JPH05258277A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance the coercive force of a magnetic recording medium and to reduce noise by forming the magnetic film of the magnetic recording medium with an alloy obtd. by adding at least one among V, Nb and Ta to CoNiCrPt. CONSTITUTION:The magnetic film of a magnetic recording medium is formed with an alloy consisting of, by atom, 3-30% Ni, 5-15% Cr, 1-10% Pt, 0.1-5% one or more among V, Nb and Ta and the balance Co with inevitable impurities.

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, to reduce noise and improve 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.

[0003] For example, Japanese Patent Laid-Open No. 1-261717 discloses that
A magnetic recording medium in which a magnetic film is made of a quaternary alloy of Co—Cr—Ta—Pt is disclosed. Then, the coercive force improves with the addition of Pt, and in the above case, the Pt addition amount is 1 to 1
At 5 at%, the coercive force is larger than about 1200 Oe and the squareness ratio is 0.8 or more. A magnetic film made of Co-Ni-Pt has been proposed to increase the coercive force, or Co-Ni-Pt to improve the coercive force.
The applicant has studied a magnetic recording medium having a magnetic film formed of an alloy in which Pt is added to Cr.

[0004]

A conventional magnetic film is Co-N.
A magnetic recording medium made of i-Pt is known, but in that case, it has an advantage that the coercive force is large, but on the other hand, it has a low S / N ratio and a large noise, and is a noble metal in the alloy. It is expensive because it contains Pt. Also C
If a magnetic film is made of an alloy in which Pt is added to o-Ni-Cr, the coercive force is improved, but there is a problem that the noise is large as described above.

On the other hand, when the magnetic film is made of Co-Ni-Cr, the cost is lower than that of the magnetic film made of the alloy containing Pt and the noise can be reduced, but the corrosion resistance, that is, the saturation magnetization due to the change of environment is reduced. High rate and lack of reliability. Further, when high density recording is performed, there are many errors due to a large bit shift and reliability is poor. Further, in order to secure a predetermined coercive force, it is necessary to increase the thickness of the Cr film to be deposited on the substrate as a base film, and it takes a long time to form a predetermined film thickness and the productivity is poor. .. Therefore, in the present invention, the magnetic film of the magnetic recording medium is made of CoNiCrPt.
In addition, it is formed of an alloy to which at least one of V, Nb, and Ta is added, and its object is to improve coercive force and reduce noise.

[0006]

The present inventors have found that CoCr
The magnetic effect when V, Nb, Ta, etc. were added to NiPt was earnestly studied. As a result, CoNiCrPt
The present invention has been completed with the knowledge that coercive force is large and noise can be reduced by adding 0.1 to 5 atomic% of at least one of V, Nb, and Ta. That is, the present invention provides 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 base film made of a non-magnetic material.
0%, Cr 5-15%, Pt 1-10%, and V and N
At least one of b and Ta was formed of an alloy containing 0.1 to 5% and the balance Co and inevitable impurities. The reason why the magnetic film has the above composition is that the coercive force decreases when Ni is 3% or less, and both the output and the coercive force decrease when Ni is 30% or more. Also Cr
Is less than 5%, the coercive force is lowered, and if Cr is more than 15%, the output is lowered. This is because if Pt is 1% or less, the coercive force decreases, and if it is 10% or more, the coercive force is not improved and it is uneconomical. This is because if the added amount of V, Nb, or Ta is 0.1% or less, the coercive force decreases, and if it is 5% or more, the noise characteristics, the coercive force, and the output decrease.

[0007]

In the above magnetic recording medium, the magnetic film is CoNiCr.
It is formed of an alloy in which at least one of V, Nb, and Ta is added to Pt, and V, Nb, and Ta are 0.1 to 0.1%.
Since 5% is contained, the coercive force is large and the recording density is improved, and since V, Nb and Ta make the crystal grains finer, the S / N ratio becomes 30 dB or more and the noise is 3%.
It is reduced to μVrms or less.

[0008]

【Example】

(Example 1) The surface of a substrate made of an aluminum alloy containing 4% by weight of magnesium was formed into a smooth surface by turning, and the outer diameter was 95 mm, the inner diameter was 25 mm, and the thickness was 1.27 mm.
Substrate. 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 was polished smoothly and textured to prevent adsorption to the magnetic head or slider.

Next, after cleaning the substrate, a base film made of Cr and CoN are formed by, for example, a DC magnetron sputtering apparatus.
A magnetic recording medium is prepared by sequentially laminating a magnetic film made of an alloy obtained by adding at least one of V, Nb, and Ta to iCrPt and a protective film made of C. in this case,
To form a base film, the inside of the sputtering chamber is 1 × 10 ⁻⁵ mTorr.
After evacuating to less than r, the substrate is heated at 250 ° C. for 30 minutes, Ar gas is introduced, and the inside of the sputtering chamber is 10 mTorr.
And a film thickness of 100 nm was formed under the conditions of an input power of 2000 W and a film formation rate of 40 nm / min. Next, a magnetic film of an alloy obtained by adding at least one of V, Nb, and Ta to CoNiCrPt was formed on this underlayer film in the same manner as above, and the applied power was 2000 W and the film formation rate was 100 nm /
A film having a thickness of 60 nm was formed under the condition of minutes. A bias voltage of -200 V was applied during sputtering of this magnetic film. The protective film was formed on the magnetic film at a film thickness of 30 nm under the conditions of an applied power of 1000 W and a film formation rate of 8 nm / min.

