JP2001084546A - Information recording medium, and system and device for information recording and reproduction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a very high density recording to be performed by providing a laminated film of a 1st and a 2nd magnetic layer formed of thin amorphous alloy films consisting principally of rare earth transition metal, making the 1st magnetic layer less in coercive force and lower in Curie temperature than the 2nd magnetic layer, and setting the residual magnetism of the laminated film at room temperature in the absence of a magnetic field larger than a specific value. SOLUTION: The information recording medium has, on a substrate 1, the laminated film of the 1st and 2nd magnetic layers 2 and 3 formed of the thin amorphous alloy films consisting principally of rate earth transition metal showing vertical magnetic anisotropy. The 1st and 2nd magnetic layers 2 and 3 are characterized by that the coercive force Hc1 of the 1st magnetic layer is less than the coercive force Hc2 of the 2nd magnetic layer 3 or the Curie temperature Tc1 of the 1st layer 2 is less than the Curie temperature Tc2 of the 2nd layer 3. The residual magnetism of the laminated film at room temperature in the absence of a magnetic field is >50 emu/cc and when no magnetic field is applied, an interfacial magnetic wall is substantially not formed between the 1st and 2nd magnetic layers 2 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an information recording medium, an information recording / reproducing method, and an information recording / reproducing apparatus. More specifically, the present invention relates to an information recording medium capable of recording and reproducing information at an ultra-high density when recording and reproducing information magnetically and having improved recording / reproducing characteristics. The present invention relates to a device for recording and reproducing information in a device.

[0002]

2. Description of the Related Art Among information recording media, according to an information reproducing method for magnetically detecting information recorded on a magnetic recording medium,
As a result of advanced research, it has become possible to record at ultra-high density, and now the possibility of high-density recording exceeding 10 Gbit / inch ² has been shown. By the way, in the above medium, usually, for example, Co ₇₇ Cr ₁₅ Pt ₆ Ta ₂ (the number on the right side of the element symbol means mol%. ) Is used (a magnetic material exhibiting in-plane magnetic anisotropy). In addition, a CoCrPt-based polycrystalline magnetic material is used as a magnetic material having an easy axis of magnetization in the vertical direction (magnetic material exhibiting perpendicular magnetic anisotropy).

An example of using a rare earth transition metal amorphous alloy thin film for a perpendicular magnetic recording medium is disclosed in Japanese Patent Application Laid-Open No. 58-16530.
No. 6 describes this. Further, in addition to the above, there have been proposed attempts to use a perpendicular magnetic recording medium having a multilayer structure and a rare earth transition metal amorphous alloy thin film for part or all of the multilayer structure. As such proposals, for example, the following five patent publications can be cited as typical ones.

[0004] (1) Japanese Patent Application Laid-Open No. 2-279918 This publication discloses a substrate 101 as shown in FIG.
A perpendicular magnetic recording medium consisting of / lower perpendicular magnetic layer 102 / upper Co perpendicular magnetic layer 103 is described. As the lower perpendicular magnetic layer, MnBi, MnBiCu, TbFe, TbFeCo, and GdFe are used as upper perpendicular Co layers.
CoCr is described as a system perpendicular magnetic layer, and specifically, a combination of substrate / GdTbFeCo (200 nm) / Ti (30 nm) / CoCr (300 nm) is described in Examples. This publication is characterized in that an underlayer perpendicular magnetic layer is used as the underlayer instead of the conventional in-plane magnetization recording auxiliary layer. This publication also states that MnBi,
It is described that by using TbFe or the like for the recording auxiliary layer, noise caused by the underlying layer can be reduced.

(2) Japanese Patent Application Laid-Open No. 9-91660 This publication discloses a substrate 101 as shown in FIG.
/ First perpendicular magnetic layer 104 / second perpendicular magnetic layer 105 / protective layer 1
No. 06, wherein the first perpendicular magnetic layer and / or the second perpendicular magnetic layer is an amorphous rare earth transition metal alloy or a polycrystalline metal alloy, and may have a multilayer structure. Is described. This publication is
A magnetic layer having low noise and high resolution characteristics is used for the first perpendicular magnetic layer, and a magnetic layer having high output characteristics is used for the second perpendicular magnetic layer. Further, it is described that an amorphous alloy film in which a transition metal such as Fe is added to a rare earth metal such as Tb, which is being studied as a magneto-optical recording film, can be used for the perpendicular magnetic layer.

Specifically, in the embodiment, the sample (a) substrate / NiFe (100 nm, Tsub: 350 ° C., Par: 3 mTorr) / hcp structure Co
₇₀Cr₁₇Pt_TenTa_Three(25nm) / (Pd [2nm] / Co₉₀Cr_Ten[3nm]) 10 / C
(7 nm) / lubricant (5 nm), Hc = 2.7 kOe Sample (b) Substrate / NiFe (100 nm, Tsub: 350 ° C., Par: 3 mTorr) / hcp structure Co
₇₉Cr_{twenty one}(25nm) / (Pd [2nm] / Co₉₀Cr_Ten[3nm]) 10 / C (7nm) / moisture
Lubricant (5 nm), Hc = 2.2 kOe Sample (c) Substrate / NiFe (100 nm, Tsub: 350 ° C, Par: 3 mTorr) / hcp structure Co
₇₇V_{twenty three}(25nm) / (Pd [2nm] / Co₉₀Cr_Ten[3nm]) 10 / C (7nm) / moisture
Lubricant (5 nm), Hc = 1.9 kOe Sample (d) Substrate / NiFe (100 nm, Tsub: 350 ° C, Par: 3 mTorr) / hcp structure Co
₈₂Mo₁₈(25nm) / (Pd [2nm] / Co₉₀Cr_Ten[3nm]) 10 / C (7nm) / moisture
Lubricant (5 nm), Hc = 2.1 kOe Sample (e) Substrate / NiFe (100 nm, Tsub: 350 ° C, Par: 3 mTorr) / hcp structure Co
₈₄Re₁₆(25nm) / (Pd [2nm] / Co₉₀Cr_Ten[3nm]) 10 / C (7nm) / moisture
Lubricant (5 nm), Hc = 1.7 kOe Sample (f) Substrate / NiFe (100 nm, Tsub: 350 ° C, Par: 3 mTorr) / hcp structure Co
₇₀Cr₁₇Pt_TenTa_Three(25 nm) / TbFeCo (50 nm) / C (7 nm) / lubricant (5n
m), Hc = 2.6 kOe Sample (g) Substrate / hcp structure Co₇₃Cr_FifteenPt₈Ta_Four(30nm, Tsub: 200 ℃) / Tb_{twenty one}F
e₇₆Co_Three(25 nm, Tsub: room temperature) / C (5 nm) Sample (h) Substrate / Tb₁₉Fe₇₈Co_Three(25nm, Tsub: 100 ℃) / hcp structure Co₇₃Cr_Fifteen
Pt₈Ta_Four(30nm) / C (7nm) Sample (i) Substrate / hcp structure Co₇₃Cr_FifteenPt₈Ta_Four(30nm, Tsub: 200 ℃) / non-magnetic
Re (2nm) / Tb_{twenty one}Fe₇₆Co_Three(25 nm, Tsub: room temperature) / C (5 nm) Sample (j) Substrate / NiFe (100 nm, Tsub: 350 ° C) / hcp structure Co₇₀Cr₁₇Pt_TenTa
_Three(25 nm) / TbFeCo / C (7 nm) / lubricant (5 nm) Sample (k) Substrate / NiFe (100 nm, Tsub: 350 ° C., Par: 3 mTorr) / TbFeCo (25
nm) / hcp structure Co₇₀Cr₁₇Pt_{1 0}Ta_Three(25nm) / C (7nm) / lubricant (5n
m), Hc = 2.2 kOe Sample (l) Substrate / NiFe (100 nm, Tsub: 350 ° C., Par: 3 mTorr) / TbFeCo (25
nm) / hcp structure Co₇₅Cr_{twenty one}Ta_Four(25nm) / C (7nm) / lubricant (5nm), H
c = 2.5 kOe Sample (m) Substrate / NiFe (100 nm, Tsub: 350 ° C, Par: 3 mTorr) / TbFeCo (25
nm) / hcp structure Co₇₅Cr₂₀Pt _Five (25nm) / C (7nm) / lubricant (5n
m), Hc = 2.6 kOe Sample (n) Substrate / NiFe (100 nm, Tsub: 350 ° C., Par: 3 mTorr) / TbFeCo (25
nm) / hcp structure Co-CoO (25 nm) / C (7 nm) / lubricant (5 nm), Hc =
2.1kOe sample (o) Substrate / NiFe (100nm, Tsub: 350 ℃, Par: 3mTorr) / TbFeCo (25
nm) / hcp structure Co₇₁Cr₁₈Pt ₈Si_Three (25nm) / C (7nm) / lubricant (5n
m) Hc = 2.9 kOe Sample (p) Substrate / NiFe (100nm, Tsub: 350 ℃, Par: 3mTorr) / hcp structure Co
₇₀Cr₁₇Pt_TenTa_Three(25 nm) / TbFeCo (25 nm) / C (7 nm) / lubricant (5n
m), Hc = 2.6 kOe. Tsub is the substrate heating temperature,
Par is the sputtering gas pressure.

(3) Japanese Patent Laid-Open No. Hei 10-334440 In this publication, as shown in FIG.
/ Underlayer 107 / first vertical layer 108 (Co alloy) / second vertical layer 1
09 (multilayer structure or amorphous structure), t1 + t2
≦ 100 nm, t1> t2 (t1 and t2 are the thicknesses of the first vertical layer and the second vertical layer, respectively) are described, and the second vertical layer includes Co / Pt, Co /
Pd, Co alloy / Pt, Co alloy / Pd, Co alloy / P
It is described that a multilayer perpendicular magnetic layer made of a t or Pd alloy or the like or an amorphous perpendicular magnetic layer containing a rare earth element such as TbFeCo can be used.

Specifically, (a) substrate / Ti ₉₀ Cr ₁₀ (30 nm) / Co ₇₃ Cr ₁₉ Pt ₈ (30 nm) / (Co [1.5n
m] / Pt [1.5 nm]) 6 nm / C (10 nm), Ku (Co / Pt) = 2 × 10 ⁷ erg / cc,
Hc = 3.2kOe (b) substrate / Ti ₉₀ Cr ₁₀ (30nm) / Co ₇₃ Cr ₁₉ Pt ₈ (30nm) / (Co [1.5n
m] / Pd [1.5nm]) 6nm / C (10nm), Ku (Co / Pd) = 1 × 10 ⁷ erg / cc,
Hc = 2.7kOe (c) Substrate / Ti ₉₀ Cr ₁₀ (30nm) / Co ₇₃ Cr ₁₉ Pt ₈ (30nm) / (Co ₈₄ Cr ₁₆
[1.5nm] / Pd [1.5nm]) 6nm / C (10nm), Ku (CoCr / Pd) = 1.2 × 10
⁷ erg / cc, Hc = 2.8kOe (d) substrate / Ti ₉₀ Cr ₁₀ (30nm) / Co ₇₃ Cr ₁₉ Pt ₈ (30nm) / (Co [1.5n
m] / Pt ₈₀ Pd ₂₀ [1.5 nm]) 6 nm / C (10 nm), Ku (Co / PtPd) = 8 × 10 ⁶
erg / cc, Hc = 2.6 kOe (e) substrate / Ti ₉₀ Cr ₁₀ (30 nm) / Co ₇₃ Cr ₁₉ Pt ₈ (30 nm) / TbFeCo (6n
m) / C (10 nm), Ku (TbFeCo) = 6 × 10 ⁶ erg / cc, and Hc = 2.9 kOe. Here, Ku represents perpendicular magnetic anisotropy energy.

(4) Japanese Patent Application Laid-Open No. Hei 10-334443 This publication discloses a substrate 101 as shown in FIG.
/ Underlayer 107 / perpendicular magnetic layer 110 / in-plane magnetic (or soft magnetic) layer 111, the sum of the thicknesses of the perpendicular magnetic layer and the in-plane magnetic layer is greater than 100 nm, and the perpendicular magnetic layer is amorphous containing a rare earth element. A perpendicular magnetic recording medium comprising a film and being thicker than an in-plane magnetic layer is described.

(5) Japanese Patent Application Laid-Open No. H11-102510 This publication describes a perpendicular magnetic recording medium comprising two or more perpendicular magnetic layers. Mo, V, Ta, Pt, Si, B, Ir, W, Hf, Nb, R
Films containing one or more elements of u, Ni or rare earths are described. In this configuration, the perpendicular magnetic anisotropy of the magnetic layer far from the substrate surface is made larger than the perpendicular magnetic anisotropy of the magnetic layer near the substrate surface, and the magnetic layer near the substrate surface has a higher magnetic anisotropy. The purpose is to improve isolation.

[0011]

There have been many perpendicular magnetic recording media which have been intensively studied so far, mainly of CoCr type as described in the above publications (1) to (5). In a perpendicular magnetic recording medium using a CoCr-based crystal material, it was necessary to heat the substrate when preparing the magnetic layer. Therefore, when a CoCr-based magnetic layer is formed on a rare earth transition metal amorphous alloy film, there is a problem that the rare earth transition metal amorphous alloy film is crystallized. Further, the CoCr-based perpendicular magnetic recording medium cannot be formed on a plastic substrate because the substrate needs to be heated when the magnetic layer is formed.

The above publication also discloses that a rare earth transition metal amorphous alloy film can be used as a medium, but does not specifically describe what kind of structure can be used for recording. Was. Furthermore, advanced materials series "Modern Magnetic Materials" Shokabo published November 10, 1998
ISBN4-78536719-9, pp. 47-93 and JP-A-2-107718 describe that information is recorded on a magnetic layer exhibiting perpendicular magnetic anisotropy, which has been studied as a magneto-optical recording material such as MnBi. Have been. However, in the former, Figure 3.5 on page 58
As shown in the above, the recording edge is greatly disturbed, and it is impossible to perform ultra-high-density recording, which has been actively studied in recent years. This is the same in the latter case.
In other words, MnBi and rare earth transition metal amorphous alloy films
The theory that it was not suitable for magnetic recording was common.

[0013]

As described above, a medium which can be reproduced by magnetic flux using an amorphous alloy thin film containing a rare earth transition metal (hereinafter also referred to as RE-TM) as a main component is simply described. However, it is not clear at all how to realize it. In particular, there was no description about the medium configuration such that the areal recording density exceeded ²⁰ Gbit ² . Therefore, the inventors of the present invention
As a result of intensive studies on the specific configuration of an information recording medium using an amorphous alloy thin film containing a rare earth transition metal as a main component, it was found that a practical information recording medium could be obtained with the following configuration, and the present invention was accomplished. Was.

