JPH05101364A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve coercive force without adding Pt so much to a magnetic film by forming the magnetic film of an alloy consisting of respectively specific atomic % of one or two kinds of Cr, V and Nb and Pt, and the balance Co and unavoidable impurities. CONSTITUTION:After the surface of a substrate consisting of an aluminum alloy contg. 4wt.% magnesium is worked smoothly, a plating film of an Ni-P alloy is formed and is washed. A substrate film consisting of Cr, the magnetic film consisting of a Co-Cr-Pt-Nb alloy and a protective film consisting of C are thereafter successively laminated by a DC magnetron sputtering device. The magnetic film is formed of the alloy consisting, by atomic % of 1 to 18% Cr, 0.1 to 4% one or two kinds of V and Nb, 1 to 12% Pt, and the balance Co and unavoidable impurities in such a case. The coercive force is increased to about 17000e even if the Pt is added not so much to the magnetic film in this way.

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 particularly Pt in a magnetic recording medium formed with a Co--Cr--Pt alloy magnetic film. The coercive force is increased even with a small amount of added magnetic film.

[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. When recording and reproducing by a magnetic disk device, the magnetic head and the magnetic recording medium are, for example, 0.2 to 0.3.
It is usual to keep the distance to a minute interval of μm. Therefore, a floating head slider is used to prevent friction, wear, and / or damage caused by collision between the magnetic head and the magnetic recording medium. That is, the magnetic head slider is configured to maintain a minute gap between the two by utilizing the hydrodynamic levitation force generated in the gap between the two due to the relative velocity with the surface of the magnetic recording medium.

As a material for forming the magnetic film, Cr is used.
It is known that a magnetic layer of CoCrTa formed on the layer has better magnetic properties than a magnetic layer of CoNi, CoNiCr or the like formed on the Cr layer. Further, a magnetic layer of CoNiPt formed on a Cr layer in order to improve magnetic properties is disclosed in JP-A-62-141628 and JP-A-61-142524. Generally, the amount of Pt added is 15%. The coercive force is improved as described above. Further, since Pt is expensive, in a magnetic film formed on a substrate via a Cr layer, a quaternary element of CrTaPtCo is used and a Pt addition amount is reduced as a magnetic film having improved coercive force. -256017.

[0004]

As described in the above-mentioned prior art, there is a magnetic recording medium having a coercive force improved by forming a magnetic film containing Pt on a Cr layer.
Even if a magnetic film is formed with the quaternary element
It is necessary to add near atomic%, which is also expensive. Therefore, it has been desired to further reduce the amount of Pt added to the magnetic film so that a high coercive force can be obtained. Therefore, an object of the present invention is to improve the coercive force of the magnetic recording medium and reduce the amount of Pt added to the magnetic film.

[0005]

The present invention achieves the above object in a magnetic recording medium in which a magnetic film made of a magnetic material is provided on the surface of a substrate made of a non-magnetic material via a Cr underlayer. is there. Therefore, the magnetic film is C in atomic%
r1 to 18%, one or two of V and Nb was 0.1 to 4%, Pt was 1 to 12%, and the balance was an alloy composed of Co and inevitable impurities.

In the above, Cr contained in the magnetic film is 1
If it is less than atomic%, the coercive force is small and there is much noise. On the other hand, when Cr exceeds 18 atomic%, the output is lowered due to the decrease of the residual magnetization, and the bit shift is increased, which is not preferable. Further, V and Nb contained in the magnetic film contribute to the improvement of the coercive force, but the effect cannot be expected if the content is less than 0.1 atom%, and the coercive force tends to decrease if the content exceeds 4 atom%. If Pt contained in the magnetic film exceeds 12 atom%, coercive force cannot be improved, and if it is less than 1 atom%, coercive force cannot be improved.

[0007]

In the above magnetic recording medium, the magnetic film has V or N
Since it contains 0.1 to 4 atom% of 1 or 2 of b,
Coercive force of about 1700 without adding too much Pt
It becomes large with Oe.

[0008]

Example The surface of a substrate made of an aluminum alloy containing 4% by weight of magnesium was formed into a smooth surface by turning, to obtain a substrate having an outer diameter of 95 mm, an inner diameter of 25 mm and a thickness of 1.27 mm. Next, a Ni-P alloy plating film having a thickness of 5 to 15 μm is formed on the surface of this substrate, and the contact sliding characteristics (CSS) with the magnetic head or slider at the time of starting and stopping the magnetic recording medium are measured. Secure. The surface of the plated film deposited as described above is polished to be smooth, and texture processing is performed to prevent adsorption to the magnetic head or slider.

