JPH02168418A - In-plane magnetic recording media and magnetic storage devices - Google Patents

Abstract

PURPOSE:To make the recording and reproduction with high density stable by coupling all magnetic films being a composite magnetic film magnetically, providing a sole planer coercive force and increasing the planer coercive force of the magnetic film closest to the information recording layer side. CONSTITUTION:Magnetic thin films 12, 12' at the base side, magnetic thin films 13, 13' at the information recording side and nonmagnetic protection coating layers 14, 14' are formed on a nonmagnetic base 11 to form a magnetic disk. Through the constitution above, all the magnetic films being components of the composite magnetic film are coupled magnetically. Moreover, the composite magnetic film has a sole planer coercive force. Furthermore, the planer coercive force is selected to be larger than the planer coercive force of an in-plane magnetic anisotropic magnetic film being a component of the magnetic film close to the information recording side in the magnetic films being components of the composite magnetic film. Thus, high orientation, high output and low noise are attained even at high density recording. Thus, a large capacity of the magnetic recording device is attained and the size is made small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium in a magnetic storage device such as a magnetic disk device, a magnetic tape device, or a magnetic card device, and a large-capacity magnetic storage device using the same.

[Conventional technology]

In order to increase the capacity of magnetic storage devices, it is necessary to increase the recording density and output noise ratio of magnetic recording media. Conventionally, in response to this, a perpendicular magnetic recording method using a perpendicularly magnetized film and a longitudinal magnetic recording method using a thin film longitudinal medium have been studied. The historical background of these issues will be briefly explained below.

Perpendicular magnetic recording media have a small demagnetizing field between recording bits, so they are suitable in principle for increasing recording density, but they have the drawback of low output. In order to eliminate this drawback, various composite magnetic films have been proposed. As a perpendicular magnetic recording medium with high productivity and good perpendicular alignment, on top of the CoCr film having perpendicular magnetic anisotropy, a film with a thickness of 0.14 to 0.
．． A composite perpendicularly magnetized film in which a 175 μm Co-0 or Co-Ni-0 film is vertically aligned is disclosed in Japanese Patent Application Laid-Open No. 61-9821.
It has been proposed in the Publication No. Furthermore, JP-A-52-784
As stated in Japanese Patent Application Laid-open No. 03 and Japanese Patent Application Laid-Open No. 54-5184, in order to improve the recording and reproduction efficiency at high recording density and obtain high reproduction output, a high permeability soft magnetic film is coated on a non-magnetic substrate. Composite magnetic recording media in which a perpendicularly magnetized film is provided through a perpendicular magnetization film have also been proposed. Generally, media forming methods include vapor deposition, sputtering, plating, and ion beam sputtering. However, in this method, it is said that if the magnetic head rises above the medium surface due to wrinkles, the recording density will be reduced compared to the conventional longitudinal recording method. Furthermore, when a high magnetic permeability soft magnetic layer is used as an underlayer, there is a problem in that the perpendicular orientation of a perpendicular magnetic film provided thereon is deteriorated. To solve this problem, we created a high-permeability soft magnetic underlayer made of Ni-Fe to prevent the magnetic interaction between the high-permeability soft magnetic layer and the perpendicular magnetic layer, and to improve the orientation of the perpendicular magnetic layer. T to enhance
C through a non-magnetic layer such as i.

A perpendicular magnetization film such as -Or is formed, and then Ni
A perpendicular magnetic recording medium provided with a high magnetic permeability soft magnetic layer such as -Fe has been proposed in Japanese Patent Application Laid-Open No. 131228/1983.

In addition, CoCrN
CoC having large saturation magnetization and perpendicular magnetic anisotropy is placed on an isotropic low coercive force layer made of b or CoCrTa.
A perpendicular magnetic recording medium forming an r layer has been proposed. As for the substrate, CoCrNb or CoCrTa corresponds to the so-called high permeability soft magnetic M (backing M).

In these conventional composite magnetic recording media consisting of a perpendicular magnetic layer and a high permeability soft magnetic layer, the soft magnetic layer efficiently guides the recording magnetic field of the magnetic head to the perpendicular magnetic layer and stabilizes the recorded magnetization. It merely serves an auxiliary function. That is, each magnetic layer functions completely independently magnetically.

In such a configuration, the magnetic films constituting the composite magnetic thin film have only weak magnetic interaction with each other, and the in-plane magnetization curve becomes a substantially simple superposition of the in-plane magnetization curves of each layer. Therefore, a magnetization jump is observed in the magnetization curve, which is a so-called serpentine shape, and the magnetization of each layer is not reversed with the same in-plane coercive force. For high recording density, it is said that a serpentine magnetization curve having a plurality of coercive forces is preferable.

However, in any type of perpendicular magnetic recording medium,
In order to improve the recording and reproducing efficiency, it is necessary to use a main pole type magnetic head that forms a magnetic circuit with a high magnetic permeability underlayer. It is believed that improvements in practical performance cannot be expected unless changes are made from the method to the entire system. In fact, when a perpendicular magnetic recording medium of this configuration is recorded and reproduced using a conventional ring-type magnetic intermediary, the following problems occur.

That is, when the composite perpendicular film medium in which a perpendicular magnetization layer is provided on a high magnetic permeability underlayer is recorded and reproduced using a conventional ring-type magnetic head for in-plane magnetic recording, ) No. 396
Pages 4 to 3966 (J, Appl, Physics
, 57 (1985) p.

3964-p, 3966), unlike when recording and reproducing with a main pole type perpendicular magnetic recording head, very large spike-like Barkhausen noise is generated from the high magnetic permeability underlayer. However, even if spike-like Barkhausen noise is reduced, the absolute value of the noise remains large. A similar problem is thought to exist in the case of the perpendicular multilayer film medium described in Japanese Patent Application Laid-Open No. 60-261025, in which a high permeability soft magnetic layer is provided on the perpendicular magnetization layer. This basically means that the coercive force of the high magnetic permeability film is several Oe~
Because it is extremely small (about 20 Oe or less), it is difficult for strong recording magnetic fields to reach the Co-Cr perpendicular magnetization layer.
Furthermore, the output waveform is noticeably distorted due to the following reasons. That is, the magnetic coupling force between the perpendicular magnetization layer and the high magnetic permeability layer is weak, each film responds separately to an external magnetic field, and the magnetization is easily reversed individually. Furthermore, in order to prevent magnetic interaction with the perpendicular magnetization layer, a high magnetic permeability layer is provided through a non-magnetic intermediate layer of about 200 layers, and for this reason each layer is not susceptible to external magnetic fields. This is because the magnetization is reversed independently. A main pole type magnetic head does not have this problem.

As explained above, when used with the head in contact with the medium, the perpendicular magnetic recording system essentially has much superior characteristics compared to the longitudinal magnetic recording system.

However, on the other hand, research aimed at improving the conventional longitudinal magnetic recording method using a ring-type magnetic head has recently been particularly reconsidered from the viewpoint of the flying head and the overall system. As a thin film medium for longitudinal magnetic recording, it is necessary to develop a magnetic thin film material with high corrosion resistance, high saturation magnetization, and high coercive force, and the following composite media have been proposed.

That is, as a combination of vertical media and in-plane media,
As described in Japanese Patent No. 1025, etc., an in-plane high coercive force magnetic layer such as Co-Ni or a γ-Fe20. Composite magnetic recording media and magnetic recording systems have been proposed that perform recording and reproduction at high recording density using a conventional ring head by providing an isotropic high coercive force magnetic layer such as . In addition, in a similar manner to these, as a medium with a different configuration, JP-A-6
1-34721, the coercive force in the in-plane direction is 300
A two-layer film medium has also been proposed in which a Co--Cr perpendicular magnetization layer with a perpendicular coercive force of 400 Oe or more is provided on a Go--Pt in-plane thin film magnetic layer with a high coercive force of 400 Oe or more.

Further, a CoCr-based alloy layer was provided on a Co-based magnetic alloy layer having in-plane magnetic anisotropy such as CoNi or CoPt.

A highly corrosion-resistant longitudinal composite magnetic recording medium was developed in Japanese Patent Application Laid-Open No. 62-256.
It has been proposed in 217.

This is a CoCr-based alloy that has higher corrosion resistance than a CO-based magnetic alloy, and a part of the surface layer of the Co-based magnetic alloy layer is replaced.

[Problem to be solved by the invention]

As explained above, it can be said that there is a strong demand for a highly reliable magnetic recording medium that can achieve higher S/N and higher density using the conventional longitudinal magnetic recording/reproducing method.

However, the above-mentioned conventional composite media in which an in-plane high coercive force magnetic layer or an isotropic high coercive force magnetic layer is provided on a perpendicularly magnetized film has a higher output than a perpendicularly magnetized film, but cannot record at 7iE density. The problem was that it was not possible. This is because retained information is not sufficiently recorded in the perpendicularly magnetized film, which has the function of retaining information recorded in the in-plane magnetized film or the like.

In other words, since ring-type heads inherently have a small recording magnetic field strength in the perpendicular component, they are not suitable for perpendicular magnetization, and since the perpendicular magnetization film and the head face each other via an in-plane magnetization film, etc. This is because the space between them becomes wider, making it even more difficult to record. Furthermore, according to the studies of the present inventors, the recorded magnetization state is particularly unstable in this case, and the reproduced output is also complicated.

It has become clear that there is a problem in that peak shift, phase shift, etc. are likely to occur, and that a major problem remains in practical use.

Further, the same problem exists in the above two-layer film medium in which a perpendicular magnetization layer is provided on a high coercive force in-plane thin film magnetic layer.