Thus, according to the present invention, at least a laminated film of a first magnetic layer and a second magnetic layer composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy, wherein Hc2> Hc1 (Hc1 is the coercive force of the first magnetic layer,
Hc2 is the coercive force of the second magnetic layer) or the relationship of Tc2> Tc1 (Tc1
Is the Curie temperature of the first magnetic layer, and Tc2 is the Curie temperature of the second magnetic layer) or both. When the residual magnetization of the laminated film at room temperature and zero magnetic field is larger than 50 emu / cc and no magnetic field is applied, Further, there is provided an information recording medium characterized in that an interface domain wall is not substantially formed between the first magnetic layer and the second magnetic layer, and information is reproduced by detecting a magnetic flux of the laminated film. Further, according to the present invention, the first magnetic layer made of an amorphous alloy thin film mainly containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy, and the rare earth transition metal or transition metal exhibiting in-plane magnetic anisotropy are mainly used. An information recording medium is provided, which has at least a laminated film with a second magnetic layer made of an amorphous alloy thin film as a component, and reproduces information by detecting a magnetic flux of the laminated film.

According to the present invention, there is provided at least a laminated film composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy, and the value of the residual magnetization of the laminated film at room temperature and zero magnetic field. Is larger than 50 emu / cc, the coercive force at room temperature is smaller than 7 kOe, and information is reproduced by detecting the magnetic flux of the laminated film. Furthermore, according to the present invention, at least a three-layer laminated film composed of an amorphous alloy thin film containing a rare earth transition metal as a main component, wherein the laminated film has one layer exhibiting in-plane magnetic anisotropy, There is provided an information recording medium comprising two layers exhibiting anisotropy, wherein information is reproduced by detecting a magnetic flux of a laminated film.

Further, according to the present invention, there is provided an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component, wherein the alloy thin film has a composition partially different in a thickness direction thereof. In the zero magnetic field, there is substantially no interface domain wall in the film thickness direction.
Has a remanent magnetization greater than 50 emu / cc and is 2 ~
An information recording medium having a coercive force of 7 kOe and reproducing information by detecting a magnetic flux is provided. Furthermore, according to the present invention, when recording information on the information recording medium, the time for applying a magnetic field when recording a relatively short mark between long marks is such that a relatively short mark is continuously formed. The information recording method is characterized in that the recording time is shorter than the time for applying a magnetic field.

Further, according to the present invention, when reproducing the information recorded on the information recording medium, the information is recorded at substantially the center voltage level of the signal amplitude which is changed and detected corresponding to the recorded information. An information reproducing method is provided, in which recorded information is reproduced by detecting an edge of a marked mark. Further, according to the present invention, in order to reproduce the information recorded on the information recording medium by detecting a magnetic flux, a reproducing device having a magnetoresistive element as a means for detecting the magnetic flux is provided. Is provided.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a rare earth transition metal amorphous alloy film used for a magneto-optical recording medium is used as a recording film. Rare earth transition metal amorphous alloy thin film is
Even when the film is formed without heating the substrate, the film exhibits good perpendicular magnetic anisotropy or in-plane magnetic anisotropy, so that it can be easily developed into an exchange-coupled multilayer film. Various magnetic characteristics can be realized by changing the type and composition of the rare earth element. Further, since it is not necessary to heat the substrate, it is easy to form a film on a substrate having low heat resistance such as a plastic substrate. In the present invention, in particular, by laminating magnetic layers having different magnetic properties, it is possible to obtain a medium capable of recording minute marks required for ultra-high density recording and reproduction and obtaining a high reproduction output.

Hereinafter, the present invention will be described specifically. The first information recording medium of the present invention has at least a laminated film of a first magnetic layer and a second magnetic layer each composed of an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component,
(1) The relationship of Hc2> Hc1 (Hc1 is the coercive force of the first magnetic layer, Hc2
Is the coercive force of the second magnetic layer) or Tc2> Tc1 (Tc1 is the Curie temperature of the first magnetic layer, Tc2 is the Curie temperature of the second magnetic layer) or both, and (2) room temperature And the residual magnetization of the laminated film at zero magnetic field is greater than 50 emu / cc,
(3) When no magnetic field is applied, an interface domain wall is not substantially formed between the first magnetic layer and the second magnetic layer, and information is reproduced by detecting a magnetic flux of the laminated film.

The information recording medium of the present invention has the first characteristic described above.
As long as it has a laminated film of a magnetic layer and a second magnetic layer, it may have any other layers included in a normal information recording medium. Both magnetic layers are usually formed on a substrate such that one of them is a lower layer. The thicknesses of the first magnetic layer and the second magnetic layer are 4 to 30 nm and 4 to 3 nm, respectively.
It is preferably in the range of 0 nm.

Examples of rare earth transition metal amorphous alloys exhibiting perpendicular magnetic anisotropy include TbFe, TbFeCo, DyFe, DyFeCo,
GdFe, GdFeCo and the like can be mentioned. The coercive force and Curie temperature of the first magnetic layer and the second magnetic layer can be appropriately set according to the type of magnetic material used. Further, it is preferable that the first magnetic layer and the second magnetic layer have a relationship between both the coercive force and the Curie temperature. When the residual magnetization of the laminated film at room temperature and zero magnetic field is larger than 50 emu / cc, it is possible to obtain an information recording medium capable of recording and reproduction at room temperature. Here, the residual magnetization is preferably in the range of 50 to 350 emu / cc.

Next, “substantially no interface domain wall is formed between the first magnetic layer and the second magnetic layer when a magnetic field is not applied” substantially means “recording of the information recording medium of the present invention”. It means that it is not formed to the extent that it does not interfere with the characteristics of reproduction. The information recording medium of the present invention can reproduce information by detecting a magnetic flux, which is usually performed in a magnetic recording medium.

Further, the laminated film preferably has a coercive force of less than 7 kOe at room temperature. When the coercive force is larger than 7 kOe, the recording becomes non-saturated, which is not preferable. A more preferable coercive force is 2 to 7 kOe.
Furthermore, the residual magnetic flux density × film thickness product (tBr) is 50 Gauss.
It is preferably larger than μm. A more preferred tBr is 50 to 150 Gauss μm. The reason why the product of the residual magnetic flux density × the film thickness (tBr) is preferably larger than 50 Gauss μm will be described below.

First, the substrate / first amorphous film (low noise and high resolution) / second amorphous film (high output characteristics) having the structure of the combination of claims 1 and 7 of the above publication (2) were additionally tested. In addition, since there is no example corresponding to the above configuration in this publication, the following media were prototyped as corresponding to them.

First amorphous film: Composition: Gd ₂₀ Fe ₆₀ Co ₂₀ film thickness: 30 nm Film Ar gas pressure: 0.7 Pa Second amorphous film composition: Tb ₂₁ Fe ₆₀ Co ₁₉ film thickness: 8 nm Film Ar gas pressure: 0.8Pa

Recording and reproduction were performed on this magnetic recording medium using a merge type head (thin film inductive recording element + GMR reproducing element) used for longitudinal recording. Recording width is
A head having a thickness of 0.6 μm and a reproduction width of 0.5 μm was used. The coercive force Hc of the two magnetic layers is 5 kOe, and the magnetic field at which the magnetization is saturated is about
It was 7 kOe. Although the head used this time could apply a magnetic field of about 7 kOe, it was impossible to record marks shorter than 200 kFCI.

Observation of the recorded bit with a magnetic force microscope (MFM) confirmed that a mark shorter than 200 kFCI formed a striped magnetic domain and that no bit could be formed. Therefore, we consider that this result may be due to the large coercive force of the medium, and changed the composition of the second amorphous film.
Tb ₁₈ Fe ₆₀ Co ₂₂ was used. As a result, the coercive force Hc of this two-layer magnetic layer was 4 kOe, and the magnetic field at which the magnetization was saturated was 5 kOe. As described above, it was impossible to record a mark shorter than 200 kFCI as in the previous experiment, even though the recording magnetic field was sufficiently applied by reducing the Hc. Therefore, the present inventors have further increased the thickness of the second amorphous film as in the following structure.

First amorphous film: Composition: Gd ₂₀ Fe ₆₀ Co ₂₀ film thickness: 34 nm Film Ar gas pressure: 1.1 Pa Second amorphous film composition: Tb ₁₈ Fe ₆₀ Co ₂₂ Film thickness: 15 nm Film Ar gas pressure: 1.0Pa

Recording and reproduction were performed on this medium using the same head as in the above example. The coercive force of this multilayer magnetic layer is about
The magnetization was 6 kOe, and the magnetization was sufficiently saturated at 6.7 kOe. It was possible to record a mark of 300 kFCI on this medium. At this time, the value of the residual magnetic flux density × the film thickness product (tBr) is:
It was 60 Gauss μm. From this, it was confirmed that it is preferable to appropriately set tBr in order to perform recording directly on the RE-TM film.

Here, the first and / or second magnetic layers may be composed of a laminate of a plurality of magnetic layers. Further, a non-magnetic intermediate layer may be provided between the first magnetic layer and the second magnetic layer. The nonmagnetic intermediate layer may be made of any material as long as it breaks exchange coupling between the first magnetic layer and the second magnetic layer. For example, the nonmagnetic intermediate layer may be made of C, Cr, SiN, SiO ₂ or the like. Examples include a layer made of a non-magnetic material.

Further, an underlayer may be formed between the substrate and the laminate. Examples of the underlayer include NiP and NiAl. The thickness is preferably about 5 to 30 nm. NiP
Although NiAl and NiAl are relatively dense films, they have a grain structure or a fine particle structure with a thickness of about 20 nm, and the surface thereof has irregularities. Such unevenness contributes to recording of a mark of a further minute size on the magnetic layer mainly composed of a rare earth transition metal which plays a role of recording and reproducing information.

An information recording medium having an underlayer was prototyped according to the official gazette (5). Specific film structures and film forming conditions are as follows. Underlayer: Composition: Ti ₉₀ Cr ₁₀ / Co ₆₅ Cr ₃₅ Film thickness: 30 nm / 15 nm Film Ar gas pressure: 0.3 Pa First amorphous film: Composition: Gd ₂₀ Fe ₆₀ Co ₂₀ Film thickness: 34 nm Film Ar gas pressure : 0.7Pa Second amorphous film Composition: Tb ₁₈ Fe ₆₀ Co ₂₂ Film thickness: 15nm Film Ar gas pressure: 0.8Pa

The magnetic recording medium is used for longitudinal recording.
Merged head (Thin film inductive recording element + G
Recording and reproduction were performed using an MR reproducing element). Recording width is 0.6
A head having a reproduction width of 0.5 μm was used. Of this magnetic layer
The coercive force Hc is 5.5 kOe, and the magnetic field at which the magnetization is saturated is about 6 kOe
e. The head used this time can apply a magnetic field of about 7 kOe.
Shorter than 230kFCI
It was impossible to record This is a crystal
The underlayer (Ti₉₀Cr _Ten/ Co₆₅C
r₃₅) Is the same for amorphous RE-TM films.
Means not working.

Therefore, the underlayer was changed. The film configuration is as follows. Underlayer: Composition: NiP Film thickness: 15 nm Film Ar gas pressure: 1.3 Pa First amorphous film: Composition: Gd ₂₀ Fe ₆₀ Co ₂₀ Film thickness: 34 nm Film Ar gas pressure: 0.7 Pa Second amorphous film Composition: Tb ₁₈ Fe ₆₀ Co ₂₂ Film thickness: 15 nm Film Ar gas pressure: 0.8 Pa

When information was recorded on the laminated film in which the underlayer was made of NiP, it was possible to record a mark of 300 kFCI. It was found by observing the underlayer with an atomic force microscope (AFM) that the underlying NiP had moderate irregularities. Here, the moderate unevenness is
Preferably, Ra is in the range of 0.1 to 1.5 nm. In this specification, Ra is a value obtained based on JIS surface roughness (B0601). Specifically, a portion of the measurement length L is extracted from the roughness curve in the direction of the center line, the center line of the extracted portion is the X axis, the longitudinal magnification direction is the Y axis, and the roughness curve is y = f ( x)
The value obtained by the following equation is represented by nm.

[0036]

(Equation 1)

Further, it is possible to form a column having a predetermined width in the thickness direction of the laminated film by the above-mentioned unevenness. With this column, it is possible to further form minute recording marks. Note that the predetermined width is preferably 0.2 μm or less.

Further, the underlayer contains, in addition to the layer for imparting irregularities, an oxidation protective layer containing oxide or nitride as a main component in order to prevent the laminated film from being oxidized. Is preferred. Furthermore, it is preferable that an oxide protective layer containing an oxide or a nitride as a main component is included on the stacked film in order to prevent the stacked film from being oxidized. The oxidation protection layer preferably has a thickness of 5 to 20 nm.

Next, the second information recording medium of the present invention comprises a first magnetic layer comprising an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component, and an in-plane magnetic anisotropy. It has at least a laminated film with a second magnetic layer composed of a rare earth transition metal or an amorphous alloy thin film containing a transition metal as a main component, and information is reproduced by detecting a magnetic flux of the laminated film.

First, as the first magnetic layer made of an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component, the same one as the first information recording medium can be used. However, the coercive force Hc of the first magnetic layer is preferably in the range of 2 to 7 kOe at room temperature. Furthermore,
Preferably, the tBr of the first magnetic layer is greater than 50 Gauss μm, more preferably in the range of 50 to 150 Gauss μm. Further, a laminated film may be formed on the substrate as in the case of the first information recording medium.

The second magnetic layer composed of an amorphous alloy thin film mainly containing a rare earth transition metal exhibiting in-plane magnetic anisotropy includes, for example, GdFeCo, GdFe, NdFe, NdFeCo and the like. The second magnetic layer made of an amorphous alloy thin film mainly containing a transition metal exhibiting in-plane magnetic anisotropy is made of, for example, FeTa.
C, CoZrNb and the like. Either the first magnetic layer or the second magnetic layer may be located on the substrate side. Also,
Each of the first magnetic layer and the second magnetic layer has a thickness of 4 to 50 n.
m and preferably in the range of 5 to 100 nm. Further, the second information recording medium may have any structure of the non-magnetic intermediate layer, the underlayer, and the oxidation protection layer in the first information recording medium.

Next, the third information recording medium of the present invention has at least a three-layer laminated film composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy. Remanent magnetization of 50 at room temperature and zero magnetic field
The coercive force at room temperature is smaller than 7 kOe, larger than emu / cc, and information is reproduced by detecting the magnetic flux of the laminated film. First, an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component can be the same as the first information recording medium. Further, a laminated film may be formed on the substrate as in the case of the first information recording medium. In addition, since the value of the residual magnetization of the laminated film in a zero magnetic field at room temperature is greater than 50 emu / cc, an information recording medium that can record and reproduce at room temperature can be obtained. Here, the residual magnetization is preferably in the range of 50 to 350 emu / cc.