Next, after cleaning the substrate, a base film made of Cr and Co-- are formed by, for example, a DC magnetron sputtering apparatus.
A magnetic film made of a Cr-Pt-Nb alloy and a protective film made of C are sequentially stacked to form a film. In this case, for forming the base film, the sputtering chamber was evacuated to 1 × 10 ⁻⁵ Torr or less, the substrate was heated at 200 ° C. for 30 minutes, and Ar gas was introduced to maintain the sputtering chamber at 5 Torr. A film having a film thickness of 1000 Å was formed under the conditions of 2000 W and a film forming rate of 400 Å / min. Next, on this base film, Nb
And V are each changed to 0.1 to 6 atomic% and Co-C
A magnetic film made of r-Pt-Nb or Co-Cr-Pt-V was formed in the same manner as above to a film thickness of 600 Å under conditions of an input power of 2000 W and a film formation rate of 1000 Å / min. The protective film has a power input of 1000 W and a film formation rate of 80
A film having a thickness of 300 Å was formed on the magnetic film under the condition of / min.

The coercive force of various magnetic recording media produced as described above was measured and shown in FIG. As can be seen from FIG. 1, the magnetic film containing Nb or V had a maximum at about 1700 Oe when the addition amount was around 3 atom%, and tended to decrease to 1500 Oe or below when the addition amount exceeded 4 atom%.

In the above embodiment, the magnetic film is Nb.
A magnetic recording medium was prepared in which 1.5 at%, 5 at% Pt, and 0 to 20 at% Cr were changed, and the balance was formed as Co, and the coercive force thereof was measured and shown in FIG. Similarly, for the magnetic film, V2 atomic%, Pt10 atomic%, Cr 0-2
A magnetic recording medium in which the balance was changed to 0 atom% and the balance was Co was formed, and its coercive force was measured and shown in FIG.
From FIG. 2, the magnetic film made of Co-Cr-Pt-Nb has the maximum coercive force at about 11% Cr addition, and the one made of Co-Cr-Pt-V shows the Cr addition amount. Has a maximum coercive force of about 18%. However, when the Cr addition amount exceeds 18%, the saturation magnetization amount Bs is greatly reduced, and good characteristics cannot be obtained as a magnetic recording medium.
The amount of Cr added is preferably more than 1 atom% and less than 18 atom%.

Further, in the above-mentioned examples, the magnetic film was prepared by preparing magnetic recording media having the compositions shown in Table 1 below, and the saturation magnetization amount Bs and the squareness ratio Rs thereof were measured and described. It can be seen from Table 1 that it is desirable that Cr is 18 atomic% or less and V and Nb are 4 atomic% or less.

[0013]

[Table 1]

In the above embodiment, the magnetic film is V:
FIG. 3 shows the results of measuring the coercive force (Hc) of a magnetic recording medium having 1.5 at% and varying Cr in the range of 0 to 20 at%, with the balance being Co. Similarly, the magnetic film is Ta: 3.2 at% and Cr is 0 to 20.
FIG. 3 shows the result of measuring the coercive force of the magnetic film formed by changing the at% and changing the balance to Co. From Figure 3 Co-
Cr-V has the maximum coercive force when the amount of Cr added is 15 at%, while the amount of added Cr is 18 a for Co-Cr-Ta.
The coercive force becomes maximum at t%. However, the saturation magnetic flux density (B
As shown in FIG. 4, since s) sharply decreases with the amount of Cr added, good characteristics cannot be obtained as a magnetic recording medium. Therefore, the amount of Cr added is preferably less than 18 at%.

[0015]

The magnetic recording medium of the present invention comprises Co-Cr-Pt-Nb or Co-Cr-Pt on a Cr underlayer.
Since a -V magnetic film was formed and the amount of each Nb or V added was 0.1 to 4 atomic%, a magnetic recording medium having a high coercive force of about 1700 Oe can be obtained. In addition, the amount of expensive Pt added is 12 atomic% or less, which is economical.

[Brief description of drawings]

FIG. 1 is a relationship diagram between a coercive force and a V or Nb addition amount in a magnetic film.

FIG. 2 is a relationship diagram between the amount of Cr added and the coercive force in the magnetic film.

FIG. 3 is a diagram showing the relationship between the Cr content in a magnetic film and the coercive force.

FIG. 4 is a diagram showing the relationship between Cr content and saturation magnetic flux density in a magnetic film.

Claims (1)

[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 a Cr underlayer, and the magnetic film is Cr 1 to 18% in atomic%,
0.1 to 4% of one or two of V and Nb,
A magnetic recording medium, characterized in that Pt is 1 to 12% and the balance is made of an alloy containing Co and inevitable impurities.