Further, a Co-Cr-based alloy layer is provided on a Co-based alloy thin film such as Go-Ni or Go-Pt. In the above-mentioned in-plane composite medium, the saturation magnetization of Co is smaller than that of the Co-based alloy thin film.
Since the -Cr-based alloy layer is used, the reproduction output is reduced in exchange for improved corrosion resistance. Further, as a result of studies conducted by the present inventors, as shown in Table 2, it was found that the in-plane coercive force also decreased. Therefore, the reproduction output decreased more than expected, and it became clear that there was a problem in using it as a high-density magnetic recording medium.

The purpose of the present invention is to avoid the above-mentioned problems such as peak shift and deterioration of in-plane coercive force, to stably perform high-density recording and reproduction, and to have high reliability such as corrosion resistance, and high S/N. An object of the present invention is to provide a longitudinal magnetic recording medium plate and a magnetic storage device having a composite magnetic film with good reproducibility.

[Means to solve the problem]

The object of the present invention is to provide a longitudinal magnetic recording medium in which a composite magnetic film is formed on a non-magnetic substrate directly or via a non-magnetic underlayer, in which all the magnetic films constituting the composite magnetic film are magnetically coupled. and the in-plane coercive force is larger than the in-plane coercive force of the in-plane magnetic anisotropic magnetic film that constitutes the magnetic film closest to information recording among the magnetic films that constitute the composite magnetic film. This can be achieved using a magnetic recording medium plate.

When forming the composite magnetic film, all the magnetic films constituting the composite magnetic film were magnetically coupled and had a unique in-plane coercive force, so that the magnetization of all the magnetic films was simultaneously reversed. The shape of the in-plane magnetization curve is not serpentine, and no peak shift or the like occurs.

Furthermore, since the in-plane coercive force is made larger than the in-plane coercive force of the most information recording side magnetic film, high reproduction and output can be obtained.

The present invention will be explained in more detail below.

The first group consisting of Co, Fe, and at least one selected element, the magnetic film closest to information recording side, and N.

T b * G de Mo + W * Y #
S m + N d + P r +Pm, Ce, D
y, La, Pt, Ir, Ti.

Z r HHf * V + N b * T a +
Ru HOs HRh g An in-plane magnetic anisotropic thin film whose main component is an alloy containing at least one element selected from the second group consisting of Pd, Al, and Si, or at least one element of Ni, and The magnetic thin film on the substrate side has a different component or composition from the magnetic thin film on the information recording side, and further contains at least one element selected from the first group, Cu, Cr, and Mo.

W, Tb, Gd, Sm, Nd* Pry Pm, Cee
The alloy contains as a main component at least one element selected from the third group consisting of Dy, Pt, and Ir, or at least one element of Ni, and all the magnetic thin films constituting the composite magnetic film are magnetically magnetic with each other. By configuring the composite magnetic film so that the in-plane coercive force at the time of magnetization reversal in response to an in-plane external magnetic field has a value of 250 Oe or more, it has high corrosion resistance that provides high density and high output noise. Media can be provided with good reproducibility.

By using the material of the magnetic film on the outermost substrate side as described above,
This is desirable because the orientation and crystallinity of the magnetic film formed thereon cannot be increased, and the in-plane coercive force of the composite magnetic film can be stably controlled to a high value.

This is considered to be because the above-mentioned additive elements tend to segregate at grain boundaries.

The total amount of the elements in the second group is 0.1 at% or more and 30 at% or less, more preferably 0.5 at% or more and 20 at% or less, with respect to the total amount of the elements in the first group. Alternatively, saturation magnetization, coercive force, and corrosion resistance can be improved by setting Ni to 10 at% or more and 60 at% or less. Either make the saturation magnetization of the magnetic thin film closest to the information recording side higher than the saturation magnetization of the magnetic thin film closest to the substrate, or make the in-plane coercive force of the magnetic thin film closest to the substrate the highest among the magnetic thin films constituting the composite magnetic film. It is desirable to make it higher in terms of playback output and corrosion resistance. Further, a combination of the two is particularly preferred. It is more preferable that the composite magnetic film is composed of three types of magnetic thin films because it increases the degree of freedom, but five or more types is not so preferable because the film forming apparatus becomes too complicated, and in this case,
From the viewpoint of reproduction output, it is desirable that the saturation magnetization of each layer is made smaller in order from the information recording side.Furthermore, it is desirable that the in-plane coercive force be made higher in order from the information recording side, and a combination of the two is most preferable.

Considering corrosion resistance, the intermediate layer may have the highest saturation magnetization. Here, the thickness of the magnetic thin film on the side where the most information is recorded should not be more than twice the thickness of the magnetic thin film on the side of the most substrate to improve the reproducibility of in-plane coercive force, stability, recording density characteristics, and output. Preferably in terms of noise ratio, the most information recording side magnetic thin film alone is semi-hard magnetic, and the magnetic thin film adjacent to the magnetic thin film alone has perpendicular magnetic anisotropy;
Alternatively, in order to achieve high recording density, it is particularly preferable that the composite film has in-plane magnetic anisotropy and has an in-plane coercive force of 1000 Oe or more, more preferably 150008 or more. Here, semi-hard magnetism generally has a coercive force of 50a or more.
This refers to the case of 00 Oe or less. The thickness of the magnetic thin film on the most information recording side is desirably 0.005 μm or more and 0.1 μm or less in order to improve corrosion resistance and improve recording density characteristics.

Further, the magnetic thin film on the most information recording side contains at least Fe.

It is preferable to include one of Bi, since the magneto-optical effects such as Kerr effect and Faraday effect become particularly strong.

Among the above materials, the magnetic thin film on the information recording side is made of CoNi
If the magnetic thin film on the most substrate side is made of a ternary or quaternary alloy based on Co Cr or CoSm, the crystal orientation of the magnetic thin film on the most information recording side will be particularly high; This is particularly preferable since the S/N can be increased at high density.

Here, the total amount of the elements in the third group is Q with respect to the total amount of the elements in the first group, 5 at% or more and 60 at% or less, more preferably 3 at% or more and 55 at% or less, and even more preferably 10 at%. The content is preferably 50 at % or less in terms of improving orientation and magnetic properties. 1 for Ni
0at% or more and 60at% or less, more preferably 30a
From the viewpoint of magnetic properties, it is preferable that the content be t% or more and 50 at% or less. Furthermore, Ti, Zr, and Hf are added to the magnetic thin film on the outermost substrate side.
, Nb, Ta, Ru, Os.

At least one element of the fourth group consisting of Rh, Pd, Al, and Si is Q, preferably from lat% to 20at%, more preferably from 3at% to 15at%, from the viewpoint of corrosion resistance and high coercive force. An additional film thickness of 10 mm is added on the composite magnetic film.
It is preferable to provide a non-magnetic protective coating layer with a thickness of nm or more and 40 nm or less because the sliding reliability is improved. It is particularly desirable that the non-magnetic protective coating layer be formed of WC, WN, C, etc., and an organic lubricating layer with a thickness of 1 nm or more, 15 nm or more, is further applied thereon.
Ti, Zr, Hf may be provided as a non-magnetic intermediate layer between the composite magnetic film and the non-magnetic protective coating layer.
, Nb, Ta alloys or Ni-based alloys with a thickness of 5 nm
A thickness of 15 nm or less is particularly preferable from the viewpoint of corrosion resistance.

The non-magnetic underlayer may be Cr, Mo, W or T.
It is preferable to use a non-magnetic material such as i-Cr, Cr-3i, Cr-Mo, etc. whose main components are these, since this improves the in-plane crystal orientation and in-plane coercive force of the magnetic thin film on the outermost substrate side.
i, C, Ge or Ti-Cr, Ti-Nb, Ti-
By using materials containing Ta, Ti-Pt, etc. as their main components, the vertical crystal orientation of the magnetic thin film on the outermost substrate side can be improved.
This is preferable because it ultimately reduces the medium noise as a composite in-plane medium. It is preferable to perform recording and reproduction on the composite longitudinal magnetic recording medium using a ring-shaped magnetic head in which at least a portion of the magnetic core is formed of a ferromagnetic metal thin film, since recording and reproduction can be performed at a particularly high density.

[Effect]

The present invention is based on the following effects. First, the corrosion resistance, magnetic properties, and recording and reproducing properties when using a single-layer magnetic thin film will be explained.

Compared to coated media, metallic thin film media can be expected to provide higher reproduction output even at higher densities, but because they are metal, they have a problem of inferior corrosion resistance. Therefore, using a sputtering method, a 300 nm thick Cr film was deposited on a glass substrate at an input power density of 4 W/a#, an Ar gas pressure of 10 m Torr, and a substrate temperature of 100°C.
Co and through.

Coo,,Fell,3,Sc,Y,La,Ce,
Pr.

Nd, Pm, Sm, Eu, Gd, Tb, Dy.

Ho, Er, Tm, Yb, Lu, Ti, Zr.

Hf, V, Nb, Ta, Cr, Mo, W, Mn.

Ru, Os, Rh, Ir, Ni, Pd, Pt.

C,, u, Ag, Au, Alt, Si, Sn, O, N, 0.05, 0.1, 0.5, 1°10
．． 20. ! Magnetic alloy thin films doped with 50, 60, and 70 at% were formed to a thickness of 70 nm, and finally a C film was formed to a thickness of 40 nm, and its corrosion resistance was evaluated.

Among the corrosions of metal-based thin film media, pitting corrosion directly leads to data loss, and is therefore considered to be more important than --like corrosion. Therefore, as a corrosion acceleration test that causes pitting corrosion, O,OO1moQ% NaNO3*0.0
01 moU% Na, Sn4 and 1 moff% NaC
The pitting corrosion resistance of these magnetic thin films was evaluated by a salt spray trial run containing Q.