Further, a preferable tBr is 50 to 150 Gauss.
sμm. A more preferable coercive force is 2 to 7 kOe.
Note that the total thickness of the laminated film is preferably in the range of 25 to 50 nm. Further, the third information recording medium may have any structure of the nonmagnetic intermediate layer, the underlayer, and the oxidation protection layer in the first information recording medium. When the nonmagnetic intermediate layer is provided between the first magnetic layer and the second magnetic layer, overwriting can be performed more favorably by setting the thickness of the second magnetic layer to 50 to 150 nm.

Next, the fourth information recording medium of the present invention has at least a three-layer laminated film composed of an amorphous alloy thin film containing a rare earth transition metal as a main component, and the laminated film has in-plane magnetic anisotropy. The information is reproduced by detecting a magnetic flux of the laminated film, which is composed of one layer shown and two layers showing perpendicular magnetic anisotropy. First, an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component can be the same as the first information recording medium. As the amorphous alloy thin film containing a rare earth transition metal exhibiting in-plane magnetic anisotropy as a main component, the same one as the second information recording medium can be used. As in the case of the first information recording medium, a laminated film may be formed on the substrate.

The coercive force Hc of the amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy is preferably in the range of 2 to 7 kOe at room temperature. Further, the tBr of the thin film is preferably larger than 50 Gauss μm, more preferably in the range of 50 to 150 Gauss μm. The total thickness of the laminated film is 10 to 100 nm.
Is preferably within the range. Of these, the thickness of the amorphous alloy thin film mainly containing a rare earth transition metal exhibiting in-plane magnetic anisotropy is preferably in the range of 5 to 100 nm. Further, the fourth information recording medium may have any configuration of the nonmagnetic intermediate layer, the underlayer, and the oxidation protection layer in the first information recording medium.

Next, the fifth information recording medium of the present invention comprises an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component, and the alloy thin film is partially formed in its thickness direction. Have a different composition, have substantially no interfacial domain wall in the film thickness direction at zero magnetic field, have a remanent magnetization of more than 50 emu / cc at room temperature and zero magnetic field, and have a coercive force of 2 to 7 kOe at room temperature. The information is reproduced by detecting the magnetic flux. First, an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component can be the same as the first information recording medium. Further, similarly to the first information recording medium, an alloy thin film may be formed on the substrate.

When the composition ratio of the elements constituting the amorphous alloy thin film is made different from the partially different composition, other elements (for example, a rare earth element, a transition metal element, a relatively small Element) at a predetermined concentration. Specifically, rare earth elements include Tb, Dy, etc., and transition metal elements include Fb.
e, Co and the like, and relatively small elements of the metalloid series include C, B, Si and the like. The remanent magnetization is 5
It is preferably in the range of 0 to 350 emu / cc. Furthermore,
Preferred tBr is 50-150 Gauss μm. A more preferable coercive force is 2 to 7 kOe. The thickness of the amorphous alloy thin film is preferably in the range of 10 to 70 nm. Further, the fifth information recording medium may have any structure of the nonmagnetic intermediate layer, the underlayer, and the oxidation protection layer in the first information recording medium.

Next, in the present invention, the information recording medium
Under the condition that the time for applying a magnetic field when recording a relatively short mark between long marks is shorter than the time for applying a magnetic field when continuously recording relatively short marks,
It is preferable to record information. Thereby, the shift of the magnetization transition point caused by the difference in the recording pattern can be improved. Note that the latter time is preferably about 80% or less of the former time,
More preferably, it is 70%.

Next, in the present invention, the information recording medium
It is preferable that the recorded information is reproduced under the condition of detecting the edge of the recorded mark at substantially the center voltage level of the signal amplitude that is detected and changed corresponding to the recorded information. This can improve the SNR of relatively long marks. Next, in the present invention, an information recording / reproducing apparatus for reproducing information recorded on the information recording medium by detecting magnetic flux includes a reproducing device having a magnetoresistive element as a means for detecting magnetic flux. Is preferred.

Next, the present invention will be described in more detail with reference to the following embodiments. First, according to the first embodiment of the present invention, as shown in FIGS. 1A and 1B, a rare earth transition metal exhibiting perpendicular magnetic anisotropy formed on a substrate 1 is used as a main component. And a coercive force Hc1 of the first magnetic layer 2 and a second magnetic layer 3
Hc2 has a relationship of Hc2> Hc1, the value of the remanent magnetization in the zero magnetic field of the laminated film at room temperature is greater than 50 emu / cc, tBr is greater than 50 Gaussμm, and the coercive force of the laminated film at room temperature is greater than 7 kOe. The information is reproduced by detecting the magnetic flux of the laminated film without forming an interface domain wall between the first magnetic layer 2 and the second magnetic layer 3 when no magnetic field is applied. An information recording medium is provided.

Rare earth transition metal amorphous alloys exhibiting perpendicular magnetic anisotropy include TbFe, TbFeCo, DyFe, DyFeCo, and GdF.
e, GdFeCo and the like are well known, and in particular, TbFeCo and DyFeCo films are widely used in current magneto-optical recording media. Furthermore, high SNR media in which these magnetic layers are exchange-coupled multilayer films, optical modulation overwrite media, magnetic super-resolution media, domain wall motion detection media, and the like have been proposed. However, in each of these methods, information is recorded by a method called thermomagnetic recording, and information recorded by a magneto-optical effect (Kerr effect) is read. Therefore, recording / reproducing on / from these magnetic layers is hardly performed near normal temperature.

If magnetic recording is performed on the medium currently used for the magneto-optical disk and reproduction is attempted, the coercive force is too large to perform recording with the current magnetic recording head. Has a so-called compensating composition, the magnetization value at room temperature is small, and a sufficient signal cannot be obtained even with a reproducing head utilizing the recent giant magnetoresistance effect. According to the first embodiment, Tb ₂₁ Fe ₆₈ Co ₁₁ is used for the second magnetic layer and Tb ₁₅ Fe ₈₀ Co is used for the first magnetic layer of the amorphous alloy thin film mainly containing a rare earth transition metal on the substrate.
₅ etc. are used.

Specifically, the film thickness t2 = 14n of Tb ₂₁ Fe ₆₈ Co ₁₁
m, the coercive force Hc2 = 8kOe, Ms2 = 20emu / cc, thickness of Tb ₁₅ Fe ₈₀ Co ₅
When t1 = 25 nm, Hc1 = 2 kOe, Ms1 = 200 emu / cc, the coercive force Hc of the laminated film is 2.4 kOe, the squareness ratio S is 1, the remanent magnetization Mr is 135 emu / cc, and tBr is 66 Gaussμm. It is.
In this laminated film, the first magnetic layer and the second magnetic layer have a small thickness, so that there is no interface domain wall between the first magnetic layer and the second magnetic layer. By using such a laminated film, it is possible to prototype a medium having a large Hc and a large residual magnetization, so that a large signal is obtained and the recording bit is stabilized.

Next, according to the second embodiment of the present invention,
As shown in FIGS. 1A and 1B, a two-layer laminated film made of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy and formed on a substrate 1. The Curie temperature Tc1 of the first magnetic layer 2 and the Curie temperature Tc2 of the second magnetic layer 3 have a relationship of Tc2> Tc1, and the value of the remanent magnetization of the laminated film at room temperature in a zero magnetic field is larger than 50 emu / cc. Is larger than 50 Gauss μm, the coercive force of the laminated film at room temperature is smaller than 7 kOe, and when no magnetic field is applied, no interface domain wall is formed between the first magnetic layer 2 and the second magnetic layer 3. An information recording medium characterized by reproducing information by detecting a magnetic flux is provided.

As a second embodiment, (T
b ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ , and Tb ₂₁ Fe ₆₈ Co ₁₁ or the like is used for the second magnetic layer. Specifically, (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ film thickness t1 = 3
0 nm, coercive force Hc1 = 3 kOe, Ms1 = 170 emu / cc, Curie temperature Tc
1 = 140 ° C., the film thickness t2 = 12 nm of _{Tb 21 Fe 68 Co 11, Hc2} = 8kOe, Ms2 =
At 20 emu / cc and Tc2 = 250 ° C, the coercive force Hc of the laminated film is 3.2 kO
e and tBr is 67 Gauss μm. In this laminated film, the first magnetic layer and the second magnetic layer have a small thickness, so that there is no interface domain wall between the first magnetic layer and the second magnetic layer.

Next, according to the third embodiment of the present invention,
As shown in FIGS. 2A and 2B, an in-plane first magnetic layer 4 formed on a substrate 1 and formed of an amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component. A laminated film in which a second magnetic layer 5 composed of an amorphous alloy thin film mainly composed of a rare-earth transition metal exhibiting magnetic anisotropy is laminated, and the coercive force of the first magnetic layer 4 exhibiting perpendicular magnetic anisotropy
Hc is 2 to 7 kOe at room temperature, and t of the first magnetic layer 4 is
An information recording medium is provided in which Br is larger than 50 Gauss μm and information is reproduced by detecting a magnetic flux of the laminated film.

As a third embodiment, the first magnetic layer has Tb
₁₈Fe₇₇Co_FiveAnd Gd in the second magnetic layer.₁₄Fe_{7 Five}Co₁₁Etc. are used
You. Specifically, Tb₁₈Fe₇₇Co_FiveThickness t1 = 30 nm, coercive force Hc
1 = 4kOe, Ms1 = 180emu / cc, Curie temperature Tc1 = 200 ℃, Gd
₁₄Fe₇₅Co₁₁Thickness t2 = 10 nm, in-plane coercive force Hc2 = 8Oe, Ms
When 2 = 700 emu / cc and Tc2 = 240 ° C, the coercive force of the laminated film is Hc = 3
kOe and tBr is 77 Gauss μm. in this case,
Since the Ms of the second magnetic layer is large, the magnetization reversal of the second magnetic layer
In some cases, the first magnetic layer undergoes magnetization reversal due to this.

Next, according to the fourth embodiment of the present invention,
As shown in FIGS. 3A and 3B, the amorphous alloy thin film 4 mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy formed on the substrate 1 and the in-plane magnetic anisotropy are shown. A coercive force of the alloy thin film 4 having a perpendicular magnetic anisotropy of 2 to 7 kOe, which is a stacked film in which an amorphous alloy thin film 6 containing a transition metal as a main component is stacked, and by detecting a magnetic flux of the stacked film, An information recording medium characterized by reproducing information is provided.

As a fourth embodiment, a rare earth transition metal is
Tb for amorphous alloy thin film₁₈Fe₇₇Co_Five,
Fe is used for the amorphous alloy thin film mainly composed of transition metal.₈₀
Ta_TenC _TenAre used. Specifically, Tb₁₈Fe₇₇Co_FiveMembrane
Thickness t = 30nm, coercive force Hc = 4kOe, Ms = 180emu / cc, Curie temperature
Degree Tc = 200 ℃, Fe₈₀Ta_TenC_TenFilm thickness t = 8nm, coercivity in in-plane direction
When the force Hc = 2 Oe and Ms = 1000 emu / cc, the coercive force Hc of the laminated film is
2.8 kOe, and tBr is 168 Gauss μm. here
Indicates that the perpendicular magnetic layer and the in-plane magnetic layer are exchange-coupled,
The magnetization is perpendicular to the end face of the magnetic layer.

Next, according to the embodiment 4 ′ as a modification of the fourth embodiment, the amorphous alloy thin film mainly containing a rare-earth transition metal is composed mainly of Tb ₁₈ Fe ₇₇ Co ₅ and a transition metal. As the amorphous alloy thin film to be used, Fe ₈₀ Ta ₁₀ C ₁₀ or the like is used, and a non-magnetic intermediate layer is formed between the two thin films.
The thickness of the nonmagnetic intermediate layer may be about 1 nm. The nonmagnetic intermediate layer may be made of any material as long as it can cut off exchange coupling between the amorphous alloy thin film mainly composed of a rare earth transition metal and the amorphous alloy thin film mainly composed of a transition metal. For example, non-magnetic materials such as C, Cr, SiN, and SiO ₂ can be used.

A specific example of the fourth embodiment is as follows.
500 nm of Fe ₈₀ Ta ₁₀ C ₁₀ is formed on the substrate, followed by Si
N is formed to 2 nm. Further, Tb ₁₈ Fe ₇₇ Co ₅ is formed to a thickness of 34 nm. Here, Tb ₁₈ Fe ₇₇ Co ₅ has a coercive force Hc1 = 4 kOe and Ms1 = 18
0 emu / cc, Curie temperature Tc1 = 200 ° C, Fe ₈₀ Ta ₁₀ C ₁₀
Has an in-plane coercive force of 2 Oe and Ms = 1000 emu / cc. In this case, information recorded from the side of the amorphous alloy thin film mainly containing a rare earth transition metal is reproduced. The amorphous alloy thin film mainly composed of a transition metal functions as a recording auxiliary layer. This configuration is very effective when the recording head is a single pole head or a ring head with a very sharp pole tip.

According to the fourth embodiment, as a further modification of the fourth embodiment, the amorphous alloy thin film containing a rare earth transition metal as a main component and the amorphous alloy thin film containing a transition metal as a main component are suitably formed. A non-magnetic intermediate layer having various irregularities can be inserted. As a specific example of the fourth embodiment, the same magnetic layer as that of the specific example of the fourth embodiment is used, and the use of NiP for the non-magnetic intermediate layer is different. As an alternative to NiP, NiAl or the like may be used. NiP and
NiAl is a relatively dense film, but when it has a thickness of about 20 nm, it has a grain structure or a fine particle structure, and its surface has irregularities. Such irregularities enable recording of marks of even smaller size on the magnetic layer mainly composed of a rare earth transition metal that plays a role in recording and reproducing information.

According to the fifth embodiment of the present invention, FIG.
As shown in (a) and (b), a two-layer laminated film composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy and formed on a substrate 1, The coercive force Hc1 of the first magnetic layer 2 and the coercive force H of the second magnetic layer 7
c2 has a relationship of Hc2> Hc1, the value of the residual magnetization in the zero magnetic field of the laminated film at room temperature is larger than 50 emu / cc, and t2
Br is larger than 50 Gauss μm, the coercive force of the laminated film at room temperature is smaller than 7 kOe, and when no magnetic field is applied, no interface domain wall is formed between the first magnetic layer 2 and the second magnetic layer 7. An information recording medium characterized by reproducing information by detecting a magnetic flux of the second magnetic layer 7 having a large coercive force and comprising a multilayer film.

