JPH05250651A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To inhibit the irregular migration of the magnetic wall of a soft magnetic layer corresponding to the main magnetic pole of a perpendicular magnetic head due to a floating magentic field concentrated on the main magnetic pole and to prevent the demagnetization of a magnetized perpendicular recording layer with information due to the migration of the magnetic wall. CONSTITUTION:A soft magnetic layer 12 having high permeability and a perpendicular recording layer 3 having perpendicular anisotropy are successively laminated on a nonmagnetic substrate 1. The soft magnetic layer 12 is formed from an alpha-Fe16N2 film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perpendicular magnetic recording medium used in a magnetic storage device, and more particularly to a structure of a perpendicular magnetic recording medium which prevents the influence of a stray magnetic field leaking inside the device.

Along with the miniaturization and high density recording of magnetic disk devices, a soft magnetic layer having a high magnetic permeability as a magnetic recording medium capable of recording much higher density than a widely used horizontal magnetic recording medium. A perpendicular magnetic recording medium having a double-layer film structure in which a perpendicular magnetic recording layer that forms remnant magnetization in the film thickness direction is stacked is proposed, and recording by a combination of such a perpendicular magnetic recording medium and a single-pole magnetic head is performed. It is known that reproduction is optimal for high density recording.

However, in a perpendicular magnetic recording medium having a two-layer film structure combined with a single-pole type magnetic head, a stray magnetic field leaking into the device due to the presence of a soft magnetic layer having a high magnetic permeability is applied to the main pole of the magnetic head. It is easy to concentrate, and the magnetic field strengthened by this concentration tends to demagnetize or demagnetize the recording magnetization of the perpendicular magnetic recording layer in the recording medium facing the main pole. Therefore, there is a need for a reliable medium structure that prevents the effects of such stray magnetic fields in the device.

[0004]

2. Description of the Related Art A conventional perpendicular magnetic recording medium having a two-layer film structure is generally formed on a non-magnetic substrate 1 such as an aluminum disk having a NiP surface treatment, as shown in the cross-sectional view of the main part of FIG. High saturation magnetic flux density Bs compared to the widely used soft magnetic layer made of Ni-Fe film, and high reproduction output can be obtained even if the film thickness is thin. Of 0.5 μm thick γ-Fe ₄ N having a high magnetic permeability, and Co-Cr having a thickness of 0.1 μm having an easy axis of magnetization perpendicular to the thickness direction of the soft magnetic layer 2. The magnetic recording layer made of a film, that is, the perpendicular recording layer 3 is laminated in this order.

A recording magnetic field from the main magnetic pole of a single magnetic pole type perpendicular magnetic head for recording / reproducing information on / from such a perpendicular magnetic recording medium is perpendicularly magnetized and passes through the opposed perpendicular recording layer 3. And the soft magnetic layer 2 immediately below
Information is recorded by a magnetic circuit that passes through the recording medium in the horizontal direction and again vertically passes through the perpendicular recording layer 3 and returns to the side of the perpendicular magnetic head, and by the already recorded recording magnetic field from the perpendicular recording layer 3. The main magnetic pole of the perpendicular magnetic head is magnetized, and information is reproduced by extracting a voltage generated in a coil interlinking with the main magnetic pole as a reproduction signal.

[0006]

Although the perpendicular magnetic recording medium is excellent in electromagnetic conversion characteristics when combined with a single magnetic pole type perpendicular magnetic head, it has a high magnetic permeability in the perpendicular magnetic recording medium. Due to the presence of the soft magnetic layer 2, the main magnetic pole of the perpendicular magnetic head facing the recording medium,
For example, a stray magnetic field of about several Oe leaked from a disk drive motor, a head positioning voice coil motor, or the like in a magnetic disk device is concentrated, and this becomes a strong magnetic field, which is magnetized and recorded on the opposing perpendicular recording layer 3. There is a problem that the information magnetization is demagnetized or demagnetized.

The phenomenon of such demagnetization or demagnetization of the information magnetization is caused by a stray magnetic field concentrated in the main magnetic pole of the perpendicular magnetic head becoming a strong magnetic field and passing through the opposed perpendicular recording layer 3 through the soft magnetic layer immediately thereunder. 2 when flowing to the soft magnetic layer 2
This is because the magnetic domain walls of the magnetic domain that are formed irregularly move, the magnetic permeability of that portion temporarily becomes abnormally high, and many stray magnetic fields flow into that portion.