As a result, N, Tb, Mo, and W were added to Go and Fe.

G d ) Y g S rn g N d @ P
r g P m g Ce * D y eLa, Pt
, Ir, Ti, Zr, Hf, V, Nb.

It has been revealed that the corrosion resistance of the magnetic alloy can be significantly improved by adding at least 1 s of elements of the second group consisting of Ta, Ru, Os, Rh, Pd, Al, and Si. This is because these additive elements form a dense passive coating on the surface of the metal magnetic thin film, or their effects may be compounded. Regarding the amount of these additions, an effect of improving corrosion resistance was recognized if the amount was 0.1 at% or more based on the total amount of CO and Fe, but it is more desirable to add 0.5 at% or more, but the amount added If it is more than 30 at %, saturation magnetization deteriorates significantly, so it is not very preferable. Therefore, the amount added is preferably 30 at% or less, more preferably 20 at% or less.

Generally, materials with higher saturation magnetization are potentially better as magnetic materials. Therefore, when evaluating the corrosion resistance of various magnetic alloys with the same saturation magnetization, Ni is particularly preferable as an additive element because it has high corrosion resistance and also has magnetism. That is,
When Ni is added, since Ni itself is a highly corrosion resistant metal,
By further adding Ni to the magnetic alloy having the above composition, corrosion resistance can be further improved while suppressing a decrease in saturation magnetization, which is particularly preferable. That is, Ni is 10at%
It has been found that when added above, corrosion resistance is more than twice as good as that of CoCr-based alloys such as CoCr or CoCrTa, which are formed as some examples in FIG. However, if more than 60 at % of Ni is added, the coercive force decreases, which is not preferable.

Next, we generally evaluated the magnetic properties and recording/reproducing properties of magnetic recording media using these magnetic thin films alone, including materials with poor corrosion resistance.

That is, a film with a thickness of 42 mm is placed on a glass disk substrate or N1-P plating AQ alloy disk with a diameter of 130 m5φ.
CoNi alloy with a film thickness of 60 nm, C through 0 nm of Cr
oCr alloy, CoTi alloy, CoP alloy, CoS
m alloy, CoFe alloy.

CoPr alloy, CoNi Zr alloy: CoNiTi alloy, CoNiPt alloy, CoNiCr alloy, CoCrP
t alloy, CoCrTa alloy, CoN i Z r C
The magnetic thin film of R alloy, CoNlHfAQ alloy, etc., and a C protective film having a film thickness of 40 nm were formed to obtain a magnetic disk consisting of a single-layer magnetic thin film. Here, the in-plane coercive force of each medium was 300 Oe or more and less than 3000 Oe, and all exhibited in-plane magnetic anisotropy. Using a metal-in-gap type ring head with a gap length of 0.6 μm and a FeAjlSi alloy in the gap part and Mn-Zn ferrite in the rest, the relative speed was 20 m/s, and the flying height hg = 0.2 μm.
As a result of evaluating the recording and reproducing characteristics at m, 0.15 μm,
As shown in Figure 10, 1kPCI (flux chan
The playback output during low-frequency recording (ge per 1nch) does not significantly depend on the coercive force, but increases in proportion to the saturation magnetization of the magnetic thin film, and the magnitude of the playback output varies depending on the distance between the head and the medium. It was found that the narrower the line, the thicker it becomes.

From now on, in order to increase the reproduction output during recording and reproduction at low frequencies, that is, at low recording density, it is sufficient to increase the saturation magnetization of the Al thin film. However, as the saturation magnetization increases, the demagnetizing field within the magnetic thin film becomes stronger during high-density recording, so as shown in Figure 11 for the case of a flying height of 0.2 μm, the higher the saturation magnetization, the lower the density of about 1 kPCI. Recording density that is half of the playback output (output half-reduction recording density D5
．． ) decreases with increasing saturation magnetization, and becomes 40kP.
It has been found that there is a problem in that the reproduction output at a recording density as high as CI is significantly reduced.

In this way, the saturation magnetization of a magnetic thin film has opposite effects on output and recording density, so even if the above-mentioned highly corrosion-resistant magnetic alloy is used, it is impossible to simultaneously achieve high density and high reproduction output with a single layer. It was confirmed that this was extremely difficult.

Therefore, based on the above knowledge obtained from research on single-layer films, we can achieve high coercive force by combining magnetic thin films, and also achieve higher density and higher S/
We decided to seriously consider a configuration that would allow us to obtain N. Generally, corrosion progresses from the information recording side, so the magnetic thin film closest to the information recording side is limited to a magnetic material with high corrosion resistance and in-plane magnetic anisotropy, and below that, the above-mentioned general magnetic thin film made of various compositions is used. We have intensively investigated the recording and reproducing characteristics of composite magnetic recording media provided with thin films. Here, as the non-magnetic underlayer, C
We decided to study the case of using alloys such as r, Tio, N bll, and having in-plane and perpendicular anisotropy as the magnetic thin film on the outermost substrate side. First, an alloy magnetic thin film with smaller saturation magnetization or larger in-plane coercive force is provided closest to the substrate, and then magnetically interacts with this, and the surface of the magnetic thin film undergoes changes such as oxidation and nitridation. To prevent this from happening,
By controlling the vacuum quality, magnetic properties, film thickness, etc., another alloy magnetic thin film having a higher saturation magnetic flux density or a lower in-plane coercive force than the magnetic thin film was provided on the magnetic thin film. When the respective magnetic thin films interact magnetically and the substrate-side magnetic thin film has in-plane anisotropy, there is only one in-plane coercive force for magnetization reversal in each case, and the substrate-side magnetic thin film has in-plane anisotropy. When the thin film has perpendicular anisotropy, if the magnetic thin film on the information recording side has a coercive force of 4 Oe or more and 20008 or less and is semi-hard magnetic, the composite magnetic film has an in-plane coercive force that causes magnetization reversal in response to an external magnetic field. There is only one, and we were able to make its value higher than the coercive force of the semi-hard magnetic film.

The effects of the present invention will be explained in more detail below using several examples.

First, Table 1 shows typical composite magnets, in which the thickness of each magnetic layer is 25 nm.

Table Next, the example in Table 1 will be explained in detail. For the composite media of Comparative Example 2, in which CoN1Ptfi was first provided on a glass substrate and a CoCr layer was provided thereon, CoNi of Comparative Example 3 was used.
The coercive force is 76 Oe compared to the coercive force of 1050 Oe for Pt single layer media.
It can be seen that it is as low as 0 Oe. This is because CoCr inherently has a low in-plane coercive force as shown in Comparative Example 4, and if a CoCr layer is provided on a Co-based alloy thin film such as CoNiPt, the Co-based alloy thin film It is thought that this is because the originally high coercive force (shown in Table 12 and Table 3) of the material is reduced.

On the other hand, the coercive force of the composite medium of the present invention 1, in which a CoCr layer was first provided on the substrate and a CoNiPt layer was provided thereon, was surprisingly 1100 Oe, which was higher than that of the CoNiPt layer of Comparative Example 3.
It was revealed that P was higher than the coercive force of the single-shoulder membrane medium. The details of this cause have not yet been completely elucidated, but judging from the results of xg analysis and the like, it is thought to be as follows.

That is, regarding the medium of sample number 1-4 of the above clothing 1,
When the orientation of the magnetic film was examined using X-rays, the fifth
As shown in the figure, the Co Cr single layer film of Comparative Example 4 shows a strong diffraction line peak at about 44.6° at 2θ, and the C axis is likely to be vertically aligned. This is because Cr added to Co tends to segregate at grain boundaries, making it easier for Go crystal grains to be C-axis oriented. This effect was observed when the amount of Cr added was 0.1 at% or more, but when 30 at% or more was added, the CoNiPt single layer film of Comparative Example 3 had a saturation magnetization of about 43.0%, as shown in FIG. 1/1 of the diffraction line intensity observed in CoCr at 2”
It has become clear that the C-axis is slightly likely to be oriented in-plane only by showing a weak diffraction line with an intensity of 0 or less. On the other hand, as shown in FIG. 7, the CoCr/Co of Comparative Example 2
N i P is 43.2” and 44.6 in 2θ for the composite membrane.
'Only a very weak diffraction line peak comparable to that of Comparative Example 3 is observed, whereas CoNiPt/CoC of Invention 1
r (/substrate) In the composite film, as shown in Figure 8, 43
．． It became clear that extremely strong diffraction lines at 2" and 44.6 degrees, which were 10 times or more stronger than those in Comparative Example 2, were observed.

In particular, 43 indicates the in-plane orientation of the C-axis of CoNiPt.
．． The intensity of the diffraction line at 2′ is about twice as strong as the intensity of the diffraction line at 44.6°, which indicates the vertical orientation of the C axis of CoCr, and
It has become clear that the iPt film has extremely good crystal orientation as an in-plane medium. This is because the CoNiP film is epitaxially formed on top of the CoCr film with high vertical orientation, although it is not mentioned that the CoNiP film is epitaxial.
When a P film is formed on a substrate and a thin film other than CoCr such as a CoN i-based alloy or a CoS m-based alloy is provided on top of the film, these can exhibit relatively good in-plane crystal orientation. Found out. From this, if a CoCr-based alloy thin film is provided on a CoNi-based alloy film or the like.

Since Cr in CoCr is easy to segregate as mentioned above, CoC
It is considered that r is not well oriented and the magnetic properties of the CoCr/CoNi-based alloy/substrate composite medium are deteriorated.

