. The crystal structure is amorphous.
And non-conductive. And diamond-like charcoal
When the structure of the base film is measured by Raman spectroscopy
Is 1520-1560cm^-1That peaks are detected
And can be confirmed by: Carbon film structure is die
When it deviates from the diamond-like structure, Raman spectroscopy
Detected peaks deviate from the above range,
The hardness of the base film also decreases. This hard carbon protective film is meta
Alkanes such as ethane, ethane, propane, butane, or
Alkenes such as ethylene and propylene, or acetylene
From carbon-containing compounds such as alkynes
Plasma CVD or carbon under hydrogen or hydrocarbon atmosphere
The target is formed by sputtering or the like.
Can be.

The carbon film may contain H, F, N and the like. If the thickness of the hard carbon protective film is large, the electromagnetic conversion characteristics are deteriorated and the adhesion to the magnetic film is deteriorated. If the film thickness is small, the abrasion resistance is insufficient. It is preferably from 0.0025 to 0.03 μm, and particularly preferably from 0.005 to 0.010 μm.

Further, the surface of the hard carbon protective film may be treated with an oxidizing or inert gas for the purpose of further improving the adhesion with the lubricant applied on the hard carbon protective film. In the magnetic recording medium of the present invention, in order to improve running durability and corrosion resistance, it is preferable to add a lubricant or a rust inhibitor to the magnetic film or the protective film.

As the lubricant, a known hydrocarbon-based lubricant,
Fluorine-based lubricants, extreme pressure additives and the like can be used. Examples of hydrocarbon-based lubricants include stearic acid, carboxylic acids such as oleic acid, esters such as butyl stearate, sulfonic acids such as octadecylsulfonic acid, phosphates such as monooctadecyl phosphate, stearyl alcohol,
Examples thereof include alcohols such as oleyl alcohol, carboxylic acid amides such as stearic acid amide, and amines such as stearylamine.

Examples of the fluorine-based lubricant include lubricants in which part or all of the alkyl group of the hydrocarbon-based lubricant is substituted with a fluoroalkyl group or a perfluoropolyether group. Examples of the perfluoropolyether group include a perfluoromethylene oxide polymer, a perfluoroethylene oxide polymer, a perfluoro-n-propylene oxide polymer (CF ₂ CF ₂ CF ₂ O) _n , and a perfluoroisopropylene oxide polymer (CF ( CF ₃ )
CF ₂ O) _n or a copolymer thereof.

Examples of extreme pressure additives include phosphoric esters such as trilauryl phosphate, phosphites such as trilauryl phosphite, thiophosphites and thiophosphoric esters such as trilauryl trithiophosphite, and the like. And sulfur-based extreme pressure agents such as dibenzyl sulfide. The above lubricants are used alone or in combination of two or more. As a method of applying these lubricants on a magnetic film or a protective film, a lubricant is dissolved in an organic solvent and applied by a wire bar method, a gravure method, a spin coating method, a dip coating method, or a vacuum evaporation method. What is necessary is just to make it adhere.

The amount of the lubricant to be applied is 1 to 30 mg / m
² is preferable, and 2 to 20 mg / m ² is particularly preferable. Benzotriazole, as a rust inhibitor that can be used in the present invention,
Nitrogen-containing heterocycles such as benzimidazole, purine and pyrimidine and derivatives having an alkyl side chain introduced into their mother nucleus, benzothiazole, 2-mercaptone benzothiazole, tetrazaindene ring compounds, nitrogen such as thiouracil compounds, Examples include sulfur-containing heterocycles and derivatives thereof.

In the present invention, the size of the magnetic disk is suitable for the specification from 3.5 inches to 1.8 inches.

[0039]

Hereinafter, specific examples of the present invention will be described.
The present invention is not limited to this. Example 1 A polyimide amide (PI) was coated on a polyimide (PI) having a base thickness (b) of 75 μm (Mitsubishi Kasei Corporation Novax).
A) A resin (MT5050 manufactured by Toyobo Co., Ltd.) was dissolved in a mixed solvent of ethanol and toluene to prepare a coating solution having a solid content of 10% by weight. After this was applied by a gravure coating method, it was dried at 100 ° C. to form an undercoat film having a thickness of 1.5 μm. Further, the above coating solution containing 0.005% by weight of spherical silica particles having a particle diameter of 20 nm was applied thereon, and
It dried at 00 degreeC, and formed the fine protrusion on the undercoat film. Then, the mixture was heated at 300 ° C. for 5 minutes to perform curing and solvent removal treatment. A similar film was formed on the opposite surface of the base. Thereby, the total (u) of the thicknesses of the undercoat films on both sides is 3.0 μm,
A flexible support having a thickness (d) of 78 μm was prepared.

