JPH06140247A - Magnetic recording medium - Google Patents

Abstract

(57) [Summary] [Purpose] The magnetic film of the magnetic recording medium is made of CoNiCrPt.
The alloy was formed by adding at least one of V, Nb, and Ta to B, so that the coercive force could be improved and the noise could be reduced. [Structure] A magnetic film of a magnetic recording medium is made to have an atomic percentage of Ni3 to
30%, Cr 5-15%, Pt 1-10%, B0.1
5%, and 0.1 to 5% of at least one of V, Nb, and Ta with the balance Co and unavoidable 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 includes Co-Ni-Cr on a substrate material,
It is formed by depositing a magnetic film made of an alloy such as Co-Cr-Ta or Co-Cr-Pt. Recently, in order to make a 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 the magnetic film is made of a quaternary alloy of Co—Cr—Ta—Pt is disclosed. And Pt addition amount 1
It is said that the coercive force is larger than about 1200 Oe and the squareness ratio is 0.8 or more at ˜15 at%. In the 14th Japan Society for Applied Magnetics (1990), Co-Cr-T
It has been announced that the coercive force is affected by the addition of B to a and Co-Cr-Pt. The coercive force monotonously decreases when B is added to Co-Cr-Ta, and the coercive force increases with the addition of B in the case of Co-Cr-Pt. Moreover, B is added to Co-Cr-Pt.
It is said that a high coercive force of about 3000 Oe can be obtained by adding ~ 7 at%.

[0004]

As described in the above-mentioned prior art, the coercive force can be improved in the magnetic recording medium in which the magnetic film is formed by the alloy of the quaternary element of Co-Cr-Pt-B. It has been known. The present inventors have developed Co-Cr
When a magnetic film was formed by using an alloy in which 3 to 7 at% of B was added to —Pt, a magnetic recording medium was prepared, but the coercive force was improved, but there was a problem that the S / N ratio decreased and noise increased. It was Further, when B was 3% or less, the coercive force tended to decrease. In the conventional technique, CoCr is replaced by Pt.
Although the coercive force is improved by adding both B and B, it has not been studied to improve the coercive force by adding Pt and B to the CoCr alloy containing Ni. Therefore, in the present invention, the magnetic film of the magnetic recording medium is made of CoNiCrPtB.
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 even if Pt is reduced.

[0005]

The present inventors have found that CoCr
In addition, the magnetic effect when Ni, B, Pt, V, Nb, Ta or the like was added was eagerly studied. As a result, CoNiC
The present invention was completed by knowing that it is an alloy in which at least one of V, Nb, and Ta is added to rPtB, and the addition amount of B is 0.1 to 5 atomic% and the coercive force is large and noise can be reduced. did. 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 an undercoat film made of a non-magnetic material, and the magnetic film is Ni 3 to 30% in atomic%, Cr5-15
%, Pt 1-10%, B 0.1-5%, and V and Nb
And at least one of Ta and 0.1 to 5% with the balance being Co and unavoidable 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 5
%, The coercive force will decrease, and if Cr is 15% or more, the output will decrease. This is because if Pt is 1% or less, the coercive force decreases, and if it is 10% or more, noise increases. This is because the coercive force is small when B is 0.1% or less, and the output and the coercive force are reduced when B is 5% or more. Further V, N
If the amount of addition of b and Ta is less than 0.1%, there is no effect and it is 5%.
This is because the noise characteristics, the coercive force, and the output are reduced in the above.

[0006]

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 B is further added, and B is 0.1
Content of 5 atomic% and V, Nb and Ta are 0.1
Since the content is 5%, the coercive force is large and the recording density is improved, and the S / N ratio is 30 dB or more, and the noise is reduced to 3 μVrms or less. Thus S
The reason why the / N ratio is about 30 dB or more is that it is considered that the addition of B makes it difficult for noise to occur because the particles forming the magnetic film are magnetically independent of each other. Further, V, Nb, and Ta improve the noise characteristics and the output because the crystal grains are made finer and Cr is diffused into the grain boundaries to make the grains magnetically independent.

[0007]

Example 1 The surface of a substrate made of an aluminum alloy containing 4% by weight of magnesium was smoothed 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, on the surface of this substrate,
A plating film made of -P alloy is formed to a thickness of 5 to 15 μm to secure the contact sliding characteristic (CSS) with the magnetic head or slider when the magnetic recording medium is started and stopped. 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 and adding B to iCrPt and a protective film made of C. In this case, for forming the base film, the sputtering chamber is evacuated to 1 × 10 ⁻⁵ mTorr or less, and then the substrate is heated to 250 ° C.
At 30 m, the Ar gas was introduced to maintain the sputter chamber at 10 mTorr, and the input power was 2000 W.
A film having a film thickness of 100 nm was formed under the condition that the film forming speed was 40 nm / min. Next, on this base film, CoNiCrPt
In the same manner as above, a magnetic film of an alloy in which at least one of V, Nb, and Ta is added and B is added is formed into a film thickness of 60 nm under the conditions of an input power of 2000 W and a film formation rate of 100 nm / min. Filmed A bias voltage of -200 V was applied in the sputtering of this magnetic film. Further, the protective film was formed on the magnetic film with a film thickness of 30 nm under the conditions of a power input of 1000 W and a film formation rate of 8 nm / min.