In any case, the C axis is generally the magnetocrystalline anisotropy axis,
The higher the in-plane orientation component of the C-axis, the higher the in-plane coercive force, indicating that the properties as an in-plane medium are better. For this reason, in fact, as shown in Figure 9, the results of evaluating the recording and reproducing characteristics of each medium of sample numbers 1 to 4 in Table 1 using a thin film magnetic head with a gap length of 0.4 μm, the magnetic flux of any medium Quantity BS
-tIlag, the medium of the present invention has extremely small medium noise and exhibits an output noise ratio (S/N) that is more than twice as high as that of the comparative example medium. It has been revealed that because the magnetic thin film on the substrate side has a high crystal orientation, it not only has a high coercive force, but also has low media noise and a high output noise ratio.

The above effects can be obtained by using Co as the magnetic thin film on the substrate side.

At least one element selected from the first group consisting of Fe, Cu, Cr, Mo, W, Tb, and Gd.

Sm, Nd, Pr, Pm, Ce, Dy, Pt.

It was observed even when the magnetic material was made of a magnetic material whose main component was a magnetic alloy containing at least one element selected from the third group consisting of Ir and at least one element of Ni.

When the elements of the third group were included, the effect as described above was observed when the composition was set to 0.1 at% with respect to the total amount of the elements of the first group.

This is because the elements of these groups tend to segregate at grain boundaries, resulting in higher orientation. Adding more than 30 at % is not preferable because the saturation magnetization decreases.

In addition, when Ni is included, it is desirable that the composition with respect to the total amount of elements in the first group be set under magnetic conditions to increase coercive force.In either case, with respect to the total amount of elements in the first group Furthermore, Ti, Zr.

Hf, Nb, Ta, Ru, Os, Rh, Pd.

It is preferable to add Al or Si in an amount of 0.1 at % or more because it improves corrosion resistance, but it is not preferable to add more than 20 at % because the magnetic properties deteriorate.

In addition, although the above-mentioned alloys of CoMoZr and CoNiZr generally tend to become amorphous, when they become amorphous, the above-mentioned effect on crystal orientation disappears, and the coercive force also decreases to below a few + Oe, which is not preferable. It is desirable that the material be crystalline. Here, the magnetic thin film on the information recording side is highly oriented, and the magnetic thin film on the medium side is made of CoCr-based or CoS
The information recording side magnetic thin film is formed of a ternary or quaternary alloy containing at least m groups of the above elements, and the information recording side magnetic thin film is made of the CoNi-based ternary,
This is most noticeable when the alloy is formed with a quaternary alloy as the main component, so this combination is particularly preferable in terms of recording and reproducing characteristics, and further between the internal magnetic thin films.

The same effect can be obtained by providing one or more layers of another Co-based, Fe-based, or Ni-based magnetic alloy thin film.
It is also possible to have a structure of more than one layer.

Next, the effect when the magnetic thin film on the information recording side is highly saturated magnetized will be explained. As can be understood from the spacing dependence in Figure 10, it is generally better to increase the saturation magnetization of the magnetic thin film on the information recording/reproducing side compared to a single layer film having an average saturation magnetization value of each composite film. The amount of magnetization at a position with small spacing is large, and the amount of magnetic flux flowing into the reproducing head is large, so that a relatively large reproducing output can be obtained. Therefore, in the case of a composite film having two or more layers, it is particularly preferable to maximize the saturation magnetization of the magnetic thin film on the information recording side of the uppermost layer.

However, as mentioned above, from the viewpoint of corrosion resistance, it is most preferable that the uppermost layer is composed of a highly corrosion-resistant magnetic layer.

On the other hand, in general, the higher the corrosion resistance is achieved by increasing the amount of added elements, the lower the saturation magnetization is, so when corrosion resistance is of utmost importance, it is not necessarily necessary to increase the saturation magnetization amount of the top layer. However, in this case, it is most preferable to configure the magnetic film to have three or more layers, since this allows the intermediate magnetic thin film to have high saturation magnetization, improve corrosion resistance, and improve reproduction output.

Regarding recording density, since the coercive force of the composite magnetic recording medium of the present invention is higher than that of a single layer medium, the width of the magnetization transition region is narrower, and the recording density can be higher than that of a single layer medium. Furthermore, since the value of the demagnetizing field at the bit boundary during high-density recording is substantially the same as that of a thin film with small saturation magnetization, the recording density can be further increased. This is because in a magnetic thin film composed of two or more types of materials, the sawtooth-like magnetic domains formed between bits during magnetic recording interact strongly with each other, so that the magnetic domain structure and magnetic domain length tend to be the same. The width of the wide magnetization transition region in the case of a film with high saturation magnetization alone becomes smaller to be almost the same as the width of the narrower magnetization transition region observed in the case of a film with lower saturation magnetization alone. The thinner the highly saturated magnetization layer is, the more desirable the zero-line effect is, in terms of domain wall energy. In terms of the steepness of the recording magnetic field, it is also preferable because the head magnetic field distribution is steeper in relation to the reproduction output, and the width of the magnetization transition region is also relatively narrower.

The above effects were also observed when the magnetic film was composed of three or more magnetic alloy layers with different compositions and components and different saturation magnetizations.

As described above, by providing an alloy magnetic thin film made of the highly corrosion-resistant magnetic material and having the highest saturation magnetization closest to the information recording head side, and forming a composite magnetic film, a single film having an averaged saturation magnetization as a composite film is formed. It can have higher reproduction output and higher recording density characteristics than a layered film.

Next, more preferable magnetic properties of the magnetic material of the magnetic thin film closest to the substrate will be described in more detail.

First, a case with in-plane magnetic anisotropy will be explained. N
On an A2 alloy substrate with a diameter of 89aaφ plated with iP,
Ar gas pressure 15 mTorr, input power density I W/aJ
, C was deposited as a nonmagnetic underlayer with a thickness of 500 nm by DC magnetron sputtering at a substrate temperature of 100°C.
r film, film thickness 0.10°20.25,27.5.30,3
5,45,55゜60nm Co,...,Cr...
P t, ..., magnetic thin film, film thickness 60, 50, 40, 35
, 32.5, 30°25.15t 5. Onm Co, , Ni, 3. Zr. . , magnetic thin film, 5 nm thick Zr, , Hf, , I as a non-magnetic intermediate layer
1, and a WN film with a thickness of 2 nm as a non-magnetic protective coating layer to form a magnetic disk, and the relationship between the thickness magnetic properties of the magnetic thin film CoCrPt on the substrate side and the magnetic properties and recording/reproducing properties of the composite thin film medium. evaluated.

Here, the saturation magnetization M of CoCrPt and CoNiZr films is
s is 79 Oemu/cc (4πMs=9.9
kG), 73Oemu/cc (4sMs=9.2kG
), and C o Cr P t .

CoNiZr also exhibits in-plane magnetic anisotropy, and as shown in Figure 12, when CoCrPt is formed alone,
In any of the above film thickness ranges, CoN i Z
The in-plane coercive force was larger than when the r film was formed alone. Furthermore, the strength of the CoCr P film was higher than that when CoN1ZrPIA was formed alone. The recording/reproducing characteristics are CoO,..., Nboi4Z in the gap part.
r++, o* magnetic thin film was formed and evaluated using a metal-in-gap (MIG) type magnetic head (gap length 0.4 μm) at a relative speed of 12 m/s and a flying height of 0.2 μm. Figure 13 shows a composite medium and CoC as a comparative example.
The coercive force of the rPt single layer medium and the medium S/N are shown. Co
The coercive force of NiZr single-layer films and CoCrPt single-layer films has a strong dependence on film thickness, whereas the coercive force of composite films has a small dependence on film thickness, and is stable and high with good reproducibility against film thickness variations. It can be seen that a coercive force can be obtained.

As described above, coercive force and S/N can be improved by combining a CoNiZr film with a CoCr film, but in particular, the thickness of the CoNiZr magnetic thin film on the information recording side is greater than that of the CoCrPt magnetic thin film on the substrate side. thicker than twice the thickness (40
It can be seen that if the thickness is less than nm (CoCrPt film thickness is 20 nm or more), a high S/N medium with a coercive force of 1000 Oe or more and an S/N of 5 or more can be obtained. Here, it is particularly desirable if the thickness is thicker than the substrate film CoNiZr because the coercive force is high and the dependence on film thickness is small. Furthermore, if the coercive force is 1500 Oe or more, the output half-reduced recording density D1 will be high, and a relatively high medium S/N will be obtained, which is even more desirable.

Furthermore, in all composite magnetic films, the override characteristics were as high as 32 dB or more, which was much better than expected based on the coercive force and head-disk spacing. On the other hand, CoCrP with the same film thickness as 60 nm
The override characteristic of the t-single M media was 26 dB, which was significantly worse than the composite film media. In this way, the coercive force is 1
Although it is high at around 000 to 1500 Oe or more,
The detailed mechanism by which good override characteristics are obtained in the composite thin film medium of the present invention has not yet been fully elucidated, but since the recording magnetic field is strong on the information recording head side, the coercive force is high on the information recording side. This is different from the conventional common sense regarding coating media that the above is preferable as an override, and this is considered to be due to the following reasons. That is, the coercive force of the composite magnetic film of this configuration is as shown in FIG.
As is clear from Figure 3, the coercive force of the magnetic thin film on the information recording side and the substrate side is approximately an intermediate value, weighting the respective film thicknesses. High magnetic force
To make it wet, increase the coercive force of at least one magnetic thin film,
It is sufficient if the film thickness is increased.

(Here, for the sake of simplicity, we have ignored the property improvement effect of providing the substrate-side magnetic layer as shown in Table 2.) In the composite magnetic film of the present invention, the composite magnetic film is maintained in this way. In addition to increasing the magnetic force, each component magnetic thin film is magnetically coupled and the magnetization is reversed at the same time, so if the magnetization of only one magnetic thin film can be reversed, then the other magnetic thin films can also be reversed.

Even if the average value of the applied magnetic field within the medium is less than the coercive force of the composite medium, it is thought that the magnetization can be reversed as a whole. With the usual magnetic field application method for evaluating magnetic properties, it is difficult to preferentially reverse the magnetization of only one thin film. However, the strength of the head recording magnetic field decreases exponentially as it moves away from the head surface. Therefore, the recording magnetic field at the position of the magnetic thin film on the information recording side is extremely strong compared to the recording magnetic field at the position of the magnetic thin film on the substrate side, and the coercive force of the magnetic thin film on the information recording side is compared to the coercive force of the composite film. If it's small.

Information can be recorded by effectively reversing the magnetization of the magnetic thin film on the information recording side and the magnetic thin film on the substrate side that is strongly magnetically coupled with the magnetic thin film using a small effective magnetomotive force. When the saturation magnetization of the magnetic thin film on the information recording side is high, the influence of the demagnetizing field becomes stronger, so the single-line effect becomes more pronounced. In a composite magnetic film that is strongly magnetically coupled as described above, it is thought that better override characteristics can be obtained by providing a magnetic film with a high coercive force when deposited alone on the substrate side. It will be done. The same applies to a multilayer structure of three or more layers.

Regarding the non-magnetic underlayer, we have described the case where Cr is used, but Cr-based alloys such as Cr-Ti and Cr-Si, body-centered cubic structures such as Mo, W, Mo-based alloys, and W-based alloys can also be used. A metal alloy containing Cr can improve the orientation of the substrate-side magnetic thin film and provide a high coercive force, so it can be used in the same way as Cr. If the thickness of the underlayer is 10 nm or more, the effect of increasing coercive force is recognized, but if the thickness of the underlayer is 10 nm or more,
Even if the thickness is made thicker than 500 nm or less, the effect remains the same and the cost is lower, so the thickness is preferably 500 nm or less.

These magnetic thin film media were coated at a temperature of 0. The corrosion resistance was evaluated by evaluating the increase in the number of missing errors after being left in a high temperature environment of 60° C. and 80% RH for 120 hours, containing 1 ppm of SO2 gas. As a result, while the CoCrPt single-layer film increases the number of errors by more than 100 per surface, when a CoNiZr magnetic thin film with a thickness of 5 nm or more is provided on the information recording side, only 5 or fewer errors occur. When the thickness was 15 nm or more, no errors were observed and extremely good corrosion resistance was exhibited. Information recording side C
If the thickness of the oNiZr magnetic thin film is made even larger than 1100 nm, the coercive force and output half-reduced recording density D5° will decrease, which is undesirable, and it is desirable to set the thickness to 1100 nm or less.

Here, Ti, Zr, Hf, and Ta are used as a nonmagnetic intermediate layer between the composite magnetic film and the nonmagnetic protective coating layer.

Nb, or an alloy in which platinum metal elements such as Pt, Pd, Rh, Ir, Ru, and Os are added to at least one of these elements at 0.01 at % or more and 1 at % or less; Or 27 to 34 wt% Cu to Ni,
It is preferable to provide a thin film made of a Ni-based alloy to which 2-32 wt% Mo, 13-25 wt% Cr, etc. are added, and have a thickness of 5 nm or more, since the corrosion resistance of the magnetic film can be improved approximately twice. On the other hand, if the film thickness is larger than 15 nm, it is disadvantageous in terms of recording and reproducing characteristics, so it is preferable to set the film thickness to 15 nm or less, more preferably 10 nm or less.

C, i-C for non-magnetic protective coating layer.

It is desirable to use a high hardness non-magnetic material such as W'C or WN from the viewpoint of sliding strength, and in order to stably obtain high sliding resistance, it is preferable that the film thickness is 10 nm or more. A film thickness greater than 40 nm is undesirable in terms of recording and reproducing characteristics, and is preferably 40 nm or less, more preferably 30 nm or less. In addition to this, the perfluorinated coral-absorbing property improves sliding resistance, which is even more preferable.

The case where the magnetic material on the substrate side has in-plane magnetic anisotropy has been described above. Next, the case of having perpendicular magnetic anisotropy will be explained. T io, sT ao, with a film thickness of 500 nm using RF magnetron sputtering with a diameter of 130 mm.
Non-magnetic underlayer consisting of Z, substrate side magnetic thin film Coo, 300 nm thick and having perpendicular magnetic anisotropy, oCr0.95
m... 1.Continuously, the coercive force alone is 30O
e, an amorphous semi-hard magnetic material co. ,. Wo,. ,Zr,
, □, and finally a non-magnetic intermediate layer made of Zr with a film thickness of 10 nm and a film thickness of 25 nm.
A magnetic disk was prepared by forming a nonmagnetic protective coating layer made of WN with a thickness of 10 nm. As described above, when a semi-hard magnetic thin film is continuously formed on the perpendicular magnetization layer, the two become magnetically coupled, and unlike what is stated in Japanese Patent Application Laid-Open No. 61-222022, As shown in FIG. 14, magnetization is reversed with a single coercive force as high as about 350 Oe for both in-plane and perpendicular magnetic fields. Here, the magnetic thin film on the information recording side is semi-hard magnetic when it is alone, and its in-plane coercive force is the in-plane coercive force of the magnetic thin film on the substrate side that has perpendicular magnetic anisotropy as shown in Table 3. Because it is small compared to
As a composite membrane, it has approximately isotropic properties. When recording and reproducing data on this medium using the MIG type ring head, excellent override characteristics can be obtained using the same mechanism as described above. Further, in the composite medium of the present invention, although the details of the mechanism are not detailed, due to the interaction with the upper semi-hard magnetic thin film, the perpendicular magnetic anisotropic thin film on the substrate side substantially functions as an in-plane medium. This property is essentially close to that of a perpendicularly magnetized film. Therefore, the recording magnetization mode has many isotropic or perpendicular components rather than completely in-plane, and high-density recording and reproduction is possible despite the low coercive force.

In the above example, a Ti-Ta alloy was used as the non-magnetic underlayer, but Ti or Ti with Nb, Cr, Pt
A similar effect in improving the vertical alignment of the magnetic thin film on the substrate side can also be observed by using a Ti-based alloy to which a group element or the like is added, or by using C, Ge, or the like. The above effect is observed when the thickness of the non-magnetic underlayer is 10 nm or more;
Even if the thickness is made larger than 500 nm, further improvement in the effect is not expected, and on the contrary, it causes a problem in terms of cost, so it is preferable to make the thickness 500 nm or less. When reading information from these magnetic recording media, a ring-type magnetic head using at least a metal magnetic thin film as part of the magnetic path may be used, or a magneto-optical effect such as the Kerr effect or Faraday effect may be used. At this time, it is more desirable to include at least one of Bi or Fe in the first magnetic thin film because the magneto-optical effect can be particularly enhanced.

By using the above magnetic recording medium and magnetic recording/reproduction method,
This is particularly preferable since it is possible to provide a small-sized, large-capacity magnetic storage device.

〔Example〕

Example 1 Hereinafter, Example 1 of the present invention will be explained in Section 1. Non-magnetic substrates such as alloy substrates and plastic substrates, 12.12' are C
Substrate-side magnetic thin film made of oPt, CoFePt, CoCrPt, etc.; 13°13' has higher saturation magnetization than 12.12'; information-recording side magnetic thin film made of CoNiZr, CoNiSm, CoNiPr, etc.; 14. ．． 14' is C9W
C, WN, TiN, ZrN, HfN, TiC.

This is a non-magnetic protective liquid U such as ZrC or HfC. This example will be described in more detail below.

An AQ alloy substrate 11 with an outer diameter of 130 u+n+φ, plated with N1-P to a thickness of 10 μm and polished so that minute scratches are formed on the surface so that the center line average surface roughness is 10 nm in the circumferential direction.
The substrate temperature was 150°C, and the Ar gas pressure was 10 m Torr.
, DC with input power density 2 W/al? The saturation magnetization Ms is 56 Oemu/cc (4π
Ms=7.0kG) Co, , gCrI, 2°T a,. , membrane 12.12'
After forming Co to a thickness of 20 nm, a 20 nm thick Co
,,5. Ni, 2. P to, , membrane (41M s =
1, 1kG) 13.13', and finally a C film 14.14' with a thickness of 30 nm was formed to form a magnetic disk. A 2 nm thick perfluoroalkyl polyether having a polar group of 10H is formed on this magnetic disk, and F e A Q S is applied to the gap portion with a gap length of 0.4 μm.
Using a metal-in-gap ring head provided with an i-alloy thin film, the recording and reproducing characteristics were evaluated at a relative speed of 20 m/s and 90 MHz (recording density D = 23 kPCI), and compared to a comparative example in which the film was formed under the same conditions. As shown in Table 2, the output E2F at high density was high, and excellent recording and reproducing characteristics were exhibited. Furthermore, the medium made according to the present invention has low noise.

For example, it was less than half of Comparative Example 1, which uses a CoCr-based alloy as the upper layer, and exhibited an extremely high value as a medium S/N.

