JP2002269716A - Perpendicular magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the noise of a perpendicular magnetic recording medium formed by using a rare earth-transition metal amorphous magnetic alloy film as a perpendicularly magnetized film. SOLUTION: The perpendicular magnetic recording medium has a laminated structure having a substrate 2, the perpendicularly magnetized film 3 formed on the substrate 2 and protective film 4 formed on the perpendicularly magnetized film 3. The perpendicularly magnetized film 3 has a non-magnetic material as a base material and is a rare earth-transition metal system granular thin film wherein the particles of the magnetic alloy consisting essentially of the rare earth metal-transition metal system alloy are dispersed in the base material.

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 as a magnetic disk or the like in a storage device such as a computer.

[0002]

2. Description of the Related Art In recent years, hard disk drives are used not only for personal computers and workstations but also for hard disk drives.
It has also been used for V equipment and the like, and is required to have a large capacity and a small size. Magnetic disks are required to have a higher recording density. However, in order to achieve a high recording density with the widely used longitudinal magnetic recording method, there is a problem of thermal fluctuation of recording magnetization due to miniaturization of recording bits and a high coercive force that may exceed the recording capability of the recording head. Problems arise. Therefore, a perpendicular magnetic recording system is being studied as a means for resolving these problems and greatly increasing the areal recording density.

As one of the perpendicular magnetic recording media for realizing the perpendicular magnetic recording system, a perpendicular two-layer film comprising a soft magnetic film having a high magnetic permeability and a perpendicular magnetic film having a high perpendicular anisotropy has been proposed.

[0004] Hereinafter, referring to FIG.
The configuration of the layered medium will be described. FIG. 4 is a schematic substrate sectional view of a conventional perpendicular magnetic recording medium. A conventional perpendicular magnetic recording medium 100 is formed by sequentially forming a soft magnetic film 102, a perpendicular magnetization film 103, and a protective film 104 on a substrate 101. For example, the permalloy (N
A cobalt-chromium (Co-Cr) alloy film is used for the i-Fe) film and the perpendicular magnetization film 103, and carbon (C) is used for the protection film 104, respectively. Here, the soft magnetic film 102 operates as a part of the recording head. The magnetic field from the main magnetic pole of the magnetic head passes through the soft magnetic film 102 and the auxiliary magnetic pole to form one closed magnetic path. With such a configuration, the perpendicular magnetic field in the medium can be strengthened, and the recording sensitivity can be improved.
ol. 8, No. 1, 1984, p. 17).

[0005] In the perpendicular magnetic recording system,
There is a problem that noise is large in DC erasure (saturated remanent magnetization) of a perpendicular magnetic recording medium, and a reverse magnetic domain formed in the recording medium is considered as a noise source. In order to reduce the noise caused by the reverse magnetic domains, it is necessary to reduce the reverse magnetic domains and reduce the number of the reverse magnetic domains. Reducing the number of reverse magnetic domains corresponds to increasing the squareness ratio (the ratio of the residual magnetization to the saturation magnetization) in the MH (magnetization-magnetic field) loop perpendicular to the substrate surface of the perpendicular magnetic recording medium. are doing.

As a perpendicular magnetization film having a large squareness ratio, a rare earth metal-transition metal (RE-T
M) -based amorphous alloy films are known. Since it has an amorphous structure, there is little problem of thermal fluctuation due to finer particles, and since it has a large perpendicular magnetic anisotropy, it has attracted attention as a perpendicular magnetic recording medium.

[0007]

However, Co-
Because the microstructure of the Cr-based alloy is an inhomogeneous structure consisting of a ferromagnetic region and a non-magnetic region, domain wall pinning during magnetization reversal was possible, whereas the RE-TM-based amorphous alloy film was Is a continuous film of a uniform ferromagnetic material, and there is no pinning site of the domain wall, and the magnetic domain becomes unstable.

As described above, in the RE-TM-based amorphous alloy film, the recording magnetization transition region becomes unstable, and transition noise increases with the recording density. is there.

Therefore, an object of the present invention is to make use of the advantage of the RE-TM type amorphous film that DC noise is suppressed by a high squareness ratio, suppress transitional noise, and realize a high recording density. It is to provide a recording medium.

[0010]

In order to achieve the above object, a perpendicular magnetic recording medium according to the present invention comprises a substrate, a perpendicular magnetic film provided on the substrate, and a protective film provided on the perpendicular magnetic film. In a perpendicular magnetic recording medium having at least
The perpendicular magnetization film is a granular thin film made of a magnetic alloy containing a rare earth metal-transition metal alloy as a main component and a nonmagnetic material, wherein the nonmagnetic material is a base material of the granular thin film, and the rare earth metal-transition metal A magnetic alloy mainly composed of an alloy is a particle dispersed in a base material.

In the above configuration, the magnetic thin film having a rare earth metal-transition metal system having an amorphous structure and having no crystal grain boundaries is divided by a non-magnetic material so that the magnetic material has a discontinuous structure. Sites can be formed. Thereby, the magnetization reversal region can be stabilized, and noise can be reduced.

The perpendicular magnetic film of the perpendicular magnetic recording medium of the present invention contains at least one of Tb, Gd, and Dy as a rare earth metal, and at least one of Fe and Co as a transition metal. In addition, as a non-magnetic material, Si-
O, Al-O, Zr-O, Mg-O, Si-N, Si-
It is characterized by including at least one of C and C.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described.