Even in a layer having a relatively large Hc, it may be preferable that the Curie temperature of the large layer is different. For example, if a large amount of Co is added to increase the Curie temperature, exchange coupling in the plane between transition metals becomes large, and a small mark may not be recorded. Also, if the Curie temperature of the magnetic layer is too low, the recorded bits disappear when the temperature in the magnetic disk drive rises. Therefore, according to the fifth embodiment, it is possible to provide an information recording medium having an appropriate Curie temperature by further forming a layer having a large coercive force into two layers and further satisfying a large coercive force. There is an advantage that a minute mark can be recorded on the medium.

According to the fifth embodiment, the second magnetic layer of the amorphous alloy thin film containing a rare earth transition metal as a main component is made of Tb.
Tb ₁₅ Fe ₈₀ Co ₅ or the like is used for the first magnetic layer of an amorphous alloy thin film composed of a two-layer film of ₂₁ Fe ₇₉ and Tb ₂₂ Fe ₆₀ Co ₁₈ and containing a rare earth transition metal as a main component. Specifically, Tb ₂₁ Fe ₇₉
When the film thickness is 6 nm, the coercive force is 7 kOe, Ms = 10 emu / cc, Tb ₂₂
When the film thickness of Fe ₆₀ Co ₁₈ is 7 nm, the coercive force is 11 kOe, Ms = 5 emu /
cc. When the film thickness of Tb ₁₅ Fe ₈₀ Co ₅ is t1 = 25 nm, Hc1 = 2 kOe and Ms1 = 200 emu / cc in the first magnetic layer. More specifically, the structure is as follows.

Substrate / First magnetic layer: Tb ₁₅ Fe ₈₀ Co ₅ (25 nm) Second magnetic layer: Tb ₂₁ Fe ₇₉ (6 nm) / Tb ₂₂ Fe ₆₀ Co ₁₈ (7 nm) Alternatively, the first magnetic layer and the second magnetic layer The same effect is exhibited in the next case where the order of the magnetic layers is reversed. Substrate / Second magnetic layer: Tb ₂₁ Fe ₇₉ (6 nm) / Tb ₂₂ Fe ₆₀ Co ₁₈ (7 nm) First magnetic layer: Tb ₁₅ Fe ₈₀ Co ₅ (25 nm) Similar effects can be obtained in the following configuration in which the order is changed.

(1) Substrate / First magnetic layer: Tb ₁₅ Fe ₈₀ Co ₅ (25 nm) Second magnetic layer: Tb ₂₂ Fe ₆₀ Co ₁₈ (7 nm) / Tb ₂₁ Fe ₇₉ (6 nm) (2) Substrate / 2 magnetic layer: Tb ₂₂ Fe ₆₀ Co ₁₈ (7 nm) / Tb ₂₁ Fe ₇₉ (6 nm) 1st magnetic layer: Tb ₁₅ Fe ₈₀ Co ₅ (25 nm)

Further, according to the fifth embodiment as a modified example of the fifth embodiment, as shown in FIGS. 4A and 4B, the perpendicular magnetic anisotropic layer formed on the substrate 1 is formed. A two-layer laminated film composed of an amorphous alloy thin film containing a rare-earth transition metal as a main component, wherein the Curie temperature Tc1 of the first magnetic layer 2 and the Curie temperature Tc2 of the second magnetic layer 7 are Tc2> Tc1
The value of the residual magnetization in the zero magnetic field of the laminated film at room temperature is larger than 50 emu / cc, and tBr is 50 Gauss μm.
When the coercive force of the laminated film at room temperature is smaller than 7 kOe, the first magnetic layer 2 and the second magnetic layer 2
An information recording medium characterized by reproducing information by detecting a magnetic flux of a laminated film without forming an interface domain wall between the magnetic layers, wherein the second magnetic layer has a high Curie temperature. An information recording medium comprising a multilayer film is provided.

In general, a magnetic layer having a low Curie temperature has relatively low exchange coupling in the in-plane direction, so that it is relatively easy to form minute marks. However, thermal stability may not be good in some cases. Therefore, in the second embodiment of the present invention, (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si _{4 is used} as the first magnetic layer, and Tb ₂₁ Fe ₆₈ Co is used as the second magnetic layer.
₁₁ etc. are used. Specifically, (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ :
t1 = 30nm, Hc1 = 3kOe, Ms1 = 170emu / cc, Tc1 = 140 ℃, Tb ₂₁ F
e ₆₈ Co ₁₁ : t2 = 12 nm, Hc2 = 8 kOe, Ms2 = 20 emu / cc, Tc2 = 250
In the case of ° C., Hc of the laminated film is 3.2 kOe and tBr is 67 Gauss.
sμm. By doing so, the Curie temperature of the second magnetic layer is high, so that recorded bits can be stably present. However, there are cases where the Curie temperature of the laminated film is increased to further improve the stability of the recording bit, or the coercive force or tBr of the laminated film is desired to be increased while keeping the thermal stability constant. In such a case, it is effective to form the second magnetic layer having a high Curie temperature into two layers.

The following configuration is a specific example of the fifth embodiment. Substrate / First magnetic layer (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ : t1 = 30 nm, Hc1 = 3 kOe, M
s1 = 170 emu / cc, Tc1 = 140 ° C. Second magnetic layer Tb ₂₁ Fe ₆₈ Co ₁₁ : t2 ′ = 6 nm, Hc2 ′ = 8 kOe, Ms2 ′ = 2
0emu / cc, Tc2 '= 250 ℃ Tb 22 Fe 60 Co 18: t2''= 6nm, Hc2''= 8kOe, Ms2''= 20emu / c
c, Tc2 ″ = 310 ° C. Here, the Hc and Ms of each layer of the second magnetic layer are uniform, but this is because the amounts of Tb and Co are slightly changed. Hc of the above laminated film
Is 3.2 kOe and tBr is 67 Gauss μm. Since the Curie temperature of this medium is higher than the Curie temperature of the second embodiment, the recording bit is excellent in heat resistance.

Next, according to the fifth embodiment as a modification of the fifth embodiment, as shown in FIGS. 5A and 5B, the vertical A first magnetic layer 2 composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting magnetic anisotropy and a second magnetic layer composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting in-plane magnetic anisotropy
The coercive force Hc of the first magnetic layer 2 having a perpendicular magnetic anisotropy is 2 to 7 kOe at room temperature.
Wherein the tBr of the first magnetic layer 2 is greater than 50 Gauss μm, and the information is reproduced by detecting the magnetic flux of the laminated film. An information recording medium is provided, wherein the amorphous alloy thin film containing anisotropic rare earth transition metal as a main component is a multilayer film.

As a third embodiment, the first magnetic layer has Tb
₁₈Fe₇₇Co_FiveAnd Gd in the second magnetic layer.₁₄Fe_{7 Five}Co₁₁Etc. are used
ing. Specifically, Tb₁₈Fe₇₇Co_Five: T1 = 30 nm, Hc1 = 4 kOe, Ms1 = 180 emu / cc, Tc
1 = 200 ℃, Gd₁₄Fe₇₅Co₁₁: T2 = 10 nm, in-plane coercive force Hc2 = 8 Oe, Ms2
= 700 emu / cc, Tc2 = 240 ° C.

Of these, by making the in-plane magnetic layer of the second magnetic layer a multilayer, it is possible to record a finer mark. Specifically, the formation of minute marks is facilitated by lowering the Curie temperature of a part of the second magnetic layer. Further, it is possible to improve the recording magnetic field sensitivity by increasing the value of the saturation magnetization of a part of the second magnetic layer.

The following configuration is a specific example of the fifth embodiment. Substrate / Second magnetic layer: Gd ₁₄ Fe ₇₅ Co ₁₁ (t2 ′ = 5 nm, Hc2 ′ = 2 Oe, Ms2 ′ = 70
0emu / cc, Tc2 '= 240 ℃): (Gd 12 Fe 77 Co 11) 97 Si 3 (t2''= 5nm, Hc2''= 3 Oe, Ms2''= 65
0 emu / cc, Tc2 ″ = 230 ° C.) First magnetic layer: Tb ₁₈ Fe ₇₇ Co ₅ : t1 = 30 nm, Hc1 = 4 kOe, Ms1 = 1
80 emu / cc, Tc1 = 200 ° C. By using the magnetic layer having such a configuration, a minute mark can be formed, and further, noise can be reduced.

As another specific example of the fifth embodiment, the following configuration can be mentioned. Substrate / Second magnetic layer: Gd ₁₄ Fe ₇₅ Co ₁₁ (t2 ′ = 5 nm, Hc2 ′ = 2 Oe, Ms2 ′ = 70
0emu / cc, Tc2 '= 240 ℃): Gd 12 Fe 70 Co 18 (t2''= 5nm, Hc2''= 2 Oe, Ms2''= 850emu / c
c, Tc2 ″ = 290 ° C.) First magnetic layer: Tb ₁₈ Fe ₇₇ Co ₅ : t1 = 30 nm, Hc1 = 4 kOe, Ms1 = 1
80 emu / cc, Tc1 = 200 ° C. By using the magnetic layer having such a configuration, the recording magnetic field sensitivity is improved, the overwrite characteristics are improved, and the noise can be reduced.

Next, according to the fifth embodiment as a modification of the fifth embodiment, according to FIGS. 6 (a) and 6 (b), the perpendicular magnetic layer formed on the substrate 1 is formed. A laminated film in which an amorphous alloy thin film 9 mainly composed of a rare earth transition metal exhibiting anisotropy and an amorphous alloy thin film 5 mainly composed of a transition metal exhibiting in-plane magnetic anisotropy are laminated. An information recording medium characterized in that the coercive force of the alloy thin film 9 exhibiting the property is 2 to 7 kOe and the information is reproduced by detecting the magnetic flux of the laminated film, and the rare earth element exhibiting the perpendicular magnetic anisotropy. An information recording medium is provided, wherein the amorphous alloy thin film 9 containing a transition metal as a main component is a multilayer film.

As a fourth embodiment, a film of Tb ₁₈ Fe ₇₇ Co _{5 having} a thickness t = 30 nm, a coercive force Hc = 4 kOe, Ms = 180 emu / cc, a Curie temperature Tc = 200 ° C., and a Fe ₈₀ Ta ₁₀ C ₁₀ film When the thickness is 8 nm, the coercive force in the in-plane direction Hc = 2 Oe, and Ms = 1000 emu / cc, the coercive force Hc of the laminated film is
The medium is 2.8 kOe and tBr is 168 Gauss μm as a specific example.

According to the fifth embodiment, FIG.
And (b), the perpendicular magnetic layer is multilayered.
This means that the amorphous alloy thin film mainly composed of a rare-earth transition metal shown in the first embodiment is multilayered. In the drawing, reference numeral 9 also denotes a multilayered first magnetic layer.

According to the fifth embodiment, the following configuration is given as a specific example below. Substrate / Second magnetic layer: Tb ₂₃ Fe ₆₈ Co ₁₁ : t2 ′ = 14 nm, Hc2 ′ = 10 kOe, Ms
2 '= 10 emu / cc,: Tb ₁₅ Fe ₈₀ Co ₅ : t2 ″ = 28 nm, Hc2 ″ = 2 kOe, Ms2 ″ = 200 em
u / cc First magnetic layer: Fe ₈₀ Ta ₁₀ C ₁₀ : t = 8 nm, in-plane coercive force Hc
= 2 Oe, Ms = 1000 emu / cc In the above configuration, by using a layer having a larger coercive force for the exchange coupling film in the second magnetic layer, the coercive force of the laminated film becomes larger, and the recorded bit becomes more stable. Become.

Next, a sixth embodiment of the present invention will be described. Even in a layer having a relatively small Hc, it may be better for the layer having a small Hc to have different magnetic properties. For example, by making a small Hc film TM rich and RE rich,
There is an advantage that the coercive force of a film having a small thickness is not changed by a rise in temperature. According to the sixth embodiment, as shown in FIGS. 7A and 7B, the second magnetic layer 3 of an amorphous alloy thin film containing a rare-earth transition metal as a main component is formed of Tb according to the sixth embodiment. _A laminated film composed of Tb ₁₅ Fe ₈₀ Co ₅ and Tb ₃₀ Fe ₆₅ Co ₅ is used as the first magnetic layer 9 of an amorphous alloy thin film composed of ₂₂ Fe ₆₀ Co ₁₈ and containing a rare earth transition metal as a main component. Here Tb ₁₅ Fe ₈₀ Co ₅ is Hc decreases with increasing temperature is TM-rich film, Tb ₃₀ Fe ₆₅ Co
Reference numeral ₈ denotes a RE-rich film whose Hc increases as the temperature increases. Incidentally, Tb ₂₂ Fe ₆₀ Co ₁₈ is 9nm, Tb ₁₅ Fe ₈₀ Co ₅ 15
nm and Tb ₃₀ Fe ₆₅ Co ₅ can be used with a thickness of 15 nm or the like.

Specifically, the following structures are mentioned. Substrate / First magnetic layer: Tb ₁₅ Fe ₈₀ Co ₅ (15 nm) / Tb ₃₀ Fe ₆₅ Co ₅ (15 nm) / Second magnetic layer: Tb ₂₂ Fe ₆₀ Co ₁₈ (9 nm) By taking such a structure, The recorded bits can be present more stably with increasing temperature.

Next, according to the sixth embodiment as a modification of the sixth embodiment of the present invention, as shown in FIGS. 7A and 7B, A two-layer laminated film composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy, wherein the Curie temperature Tc1 of the first magnetic layer 9 and the Curie temperature Tc2 of the second magnetic layer 3
However, there is a relation of Tc2> Tc1, and the value of the residual magnetization in the zero magnetic field of the laminated film at room temperature is larger than 50 emu / cc, and tBr
Is larger than 50 Gauss μm, the coercive force of the laminated film at room temperature is smaller than 7 kOe, and when no magnetic field is applied, no interface domain wall is formed between the first magnetic layer 9 and the second magnetic layer 3. An information recording medium characterized by reproducing information by detecting a magnetic flux, wherein the information recording medium has a multilayered first magnetic layer 9 is provided.

According to the sixth embodiment, the second magnetic layer of the amorphous alloy thin film containing a rare earth transition metal as a main component is
Tb ₂₂ Fe ₅₈ Co ₂₀ and Tb ₁₅ Fe ₈₀ Co ₅ and D as the first magnetic layer of an amorphous alloy thin film containing a rare earth transition metal as a main component.
A laminated film of y ₁₅ Fe ₈₈ Co ₅ is used. With this configuration, the coercive force of the second magnetic layer is increased,
The coercive force of the magnetic layer can be made smaller, and the value of the residual magnetization can be made larger, so that the signal quality can be improved and the recording bit stability or the recording of minute marks can be made. Here, the coercive force Hc of the laminated film is 3.2 kOe, and tBr is 70 Gauss μm.