(Example 2) In the magnetic recording medium prepared as described above, various magnetic films were prepared to measure how the Pt content affects the magnetic characteristics. Therefore, Ni is 18 atomic%, Cr is 9 atomic%, Pt is x atomic%, at least one kind of V, Nb and Ta is 2 atomic%, and the balance is Co, and a magnetic film is formed by an alloy having a changed Pt content. It was prepared and the coercive force Hc and the output were measured, and the results are shown in FIG. From Fig. 1, the coercive force is Pt.
Is 1 to 15 atomic% and Hc is 1300 Oe or more, and 1
It has a large value at 2%. Bs decreased as the Pt amount increased, and became a large value of 0.9T at 10 atomic% or less. Therefore, it is desirable for the Pt content to be 1 to 10 atomic% in terms of magnetic properties.

Next, in the above magnetic film, various magnetic films were prepared to measure how the Ni content affects the magnetic properties. Therefore, x is Ni, Cr is 7 atomic%,
7 atomic% of Pt, at least 1 of V, Nb, and Ta
A magnetic film was made of an alloy having a Ni content of 2 atomic% or more and a balance of Co, and the Ni content was changed to obtain a coercive force Hc and an output B.
s and were measured, and the results are shown in FIG. From FIG. 2, the coercive force is 1200 Oe or more when Ni is 3 to 30 atom%,
In particular, the maximum Ni content was 25 atom%, and the maximum coercive force was 20 to 30 atom%. The output Bs was 1.0 (T) when the Ni content was 30 atomic%, and the output increased as the Ni content decreased. Therefore, the Ni content is 3 to 30 atomic%, and the coercive force and the output are desirable.

Next, in the above magnetic film, various magnetic films were prepared and measured to see how the Cr content affects the magnetic properties. Therefore, Ni is 20 atom%, Cr is x
3% atomic%, 4 atomic% Pt, 2 atomic% of at least one of V, Nb, and Ta, and the balance Co, and a coercive force Hc and output Bs were measured. The results are shown in FIG. Indicated. As can be seen from FIG. 3, the Cr content is 5 atomic%.
Thus, the coercive force was 1500 Oe, and the higher the Cr content, the higher the coercive force. The output Bs was 0.55 (T) when the Cr content was 15 atomic%, and the Bs increased as the Cr content decreased. Therefore, a Cr content of 5 to 15 atomic% is desirable for coercive force and output.

(Embodiment 3) In the magnetic film prepared in the first embodiment, that is, in the magnetic film made of an alloy in which at least one of V, Nb and Ta is added to CoNiCrPt, among V, Nb and Ta, The influence of the magnetic properties when the content of at least one kind was changed was examined. Ni
A magnetic film was prepared from an alloy containing 20 atomic% of Cr, 8 atomic% of Cr, 4 atomic% of Pt, x atomic% of V, Nb and Ta, and the balance of Co. Thus V, Nb and T
Noise characteristics and coercive force Hc when the content of a is changed
And the output Bs are measured, and each is shown in FIG.
Shown in (b) and (c).

According to FIG. 4A, V, Nb or T
The noise characteristic decreases as the content of a increases, and the noise characteristic becomes 2 μVrms at 5 atom%. Figure 4
According to (b), the coercive force is highest when the content of V, Nb, or Ta is 3 atomic%, and is decreased when the content is increased or decreased. Further, according to FIG. 4C, the output Bs
Decreases as V, Nb, or Ta increases, and their content is 1.0 T or more at 5 atomic% or less. It can be easily inferred that even when a plurality of V, Nb, and Ta are added instead of adding one kind thereof, almost the same result as in the case of single addition is obtained depending on the total addition amount thereof. From the above consideration of FIGS. 4A, 4B, and 4C,
It is desirable to add 0.1 to 5 atomic% of at least one of V, Nb, and Ta for magnetic properties.

[0015]

Since the magnetic recording medium of the present invention has at least one of V, Nb and Ta added to CoNiCrPt as an alloy material for the magnetic film, it has a larger coercive force with a small amount of Pt added. .. Further, in the magnetic recording medium of the present invention, the S / N ratio is large and noise can be sufficiently reduced.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of Pt added, the coercive force, and the output in a magnetic film of a magnetic recording medium of the present invention.

FIG. 2 is a diagram showing the relationship between the amount of Ni added, the coercive force, and the output in the magnetic film of the magnetic recording medium of the present invention.

FIG. 3 is a graph showing the relationship between the amount of added Cr, the coercive force, and the output in the magnetic film of the magnetic recording medium of the present invention.

FIG. 4 shows V and N in the magnetic film of the magnetic recording medium of the present invention.
FIG. 4 is a relational diagram of the addition amounts of b and Ta, noise characteristics (a), coercive force (b), and output (c).

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 an undercoat film made of a non-magnetic material, wherein the magnetic film is N in atomic%.
i3 to 30%, Cr 5 to 15%, Pt 1 to 10%, and at least one of V, Nb, and Ta is 0.1 to 0.1%.
A magnetic recording medium, which is formed of an alloy containing 5% of balance Co and inevitable impurities.