As can be seen from Table 2, CoCrTa, which is as thin as about 20 am, also has a small coercive force in the vertical direction.
Unlike the delivered orientation, it was magnetically oriented in-plane. When the film thickness was 150 nm or less, the magnetic orientation was similar. In addition, although the magnetization curves of the composite magnetic films all had a single high coercive force, it was noted that the magnetic thin film on the substrate side and the magnetic thin film on the information recording side were left in Ar gas for about an hour while forming the magnetic thin film on the substrate side and the magnetic thin film on the information recording side. When the upper magnetic thin film was formed via a nonmagnetic intermediate layer with a film thickness of about 10 nm or more, a serpentine magnetization curve was obtained, and no magnetic force reversal occurred with a single coercive force. CoC
Even when the film thickness of r Ta is increased to 200 nm or more and perpendicular magnetic anisotropy is imparted, the coercive force of CoNiPt is 1.
Because of its high value of 0000 e, magnetization was not reversed by a single coercive force. In such a medium, the reproduced waveform was complicated and the recording density characteristics were also poor.

Comparing Examples and Comparative Examples, the coercive force of the magnetic thin film on the information recording side changes depending on the state of the underlying layer, and in the state of the composite magnetic film, the coercive force of each magnetic thin film is simply that of each magnetic thin film. It can be seen that this is different from a thin film formed directly on a base substrate. CoNiPt, CoCrTa
Exactly the same results were obtained when the film thicknesses were made equal to 40 am, 60 am, and 80 am. Also, CoCrT
For alloy a, in addition to the above composition with Ta constant.

4 with Cr as 12at%, 15at%, 23at%
When 1M s is 8.0kG, 6.3kG, and 2.4kG, and also for CoNiPt alloy, Ni is 30at%.
, 5at% and 10at% of Pt.

9.41Ms as 20a t%. OkG, 8.7k
A similar effect was observed when G was set to 8.4 kG.

Example 2 Hereinafter, Example 2 of the present invention will be explained with reference to FIG. 2. 21
is surface resin coated tempered glass, Ti alloy.

Non-magnetic substrate such as N1-P plating AQ alloy, 22°22'
is Ti, Ti alloy, Cr, Cr alloy, Mo.

Non-magnetic underlayer with Mo alloy, C, Ge, 23°23'
are CoCr, CoMo, CoW, CoTi.

CoNiSm, CoCrTi, CoCrZr.

The substrate side magnetic thin film of the present invention is made of CoCrAfl, CoCrSi, CoSm, etc., and 24.24' is CoNbZr.
, CoTaZr, CoWZr.

CoNiZr, CoFeTa, CoNbHf.

CoTaHf, CoTaMo, CoMo Zr.

The information recording side magnetic thin film of the present invention is made of Co Mo Hf, etc., and 25.25' is C, Rh.

It is a non-magnetic protective thin film made of S i O, Z r O2, A O20, etc. Note that this embodiment will be described in more detail below in Section 9, in which the non-magnetic protective film is not particularly provided, and only an organic lubricant may be provided.

A non-magnetic substrate 21 with a diameter of 89IIIφ was provided with an ultraviolet curable resin having grooves with a center line average surface roughness of 8 nm in the circumferential direction of the disk on an AQ alloy disk substrate with a thickness of 1 m, and the substrate temperature was 100. °C, purity 99.999% A
A film with a thickness of 250 nm was formed by DC magnetron sputtering at a gas pressure of 15 mTorr and an input power density of I W/a#.
iO,, □N bo, □, alloy nonmagnetic underlayer 22.2
2', then CO, , Cro, with a film thickness of 250 nm.
Zroo, consists of a film, saturation magnetization Ms is 56Oem
The magnetic thin film 23,23' on the substrate side is u/cc (4sMs=7kG), and the CO(
1,7s M OO,x, Z r, , consisting of a film,
The saturation magnetization Ms is 700 em u / c c (4π
Ms=8.8kG) information recording side magnetic thin film 24.2
4' and then finally AQ20 with a film thickness of 20 nm.
．． A non-magnetic protective coating layer 25°25' was formed to obtain a magnetic disk. When a magnetic field was applied to this magnetic disk from the outside, it was in-plane.

The vertical coercive forces Hcl and Hc are each 363
It showed a single magnetization curve of 369 Oe. Here, the in-plane and perpendicular magnetization curves were similar to those shown in FIG. This magnetic disk was coated with adsorbent perfluoroalkyl polyether with a film thickness of 3 nm using the dip method, and an MIG head with a gap length of 0.3 μm (the area near the gap was made of Fe-
When the recording and reproducing characteristics were evaluated in a contact state using a composite magnetic head (formed from a high saturation magnetic flux density alloy such as Afl-Si alloy), as shown in Table 3, C
Compared to the comparative example in which oCrZr and CoMoZr were formed in the reverse order, a high reproduction output was obtained even at a high recording density. Here, CoMo Zr was amorphous.

Note that when CoMoZr alone is directly formed on a substrate on which T1Nb is formed, the in-plane and perpendicular coercive forces are 25,110 Oe, respectively, and CoMoZr alone exhibits semi-hard magnetism. However, since the value of coercive force generally varies greatly depending on the condition of the underlying film, etc., the magnetic properties when formed on CoCrZr as in the example are not precisely known. Also,
When CoCrZr is directly formed on T1Nb on a substrate, the in-plane and perpendicular coercive forces Ha, , I (CJL are each 240.370 Oe, and CoCrZr in the example showed perpendicular anisotropy. As in the example, the substrate side magnetic thin film 23, 23' and the information recording side magnetic thin film 24, 24' are formed of a magnetic alloy containing Co as a main component, and an oxide layer or the like is added at the interface so as to magnetically couple the two. By preventing the formation of a non-magnetic intervening layer, even if the information recording side magnetic thin film 24, 24' is a perpendicularly magnetized film, the composite magnetic thin film can be made into an in-plane magnetized film.This effect is as follows. The smaller the perpendicular coercive force of the perpendicularly magnetized film and the smaller the film thickness, the more significant this is, but this is due to the strong exchange interaction in the film whose main component is Co.

The CoCrZr film has a film thickness of 0.15 μm.

Similar results were obtained with the thicknesses of 0.2 μm, 0.3 μm+o, and 5 μm, and when the CoMoZr film was further increased in thickness to 20 nm, 40 nm, 60 nm, and 80 nm, high reproduction output was obtained even during high-density recording. was gotten. T
Ti-Cr instead of 1Nb.

Similar effects were observed using Ti-based alloys such as Ti-Ta, Ti, C, and Ge.

The above effects can be achieved as a magnetic thin film on the substrate side. CoCr, CoMo instead of Co　Cr　Z　r.

Co W , Co T i , Co S i ,
Co An.

It was also obtained using a perpendicular magnetization film such as CoSm, NdFeB, PrFeB, etc. In addition, as a magnetic thin film on the information recording side,
Instead of CoMoZr, CoNbZr, C
oTaZr, CoFeTa.

A similar effect was observed even when a magnetic alloy such as CoWZr was used. These are materials that were conventionally semi-hard magnetic or soft magnetic and not used as magnetic recording media, and each has a magnetic field of 3 to 4 Jll.
As a comparative example, the case of lamination was investigated, but no improvement in properties was observed. No effect was observed even when 4 to 5 substrate-side magnetic thin films and SiO2 nonmagnetic layers were alternately laminated.

Example 3 Example 3 will be explained with reference to FIG. 21 is a non-magnetic substrate such as surface glass coated tempered glass, organic resin, N1-P plating AQ alloy, etc. 22.22' is Cr, Cr-8i, Cr
-Ti, Mo-8i.

A non-magnetic underlayer such as M o -Ti, 23.23' is
CoNiSm, CoCu5m, CoNiPr.

CoNiIr, CoNiPtAl2. CoNiTi
.

CoNiPt, CoNiCr, CoCrTa.

Substrate side magnetic thin film made of CoCrTaSi, CoCrPt, etc., 24.24' is NiFe.

NiFeMo, GdFeCoPt.

It is made of GdB1FeCo, TbFeCo, CoTaZr, etc. Information recording side magnetic thin film, 25, 25' are C, i-C
, WN, TiN, WC, ZrCN.

It is a non-magnetic protective coating layer made of H, fCN, HfN, etc.

This example will be described in more detail below.

An Af1 alloy substrate with a thickness of 1.9 nm and a diameter of 133 noφ was plated with N1-P to a thickness of 15 μm, and the surface was polished in the circumferential direction so that minute scratches were formed to have a center line average surface roughness of 8 nm. and a non-magnetic substrate 21.

On top of this, the substrate temperature is 120℃ and the Ar gas pressure is 15mTorr.
, a Cr nonmagnetic underlayer 22.22' with a film thickness of 400 nm was formed by RF magnetron sputtering with an input power of I W/aJ.
, then Co with a film thickness of 50 nm, , 1Cr, , 8. P
Consisting of t, , s, saturation magnetization Ms 70Oemu/c
c (4iMs=8.8kG) and a substrate-side magnetic thin film 23°23' having in-plane magnetic anisotropy, and then a Go, 7,2T film with a film thickness of 26 nm at an input power density of 0.5 W/d.
ao,. 4Z r... , and the saturation magnetization Ms 1
200 em, u/cc (4πMs=15kG)
Information recording side magnetic thin film 24.2 having in-plane magnetic anisotropy at
After forming Z r CN films 25 and 25' with a thickness of 25 nm as a non-magnetic protective coating layer, the magnetization was reversed in the magnetic field of a magnetic disk of 1200 Oe (single coercive crab 1200 Oe). In addition, when the magnetic thin films on the substrate side and the information recording side are formed directly on the Cr film, the in-plane magnetized films each have in-plane magnetic anisotropy and coercive force values of 1600 Oe and 60 Oe, respectively. there were. Furthermore, perfluoroalkyl polyether having a film thickness of 4 nm and having an ester group was formed on the magnetic disk of this example by the dip method, and the flying height was set to 0.18 μm using an MIG head with a gap length of 0.4 μm, and the magnetic disk was incorporated into a magnetic disk device.
When we evaluated its recording and reproducing characteristics, we found that it was approximately 1.2 times as high at a high density of about 40 kPCI as compared to a comparative example in which the substrate side magnetic thin film and information side magnetic thin film were formed in reverse, and a comparative example in which only a single layer was formed. A high playback output can be obtained, 1
．． A device with a device capacity more than twice as high was obtained. CoTa
The corrosion resistance of the Zr film is more than twice as high as that of the CoCr P film, and this example exhibited corrosion resistance that is about twice as high as that of the CoNiZrCr single-layer film.