According to the sixth embodiment of the present invention, as a modification of the sixth embodiment, as shown in FIGS. 8A and 8B, the perpendicular magnetic A first magnetic layer 9 composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting anisotropy and a second magnetic layer composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting in-plane magnetic anisotropy.
The coercive force Hc of the first magnetic layer 9 showing perpendicular magnetic anisotropy is 2 to 7 kOe at room temperature.
An information recording medium characterized in that tBr of the first magnetic layer 9 is larger than 50 Gauss μm, and information is reproduced by detecting a magnetic flux of the laminated film. The first consisting of alloy thin film
(1) An information recording medium is provided in which the magnetic layer 9 is formed of a laminated film.

In the sixth embodiment of the present invention, the perpendicular magnetic
The first magnetic layer exhibiting anisotropy has a multilayer structure, for example, Dy₁₉
Fe₇₀Co₁₁And Tb_FifteenFe₈₀Co_FiveAnd the second magnetic layer is Gd₁₄Fe
₇₅Co_{1 1}Consists of With such a multilayer structure,
Small marks can be recorded, and the stability of recording bits is improved.
Up.

Next, according to a sixth embodiment of the present invention, as a modification of the sixth embodiment, as shown in FIGS. A laminated film obtained by laminating an amorphous alloy thin film 2 mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy and an amorphous alloy thin film 10 mainly composed of a transition metal exhibiting in-plane magnetic anisotropy, The coercive force of the alloy thin film 2 exhibiting perpendicular magnetic anisotropy is 2 to
7 kOe, and by detecting the magnetic flux of the laminated film,
An information recording medium for reproducing information, comprising an amorphous alloy thin film 10 mainly containing a transition metal.
Is an information recording medium characterized in that it is a multilayer film.

Specifically, the following structures are mentioned. Second magnetic layer: Dy ₁₈ Fe ₇₀ Co ₁₂ : t = 35 nm, Hc = 5 kOe, Ms = 180 emu
/ cc First magnetic layer: Fe ₈₀ Ta ₁₀ C ₁₀ : t = 8 nm, coercive force Hc in in-plane direction
= 2 Oe, Ms = 1000 emu / cc,: Fe ₆₀ Co ₂₀ Si ₁₀ : t = 4 nm, coercive force in the in-plane direction Hc = 4 Oe, Ms = 8
00emu / cc As described above, by using an amorphous alloy thin film mainly composed of a transition metal as a multilayer and adding Co to one layer, the value of Ms at around 60 ° C. can be increased to some extent. As a result, even if the temperature inside the drive increases, the overwrite characteristics are improved.

Next, according to the seventh embodiment of the present invention,
As shown in FIG. 10, a non-magnetic intermediate layer 12 is inserted between two magnetic layers (11 and 13) in the information recording medium. The magnetic layers 11 and 13 are composed of the RE-TM magnetic layer and the RE-TM magnetic layer.
TM magnetic layer, RE-TM magnetic layer and RE-TM multilayer magnetic layer, RE-TM multilayer magnetic layer and RE-TM magnetic layer, TM magnetic layer and RE-TM magnetic layer, RE-TM magnetic layer and TM magnetic layer, Examples of the combination include a TM multilayer magnetic layer and a RE-TM magnetic layer, a RE-TM magnetic layer and a TM multilayer magnetic layer, a TM magnetic layer and a RE-TM multilayer magnetic layer, and a combination of a RE-TM multilayer magnetic layer and a TM magnetic layer.

Specifically, the thickness t2 of Tb ₁₉ Fe ₆₈ Co ₁₁ is 14 nm, the coercive force Hc 2 is 3.7 kOe, and Ms 2 = 1.
85emu / cc, the film thickness of Dy ₁₈ Fe ₇₀ Co ₁₂ is t1 = 22 nm, Hc1 = 3 kOe,
2 nm of SiN can be inserted as a nonmagnetic intermediate layer between the stacked films of Ms1 = 200 emu / cc. The material of the non-magnetic intermediate layer is C,
Any material that cuts the exchange coupling of the magnetic layer, such as Cr, SiO2, or SiN, may be used.

By cutting the magnetic layer in the film thickness direction in this manner, the columnar structure width or the grain size of the amorphous film is reduced, and as a result, the jitter value can be reduced. In the conventional CoCr-based perpendicular magnetic recording medium, the material of the intermediate layer is limited to Ti or the like in order to direct the C axis of the crystal axis in a direction perpendicular to the film surface. However, when an amorphous magnetic layer is used, there is a feature that a perpendicular magnetic layer can be formed without special consideration of such a crystal orientation.

Next, a modification of the seventh embodiment of the present invention will be described.
According to the seventh '' embodiment, between the two-layer film and the two-layer film
A non-magnetic intermediate layer is inserted into the first layer. Specifically, the first magnetic layer
As (Tb₁₇Fe₈₁Co_Two)₉₆Si_Four, Tb as the second magnetic layer_{twenty one}Fe ₆₈
Co₁₁Etc., and then Y-SiO_TwoThe 2nm type
And then (Tb₁₉Fe₈₁Co_Two)₉₆Si_FourAs the second magnetic layer
Tb_{twenty one}Fe₆₈Co₁₁Are formed. Organize the configuration
Then, it becomes as follows.

Substrate / First magnetic layer: (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ : 7 nm: Tb ₂₁ Fe ₆₈ Co ₁₁ : 7 nm Intermediate layer: Y-SiO ₂ : 3 nm Second magnetic layer: (Tb ₁₉ Fe) ₈₁ Co ₂ ) ₉₆ Si ₄ : 7 nm: Tb ₂₁ Fe ₆₈ Co ₁₁ : 7 nm

In this case as well, the coercive force of the second magnetic layer is slightly increased, but the noise at the bit boundary is small, and the edge can be recorded clearly. This is because the column structure was emphasized by inserting the nonmagnetic intermediate layer. Next, according to the eighth embodiment of the present invention, as shown in FIGS. 11A and 11B, in the information recording medium, the magnetic layers (15 and 16) close to the substrate and the substrate 1 At least one underlayer 14 is formed between the first and second layers, and at least one underlayer 14 has a Ra of 0.1 to 1.5 nm.
Having.

As a specific example, Tb _{21 is used} as a second magnetic layer of an amorphous alloy thin film containing a rare earth transition metal as a main component.
Fe ₆₈ Co ₁₁ and Tb ₁₅ Fe ₈₀ Co ₅ are used as the first magnetic layer. The underlayer formed between the substrate and the magnetic layer is preferably made of a material in which relatively small grains are formed, and specifically, NiP, NiAl, Cr, an Ag-based alloy or an intermetallic compound. Can be

Specifically, the following configuration is provided. Substrate / NiP: 8 nm / (film-forming gas pressure: 1.5 Pa) C: 2 nm / (film-forming gas pressure: 0.5 Pa) Second magnetic layer (amorphous film): Composition: Tb ₂₁ Fe ₆₈ Co ₁₁ , coercive force Hc2 = 8 kOe, Ms2 = 20 emu / cc film thickness: 14 nm Film Ar gas pressure: 0.7 Pa First magnetic layer (amorphous film) Composition: Tb ₁₅ Fe ₈₀ Co ₅ , Hc1 = 2 kOe, Ms1 = 200 emu / cc Film thickness: 25 nm Film Ar gas pressure: 0.8 Pa C: 15 nm The coercive force of the laminated film is about 2.3 kOe.

A merge type head (thin film inductive recording element + G) used for in-plane recording on this information recording medium
Recording and reproduction were performed using an MR reproducing element). Recording width is 0.6
A head having a reproduction width of 0.5 μm was used. The information recording medium can record a smaller mark as compared to a case without NiP. Further, even at a linear density of 380 kFCI, bit transition was sufficiently observable, and recorded bits were also observed at 440 kFCI. This is because small bits can be recorded because the unevenness of the underlayer cuts the magnetic coupling in the in-plane direction of the rare earth transition metal amorphous alloy thin film to some extent.

Next, as a modified example of the eighth embodiment of the present invention, according to the eighth embodiment, the following configuration is provided. NiP: 9 nm (1.5 Pa) C: 3 nm (0.5 Pa) (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ : 30 nm (coercive force Hc1 = 3 kOe, Ms1 = 170 e)
mu / cc, a Curie temperature _{Tc1 = 140 ℃) Tb 21 Fe} 68 Co 11: = 12nm (Hc2 = 8kOe, Ms2 = 20emu / cc, Tc2 = 2
50 ℃) SiN: 10nm C: 3nm

The coercive force Hc of the laminated film is 3.0 kOe, and t
Br is 67 Gauss μm. In this laminated film, since the first magnetic layer and the second magnetic layer were thin, no interface magnetic wall was generated between the first magnetic layer and the second magnetic layer. Recording and reproduction were performed on this magnetic recording medium using a merge type head (thin film inductive recording element + GMR reproducing element) used for in-plane recording. A head having a recording width of 0.6 μm and a reproduction width of 0.5 μm was used. The information recording medium can record a smaller mark as compared to a case without NiP.
Further, even at a linear density of 380 kFCI, bit transition was sufficiently observable, and recorded bits were also observed at 440 kFCI. This is because small bits can be recorded because the irregularities of the underlying layer cut off the magnetic coupling in the in-plane direction of the rare earth transition metal amorphous alloy thin film to some extent.

Next, as a modified example of the eighth embodiment of the present invention, as shown in FIGS. 12A and 12B, according to the eighth embodiment, the following configuration is provided. . In the figure, 1
Reference numeral 7 denotes a magnetic layer (in-plane magnetization), and reference numeral 18 denotes a magnetic layer (perpendicular magnetization). NiP: 9 nm (1.5 Pa) C: 3 nm (0.5 Pa) Tb ₁₈ Fe ₇₇ Co ₅ : 30 nm (coercive force Hc1 = 4 kOe, Ms1 = 180 emu / c)
c, a Curie temperature _{Tc1 = 200 ℃) Gd 14 Fe} 75 Co 11: 10nm ( plane direction coercive force Hc2 = 8 Oe, Ms2 = 70
0emu / cc, Tc2 = 240 ℃)

The coercive force Hc of the above laminated film is 3 kOe and tB
r is 77 Gauss μm. Recording and reproduction were performed on this magnetic recording medium using a merge type head (thin film inductive recording element + GMR reproducing element) used for in-plane recording. A head having a recording width of 0.6 μm and a reproduction width of 0.5 μm was used. The information recording medium can record a smaller mark as compared to a case without NiP. Also, 380k
Bit transitions are sufficiently observable even at the linear density of FCI.
The recorded bits could be observed even at 40kFCI.

In these, the unevenness of the underlayer is a rare earth transition metal alloy.
A certain degree of in-plane magnetic coupling of the morphus alloy thin film
Cutting allows for recording of small bits
It is because it becomes. Next, according to a ninth embodiment of the present invention.
For example, in the configuration shown in FIGS.
A material layer or a nitride layer is formed. As nitrides and oxides
SiN and SiO _Two, Y-SiO_TwoAre typical.

Specifically, the following configuration can be mentioned. (1) Substrate / SiN: 5 nm NiP: 9 nm (1.5 Pa) C: 3 nm (0.5 Pa) (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ : 30 nm (coercive force Hc1 = 3 kOe, Ms1 = 170e)
mu / cc, a Curie temperature _{Tc1 = 140 ℃) Tb 21 Fe} 68 Co 11: = 12nm (Hc2 = 8kOe, Ms2 = 20emu / cc, Tc2 = 2
(50 ° C) SiN: 10 nm C: 3 nm (2) substrate / SiN: 5 nm NiP: 9 nm (1.5 Pa) SiN: 3 nm (0.5 Pa) (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ : 30 nm (coercive force Hc1 = 3 kOe) , Ms1 = 170e
mu / cc, a Curie temperature _{Tc1 = 140 ℃) Tb 21 Fe} 68 Co 11: = 12nm (Hc2 = 8kOe, Ms2 = 20emu / cc, Tc2 = 2
50 ℃) SiN: 10nm C: 3nm

In the case of (1), the SiN layer is composed of the substrate and NiP.
It plays a role of bonding the layers and a role of protecting the entire multilayer film including the underlayer from oxidation. In the case of (2), SiN
The layer particularly enhances the protective effect of the magnetic layer.

Next, according to the tenth embodiment of the present invention,
As shown in FIG. 13, an oxide layer or a nitride layer 21 is formed on a magnetic layer far from the substrate 1. Typical nitrides and oxides include SiN, SiO ₂ , and Y—SiO ₂ .
In the figure, 19 and 20 are the vertical RE-TM magnetic layer and the vertical R
E-TM magnetic layer, vertical RE-TM magnetic layer and in-plane RE-T
M magnetic layer, in-plane RE-TM magnetic layer and vertical RE-TM magnetic layer, vertical RE-TM magnetic layer and in-plane TM magnetic layer, in-plane TM
Any combination of the magnetic layer and the vertical RE-TM magnetic layer may be used.

Next, according to the eleventh embodiment of the present invention,
As shown in FIG. 14, a three-layer laminated film composed of an amorphous alloy thin film (22 to 24) mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy and formed on the substrate 1, The value of the residual magnetization in a zero magnetic field at room temperature is greater than 50 emu / cc, tBr is greater than 50 Gaussμm,
An information recording medium is provided which has a coercive force at room temperature of less than 7 kOe and reproduces information by detecting a magnetic flux of the laminated film.

The above configuration is effective when the residual magnetization or coercive force for sufficiently high-density recording cannot be obtained with a two-layer laminated film, or when further reduction in noise is desired. The three laminated films are almost the same in composition, but also include a slightly different film structure. For example, the first
The magnetic layer and the third magnetic layer may have relatively strong in-plane exchange coupling, and the second magnetic layer may have relatively weak in-plane exchange coupling. Conversely, the second magnetic layer can have relatively strong exchange coupling in the film plane direction, and the first and third magnetic layers can have relatively weak exchange coupling in the film plane direction. When the composition of such a three-layer film is almost the same and the film structure is different, the same target can be used at the time of film formation.
There is also an advantage that the manufacturing process can be simplified.

As a specific example, the following configuration can be mentioned. Substrate / Tb ₁₆ Fe ₇₅ Co ₉ (7 nm) / (Tb ₁₇ Fe ₈₀ Co ₃ ) ₉₈ Cr ₂ (20 nm) / Tb
₁₉ Fe ₆₀ Co ₂₁ (8 nm) The coercive force of this laminated film is about 3.2 kOe, and tBr is 98 Gaussμ.
m. Further, when the magnetization rotation mechanism was examined using a vibrating sample magnetometer, it was found that the magnetization reversal was performed in a so-called magnetization rotation mode instead of the domain wall displacement type. This is because a layer having a relatively low Curie temperature and a small exchange coupling in the in-plane direction is used for the second magnetic layer.