In view of the above-mentioned conventional problems, the present invention suppresses the irregular movement of the domain wall of the soft magnetic layer due to the stray magnetic field concentrated on the main pole of the perpendicular magnetic head to reduce the information magnetization of the perpendicular recording layer. It is an object of the present invention to provide a novel perpendicular magnetic recording medium that prevents the generation of magnetism and demagnetization.

[0009]

In order to achieve the above-mentioned object, the present invention is a two-layer structure in which a magnetic recording layer having perpendicular anisotropy is laminated on a non-magnetic substrate via a soft magnetic layer having a high magnetic permeability. In a perpendicular magnetic recording medium having a film structure, the soft magnetic layer is formed by α-F
It is composed of an e ₁₆ N ₂ film.

Further, iron nitride (γ-Fe ₄
In a perpendicular magnetic recording medium having a two-layer film structure in which a high-permeability soft magnetic layer made of N) and a magnetic recording layer having perpendicular anisotropy are laminated in this order, α is provided between the soft magnetic layer and the magnetic recording layer. -F
The structure has an e ₁₆ N ₂ layer interposed.

[0011]

In the present invention, the soft magnetic layer and the magnet having perpendicular anisotropy are used.
Applied to Japan as a soft magnetic layer in a two-layer structure with an air recording layer
Journal of Magnetics, Vol.14, No.2, P271-274, (1990) `` Nitrogen Io
Fe produced by ion implantation₁₆N₂Thin film structure and magnetism "
Formed by a method substantially similar to the described forming method
And a high saturation magnetic flux density Bs, and concentrated on the main pole of the perpendicular magnetic head.
Coercive force Hc of several tens to several hundreds Oe higher than the stray magnetic field inside
Have α-Fe₁₆N ₂Structure using a film or iron nitride (γ
−Fe_FourThe same between the soft magnetic layer consisting of N) and the magnetic recording layer
Α-Fe with high saturation magnetic flux density and high coercive force₁₆N₂Layers
With the interposition, the main structure of the perpendicular magnetic head
The stray magnetic field concentrated in the magnetic poles passes through the magnetic recording layer to α-F
e₁₆N₂Through the soft magnetic layer or magnetic recording layer
Α-Fe interposed between the magnetic recording layer and the soft magnetic layer₁₆N₂layer
Even if it flows to the
Stray magnetic field strength is α-Fe₁₆N₂A soft magnetic layer consisting of a film, or
Or the intervening α-Fe₁₆N₂The coercive force of the layer is less than Hc
Therefore, the partial domain wall irregular displacement of the magnetic domains in those layers
Motion is suppressed.

As a result, a large amount of stray magnetic field is partially prevented from flowing into the soft magnetic layer formed of the α-Fe ₁₆ N ₂ film or the interposed α-Fe ₁₆ N ₂ layer, and the magnetic recording is performed. It is possible to prevent demagnetization and demagnetization of the information magnetization of the layer.

[0013]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part showing an embodiment of a perpendicular magnetic recording medium according to the present invention. In FIG.
The same reference numerals are given to the portions corresponding to the constituent portions shown in.

As shown in the figure, the saturation magnetic flux density Bs is higher on the non-magnetic substrate 1 made of an aluminum disc or the like which has been subjected to NiP surface treatment or the like, as compared with the high magnetic permeability soft magnetic layer made of a Ni-Fe film. , Through the high-permeability soft magnetic layer 12 made of an α-Fe ₁₆ N ₂ film having a film thickness of 0.5 μm, which has a coercive force Hc higher than the stray magnetic field leaking from the outside concentrated on the main magnetic pole of the perpendicular magnetic head. A magnetic recording layer made of a Co—Cr film having a thickness of 0.1 μm, that is, a perpendicular recording layer 3 is laminated.

The high magnetic permeability soft magnetic layer 12 made of the α-Fe ₁₆ N ₂ film is described in Japanese Society of Applied Magnetics, Vol. 14, No. 2, P271-.
274, (1990) "Fe ₁₆ N ₂ prepared by nitrogen ion implantation
In the same manner as the forming method described in "Structure and magnetism of thin film", for example, an α-Fe film having a thickness of 0.5 μm is formed on the non-magnetic substrate 1 by a sputtering method, and then the α-Fe film is formed. Nitrogen by an ion implantation method, for example, a nitrogen implantation amount of 10
A uniform coercive force Hc of several tens to several hundreds Oe is obtained by controlling the implantation energy in the film thickness direction to 30 to 150 keV under the conditions of ¹⁶ to 10 ¹⁷ cm ^-2 and current density of 1 μA / cm ^2. It is possible to form the high magnetic permeability soft magnetic layer 12 made of the desired α-Fe ₁₆ N ₂ film.

The magnetization characteristics of the soft magnetic layer 12 composed of the α-Fe ₁₆ N ₂ film of the present embodiment and the soft magnetic layer 2 composed of the γ-Fe ₄ N film of the conventional example are shown in FIGS. b) M (magnetization) -H
(Magnetic field) Curved diagram is shown.

That is, as shown in FIG. 3 (b), the conventional γ-
The coercive force Hc of the soft magnetic layer 2 made of Fe ₄ N film is at most Oe.
On the other hand, the coercive force Hc of the soft magnetic layer 12 made of the α-Fe ₁₆ N ₂ film of this embodiment is 10 Oe to 100 Oe as shown in FIG. 3 (a). Higher coercive force than the stray magnetic field leaking from the outside concentrated on the main pole of the perpendicular magnetic head
Has Hc.

Therefore, the stray magnetic field in the device concentrated in the main magnetic pole of the perpendicular magnetic head flows through the perpendicular recording layer 3 in the perpendicular magnetic recording medium of this embodiment to the soft magnetic layer 12 made of the α-Fe ₁₆ N ₂ film. However, since the strength of the stray magnetic field is less than or equal to the coercive force Hc of the soft magnetic layer 12, irregular movement of partial domain walls in the layer is suppressed, and the magnetic permeability is temporarily abnormally high. Or, it is possible to prevent a large amount of stray magnetic field from flowing partially due to this, so that it is possible to prevent demagnetization and demagnetization of the magnetization information recorded in the perpendicular recording layer.

The perpendicular magnetic recording medium provided with the soft magnetic layer 12 made of the α-Fe ₁₆ N ₂ film of the present embodiment and the γ of the conventional example.
A perpendicular magnetic recording medium provided with a soft magnetic layer 2 made of a —Fe ₄ N film was combined with a single magnetic pole type perpendicular magnetic head, respectively, and there was no external magnetic field to those medium surfaces during reproduction, and several Gauss. Comparing the reproduction output waveforms in the presence of an external magnetic field, as shown in FIG. 5 (a), when there is no external magnetic field for the conventional perpendicular magnetic recording medium, the waveform of the reproduction output signal is at a constant level. However, when an external magnetic field of several Gauss is applied, the reproduction output of a part of the waveform of the reproduction output signal decreases as shown in FIG. 5 (b). This is because the magnetization information recorded in the perpendicular recording layer 3 is partially demagnetized or demagnetized by the external magnetic field.

In contrast to such a conventional example, as shown in FIG. 4 (a), the waveform of the reproduction output signal when the external magnetic field is not applied to the perpendicular magnetic recording medium of the present embodiment has a constant level, Even if an external magnetic field similar to the above is applied, the reproduction output signal waveform shows no decrease in reproduction output as shown in FIG. 4 (b), and the magnetization information recorded in the perpendicular recording layer 3 by the external magnetic field is It is not partially demagnetized or demagnetized.

Further, FIG. 2 is a cross-sectional view of an essential part showing another embodiment of the perpendicular magnetic recording medium according to the present invention. In FIG. 2, parts corresponding to the parts shown in FIG. is doing.

The embodiment shown in this figure is different from the embodiment shown in FIG. 1 in that, for example, 0.4 μm is provided on a non-magnetic substrate 1 made of an aluminum disk or the like which has been subjected to NiP surface treatment or the like.
On the soft magnetic layer 22 made of γ-Fe ₄ N film of
Nitrogen was formed by ion implantation by m the same ion implantation with the examples alpha-Fe film having a thickness of α-Fe ₁₆ N ₂ film 23
That is, the perpendicular recording layer 3 made of a Co—Cr film having a film thickness of 0.1 μm is laminated through the layer.