The magnetic thin films on the substrate side and information recording side are each made of CoCrS.
m, CoNi Zr, CoCrTaSi,
Similar effects were observed when CoNiZr was used.

Furthermore, a similar effect was observed when each layer was formed of a CoNiZr alloy and the compositions of the two magnetic thin films were selected so that the information recording side magnetic thin film had higher saturation magnetization.

Embodiment 4 Another embodiment 4 having the same configuration as embodiment 3 will be described. Reinforced substrate 21 with a thickness of 1.2 an and a diameter of 51 mφ
Above, Ar containing 0.05 voQ of 02 at a substrate temperature of 80°C.
Gas pressure I Q m T orr + input power density 1.5
W/d, film thickness 300 by DC magnetron sputtering
nm of Cr,,,Tio,3 non-magnetic underlayer 2,2.2
2', then Co, . . . Ni0.2' with a film thickness of 50 nm. ,Z
r. ,Cr,,8. Saturation magnetization Ms30Oe consisting of
The substrate side magnetic thin film 23.23' of mu/cc (4 films Ms=3.8 kG) is further continuously coated with a film thickness of 30 nm and a saturation magnetization Ms of 50 Oemu/cc (4πMs =
6.3 kG) T b, , , Fe, , Co. ,
Nb. , film or film thickness 30 nm, saturation magnetization M s
600 e m u / c c (4 films Ms = 7.5
kG) G d,, 17F e, , Co, ,, N b,,
, 4 films or film thickness 30 nm, saturation magnetization Ms 80O
Ni@4Fe of emu/cc (4 films Mg=10kG)
An information recording side magnetic thin film 24, 24' consisting of , , , and finally a WN nonmagnetic layer 25, 25' having a thickness of 30 nm were formed to form a magnetic disk. These magnetic disks exhibit magnetization curves with a single in-plane coercive force of 500 and 600°300 Oe, respectively, indicating that the magnetic thin films on the substrate side and the information recording side are strongly magnetically coupled to each other. confirmed. The respective in-plane coercive forces when the substrate side magnetic layer is not provided are 200, 300, and 50 Oe.
Met. Furthermore, when both magnetic disks were installed in a magnetic disk drive, recorded with an Mn-Zn ferrite ring head, and reproduced using a semiconductor laser using the Kerr effect, a high recording speed of about 100 Mb/in was obtained. At high density, an S/N ratio more than 5 times higher than that obtained when reproducing using a ring head was obtained.

Here, we also considered the case where Co, ..., Ta, 4Z ro, o* was used for the magnetic thin film on the information recording side, but if at least one of Fe or Bi is included, the S/ This is more desirable because N can be obtained.

Embodiment 5 Another embodiment 5 will be explained with reference to FIG. 3
1 is tempered glass, alumite surface treated A2 alloy, Ti-
Non-magnetic substrate such as Mg alloy, 32°32' is Ti, Ti-
Nb alloy, Ti-Ta alloy.

Non-magnetic underlayer such as Cr, Cr-Ti alloy, 33°33'
are CoCr, CoCrTa, and CoCrSi.

CoTi, CoMo, CoW,
Co N i Z r Cr .

The substrate side magnetic thin film is made of a magnetic alloy such as CoCrSm or CoPtSm, and 34.34' is CoNiCr.

CoNiZr, CoNi, CoFeZr.

FeCoNi, CoFePt, CoPt.

Co N i P t , Co Cr P t ,
NdFeB.

SmCo, CoPr, CoCe,
Co G d.

CoY, CoNd, CoPr,
CoPm.

CoDy, CoLa, CoIr, CoTi.

CoZr, CoHf, CoV, CoNb.

CoTa, CoRu, Coos, CoRh.

This is an intermediate magnetic thin film made of a magnetic alloy such as CoPd, CoAl, CoSi, etc. Here, it is more desirable that the intermediate magnetic thin film has a higher saturation magnetization than at least the substrate side magnetic thin film.
r, CoTaHf.

CoNbTa, CoNbTi, CoNbZr.

CoNbHf, CoTaMo, CoNbMo.

Co Z r M o , Co Z r W , C
The information recording side magnetic thin film, 36°36', is made of a magnetic alloy such as o HfMo, WC, WN, WCH, HfC,
HfN.

NbN, NbC, NbCN, C, i-C.

It is a non-magnetic protective coating layer made of ZrO2, TaC, TaN, TaCN, etc.

This example will be described in more detail below.

An AQ alloy substrate with a thickness of 2.5 m and a diameter of 22001φ was plated with N1-P to a thickness of 12 μm, and the surface was polished to create minute scratches, with a center line average surface roughness of 6 nm in the approximately circular direction. A non-magnetic substrate 31 with a temperature of 150° C.
Ar gas pressure 10 m Torrs Input power density 3 W/a
d to a film thickness of 500 nm using DC magnetron sputtering.
r, ,, T i, 2 underlayer 32.32'& input power density 2 W/aj, film thickness 40 nm, saturation magnetization M s 80
0 e m u / c c (4xMs=10kG)
Substrate side magnetic thin film 33.33' consisting of Co, , Cr, , iTa, , o, P t, , 1°, and then successively applied power of 1.5 W/aJ to a film thickness of 30 nm and saturation magnetization. M
C of s104Qemu/cc (4πMs=13kG)
Intermediate magnetic thin film 34.34' consisting of O@, 1@N i@4Cro, oz, and further successively an input power density of 1.0
W/J, film thickness 20nm, saturation magnetization Ms120Oemu
/cc (4πMg=15kG) Co,..., Ta
o, lls Z r, 8. , an information recording side magnetic thin film 35.35', and finally, a lubricating layer with a thickness of 4 nm is formed by dipping it into Freon containing a non-magnetic protective chill made of WN with a thickness of 30 nm at an input power of 3 W/j. It was formed into a magnetic disk. When the magnetostatic properties of this magnetic disk were evaluated, it was confirmed that the magnetization was reversed with a single coercive force of 1100 Oe. In addition, CoNiCr, Co
The coercivity of TaZr single layer media is 1000 and 60, respectively.
It was 0 Oe. Furthermore, when we combined these eight magnetic disks and 32 thin-film magnetic heads with a gap length of 0.4 μm to form a magnetic disk device, and evaluated its recording and reproducing characteristics, we found that CoCrTaPt or CoNiCr formed as a comparative example. 1 at a higher recording density of 30 kPCI, respectively, compared to a medium made of a CoTaZr single layer film and having the same amount of magnetic flux (product of saturation magnetic flux density and film thickness) as in this example.
．． 2, 1.3, 1.3 times higher reproduction output can be obtained, and the areal recording density is as high as 100 to 120 Mb/in2 (compared to the conventional technology, a high-performance magnetic disk and a large-capacity magnetic recording device can be obtained). It was done.

Example 6 A magnetic thin film on the substrate side, a magnetic thin film on the information recording side, and a nonmagnetic protective coating layer were formed on only one side of the substrate in the same manner as in Example 1 on an organic nonmagnetic substrate such as Upilex ■ or polyimide to produce a magnetic tape. A combination of a zero magnetic tape and a magnetic head in which a magnetic core is formed using a metal magnetic thin film on a non-magnetic substrate is used in a VTR and a backup magnetic storage device.

The capacity can be increased by 1.2 to 1.5 times compared to conventional media.

Furthermore, corrosion resistance was more than twice as high as that of conventional metal tape media.

Example 7 Under the same conditions as Example 3, a magnetic disk was fabricated using the magnetic thin film shown in Table 4.

Both magnetic disks have magnetization reversal with a single coercive force of 40kP, which is higher than when no substrate-side magnetic layer is provided.
It exhibited high medium S/N at a high density comparable to CI. Furthermore, the corrosion resistance was also good.

Table 5 Example 8 Under the same conditions as Example 4, a magnetic disk was fabricated using the magnetic films shown in Table 5.

Magnetization is reversed with a single coercive force, which is higher than when
It exhibited a high medium S/N ratio at a high density of about 37 kPCI.

It also has good corrosion resistance, and by using this medium, the areal recording density can be reduced to 1.
We were able to provide a compact magnetic disk device with an extremely high capacity of 50 to 300 Mb/in.