FIG. 1 is a sectional view of a substrate showing an example of the configuration of a perpendicular magnetic recording medium of the present invention. The perpendicular magnetic recording medium 1 of the present invention is obtained by forming a rare earth-transition metal based granular perpendicular magnetization film 3 and a protective film 4 on a substrate 2 in this order. FIG. 2 is a schematic diagram of the fine structure of the perpendicular magnetization film in the perpendicular magnetic recording medium of the present invention. The rare earth metal-transition metal based magnetic alloy 5 is separated by a nonmagnetic material 6.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of the present invention will be described. FIG. 3 is a cross-sectional view of the substrate showing the configuration of the perpendicular magnetic recording medium in the present embodiment. The perpendicular magnetic recording medium 7 of this embodiment has a length of 65 m.
a substrate 8 having a diameter of m and a thickness of 500 nm formed on the substrate 8
A soft magnetic film 9 made of Ni-Fe, a rare earth-transition metal based granular perpendicular magnetization film 10 made of Tb-Fe-Co and SiO2 formed on the soft magnetic film 9, and a protective film 11 made of carbon. Is formed as a laminated structure having

Hereinafter, a method of manufacturing the perpendicular magnetic recording medium 7 of the present embodiment will be described. First, a Ni-F film having a thickness of 500 nm is formed on a substrate 8 having a diameter of 65 mm by sputtering.
A soft magnetic film 9 made of an e film was formed. Next, an 80 nm-thick Tb-F film is formed on the soft magnetic film 9 by a simultaneous sputtering method using a Tb-Fe-Co and SiO2 target.
A rare earth-transition metal-based granular perpendicular magnetization film 10 made of e-Co and SiO2 was formed at room temperature. Si
The volume fraction of O2 was controlled by electric power applied to the target, and was set to 30%. Further, an 8 nm-thick carbon protective film 11 was formed on the rare earth-transition metal-based granular perpendicular magnetization film 10 to produce a perpendicular magnetic recording medium. On the other hand, as a comparative example, a perpendicular magnetic recording medium having a perpendicular magnetization film having a thickness of 80 nm was manufactured using only the Tb-Fe-Co target.

In order to evaluate the perpendicular magnetic recording medium of this embodiment, recording / reproducing characteristics were measured using a single-pole head for recording signals and an MR head for reading signals.
Here, the track width of the single pole head was 0.5 μm, and the main pole film thickness was 2 μm. The reproduction track width of the MR head was 0.3 μm, and the distance between the shields was 0.1 μm.
The measurement was performed at a peripheral velocity of 12.7 m / sec and a flying height of 20 m / sec.
nm and a noise band band of 45 MHz.

Table 1 shows the medium S / N ratio and the medium noise at a recording density of 250 kFRPI based on a comparative example.

[0019]

[Table 1]

The medium according to the present embodiment had a higher S / N ratio by 2 dB and lower noise by 3 dB than the medium of the comparative example. This is because the non-magnetic material mixed in the magnetic film reduces the magnetization of the film and reduces the output, but the noise reduction due to the pinning effect is large, and the S / N ratio is good. Thus, the use of the perpendicular magnetic recording medium of the present invention facilitates realization of a high recording density.

As described above, the use of the perpendicular magnetic recording medium of the present invention facilitates realization of a high recording density.

In the above embodiment, the rare earth-transition metal based alloy in the rare earth-transition metal based granular perpendicular magnetization film 10 is not limited to the Tb-Fe-Co alloy.
Tb-Fe, Tb-Co, Gd-Fe, Gd-Co, G
d-Fe-Co, Dy-Fe, Dy-Co, Dy-Fe
-Co or the like can be used. Also, as a non-magnetic material,
In addition to SiO2, Al-O, Zr-O, Mg-O, S
i-N, Si-C, C and the like can be used.

Further, in the above embodiment, the structure in which the soft magnetic film is provided between the substrate and the perpendicular magnetization film, and the thin film for fixing the domain wall of the soft magnetic film between the substrate and the soft magnetic film The effect does not change even in the configuration provided with.

[0024]

According to the perpendicular magnetic recording medium of the present invention, the rare earth metal-transition metal magnetic thin film having an amorphous structure is divided by a non-magnetic material into a discontinuous structure, so that domain wall pinning becomes possible. By stabilizing the magnetization switching region, noise can be reduced. With this effect, a perpendicular magnetic recording medium having excellent recording and reproducing characteristics can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a configuration of a perpendicular magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a fine structure of a perpendicular magnetization film in the perpendicular magnetic recording medium of the present invention.

FIG. 3 is a sectional view showing an example of a configuration of a perpendicular magnetic recording medium according to an embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a conventional perpendicular magnetic recording medium.

[Description of Signs] 1 Perpendicular magnetic recording medium 2 Substrate 3 Rare earth-transition metal based granular perpendicular magnetization film 4 Protective film 5 Rare earth-transition metal based magnetic alloy 6 Non-magnetic material 7 Perpendicular magnetic recording medium 8 Substrate 9 Soft magnetic film 10 Rare earth -Transition metal-based granular perpendicular magnetic film 11 protective film 100 perpendicular magnetic recording medium 101 substrate 102 soft magnetic film 103 perpendicular magnetic film 104 protective film

Claims (2)

[Claims] 1. A perpendicular magnetic recording medium having at least a substrate, a perpendicular magnetic film provided on the substrate, and a protective film provided on the perpendicular magnetic film, wherein the perpendicular magnetic film is made of a rare earth metal A magnetic thin film comprising a transition metal alloy-based magnetic alloy and a non-magnetic material, wherein the non-magnetic material is a base material of the granular thin film,
A perpendicular magnetic recording medium, wherein the magnetic alloy mainly composed of a rare earth metal-transition metal alloy is particles dispersed in a base material. 2. The rare earth metal includes one or more of Tb, Gd, and Dy, the transition metal includes one or more of Fe and Co, and the nonmagnetic material includes Si—O, Al
2. The perpendicular magnetic recording medium according to claim 1, comprising one or more of -O, Zr-O, Mg-O, Si-N, Si-C, and C.