This film was set in a sputtering apparatus, and a Cr—Ti underlayer was formed to a thickness of 0.06 μm using a DC magnetron sputtering method at a substrate temperature of 200 ° C., and a Co—Cr—Pt—Ta magnetic film was further formed to a thickness of 0 μm. .03 μm was formed. Next, this film is set in a plasma CVD apparatus,
A hard carbon protective film having a thickness of 0.02 μm was formed on the magnetic film by a plasma CVD method using ethylene as a raw material. Next, a solution obtained by dissolving a perfluoropolyether-based lubricant (FOMBLINZ-DOL manufactured by Ausimont) in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M) was applied on the protective film by dip coating to form a 2 nm thick film. A lubricating film was formed. The base film, the magnetic film, the protective film, and the lubricating film were formed on both sides of the film, and the total thickness (t) of the thin film was 0.22 μm.
This was punched out into a 2.5-inch disk and inserted into a cartridge having a liner to obtain a sample of Example 1.

Examples 2 to 7 and Comparative Examples 1 to 10 Samples were prepared in the same manner as in Example 1 except that the material of the underlayer and the material of the magnetic film were changed, but the thickness was changed (Tables 1 and 2). Examples 8 to 13 A solution obtained by dissolving an imide monomer (BANI-NB manufactured by Maruzen Petrochemical Co., Ltd.) in toluene was applied by a gravure coating method, and then dried at 100 ° C. to form a coating film.
Heat at 0 ° C. for 1 hour to polymerize the imide monomer to form an undercoat film of polyimide (PI), and further apply the imide monomer solution containing spherical silica particles thereon to form fine protrusions on the undercoat film. Formed. Thereafter, a thin film was formed on the flexible support in the same manner as in Example 1.

The above samples were evaluated as follows. TA (frequency, size): inductive head with track width of 5 μm and gap length of 0.3 μm, track width of 3 μm
140 KF at 4000 rpm using a merged MR head with an integrated MR head with a gap length of 0.3 μm
RPI recording and playback was performed. The frequency of TA was obtained by measuring the reproduced signal in one round ten times and averaging the number of occurrences per round. The average value of the envelope of the oscilloscope was determined for the magnitude of TA (signal intensity).

Modulation: In the above recording / reproduction, the level when no TA is generated is obtained by taking a photo of the envelope and modulating it by {C (max) -C (min)} / {C (max) + C (min)}. And At this time, TA was excluded. The maximum value in one round of the playback waveform is C (max) and the minimum value is C (min)
And

Continuous durability: Using a two-rail taper flat type head at normal temperature and normal humidity, while rotating at 3600 rpm, a reproduction signal was monitored, and the value was 6 from the initial value.
It was a value until it decreased by dB or more. Table 3 shows the results.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3] From the above results, it can be seen that the examples of the present invention exhibited excellent properties in all of continuous durability, TA and modulation, and that high durability and good head contact were realized by the present invention. On the other hand, the comparative examples that do not satisfy at least one of the thickness of the flexible support, the total thickness of the thin film, and (t ³ / d ³ ) are those that satisfy all of the continuous durability, TA, and modulation. It was found that at least one was inferior to the present invention.

[0048]

According to the present invention, a magnetic disk having at least a ferromagnetic metal thin film formed on both sides of a flexible support by a vacuum film forming method is stored in a cartridge in a rotatable state at 3000 rpm or more. In a magnetic recording / reproducing system in which recording is performed by rotating the magnetic recording medium and reproduction is performed using an MR (magnetoresistive) head, the total thickness (t) of the thin film formed on the flexible support by a vacuum film formation method is determined. 0.08-0.36
μm, and the thickness (d) of the flexible support is 30 to 100 μm.
m, and (t ³ / d ³ ) is changed from 3.5 × 10 ⁻⁷ to 1 × 10
^-9, and by providing minute projections on the surface of the ferromagnetic metal thin film, suppress generation of TA and increase durability,
It is also possible to provide a magnetic recording / reproducing system which is inexpensive and can be used at a high rotation speed and capable of high-density recording and reproduction.

Claims (1)

[Claims] 1. A magnetic disk provided with at least a ferromagnetic metal thin film formed on both sides of a flexible support by a vacuum film forming method is rotated at 3000 rpm or more while being rotatably housed in a cartridge. Make a record and MR
(Magnetic resistance type) In a magnetic recording / reproducing system for reproducing with a head, a total thickness (t) of a thin film formed on the flexible support by a vacuum film forming method is 0.08 to 0.36 μm. The thickness (d) of the flexible support is 30 to 100 μm, and (t ³ / d ³ ) is 3.5 × 10 ⁻⁷ to 1 × 1.
A 0 ^-9, magnetic recording and reproducing system, characterized in that the surface of the ferromagnetic metal thin film has minute protrusions.