It is generally believed that an amorphous alloy thin film containing a rare-earth transition metal as a main component is of a domain wall displacement type, and is therefore considered to be unsuitable for a magnetic recording medium. This enables high-density recording. Further specific examples include the following configuration. Substrate / Tb ₁₆ Fe ₈₂ Co ₂ (7 nm) / Tb ₁₇ Fe ₈₀ Co ₃ (20 nm) / Tb ₁₆ Fe ₈₁ Co
₃ (8 nm) The coercive force of this laminated film is about 2.9 kOe, and tBr is 87 Gaussμ.
m.

Here, in this method for forming a laminated film,
If the laminated layers are a first magnetic layer, a second magnetic layer, and a third magnetic layer from the substrate side, the film structure can be changed by using the same target and changing only the film forming conditions. Specifically, the deposition rates of the first magnetic layer and the third magnetic layer are set to the second
This can be realized by increasing the film formation rate of the magnetic layer. Alternatively, it can be realized by setting the film forming gas pressure of the first magnetic layer and the third magnetic layer higher than the film forming gas pressure of the second magnetic layer. Further, in the case where a laminated film is trial-produced using the same target, an information recording medium capable of high-density recording with good controllability by slightly changing the film forming gas pressure or the film forming rate of the first magnetic layer and the third magnetic layer. Can be produced.

Next, according to the twelfth embodiment of the present invention,
As shown in FIGS. 15A to 15C, a three-layer laminated film composed of an amorphous alloy thin film containing a rare-earth transition metal as a main component and formed on a substrate 1, at least one of which is a layer 27. It shows in-plane magnetic anisotropy, and the other layers (2
5 and 26) show perpendicular magnetic anisotropy, and an information recording medium characterized by reproducing information by detecting a magnetic flux of a laminated film is provided.

A rare earth transition metal amorphous alloy thin film exhibiting in-plane magnetization has the advantage that the value of the saturation magnetization is relatively large and the reproduction signal can be increased. Furthermore,
When the magnetic layer is formed as an in-plane magnetic layer, there is an advantage that exchange coupling in the magnetic layer is relatively small and noise can be reduced. However, these are not suitable for actual recording and reproduction because of their small residual magnetization. Therefore, according to the present embodiment, a good hysteresis loop is obtained by exchange coupling the in-plane magnetic layer and the perpendicular magnetic layer,
Ultra-high density recording can be performed.

Specifically, the following configuration can be mentioned. Substrate / Dy ₂₀ Fe ₇₄ Co ₇ (8 nm) / Gd ₁₀ Tb ₅ Fe ₈₀ Co ₁₀ (26 nm) / Tb ₁₉ Fe
₈₀ Co ₁ (10 nm) The coercive force of this medium is 3.1 kOe and tBr is 110 Gauss μm. When the magnetization reversal type was examined in the same manner as in the eleventh embodiment, the magnetization rotation mode was the mainstream, and there was almost no domain wall motion mode.

Next, according to a thirteenth embodiment of the present invention,
As shown in FIGS. 16A to 16D, the eleventh embodiment
And an information recording medium in which a certain degree of unevenness is formed on the underlayer 14 of the information recording medium. Examples of the underlayer include those capable of forming irregularities appropriately, such as NiP, NiAl, Cr, Ag-based alloys or intermetallic compounds. Its film thickness is 30
If it is less than nm, the desired Ra can be obtained. According to the present invention, Ra is preferably about 0.1 to 1.5 nm.
When the thickness is flatter, the exchange coupling in the in-plane direction in the magnetic layer becomes stronger, and when it is larger than 1.5 nm, the uniaxial magnetic anisotropy of the magnetic layer is likely to be deteriorated, and the manufacturing conditions of the magnetic layer may be severe. .

Next, according to a fourteenth embodiment of the present invention,
As shown in FIG. 17, an amorphous alloy thin film 28 formed on a substrate 1 and containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component, the composition of which partially differs in the thickness direction, No interface domain wall occurs in the direction of the film thickness in the zero magnetic field, the value of the residual magnetization in the zero magnetic field at room temperature is greater than 50 emu / cc, the tBr is greater than 50 Gauss μm, the coercive force at room temperature is 2 to 7 kOe, The present invention provides an information recording medium characterized in that information is reproduced by detecting the information.

More specifically, it is effective to distribute a rare earth element, a transition metal element, or a relatively small metalloid element in the thickness direction of the magnetic layer. This is effective as a means for controlling the exchange coupling force in the in-plane direction of the entire magnetic layer. For example, when a magnetic layer is formed on a substrate by a sputtering method using a target having a composition of Tb ₁₉ Fe ₇₀ Co _11, a small amount of Si is co-sputtered at the initial growth stage at the same time, and more Si is deposited near the intermediate film thickness. Can be formed by a method in which the addition of Si is stopped near the final film thickness.

Thus, the composition of the magnetic layer is slightly changed.
It is difficult to make a quantitative change from ₁₉Fe₇₀Co₁₁(40nm)
Add 3% Si in the initial stage and 4% Si in the middle stage to final
If no Si is added at this stage, the coercive force is about 3.6 kOe.
TBr was 114 Gauss μm. Further, a thirteenth embodiment
In the same manner as above, NiP with Ra of about 1 nm is formed on
2 nm, the above magnetic layer, SiO_TwoLayer 10nm, layer C 5nm
Record 500kFCI signal on the formed medium and use magnetic force microscope
Observed the record mark with, very beautiful mark
Could be observed.

The core width of the magnetic head used this time was 0.6 μm
Since it is 42.3 TPI, it has been found that a surface recording density of about 22 Gbit / inch ² can be reliably realized. In addition,
Observation of the cross-sections of the media manufactured so far reveals that the column structure is formed in each of the magnetic layers. In particular, it is found that the column width of a medium on which a very fine mark can be recorded is 0.2 μm or less. In particular, NiP and NiA
The column diameter of an information recording medium formed on a base such as L is 3
0 nm or less.

A random pattern was actually recorded on these media. As a result, it has been found that when an isolated pattern is recorded at the center of a pattern having a relatively long period, the mark length becomes long. Therefore, when recording an isolated mark, by setting the recording magnetic field reversal time to the time for recording a continuous mark, that is, about 90% of the time corresponding to the actual pattern, the isolated mark can be recorded at an optimum interval. It turned out to be.

[0119]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the structures of these examples. Example 1 Here, the magnetic recording characteristics of a two-layer laminated film of an amorphous alloy mainly composed of a rare-earth transition metal exhibiting perpendicular magnetic anisotropy were examined. In particular, the case where the relationship between the coercive force of the first magnetic layer and the second magnetic layer is Hc2> Hc1 was examined. The following samples were prepared.

An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. The target size is 6 inches φ, and NiAl, NiP, Tb ₂₁ Fe ₆₈ C
o ₁₁ , Tb ₁₅ Fe ₈₀ Co ₅ , and 5 targets were set. In another sputtering chamber, a SiN target and Y-SiO ₂ (Y:
(50at%) was set so that sputtering could be performed with an RF power supply. The substrate has a structure that revolves around the target. The manufacturing conditions are described below.

Substrate: 2.5-inch size glass substrate Underlayer: Ni ₄ P ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 Pa,
Sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputtering gas pressure = 0.4 Pa, sputtering rate = 7 nm / sec Tb ₂₁ Fe ₆₈ Co ₁₁ : film thickness = 14 nm, Ar gas pressure = 1.4 Pa, sputtering Rate = 20 nm / sec Tb ₁₅ Fe ₈₀ Co ₅ : film thickness = 25 nm, Ar gas pressure = 2.4 Pa, sputter rate = 21 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm lubricating film: C, film thickness = 3 nm, Ar sputtering gas pressure = 0.4 Pa, sputtering rate = 7 nm / sec

The coercive force Hc of this medium was 2.4 kOe. t
Br was 66 Gauss μm. The squareness ratio was 1. Also,
The magnetization reversal was such that the first magnetic layer and the second magnetic layer symmetrically generated a zero magnetic field at the same time. Further, when the magnetization reversal type of this medium was examined, it was found to be close to the magnetization rotation mode. The coercive force of a single layer of Tb ₂₁ Fe ₆₈ Co ₁₁ (14 nm in thickness) was 8 kOe, and the coercive force of a single layer of Tb ₁₅ Fe ₈₀ Co ₅ (25 nm in thickness) was 2.4 kOe.

Further, a similar experiment was carried out in the above-described embodiment by changing the composition of the layer having a large coercive force. The film structure and film forming conditions are as follows. Substrate: 2.5 inch size glass substrate Underlayer: Ni ₄ P ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 Pa,
Sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Tb ₂₂ Fe ₆₀ Co ₁₈ : film thickness = 14 nm, Ar gas pressure = 1.4 Pa, sputter Rate = 20 nm / sec Tb ₁₅ Fe ₈₀ Co ₅ : film thickness = 25 nm, Ar gas pressure = 2.4 Pa, sputter rate = 21 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm lubricating film: C, film thickness = 3 nm, Ar sputtering gas pressure = 0.4 Pa, sputtering rate = 7 nm / sec

The coercive force Hc of this medium was 4.1 kOe. t
Br was 72 Gauss μm. The squareness ratio was 1. Also,
The magnetization reversal was such that the first magnetic layer and the second magnetic layer symmetrically generated a zero magnetic field at the same time. Further, when the magnetization reversal type of this medium was examined, it was found to be close to the magnetization rotation mode. Here, both magnetic layers showed a TM-rich composition.
As described above, the coercive force can be increased by providing the relationship of Hc2> Hc1, and the value of the residual magnetization can be increased by increasing the amount of Co added to the second magnetic layer. It was confirmed that a magnetic layer that can also have the same internal structure can be manufactured.

Comparative Example 1 As a comparative example, a medium was trial-produced without forming the second magnetic layer, with the thickness of the first magnetic layer being 39 nm. The manufacturing method is as follows. Substrate: 2.5 inch size glass substrate Underlayer: Ni ₄ P ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 Pa,
Sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Tb ₁₅ Fe ₈₀ Co ₅ : film thickness = 39 nm, Ar gas pressure = 2.4 Pa, sputter Rate = 21 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Lubricating film: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec

The coercive force Hc of this medium was 1.3 kOe. t
Br was 48 Gauss μm. The squareness ratio was 0.7. When the magnetization reversal type of this medium was examined, it was close to the magnetization rotation mode. However, since the coercive force is small and the squareness ratio is smaller than 1, it is not suitable as a magnetic recording medium, and it has been found that the medium having two layers as described above is more suitable for high-density recording. .

Example 2 Next, a medium in which tBr was changed by changing the film thickness of the Tb ₂₂ Fe ₆₀ Co ₁₈ / Tb ₁₅ Fe ₈₀ Co ₅ multilayer film of Example 1 was tested, and the change in SNR at 270 kFCI was examined. Was. Here, the recording / reproducing head is a merge type head (thin film inductive recording element + GMR reproducing element) used for in-plane recording on a magnetic recording medium.
Was used. A head having a recording width of 0.6 μm and a reproduction width of 0.5 μm was used. The reproduction core gap was 0.12 μm.

The results are described below. tBr: 250, 200, 150, 100, 72, 60, 55, 50, 45, 40 SNR: 17.2, 20.5, 21.7, 22.2, 22.0, 22.0, 21.0, 20.8, 18.9, 16.7 X It was found that a better signal quality could be obtained if the film thickness product was greater than 50 Gauss μm.

Example 3 Next, the overwrite characteristics were examined by changing the coercive force by changing the film thickness of Tb ₂₂ Fe ₆₀ Co ₁₈ and Tb ₁₅ Fe ₈₀ Co ₅ of Example 1. 270kFC over 40kFCI overwrite characteristics
The residual signal of the 40 kFCI signal was examined by recording the I signal. The results are described below. Hc (kOe): 1.7, 2.3, 3.5, 4.1, 5.2, 6.8, 7.2, 8.1 O / W (dB): -45, -45, -46, -44, -42, -40, -27, -11 From the above, it was confirmed that Hc should be 7 kOe or less in order to improve the overwrite characteristics.

Example 4 Next, the linear recording density of the medium used in Example 3 which was half the signal amplitude when recorded at a low linear recording density was examined. Here, the magnetic head used in Example 2 was used. Hc (kOe): 1.7, 2.3, 3.5, 4.1, 5.2, 6.8, 7.2, 8.1 D50 (kFCI): 240, 280, 290, 294, 298, 300, -27, -11 From the above, the coercive force is 2 kOe. It turns out that it is necessary. Therefore, it was found from Examples 3 and 4 that the coercive force as a medium was suitably 2 to 7 kOe.

Example 5 Here, the magnetic recording characteristics of an amorphous alloy laminated film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy were examined. In particular, the case where the relationship between the Curie temperatures of the first magnetic layer and the second magnetic layer is Tc2> Tc1 was examined. The following samples were prepared. An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. Target size is 6 inch φ
In the main chamber, NiAl, NiP, (Tb ₁₇ Fe ₈₁
Five targets of Co ₂ ) ₉₆ Si ₄ , Tb ₂₁ Fe ₆₈ Co ₁₁ , and C were set. Another sputter chamber contains SiN target and Y
-SiO ₂ (Y: 50at%) was setting, and to be sputtered with RF power. The substrate has a structure that revolves around the target.

Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ : film thickness = 30 nm, Ar Gas pressure = 2.7 Pa, sputter rate = ₂₁ nm / sec Tb ₂₁ Fe ₆₈ Co ₁₁ : film thickness = 12 nm, Ar gas pressure = 1.2 Pa, sputter rate = ₂₁ nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3Pa, sputter rate = 10nm Lubricating film: C, thickness = 3nm, Ar sputter gas pressure = 0.4Pa, sputter rate = 7nm / sec

The coercive force Hc of this medium was 3.2 kOe. t
Br was 67 Gauss μm. The squareness ratio was 1. Also,
The magnetization reversal was such that the first magnetic layer and the second magnetic layer symmetrically generated a zero magnetic field at the same time. Further, when the magnetization reversal type of this medium was examined, it was found to be close to the magnetization rotation mode. The Curie temperature of (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ was 140 ° C., and the Curie temperature of Tb ₂₁ Fe ₆₈ Co ₁₁ was 250 ° C.

In order to examine the magnetization stability of the medium, the change in residual magnetization within the operating temperature of the medium was examined. Temperature (° C.): 25, 40, 50, 65 Squareness ratio: 1.00, 1.00, 1.00, 1.00 As described above, the squareness ratio maintained 1 regardless of the temperature change. Furthermore, when the time change of the squareness ratio was examined at 65 ° C., no change was observed even after 10,000 seconds.

