JPH03102615A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the recording medium which has excellent corrosion resistance, is small in bit shift and is large in residual magnetization by using Co-Cr- Nb or Co-Cr-V as the alloy compsn. to form a magnetic film. CONSTITUTION:The magnetic film is formed of the alloy consisting, by atomic %, of 5.0 to 15.0% Cr, 2.0 to 8.0% Nb, and the balance Co and unavoidable impurities. The corrosion resistance degrades if the content of the Cr is below 5.0atomic%. Namely, the rate of decrease in the saturation magnetization by an environmental change is large and the bit shift is increased. On the other hand, the degradation in output is resulted from a decrease in the residual magnetization and the increase in the bit shift is resulted as well if the content of the Cr exceeds 15.0atomic%. The Nb contributes to the improvement in the bit shift characteristics but this effect cannot be expected if the content thereof is below 2.0atomic%. On the other hand, the residual magnetization decreases and the degradation in the output and the increase in the bit shift are resulted if the content thereof exceeds 8.0atomic%. The magnetic recording medium which is particularly excellent in the corrosion resistance and is improved in the bit shift and residual magnetization characteristics is obtd. in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording medium for recording and reproducing information between, for example, a magnetic head. It is related to recording media.

(Prior Art) Magnetic disk devices have conventionally been used to record information on a magnetic recording medium or to reproduce and output information recorded on the medium. For example, the magnetic head and magnetic recording medium are 0.2 to 0.3
It is usually held in a micro gap of μm. Therefore, a two-floating hend slider is used to prevent friction and wear caused by contact between the magnetic head and the magnetic recording medium, and/or damage caused by collision between the two. In other words, the magnetic hend slider utilizes the hydrodynamic levitation force generated in the gap between the magnetic recording medium and the surface due to the relative speed between the two. Measures are taken to maintain a small gap between the two. On the other hand, the specifications required for magnetic recording media in recent years have become increasingly strict.
A magnetic film that not only has a high recording density but also has a small focus shift and a large residual magnetization is required.

[Problem to be solved by the invention] The material for forming the magnetic film is Co-NiP.
Although the former has the advantage of a large coercive force, it has a low S/N ratio and large noise, and also contains precious metals in the alloy. Since it contains a certain pt, it has the disadvantage of being expensive.

On the other hand, the latter is lower in cost than the former and can reduce noise, but has the disadvantage of being insufficient in terms of corrosion resistance, that is, the rate of decrease in saturation magnetization due to environmental changes, and reliability. In addition, when performing high-density recording in recent years, there are many errors due to large bit shifts.
For example, at an error rate of 10-9, it is about 28 ns, which is poor reliability. Furthermore, in order to ensure the specified coercive force. Crll to be deposited on the substrate as a base film
It is necessary to increase the thickness of the There is a problem in that it takes a long time to form to a predetermined IIR thickness, leading to a decrease in productivity.

As a means to solve the above problems, CoCr-
There is a proposal to form a magnetic film using a Ta-based alloy (for example, Japanese Patent Application Laid-Open No. 1-133217, IEEE T
transactions on Magnetics,
Vol. M.A.G. 23, No. 1, January
ry 19B7 etc.). It is disclosed that a magnetic recording medium with high coercive force and low noise can be obtained by these proposals. However, Ta, which constitutes the above alloy, has the following problems in addition to being expensive. In other words, sputtering has recently been widely used as a means of forming magnetic films. There is a drawback that the Ta target used in this case is complicated to manufacture. Ta targets are manufactured by melting a predetermined set of alloys into ingots and then rolling them with rolls, but they often break during roll rolling. Therefore, there is a problem in that the task of manufacturing a target of a predetermined thickness is extremely complicated.

The present invention is. Eliminates the problems existing in the above conventional technology. It is an object of the present invention to provide a magnetic recording medium that has particularly excellent corrosion resistance and can improve bit shift and residual magnetization characteristics.

[Means to solve the problem]

In order to achieve the above object, first of all, in the first invention.
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 with an underlying film made of a non-magnetic material interposed therebetween, the magnetic film has Cr 5.0 to 5.0 atomic %.
15.0%, Nb 2.0 to 8.0%, balance Co
formed by an alloy consisting of and unavoidable impurities,
A technical method was adopted.

Further, in a second invention, 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 nonmagnetic material with an underlying film made of a nonmagnetic material interposed therebetween, the magnetic film is made of Cr5 at atomic%. .0~l5.0%, V 2.0
A technical measure was adopted in which the alloy was formed from an alloy consisting of ~10.0% Co, the balance being Co and unavoidable impurities.

In the above invention, if the Cr content is less than 5.0 at%, the corrosion resistance decreases, that is, the rate of decrease in saturation magnetization due to environmental changes is large. This is disadvantageous because it increases the bit shift. On the other hand, if Cr exceeds 15.0 atomic %, this is not preferable because it causes a decrease in output due to a decrease in residual magnetization and also increases bit shift.

Next, Nb contributes to improving bit shift characteristics, but 2
．． If it is less than 0 atomic %, no effect can be expected, whereas if it exceeds 8.0 atomic %, it will result in a decrease in residual magnetization. This is undesirable because it lowers the output and increases bit shifts.

Also, like Nb, ■ is an element that contributes to improving the focus shift characteristics, but if it is less than 2.0 at%, no such effect can be expected. On the other hand, if it exceeds 10.0 at%, the above N
As in case b, this is not preferable because it causes an increase in bit shift, a decrease in residual magnetization, and a decrease in output.