According to the structure of this embodiment as well, the stray magnetic field concentrated in the main magnetic pole of the perpendicular magnetic head passes through the perpendicular recording layer 3 in the perpendicular magnetic recording medium and passes through α-Fe ₁₆ N _2.
Even if it flows into the film 23, the strength of the stray magnetic field is increased by the α-Fe ₁₆ N ₂
Since the coercive force of the film 23 is Hc (10 Oe to several 100 Oe) or less, partial irregular movement of the domain wall in the layer is suppressed.

Therefore, the magnetic permeability is temporarily increased abnormally, and a large amount of stray magnetic field is partially prevented from flowing due to the magnetic permeability, and the soft magnetic field formed by the γ-Fe ₄ N film immediately below is prevented. Since it is prevented from flowing into the layer 22,
It is possible to prevent demagnetization and demagnetization of the magnetization information recorded in the perpendicular recording layer 3, and it is possible to achieve the same purpose and effect as the embodiment according to FIG.

In the other embodiment, γ-Fe is used._FourN film
Α-Fe on the soft magnetic layer 22 consisting of₁₆N₂The film 23 is formed on the soft magnetic layer 2
2 Nitrogen was implanted into the α-Fe film deposited on the surface by ion implantation.
On-injected and α-Fe₁₆N₂An example of when the film 23 is formed
However, apart from this example, for example, the nitrogen content concentration
Is α-Fe₁₆N₂Soft magnetic layer consisting of iron nitride film lower than the film
Ion implantation of nitrogen only to the depth of 0.1 μm from the surface of
By controlling the injection energy by the method
Therefore, α-Fe is formed on the surface of the soft magnetic layer.₁₆N ₂Shape the membrane
Can be made.

[0026]

As is apparent from the above description, according to the perpendicular magnetic recording medium of the present invention, the magnetization information of the perpendicular recording layer due to the action of the stray magnetic field in the device concentrated on the main magnetic pole of the perpendicular magnetic head can be obtained. Demagnetization or demagnetization can be prevented, and the practically excellent effects such as the remarkably improved reliability in maintaining information recording are achieved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a perpendicular magnetic recording medium of the present invention.

FIG. 2 is a cross-sectional view of essential parts showing another embodiment of the perpendicular magnetic recording medium of the present invention.

FIG. 3 shows an α-Fe ₁₆ N ₂ soft magnetic layer of the present invention and a conventional γ-.
Is a M-H curve chart showing an example of magnetization properties of Fe ₄ N soft magnetic layer.

FIG. 4 is a diagram showing a waveform of a reproduction output signal with / without applying an external magnetic field to the perpendicular magnetic recording medium of the present invention.

FIG. 5 is a diagram showing a waveform of a reproduction output signal with and without application of an external magnetic field to a conventional perpendicular magnetic recording medium.

FIG. 6 is a cross-sectional view of a main part for explaining a conventional perpendicular magnetic recording medium.

[Explanation of symbols]

1 non-magnetic substrate 3 perpendicular recording layer 12, 22 soft magnetic layer 23 α-Fe ₁₆ N ₂ film

Claims (2)

[Claims] 1. A perpendicular magnetic recording having a double-layer structure in which a soft magnetic layer (12) having a high magnetic permeability and a magnetic recording layer (3) having perpendicular anisotropy are sequentially laminated on a non-magnetic substrate (1). In the medium, the perpendicular magnetic recording medium characterized in that the soft magnetic layer (12) is composed of an α-Fe ₁₆ N ₂ film. 2. Iron nitride (Fe ₄ N) on a non-magnetic substrate (1)
In a perpendicular magnetic recording medium having a two-layer film structure in which a high-permeability soft magnetic layer (22) and a magnetic recording layer (3) having perpendicular anisotropy are sequentially laminated, the soft magnetic layer (22) and the magnetic layer Α-Fe ₁₆ N between recording layer (3)
A perpendicular magnetic recording medium having _two layers (23) interposed.