Comparative Example 2 As a comparative example, a magnetic layer having a thickness of 42 nm was formed from a (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ single layer film. Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ : film thickness = 42 nm, Ar Gas pressure = 2.7 Pa, sputter rate = 21 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm

The coercive force of this medium was about 1.8 kOe.
The squareness ratio was 0.85. Since the Curie temperature of this medium is low and the exchange coupling force in the in-plane direction of the film is small, it is possible to record a fine mark. However, the squareness ratio decreases as the temperature increases. The results are shown below. Temperature (° C): 25, 40, 50, 65 Squareness ratio: 0.85, 0.79, 0.72, 0.65

Further, the change of the residual magnetization with time was examined. Here, the temperature at the time of measurement was set to 65 ° C. After applying the magnetic field until saturation, return to zero magnetic field
Shows the value of Mr's change normalized by Ms. Time (sec): 1, 10, 100, 1000, 10000, 100000 Squareness ratio: 0.65, 0.60, 0.55, 0.5, 0.5, 0.50 Thus, (Tb ₁₇ Fe ₈₁ Co ₂ ) ₉₆ Si ₄ single layer film It was found that the stability of the recording bit was poor. From the above, it was found that by forming a layer having a high Curie temperature on a layer having a relatively low Curie temperature and capable of forming minute marks, a medium capable of forming minute marks and having excellent bit stability was possible. .

Example 6 Here, the recording and reproducing characteristics of a medium using Tb ₁₈ Fe ₇₇ Co ₅ as the first magnetic layer and Gd ₁₄ Fe ₇₅ Co ₁₁ as the second magnetic layer were examined. An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. The target size is 6 inch φ, and NiAl, NiP, Gd ₁₄ Fe ₇₅ Co ₁₁ , Tb ₁₈ Fe
_Five targets of ₇₇ Co ₅ and C were set. In another sputtering chamber, a SiN target and Y-SiO ₂ (Y: 50 at%) were set so that sputtering could be performed with an RF power supply. The substrate has a structure that revolves around the target.

Substrate: 2.5-inch size glass substrate Underlayer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Underlayer: Ni ₄ P ₁ , film thickness = 10 nm, Ar sputter gas pressure = 2.6 Pa,
Sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Gd ₁₄ Fe ₇₅ Co ₁₁ : film thickness = 10 nm, Ar gas pressure = 2.4 Pa, sputter Rate = 22 nm / sec Tb ₁₈ Fe ₇₇ Co ₅ : film thickness = 30 nm, Ar gas pressure = 1.9 Pa, sputter rate = 19 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm lubricating film: C, thickness = 3 nm, Ar sputtering gas pressure = 0.4 Pa, sputtering rate = 7 nm / sec. The coercive force of this medium was Hc = 3.2 kOe. tBr = 73Gauss
μm. The squareness ratio was 1. When the magnetization reversal type of this medium was examined, it was close to the magnetization rotation mode.

Next, the improvement of overwrite characteristics by forming an in-plane magnetic layer was examined. The above structure was kept constant except that the measurement method of the GdFeCo film was changed. The overwrite characteristics were evaluated by recording a signal of 270 kFCI on 40 kFCI, and examining the remaining unerased signal of 40 kFCI. GdFeCo film thickness (nm): 0, 5, 10, 15, 20, 25 Hc (kOe): 4.9, 4.1, 3.2, 2.8, 2.2, 1.8 O / W (dB): -41, -44, -45, -47, -45, -38

The overwrite characteristics were improved by adding an in-plane magnetic layer. On the other hand, if the thickness of the GdFeCo film is too large, the coercive force of the magnetic layer becomes too small.
The CI signal could not be recorded successfully, resulting in poor overwrite characteristics. Example 7 Here, Tb ₁₈ Fe ₇₇ Co ₅ was used as an amorphous alloy mainly containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy,
Fe as an amorphous alloy thin film mainly composed of transition metal
An information recording medium using ₈₀ Ta ₁₀ C ₁₀ was studied.

An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. The target size is 6 inches φ, and NiAl, NiP, Tb ₁₈ Fe ₇₇ Co ₅ ,
Five targets of Fe ₈₀ Ta ₁₀ C ₁₀ and C were set. Another sputtering chamber contains a SiN target and Y-SiO ₂ (Y: 50at
%) So that sputtering can be performed with an RF power supply. The substrate has a structure that revolves around the target.

Substrate: 2.5 inch size glass substrate Underlayer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Underlayer: Ni ₄ P ₁ , film thickness = 10 nm, Ar sputter gas pressure = 2.6 Pa,
Sputter rate = 25 nm / sec Protective layer: SiN, film thickness = 3 nm, Ar sputter gas pressure = 0.3 Pa, sputter rate = 10 nm / sec Fe ₈₀ Ta ₁₀ C ₁₀ : film thickness = 8 nm, Ar sputter gas pressure = 0.3 Pa, Sputter rate = 24 nm / sec Tb ₁₈ Fe ₇₇ Co ₅ : film thickness = 30 nm, Ar gas pressure = 2.3 Pa, sputter rate = 19 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10nm Lubricating film: C, thickness = 3nm, Ar sputter gas pressure = 0.4Pa, sputter rate = 7nm / sec

The coercive force Hc of the laminated film is 2.8 kOe, and tBr is 1
68 Gauss μm. The squareness ratio was 1. When the magnetization reversal type of this medium was examined, it was close to the magnetization rotation mode. Next, the recording / reproducing characteristics of this medium were examined. Here, a merge type head (thin film inductive recording element + GMR reproducing element) used for in-plane recording on a magnetic recording medium was used as the recording / reproducing head. The recording width is 0.
A head having a thickness of 6 μm and a reproduction width of 0.5 μm was used. The reproduction core gap was 0.12 μm. The SNR at 270 kFCI was 22 dB. Thus, it was found that a transition metal amorphous alloy thin film had sufficient characteristics without using an amorphous alloy thin film made of a rare earth transition metal as the in-plane magnetic layer.

Example 8 A magnetic layer made of Fe ₈₀ Ta ₁₀ C ₁₀ has a small coercive force in the in-plane direction and is excellent as a soft magnetic layer. Therefore, the following medium was trial-produced using this as a soft magnetic layer. Underlayer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Fe ₈₀ Ta ₁₀ C ₁₀ : film thickness = 500 nm, Ar sputter gas pressure = 0.3 Pa,
Sputter rate = 24 nm / sec Underlayer: Ni ₄ P ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 Pa,
Sputter rate = 25 nm / sec Protective layer: SiN, film thickness = 3 nm, Ar sputter gas pressure = 0.3 Pa, sputter rate = 10 nm / sec Tb ₁₈ Fe ₇₇ Co ₅ : film thickness = 30 nm, Ar gas pressure = 2.3 Pa, sputter Rate = 19 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Lubricating film: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec

The same recording width as that used in Example 7 was used.
A head having a thickness of 0.6 μm and a reproduction width of 0.5 μm was used. The reproduction core gap was 0.12 μm. The coercive force of this vertical layer was 4 kOe. Sufficient recording is possible, and the SNR at 270 kFCI is 23
dB. This is because the magnetic coupling between the head and Fe ₈₀ Ta ₁₀ C ₁₀ is increased, the effect of rewriting is reduced, and the noise is reduced by 1 dB because no extra magnetic field is applied to the data once recorded. by. Further, the SNR of 270 kFCI when the coercive force was changed while tBr of the perpendicular magnetic layer TbFeCo was kept constant was examined. It can be seen that a good SNR can be obtained by setting the coercive force to about 2 to 7 kOe. Although FeTaC is used here, a Co-based amorphous material such as CoZrNb may be used.

Example 9 The recording / reproducing characteristics when the Ra of the underlayer was changed were examined. Here, the surface roughness (Ra) is changed by changing the thickness of the underlayer.
The recording / reproducing characteristics in the case where the value was changed were examined. Example 1
A medium close to the configuration of the medium used in step 1 was used. Substrate: 2.5 inch size glass substrate Underlayer: NiP: film thickness = change, Ar sputtering gas pressure = 2.6 Pa,
Sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputtering gas pressure = 0.4 Pa, sputtering rate = 7 nm / sec Tb ₂₁ Fe ₆₈ Co ₁₁ : film thickness = 14 nm, Ar gas pressure = 1.4 Pa, sputtering Rate = 20 nm / sec Tb ₁₆ Fe ₇₉ Co ₅ : film thickness = 25 nm, Ar gas pressure = 2.4 Pa, sputter rate = 21 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm lubricating film: C, film thickness = 3 nm, Ar sputtering gas pressure = 0.4 Pa, sputtering rate = 7 nm / sec

Although the coercive force of this medium changes depending on the thickness of the underlayer, the tBr was about 66 Gauss μm. The squareness ratio was 1. Ra change and 270kFCI for underlayer thickness
5 shows the change in SNR in FIG. NiP film thickness (nm): 2, 5, 8, 10, 15, 20, 30, 40, 50 Ra (nm): 0.05, 0.15, 0.23, 0.55, 0.73, 0.90, 1.42, 1.70, 1.96 SNR (dB) : 18.9, 20.3, 21.4, 22.3, 22.8, 23.1, 22.1, 19.1, 17.9 From above, it was found that Ra was suitable to be about 0.1 to 1.5 nm. Similar experiments were also performed on NiAl, AgPd, and AgPdCu.
Was able to get the change.

Example 10 Tb ₁₆ Fe ₇₅ Co ₉ , (Tb ₁₇ Fe ₈₀ Co ₃ ) ₉₈ Cr ₂ , and Tb ₁₉ Fe ₆₀ Co ₂₁
An information recording medium composed of layers was prototyped. The fabrication method and film structure are as follows. An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. The target size is 6 inches φ, and NiAl, Tb ₁₆ Fe ₇₅ Co
₉ , five targets of (Tb ₁₇ Fe ₈₀ Co ₃ ) ₉₈ Cr ₂ , Tb ₁₉ Fe ₆₀ Co ₂₁ , and C were set. SiN in another sputter chamber
The target and Y-SiO ₂ (Y: 50at%) were set so that sputtering could be performed with an RF power supply. The substrate has a structure that revolves around the target.

Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Tb ₁₆ Fe ₇₅ Co ₉ : film thickness = 7 nm, Ar sputter pressure = 1.0 Pa , Sputter rate = 20 nm / sec (Tb ₁₇ Fe ₈₀ Co ₃ ) ₉₈ Cr ₂ : film thickness = 20 nm, Ar gas pressure = 3.2 Pa, sputter rate = ₂₁ nm / sec Tb ₁₉ Fe ₆₀ Co ₂₁ : film thickness = 8 nm, Ar Gas pressure = 1.2 Pa, sputter rate = 22 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Lubricating film: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa The sputter rate was 7 nm / sec. The coercive force was 3.2 kOe and tBr was 98 Gauss μm. Using a head having a recording width of 0.6 μm and a reproduction width of 0.5 μm and a reproduction core width of 0.12 μm, the SNR at 270 kFCI was 23.1 dB.

Example 11 Next, a three-layer film was trial-produced using a Tb ₁₇ Fe ₈₀ Co ₃ target while changing the film forming conditions. An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. The target size is 6 inches φ, and NiP, NiAl, Tb ₁₇ Fe
Four targets of ₈₀ Co ₃ and C were set. In another sputtering chamber, a SiN target and Y-SiO ₂ (Y: 50 at%) were set so that sputtering could be performed with an RF power supply. The substrate has a structure that revolves around the target.

Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Tb ₁₆ Fe ₈₂ Co ₂ : film thickness = 7 nm, Ar sputter pressure = 1.0 Pa , Sputter rate = 20 nm / sec Tb ₁₇ Fe ₈₀ Co ₃ : film thickness = 20 nm, Ar gas pressure = 3.3 Pa, sputter rate = 21 nm / sec Tb ₁₆ Fe ₈₁ Co ₃ : film thickness = 8 nm, Ar gas pressure = 1.2 Pa , Sputter rate = 22 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Lubricating film: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec

The slight difference in the composition despite the use of the same target is due to the slightly different gas pressure during sputtering. Recording width is 0.6μm, reproduction width is 0.5μm
When the reproducing core width was set to 0.12 μm using the head of
The SNR at 70 kFCI was 23.2 dB. Since this is the same value as in Example 10, it was found that sufficient recording / reproducing characteristics can be obtained even with the three layers formed using the same target.

Example 12 Next, using a Tb ₁₇ Fe ₈₀ Co ₃ target, Si was partially co-sputtered during the film formation. An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. The target size is
The main chamber was set with four targets of NiAl, B-doped Si, Tb ₁₉ Fe ₇₀ Co ₁₁ , and C. Another sputter chamber contains SiN target and Y-SiO
₂ (Y: 50at%) was set so that sputtering could be performed with an RF power supply. The substrate has a structure that revolves around the target.

Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Tb ₁₉ Fe ₇₀ Co ₁₁ : Ar sputter pressure = 1.0 Pa, input power 1 kW ( (Co-sputter) + Si: input power 0.1 kW Tb ₁₉ Fe ₇₀ Co ₁₁ : Ar gas pressure = 2.0 Pa, input power 1 kW (co-sputter) + Si: input power 0.2 kW Tb ₁₉ Fe ₇₀ Co ₁₁ : Ar gas pressure = 2.0 Pa, input power 1kW Protective layer: SiN, film thickness = 10nm, Ar gas pressure = 0.3Pa, sputter rate = 10nm Lubricating film: C, film thickness = 3nm, Ar sputter gas pressure = 0.4Pa, sputter rate = 7nm / sec

The content of Si was about 2% in the initial region and about 4% in the intermediate region. The coercivity is about 3.6 kOe and tBr is 11
4 Gauss μm. When a signal of 590 kFCI was recorded on this medium and recorded marks were observed with a magnetic force microscope, very clear marks could be observed. In this medium,
Even with 298kFCI, 23dB SNR could be obtained. Therefore, the track width of the head used this time is 42.3KTPI,
It was found that a recording density of 25 Gbit / inch ² was realized. Example 13

Next, using a Tb ₁₇ Fe ₈₀ Co ₃ target, a three-layer film was trial-produced under different film forming conditions. In Example 11, the magnetic characteristics of each layer were changed by changing the sputtering gas pressure, but here, the magnetic characteristics were changed by changing the input power and changing the sputtering rate. An ordinary DC magnetron sputtering apparatus was used for film formation of the medium. The target size is
6 inch φ, NiP, NiAl,
Four targets of Tb ₁₇ Fe ₈₀ Co ₃ and C were set. Another sputtering chamber contains a SiN target and Y-SiO ₂ (Y: 50at
%) So that sputtering can be performed with an RF power supply. The substrate has a structure that revolves around the target.

Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Tb ₁₆ Fe ₈₂ Co ₂ : film thickness = 7 nm, Ar sputter pressure = 1.0 Pa , Sputter rate = 20 nm / sec Tb ₁₇ Fe ₈₀ Co ₃ : film thickness = 20 nm, Ar gas pressure = 1.4 Pa, sputter rate = 8.9 nm / sec Tb ₁₆ Fe ₈₁ Co ₃ : film thickness = 8 nm, Ar gas pressure = 1.2 Pa, sputter rate = 22 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Lubricating film: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7nm / sec

The slight difference in the composition despite the use of the same target is due to the fact that the sputter rate accompanying the change in the input power is slightly different. Recording width is 0.6μ
m and a reproducing width of 0.5 μm were used. Reproduction core width is 0.1
It was 2 μm. The SNR at 270 kFCI was 23.1 dB. Since this is the same value as in Example 11, it was found that sufficient recording / reproducing characteristics can be obtained even with the three layers formed using the same target.

Example 14 The domain wall coercive force of the medium experimentally manufactured in Example 13 was measured. The magnetic domain state of the medium is as-depo (as deposited),
Assuming that a magnetic field where a change in magnetization appears when a magnetic field is applied from this state is a domain wall coercive force Ha, Ha of this medium was 2.5 kOe. On the other hand, the coercive force Hc was 2.9 kOe. Therefore, Ha / Hc = 0.
It became 86.

Then, the film thickness was set to 20 nm under the film forming conditions of Example 13.
The relationship between noise and Ha / Hc was investigated for media with different sputter rates. Here, the same head was used as the medium, and the medium noise when a 270 kFCI signal was recorded was measured. By setting Ha / Hc to 0.8 or more, the medium noise Nm settled at a constant value, and thus it was found that Ha / Hc is preferably larger than 0.8.

Embodiment 15 A random pattern including an isolated bit was recorded on the medium experimentally manufactured in Embodiment 13 instead of a continuous mark. At that time, FIG.
As shown in FIG. 8 (a), it has been found that a problem that the mark length of the isolated bit becomes longer occurs. Therefore, so-called recording compensation was performed by changing the magnetic field reversal time when recording an isolated bit. As a result, it was found that a mark of a specified length can be recorded by shortening the magnetic field reversal time corresponding to the actual bit length to about 80% (see FIG. 18B).

Example 16 The medium of Example 13 was recorded with a 1/7 RLL code by reversing the magnetic field with NRZI. Regeneration determined the slice level near zero volts. Here, the error rate was measured without passing the reproduced signal through the differentiator. The shortest mark length (= twice the window length) is 0.0635 μm (400 kFCI) and the bit length is 4
Assuming 7.7 nm (532 KBPI), the detrack margin for error rates of 10 ^-6 bits or less is ± 0.1 μm, and 22.5 Gbit / inc
It has been found that it is possible to realize the h ^2.

Example 17 Here, a medium in which a part of the laminated film was formed into a multilayer was examined. In the same manner as in the previous examples, the following required targets were set in a sputtering apparatus, and an information recording medium was prototyped.

Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec First magnetic layer: Tb ₁₅ Fe ₈₀ Co ₅ (25 nm), Ar sputter pressure = 1.0P
a, sputter rate = 20 nm / sec Second magnetic layer: Tb ₂₁ Fe ₇₉ (6 nm) /, Ar sputtering pressure = 3.0 Pa, sputtering rate = ₂₁ nm / sec: Tb ₂₂ Fe ₆₀ Co ₁₈ (7 nm), Ar sputtering pressure = 3.0 Pa, sputter rate = 210 nm / sec Protective layer: SiN, film thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Lubricating film: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec The coercive force of the second magnetic layer is about 8 kOe and the coercive force of the first magnetic layer is about 2 kOe.
kOe and tBr was 71 Gauss μm. When a signal of 270 kFCI was recorded on this medium with the head used so far, the SNR was 23.9 dB, and the medium noise was 19 μVrms.

[0166] SNR when the second magnetic layer of the medium as a comparative example 3 comparative example was recorded signals 270kFCI in the case of the Tb ₂₂ Fe ₆₀ Co ₁₈ is 22.4DB, medium noise was 21μVrms . From this,
By replacing a part of the second magnetic layer with a layer having a relatively low Curie temperature while having the same level of coercive force, it is possible to reduce noise and improve the SNR. Was.

Example 19 Here, an information recording medium in which a non-magnetic intermediate layer was inserted between an amorphous alloy film containing a rare earth transition metal as a main component was produced on a trial basis. Dy ₁₉ Fe ₆₁ Co ₂₀ , Dy ₂₁ Fe ₆₀ Co ₁₉
Was used. The medium used the same sputtering apparatus as before, and the target was changed to the above.

Substrate: 2.5 inch size glass substrate Underlayer: Ni ₃ Al ₁ , film thickness = 10 nm, Ar sputtering gas pressure = 2.6 P
a, sputter rate = 25 nm / sec Protective layer: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec Dy ₁₉ Fe ₆₁ Co ₂₀ : ( ₂₁ nm), Ar sputter pressure = 1.0 Pa, Sputter rate = 20 nm / sec SiN: (3 nm) Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Dy ₂₁ Fe ₆₀ Co ₁₉ : (15 nm) /, Ar sputter pressure = 3.0 Pa, sputter rate = ₂₁ nm / sec Protective layer: Y-SiO ₂ , thickness = 10 nm, Ar gas pressure = 0.3 Pa, sputter rate = 10 nm Lubricating film: C, film thickness = 3 nm, Ar sputter gas pressure = 0.4 Pa, sputter rate = 7 nm / sec

With the head used so far for this medium,
When a signal of 270 kFCI was recorded, the SNR was 22.9 dB, and the medium noise was 20 μVrms. Next, the SNR for the type of the nonmagnetic intermediate layer was examined. SNR is a value at 270 kFCI. Interlayer _{material: SiN, Y-SiO 2,} SiO 2, C, NiP, NiAl SNR (dB): 22.9, 22.8, 22.9, 22.7, 23.1, 23.2

The thickness of the non-magnetic intermediate layer was examined. The SNR was measured while changing the thickness of the non-magnetic intermediate layer of the above-described prototype medium to SiN. SNR is a value at 270 kFCI. SiN film thickness (nm): 0, 1, 2, 3, 7, 10, 16, 20 SNR (dB): 21.5, 22.0, 22.4, 22.9, 22.7, 22.7, 22.4, 21.9 Therefore, the film of the non-magnetic intermediate layer The thickness is between 1 nm and 20 nm
It can be seen that the NR is improved.

Comparative Example 4 As a comparative example, a medium having no intermediate layer of the above-mentioned information recording medium was experimentally manufactured, and SNR and medium noise when a signal of 270 kFCI was recorded were measured. SNR = 21.9 dB, medium noise = 21.5 μVrm
s. For this reason, the column structure of the magnetic layer was promoted by the insertion of the non-magnetic intermediate layer, and low noise was realized.

The information recording medium of the present invention may have the following configuration. (1) The laminated film has a coercive force of 2 to 7 kOe at room temperature. (2) The laminated film has a product of residual magnetic flux density × film thickness larger than 50 Gauss μm. (3) The first magnetic layer has a coercive force of 2 to 7 kOe at room temperature. (4) The first magnetic layer has a product of residual magnetic flux density × film thickness larger than 50 Gauss μm. (5) The first magnetic layer, the second magnetic layer, or both layers are formed of a laminate of a plurality of magnetic layers. (6) A non-magnetic intermediate layer is formed between the first magnetic layer and the second magnetic layer. (7) At least one underlayer is formed between the laminated film and the substrate, and the underlayer has a Ra surface of 0.1 to 1.5 nm. (8) At least one underlayer is formed between the laminated film and the substrate, and the underlayer includes at least an oxidation protection layer mainly containing an oxide or a nitride. (9) An oxidation protection layer mainly composed of oxide or nitride is formed on the laminated film. (10) A column having a width of 0.2 μm or less in the thickness direction is formed of an amorphous alloy thin film containing a rare earth transition metal as a main component. (11) The amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy contains at least Tb or Dy as a rare earth element. (12) The laminate has a domain wall coercive force greater than 80% of the coercive force.

[0173]

According to the present invention, there is provided a magnetically reproducible medium capable of ultrahigh-density recording, a method of manufacturing the same, and a method of compensating recording by using the multilayer amorphous magnetic recording medium of the present invention. The information recording medium of the present invention can be applied to a thermomagnetic recording method which makes it easy to record information by supplementarily applying heat, in addition to writing by a magnetic head near room temperature.
Further, by introducing such a technology, further ultra-high density recording becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a medium according to Embodiments 1 and 2 of the present invention.

FIG. 2 is a schematic sectional view of a medium according to a third embodiment of the present invention.

FIG. 3 is a schematic sectional view of a medium according to a fourth embodiment of the present invention.

FIG. 4 is a schematic sectional view of a medium according to Embodiments 5 and 5 ′ of the present invention.

FIG. 5 is a schematic sectional view of a medium according to a fifth embodiment of the present invention.

FIG. 6 is a schematic sectional view of a medium according to a fifth embodiment of the present invention.

FIG. 7 is a schematic sectional view of a medium according to Embodiments 6 and 6 ′ of the present invention.

FIG. 8 is a schematic sectional view of a medium according to a sixth embodiment of the present invention.

FIG. 9 is a schematic sectional view of a medium according to a sixth embodiment of the present invention.

FIG. 10 is a schematic sectional view of a medium according to a seventh embodiment of the present invention.

FIG. 11 is a schematic sectional view of a medium according to an eighth embodiment of the present invention.

FIG. 12 is a schematic sectional view of a medium according to an eighth embodiment of the present invention.

FIG. 13 is a schematic sectional view of a medium according to a tenth embodiment of the present invention.

FIG. 14 is a schematic sectional view of a medium according to Embodiment 11 of the present invention.

FIG. 15 is a schematic sectional view of a medium according to a twelfth embodiment of the present invention.

FIG. 16 is a schematic sectional view of a medium according to a thirteenth embodiment of the present invention.

FIG. 17 is a schematic sectional view of a medium according to a fourteenth embodiment of the present invention.

FIG. 18 is a diagram illustrating an example of recording compensation of a medium according to the present invention.

FIG. 19 is a schematic sectional view of a conventional medium.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2 1st magnetic layer (RE-TM, perpendicular magnetization) 3 2nd magnetic layer (RE-TM, perpendicular magnetization) 4 1st magnetic layer (RE-TM, in-plane magnetization) 5 2nd magnetic layer (RE-TM) TM, in-plane magnetization) 6 Second magnetic layer (TM, in-plane magnetization) 7 Second magnetic layer (RE-TM, multilayer, perpendicular magnetization) 8 Second magnetic layer (RE-TM, multilayer, in-plane magnetization) 9 First magnetic layer and amorphous alloy thin film (RE-T
M, multilayer, perpendicular magnetization) 10 Second magnetic layer (TM, multilayer, in-plane magnetization) 11, 13, 15, 16, 19, 20, 22, 23, 2
4, 26, 28 Magnetic layer 12 Non-magnetic intermediate layer 14, 107 Underlayer 17, 27 Magnetic layer (in-plane magnetization) 18, 25, 26 Magnetic layer (perpendicular magnetization) 21 Oxide layer or nitride layer 28 Alloy thin film 101 Substrates 102, 103, 110 Perpendicular magnetic layer 104 First perpendicular magnetic layer 105 Second perpendicular magnetic layer 106 Protective layer 108 First perpendicular layer 109 Second perpendicular layer 111 In-plane magnetic layer

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ikuya Tagawa 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu Limited (reference) 5D006 BB01 BB07 BB08 DA03 EA03 FA09 5D091 AA10 BB06 CC11 DD03 HH20

Claims (8)

[Claims] The present invention has at least a laminated film of a first magnetic layer and a second magnetic layer each composed of an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy, and a relationship of Hc2> Hc1 (where Hc1 is The coercive force of the first magnetic layer, Hc2 is the coercive force of the second magnetic layer), or the relationship of Tc2> Tc1 (Tc1 is the Curie temperature of the first magnetic layer, Tc2 is the Curie temperature of the second magnetic layer) or both When the residual magnetization of the laminated film at room temperature and zero magnetic field is greater than 50 emu / cc and no magnetic field is applied,
An information recording medium, wherein an interface domain wall is not substantially formed between a magnetic layer and a second magnetic layer, and information is reproduced by detecting a magnetic flux of a laminated film. 2. A first magnetic layer comprising an amorphous alloy thin film mainly composed of a rare earth transition metal exhibiting perpendicular magnetic anisotropy, and a rare earth transition metal exhibiting in-plane magnetic anisotropy or a transition metal mainly containing a transition metal. An information recording medium having at least a laminated film with a second magnetic layer made of an amorphous alloy thin film, and reproducing information by detecting a magnetic flux of the laminated film. 3. At least three laminated films composed of an amorphous alloy thin film mainly composed of a rare-earth transition metal exhibiting perpendicular magnetic anisotropy, and the laminated film has a residual magnetization of 50 emu / cm at room temperature and zero magnetic field. An information recording medium characterized by being larger than cc, having a coercive force at room temperature smaller than 7 kOe, and reproducing information by detecting a magnetic flux of the laminated film. 4. It has at least a three-layer laminated film composed of an amorphous alloy thin film containing a rare earth transition metal as a main component,
Information characterized in that the laminated film is composed of one layer exhibiting in-plane magnetic anisotropy and two layers exhibiting perpendicular magnetic anisotropy, and information is reproduced by detecting magnetic flux of the laminated film. recoding media. 5. An amorphous alloy thin film containing a rare earth transition metal exhibiting perpendicular magnetic anisotropy as a main component, wherein the alloy thin film has a composition partially different in a thickness direction thereof, and the film is formed at zero magnetic field. Has substantially no interfacial domain wall in the thickness direction, has a remanent magnetization of more than 50 emu / cc at room temperature and zero magnetic field, has a coercive force of 2 to 7 kOe at room temperature,
An information recording medium wherein information is reproduced by detecting a magnetic flux. 6. When recording information on the information recording medium according to any one of claims 1 to 5, the time for applying a magnetic field when recording relatively short marks between long marks is relatively short. An information recording method characterized in that it is shorter than the time for applying a magnetic field when continuously recording short marks continuously. 7. When reproducing information recorded on the information recording medium according to any one of claims 1 to 5, a substantially center voltage of a signal amplitude which is detected by being changed corresponding to the recorded information. An information reproducing method characterized in that recorded information is reproduced by detecting an edge of a recorded mark at a level. 8. A reproducing device comprising a magnetoresistive element as a means for detecting a magnetic flux in order to reproduce information recorded on the information recording medium according to claim 1 by detecting the magnetic flux. An information recording / reproducing device comprising: