JPH05189741A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance coercive force, to reduce noise and to improve electromagnetic transducing characteristics by forming a magnetic film with a specified alloy having a required ratio among the components. CONSTITUTION:The CoCrPtNiB magnetic film of this magnetic recording medium is formed with an alloy consisting of, by atom, 5-15% Ni, 1-15% Cr, 1-12% Pt, 0.1-5% B and the balance Co. High coercive force of >=1,200 Oe, >=30 dB S/N and reduced noise are attained and electromagnetic transducing characteristics are improved because of high saturation magnetization of >=10kG. When 0.1-5% Ru and 0.1-5% Ti are added to the film forming alloy, similar effects are produced without deteriorating the corrosion resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium for recording and reproducing information with, for example, a magnetic head, and more particularly to reducing noise and improving coercive force.

[0002]

2. Description of the Related Art In a magnetic disk device, a magnetic head is opposed to a magnetic recording medium at minute intervals so that the magnetic head reads magnetic information recorded on the magnetic recording medium or magnetically records the magnetic information from the magnetic head onto the magnetic recording medium. It is supposed to do. The magnetic recording medium uses Co-Ni-Cr, C as the substrate material.
It is formed by depositing a magnetic film made of an alloy such as o-Cr-Ta or Co-Cr-Pt. Recently, in order to make the magnetic recording medium have a high recording density, it is necessary to increase the coercive force of the magnetic film. Have been proposed.

For example, Japanese Patent Laid-Open No. 1-256017 discloses a magnetic recording medium in which a magnetic film is made of a quaternary alloy of Co--Cr--Ta--Pt. When the amount of Pt added is 1 to 15 at%, the coercive force is larger than about 1200 Oe and the squareness ratio is 0.8 or more. In addition, foreign specialized magazines Magnetism and Magnetic Materials. 86 (199
0) 159-168., In a Co-Cr-Pt magnetic film, P
It describes how the magnetic properties are affected by the content of t. Then, as shown in FIG. 1 (b), Pt1
The coercive force is 1000 Oe or more at 2 at%, the squareness ratio is 0.7 to 0.9 at Pt 6 to 18%, and the residual magnetization and the saturation magnetization tend to be as shown in FIG.

Further, in JP-A-1-232522, a magnetic film of a magnetic recording medium has a Ni content of 30.
% Or less CoNi alloys are disclosed. It is described that the amount of Ni added is set to 30% or less because the remanent magnetization of the magnetic film is significantly reduced and the electromagnetic conversion characteristics are deteriorated when Ni is added more than 30%. A magnetic film made of a CoNi-based alloy has a coercive force of 700-
1500 Oe and saturation magnetization 8000 to 13900
It states that it will be Gaussian and further improves the corrosion resistance.

The 14th Japan Society for Applied Magnetics (1990)
(Year), it was announced that the coercive force is affected by adding B to CoCrTa and CoCrPt. The coercive force monotonically decreases as the amount of B added to CoCrTa increases, and the coercive force increases as the amount of B added increases in the case of CoCrPt. Also CoCrP
Approximately 3000 O by adding 3 to 7 at% of B to t
It is said that a high coercive force of e can be obtained.

[0006]

As described in the above-mentioned prior art, various magnetic films using a Co-based alloy have been prepared, but coercive force, remanent magnetization, and S / N ratio are all sufficiently preferable. Things have not been obtained. In addition, Co-based alloys with Ni
The magnetic film made of the material added with was satisfactory in terms of coercive force and saturation magnetization, but had a small S / N ratio and could not sufficiently reduce noise. This is because the added amount of Ni is 30% or less and the improvement of the S / N ratio is not considered. Further, it is known that the coercive force of the magnetic film made of the alloy in which B is added to CoCrPt is improved as described above. However, B is added to CoCrPt by 5
When a magnetic film was formed from an alloy added with ˜7%, the coercive force was improved, but the S / N ratio decreased and the noise increased in some cases. Therefore, it is an object of the present invention to improve the coercive force of a magnetic recording medium, reduce noise, and make saturation magnetization preferable.

[0007]

The present inventors have found that CoCr
Magnetic films were prepared from alloys in which B was added to PtNi in various proportions, and desired magnetic films were completed in terms of coercive force, S / N ratio, and saturation magnetization. That is, in the magnetic recording medium of the present invention, the magnetic film is composed of Ni 5 to 15% in atomic% and Cr.
1-15%, Pt 1-12%, B 0.1-5%, balance C
It was made of an alloy of o. The present invention also includes a magnetic film formed by adding 0.1 to 5% of Ru to the above composition, or 0.1 to 5% of Ti. In the above description, Ni is 5 to 15%, Cr is 1 to 15%, and Pt is 1 to 12% because the S / N ratio is poor outside these ranges. B is set to 0.1 to 5% because the coercive force and S are outside the range.
This is because the / N ratio is inferior. The addition amounts of Ru and Ti are set within the above range because the corrosion resistance is poor outside the range.

[0008]

In the above magnetic recording medium, the magnetic film is CoNiCr.
Since it is composed of a quinary element of PtB and contains Ni in an amount of 5 to 15 atomic%, the coercive force is as large as 1200 Oe or more, and the S / N ratio is 30 or more, so that noise can be reduced, Further, since the saturation magnetization is 10 K gauss or more, the electromagnetic conversion characteristics can be made favorable.

[0009]

Example A NiP electroless plating film is formed on the surface of a 3.5 inch diameter aluminum alloy substrate (outer diameter 95 mm, inner diameter 25 mm, thickness 1.27 mm) to a thickness of 5 to 15 μm, and the surface is mirror-finished. I made a disc. After the disk was washed, the surface was textured so that the surface roughness was Ra7 nm. After cleaning the disk again, DC
Use a magnetron sputter device to move 1 inside the sputter chamber.
After evacuation below × ^1--5 Torr, Ar gas was introduced, to maintain the pressure of the chamber to 5MmTorr, put pressure 2000
W, 50 n of underlying Cr layer under conditions of film formation speed 40 nm / min
The film was formed to a thickness of m. At this time, the temperature of the disk is 200
It was ℃. Further, a magnetic film was formed on this base film. The magnetic film was made of a CoNiCrPtB alloy (shown in Table 1), an alloy to which Ru was added (shown in Table 2), and an alloy to which Ti was added (shown in Table 2). Input power for sputtering the magnetic film is 200 W, deposition rate is 10
The film thickness was 50 nm at 0 nm / min. The disk temperature was maintained at approximately 200 ° C. during this entire process. Further, a carbon film was formed as a protective film on the magnetic film, and the film forming conditions were an input power of 1000 W, a film forming rate of 8 nm / min and a thickness of 30 nm.

The coercive force Hc, the saturation magnetization 4πMs and the residual magnetization 4πMr of the magnetic recording medium prepared as described above were measured using VSM under an applied magnetic field of 10 K gauss. The magnetic head used for the measurement was a MIG head in which CaTiO ₃ was used as a slider material and a sendust thin film was formed on MnZn ferrite by sputtering. The track width of the magnetic head is 13 μm and the slider width is 60 μm.
The measurement was performed at 0 μm, a gimbal spring pressure of 9.5 g, and a disk radius of 24 mm at a disk rotation speed of 3600 rpm.

First, a linear recording density of 30KFcl is written on a disk, and a reproduction signal containing no noise is measured by a spectroanalyzer with a band material of 0 to 20 MHz. Next, the noise including the magnetic head of the measuring instrument used is measured under the same conditions, and the noise power is further measured using the rms voltage side to obtain rehabilitation data. The medium noise was calculated by comparing the value obtained by subtracting the measuring instrument noise from the noise during reproduction with the rms value rehabilitation data. The S / N ratio of the magnetic recording medium prepared in the above manner was used. The obtained measurement results are shown in Tables 1 and 2 below.

[0012]

[Table 1]

From Table 1, the Pt content is less than 1% and 15
If it is larger than%, the S / N ratio is inferior. Further, when Cr is not contained, or when it is 18% or more, the S / N ratio is inferior, Ni is less than 3%, and when 18% or more, the S / N ratio is inferior, and B is less than 1% and S / N is 6% or more. It turns out that the ratio is inferior. Further, from Table 1, regarding the saturation magnetization, the Pt content is 1
When it is as large as 5%, it is inferior, and when it comes to the residual magnetization, when it is as large as 16%, it is inferior. Furthermore, the coercive force is inferior when the added amount of Pt becomes zero. From the above, the magnetic film is made to have an atomic% of Ni5 to 15% and Cr1 to 15%.
%, Pt 1 to 12%, B 0.1 to 5%, and the balance Co is desirable.

[0014]

[Table 2]

From Table 2, the added amount of Ru is 0.1-5%,
The amount of Ti added should be 0.1-5% for Hc and S /
It is desirable in terms of N ratio.

[0016]

The magnetic recording medium of the present invention is made of CoNiCr.
Since the magnetic film is made of an alloy containing 5 to 15% of PtB and 5 to 15% of Ni and 0.1 to 5% of B, the S / N ratio is increased and the noise is reduced. In addition, since the residual magnetization is large to some extent, the electromagnetic conversion characteristics are improved and the coercive force is also improved.

[Brief description of drawings]

FIG. 1A is a diagram showing a residual magnetization and a saturation magnetization of a conventional magnetic film, and FIG. 1B is a diagram showing a coercive force and a squareness ratio.

Claims (3)

[Claims] 1. A magnetic recording medium in which a magnetic film made of a magnetic material is provided on a surface of a substrate made of a non-magnetic material via an undercoat film made of a non-magnetic material, the magnetic film having an atomic% of Ni of 5 to 15%. , Cr 1-15%, Pt 1-12%, B
A magnetic recording medium formed of an alloy of 0.1 to 5% and the balance being Co. 2. A magnetic recording medium in which a magnetic film made of a magnetic material is provided on a surface of a substrate made of a non-magnetic material via an undercoat film made of a non-magnetic material, wherein the magnetic film is Ni 5 to 15% in atomic%. , Cr 1-15%, Pt 1-12%, B
A magnetic recording medium formed of an alloy of 0.1 to 5%, Ru 0.1 to 5%, and the balance Co. 3. The magnetic recording medium according to claim 2, wherein the alloy forming the magnetic film further contains Ti in an atomic percentage of 0.1 to 5%.
Added magnetic recording medium.