〔Effect of the invention〕

According to the present invention, the orientation is higher than that of conventional media even during high-density recording, and it is possible to achieve at least 1.2 times higher output and lower noise, which is effective in increasing the capacity and reducing the size of magnetic storage devices. be. Further, since the same recording density as the conventional one can be achieved even if the flying height of the magnetic head is increased, there is also the effect of improving the sliding reliability. Furthermore, semi-hard magnetic materials, which conventionally could not be used as magnetic recording media due to their high saturation magnetization but low coercive force, can be used according to the present invention. spreads,
It also has the effect of significantly improving corrosion resistance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of Embodiment 1 and Embodiment 6 of the present invention, and FIG. 2 is a sectional view of Embodiment 2 of the present invention. Example 3. Example 4. Cross-sectional views of Example 7 and Example 8, FIG. 3 is Example 5 of the present invention
4 is a diagram showing the corrosion resistance of magnetic thin films, and FIGS. 5, 6, 7, and 8 are CoCr, CoN, respectively.
iPt. CoCr/CoNiPt. A diagram showing the orientation of the CoNiPt/CoCr film, and FIG. 9 shows the medium S/N and medium magnetic flux amount Bs of the magnetic disks with the configurations shown in FIGS. 5, 6, 7, and 8.・L
Figure 10 is a diagram showing the relationship between reproduction output, spacing, and saturation magnetization, Figure 11 is a diagram showing the relationship between output half-reduced recording density and saturation magnetization, and Figure 12 is a diagram showing the relationship between magnetic FIG. 13 is a diagram showing the relationship between the coercive force and film thickness of the film. FIG. 13 is a diagram showing the relationship between the magnetic properties, recording and reproducing characteristics, and film thickness of the composite magnetic medium of the present invention. FIG. 1 of magnetization curve
It is a figure which shows an example. 11.21.31...Nonmagnetic substrate, 12.12'23
．． 23', 33, 33'... Substrate side magnetic thin film, 13
．． 13', 24.24', 35.35'... Information recording side magnetic thin film, 14, 14' 25, 25' 36.3
6'...Nonmagnetic protective coating layer, 22.22'32.32
'...Nonmagnetic underlayer, 34.34'...Intermediate magnetic thin film. $t/- Figure time CI: L) Plane T7! No. 7 direction rly) 4' 1 direction (-il ' Figure 2 Figure 7 name g Figure 2σ (a) 27F (Sukura 7m f3t- t-al (gσ cotton) 70 figure a $m iko tsuta 1s (T) 4υσ厖厖廝る MsCT)

Claims (1)

[Claims] 1. In a longitudinal magnetic recording medium in which a composite magnetic film is formed on a non-magnetic substrate directly or via a non-magnetic underlayer, all the magnetic films constituting the composite magnetic film are magnetically The composite magnetic film has only one in-plane coercive force, and the in-plane coercive force constitutes the magnetic film closest to the information recording side among the magnetic films constituting the composite magnetic film. An in-plane magnetic recording medium characterized in that the in-plane coercive force is greater than that of an in-plane magnetic anisotropic magnetic film. 2. The most information recording side magnetic thin film is semi-hard magnetic by itself,
The longitudinal magnetic recording medium according to claim 1, wherein the magnetic thin film adjacent to the magnetic thin film alone has perpendicular magnetic anisotropy. 3. The in-plane magnetic recording medium according to claim 1, wherein the magnetic thin film adjacent to the most information recording side magnetic thin film alone has in-plane magnetic anisotropy. 4. The in-plane magnetic recording medium according to claim 1, wherein the composite magnetic film has an in-plane coercive force of 1000 Oe or more. 5. The longitudinal magnetic recording medium according to claim 4, wherein the composite magnetic film has an in-plane coercive force of 1500 Oe or more. 6. The longitudinal magnetic recording medium according to claim 1, wherein the saturation magnetization of the magnetic film on the most information recording side is higher than the saturation magnetization of the magnetic film on the most substrate side. 7. The longitudinal magnetic recording medium according to claim 6, wherein the single in-plane coercive force of each of the magnetic films constituting the composite magnetic film is the highest in-plane coercive force of the magnetic film closest to the substrate. 8. The saturation magnetization decreases sequentially from the most information recording side magnetic film to the most substrate side magnetic film, and the in-plane coercive force decreases from the most information recording side magnetic film to the most substrate side magnetic film. The longitudinal magnetic recording medium according to claim 7, which is increasing in number. 9. In a composite magnetic recording medium consisting of at least two types of magnetic thin films formed directly on a non-magnetic substrate or via a non-magnetic underlayer, the magnetic thin film closest to the information recording side is Co.
, at least one element selected from the first group consisting of Fe, and N, Tb, Mo, W, Gd, Y, Sm, Nd,
Pr, Pm, Ce, Dy, La, Pt, Ir, Ti, Z
r, Hf, V, Nb, Ta, Ru, Os, Rh, Pd,
A magnetic thin film with in-plane magnetic anisotropy, the main component of which is an alloy containing at least one element selected from the second group consisting of Al and Si or at least one element of Ni, and the magnetic thin film on the outermost substrate side. has a different component or composition from the most information recording side magnetic film, and contains at least one element selected from the first group, and Cu, Cr, Mo, W, Tb, and G.
d, Sm, Nd, Pm, Pr, Ce, Dy, Pt, Ir
The main component is an alloy containing at least one element selected from the third group consisting of and at least one type of Ni, and all the magnetic thin films constituting the composite magnetic film are magnetically coupled. , the in-plane coercive force of the composite magnetic film when magnetization is reversed in response to an in-plane external magnetic field is 250 Oe.
A longitudinal magnetic recording medium characterized by having one of the above values. 10. The most information recording side magnetic thin film contains at least the elements of the second group, and the total amount of the elements of the second group is 0.1 at% or more and 30 at% of the total amount of the elements of the first group. A longitudinal magnetic recording medium according to claim 9, which is as follows. 11. The most information recording side magnetic thin film contains at least Ni, and the Ni composition is 10% of the total amount of elements in the first group.
Claim 10: at% or more and 60 at% or less
The longitudinal magnetic recording medium described in . 12. The substrate-side magnetic thin film contains at least an element of the third group, and the total amount of the third group of elements is 0.1 at% or more 30a with respect to the total amount of the first group of elements.
The longitudinal magnetic recording medium according to claim 9, wherein the longitudinal magnetic recording medium is t% or less. 13. The most substrate-side magnetic thin film contains at least Ni,
The composition of Ni is 1 with respect to the total amount of the elements of the first group.
Claim 1 which is 0 at% or more and 60 at% or less
2. The longitudinal magnetic recording medium according to item 2. 14. The substrate-side magnetic thin film further contains Ti, Zr, Hf, Nb, Ta, Ru,
The surface according to claim 9, which contains at least one element of the fourth group consisting of Os, Rh, Pd, Al, and Si from 0.1 at% to 20 at%, and is predominantly crystalline. Internal magnetic recording medium. 15. Claim 9, wherein the magnetic thin film on the most information recording side is a CoNi-based ternary or quaternary alloy, and the magnetic thin film on the most substrate side is a CoCr or CoSm-based ternary or quaternary alloy.
The longitudinal magnetic recording medium described in . 16. The most information recording side magnetic thin film contains at least Fe and B.
The longitudinal magnetic recording medium according to claim 9, which includes one of i. 17. Claim 9, wherein the thickness of the magnetic thin film on the most information recording side is not more than twice the thickness of the magnetic thin film on the most substrate side.
The longitudinal magnetic recording medium described in . 18. The longitudinal magnetic recording medium according to claim 17, which has a thickness of 100 nm or less. 19. The longitudinal magnetic recording medium according to claim 9, wherein the saturation magnetization of the magnetic thin film on the most information recording side is higher than the saturation magnetization of the magnetic thin film on the most substrate side. 20. The in-plane magnetic recording medium according to claim 19, wherein the in-plane coercive force of each of the magnetic thin films constituting the composite magnetic film is the highest in-plane coercive force of the magnetic thin film closest to the substrate. 21. The saturation magnetization decreases sequentially from the most information recording side magnetic film to the most substrate side magnetic film, and the in-plane coercive force decreases from the most information recording side magnetic film to the most substrate side magnetic film. The longitudinal magnetic recording medium according to claim 20, which is increasing in number. 22. The longitudinal magnetic recording medium according to claim 9, wherein the composite magnetic film is composed of at least three types of magnetic thin films. 23. The in-plane magnetic recording medium according to claim 9, wherein the magnetic thin film on the most information recording side is semi-hard magnetic by itself, and the magnetic thin film adjacent to the magnetic thin film by itself has perpendicular magnetic anisotropy. 24. The in-plane magnetic recording medium according to claim 9, wherein the magnetic thin film adjacent to the most information recording side magnetic thin film alone has in-plane magnetic anisotropy. 25. The in-plane magnetic recording medium according to claim 9, wherein the composite magnetic film has an in-plane coercive force of 1000 Oe or more. 26. The longitudinal magnetic recording medium according to claim 25, wherein the composite magnetic film has an in-plane coercive force of 1500 Oe or more. 27. The non-magnetic underlayer is made of Cr, Mo, W, Ti, C
, Ge, or a nonmagnetic material containing these as main components. 28. Further film thickness 10 on the most information recording side magnetic thin film
10. The longitudinal magnetic recording medium according to claim 9, wherein a non-magnetic protective coating layer with a thickness of nm or more and 40 nm or less is formed. 29. In a longitudinal magnetic recording medium in which a composite magnetic film is formed on a non-magnetic substrate directly or via a non-magnetic underlayer, the composite magnetic film has only one in-plane coercive force, and A longitudinal magnetic recording medium having an internal coercive force of 1000 Oe or more. 30. The in-plane magnetic recording medium according to claim 29, wherein the in-plane coercive force is 1500 Oe or more. 31. A magnetic storage device having an areal recording density of 100 Mb/in^2 or more. 32. The magnetic storage device according to claim 31, wherein the areal recording density is 150 Mb/in^2 or more. 33. A magnetic storage device for recording and reproducing the longitudinal magnetic recording medium according to claim 1 using a ring-shaped magnetic head in which at least a portion of the magnetic core is formed of a ferromagnetic metal thin film. 34. A magnetic storage device for reproducing the magnetic recording medium according to claim 1 using light.