Note that it is preferable that the base film is made of Cr or a Cr alloy. In this case, the Cr alloy is Cr
-Mo', Cr-V, Cr-Mn, and other alloys can be used.

It is also preferred that the substrate be made of aluminum or an aluminum-based alloy.

[For production]

With the above structure, it is possible to record and reproduce information between, for example, a magnetic head, and it has excellent corrosion resistance. It can be used as a magnetic recording medium with high bit shift and residual magnetization performance. [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. Outer diameter 9
5e+m, inner diameter 25m. The substrate had a thickness of 1.27 rum. Next, a plating film made of Ni-P alloy is formed on the surface of this substrate to a thickness of 5 to 15 μ-. Start an
d Stop (hereinafter referred to as CSS) characteristics. The surface of the plated film deposited as described above is polished to be smooth and textured to prevent it from attracting magnetically or adhering to the slider. Next, after cleaning the substrate, a base film made of Cr, a magnetic film made of a Co-Cr-Nb alloy, and a holding film made of C are successively deposited using, for example, a DC magnetron sputtering device. In this case, for the I'Ii film as the base film, the inside of the sputtering chamber is 1 x
After evacuation to below to-' Torr, the substrate was heated at 200°C for 30 minutes, and Ar gas was introduced to maintain the inside of the spatter chamber at 5 mTorr. Under the conditions of input power of 2000 W and membrane speed of 400 people/min, the membrane thickness was reduced to 1000 people. Next, on top of this base film, Co as shown in Table 1 below is applied.
-A magnetic film made of a Cr-Nb alloy is made of the same material as above.
A film was formed to a thickness of 600 cm under conditions of input power of 2000 W and film formation speed of 1000 people.

The protective film has an input power of 1000 W and a film speed of 80 A.
A film was deposited on the magnetic film at a thickness of 300 ml under conditions of 300 min. A liquid lubricant was applied to the surface of the magnetic recording medium prepared as described above. Table 1 also shows the results of measurements of bit shift and residual magnetization when installed in a 3.5 inφ disk drive. The magnetic head used in the measurement was a Mn-Zn mini-monosylink type (track width 20 μm), slider width 610 μm, gimbal spring pressure 9.5 gF. Flying height at a radius of 24 m 0, 2μ. , TI1 recording medium rotation speed 2400
r. ρ． Measurements were made under the following conditions.

(Margins below) Table 1 As is clear from Table 1, 1Nαl has a low Cr content and therefore has insufficient corrosion resistance. Bit shift is large. Corrosion resistance improves as the Cr content increases. Improvement in bit shift is observed. However, on the other hand, the value of residual magnetization freezes. In particular, in Nα6, the Cr content is too high, which not only reduces the value of residual magnetization, but also causes a decrease in output. The results show that the value of the binoto shift is large.

Next, consider the influence of Nb on Nα7-11. First, in Toru 7, the corrosion resistance and bit shift values are unsatisfactory because the Nb content is small. Nbil
As the value increases, the corrosion resistance becomes better and the bit shift value becomes smaller. However, in NcLil, the value of residual magnetization decreases and the value of bit shift increases.

On the other hand, in N1112-5 and N118-10, it is recognized that the corrosion resistance is good, the bit shift value is small, and the residual magnetization value also maintains a predetermined value.

Next, Table 2 shows the results of forming a magnetic film using a Co-Cr-V alloy. Note that this is the same as above except that the composition of the magnetic film is different.

As is clear from Table 2. ■ is also N in Table 1 above.
It can be seen that it shows the same effect as b. i.e. k1-6
The corrosion resistance is good when the Cr content is in the range of 5.0 to 15.0 at%. The values of focus shift and residual magnetization are within predetermined ranges. Also No. 7-1
In No. 1, when ■ is in the range of 2.0 to 10.0 at %, the corrosion resistance is good like the above-mentioned Nb. The bit shift and residual magnetization values are satisfactory.

In this example, an example of Cr was described as the material forming the base film, but Cr is not the only material that can be used as the base film.
, Cr-Mo, Cr-V, Cr-Mn, and other Cr alloys may be used. Furthermore, the material for forming the substrate is not limited to an aluminum-based alloy containing magnesium, but may also be aluminum, other metal materials, or non-metal materials.

Furthermore, the means for processing the substrate is not limited to turning, but may also be other methods such as grinding. Note that the Ar gas pressure in the spatter chamber can be arbitrarily selected within the range of 2 to 3 Q mTorr.

There is an effect that can be obtained. In particular, Co-Cr-Nb or Co-
Because it uses Cr-V. Conventional Co-C
Although it is cheaper than those using r-Ta alloy. Possesses equivalent characteristics. Another advantage is that it is extremely easy to manufacture a target material used in forming a certain film.

Claims (2)

[Claims] (1) 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 with an underlying film made of a non-magnetic material interposed therebetween, the magnetic film has a Cr5.
15.0% of Nb, 2.0 to 8.0% of Nb, the balance being Co and inevitable impurities. (2) 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 nonmagnetic material with an underlying film made of a nonmagnetic material interposed therebetween, the magnetic film is made of Cr5.0 at %.
15.0%, V2.0 to 10.0%, the balance being Co and inevitable impurities.