(Embodiment 2) Here, in the magnetic recording medium produced as described above, the effect of the magnetic characteristics when B is added to a magnetic film containing no V, Nb and Ta was investigated. . Therefore, Ni is 20 atomic%, Cr is 12 atomic%, Pt is 7 atomic%, B is x atomic%, and the balance Co is B.
A magnetic film was prepared from alloys having different addition amounts of, and its coercive force Hc and output Bs were measured and shown in FIG. Figure 1
As can be seen from the figure, 0.1 to 5 atomic% of B is used as a magnetic film.
As for the added one, the coercive force increases as the added amount of B increases,
It can be seen that the content tends to decrease when the content exceeds 5 atomic%.
Further, it can be seen from FIG. 1 that Bs corresponding to the output has a Bs of about 0.7 T or more, which is desirable when B is added in an amount of 0.1 to 5 atomic%. Furthermore, in the case of FIG.
The N ratio and the disk noise were measured and shown in FIG. From FIG. 2, the S / N ratio is 3 when the addition amount of B is in the range of 0.1 to 5 atom%.
When the noise level becomes 0 dB or more, the noise becomes 2.3 μVrms or more, which is desirable for noise reduction.

Next, how the Pt content affects the magnetic properties of the magnetic film was measured by preparing a magnetic film. Therefore, Ni 15 atomic%, Cr 8 atomic%, P
t is x atomic%, B is 4 atomic%, at least one of V, Nb, and Ta is 2 atomic%, and the balance is Co.
A magnetic film was prepared from alloys having different t contents, coercive forces Hc and Bs were measured, and the results are shown in FIG.
From FIG. 3, the coercive force is 1500 Oe when Pt is 1 to 15 atomic%.
It is above, with a large value at 12%. Bs is P
It decreases as the amount of t increases, and it becomes 0.9T at 10 atomic% or less.
It was a big output of. Therefore, the Pt content is 1 to 10
It is desirable to set the content to be atomic% in terms of magnetic properties.

Next, in the above-mentioned magnetic film, how the Ni content affects the magnetic properties was measured by making a magnetic film. Therefore, Ni is x%, Cr is 8 atomic%, Pt is 5 atomic%, B is 3 atomic%, at least one of V, Nb, and Ta is 2 atomic%, and the balance is Co. A magnetic film was formed from the changed alloy, and the coercive force Hc and the output Bs were measured, and the results are shown in FIG.
From FIG. 4, the coercive force is 1500 Oe when Ni is 3 to 30 atomic%.
As described above, the maximum Ni content was 25 atomic%, and the maximum coercive force was 20 to 30 atomic%. Also Bs
Is 1.05 (T) when the Ni content is 30 atomic%,
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, the influence of Cr content on the magnetic characteristics was measured by making a magnetic film. Therefore, a magnetic film is formed by using 20 atomic% of Ni, x atomic% of Cr, 7 atomic% of Pt, 3 atomic% of B, 2 atomic% of at least one of V, Nb, and Ta, and the balance Co. Then, the coercive force Hc and the output Bs were measured, and the results are shown in FIG. As can be seen from FIG. 5, the coercive force was larger as the Cr content was 5 to 15 atom% and the coercive force was 1700 Oe or more. The output Bs is 0.5 (T) when the Cr content is 15 atomic% or less,
The smaller the content, the larger the output. Therefore, the 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 and B is added to CoNiCrPt, The influence of the magnetic characteristics when the content of at least one of Nb and Ta was changed was examined. In addition, Ni is 20 atomic%, Cr is 8 atomic%,
5 atom% of Pt, 3 atom% of B, and V, Nb, and Ta
A magnetic film was prepared from an alloy with the content of x at% and the balance Co. Thus, the noise characteristics, the coercive force Hc, and the output Bs when the contents of V, Nb, and Ta were changed were measured, and shown in FIGS. 6A, 6B, and 6C, respectively. .

According to FIG. 6A, V, Nb or T
The noise characteristic decreases as the content of a increases, and
The noise characteristic is 2.0 to 8.1 μVrms at up to 5 atom%. According to FIG. 6 (b), the coercive force reaches its maximum when the content of V, Nb or Ta is about 3 atom%, and decreases when the content is increased or decreased. Further, according to FIG. 6C, the Bs related to the output decreases as V or Ta increases, and when the content is 0.1 to 5 atomic%,
It is over 6T. Note that V, Nb, and Ta are those 1
It can be easily presumed that even when a plurality of additions are made instead of the addition of the seeds, almost the same result as in the case of a single addition is obtained depending on the total addition amount thereof. FIG. 6 (a) above
From the consideration of (b) and (c), it is desirable to add 0.1 to 5 atomic% of at least one of V, Nb, and Ta for magnetic properties.

[0015]

In the magnetic recording medium of the present invention, since CoNiCrPt is added as B as an alloy material for the magnetic film, the coercive force is improved, and at least one of V, Nb and Ta is added to the alloy material. Therefore, 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 B added, the coercive force, and the output in a magnetic film of a magnetic recording medium of the present invention.

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

FIG. 4 is a graph 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. 5 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. 6 shows V and N in the magnetic film of the magnetic recording medium of the present invention.
It is a relational diagram of the addition amount of b and Ta, and noise characteristic (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, the magnetic film being N in atomic%.
i3-30%, Cr5-15%, Pt1-10%, B
A magnetic recording medium characterized by being formed of an alloy of 0.1 to 5%, 0.1 to 5% of at least one of V, Nb, and Ta, and the balance Co and unavoidable impurities.