JPH0249214A - Magnetic recording medium and magnetic memory device - Google Patents

Abstract

PURPOSE:To obtain the medium which has excellent corrosion resistance, is small in noise at the time of high-density recording and reproducing and has high S/N by incorporating Co into a magnetic layer and incorporating prescribed elements further into the layer. CONSTITUTION:Metallic underlying layers 11, 11' consisting of Cr, Mo, W, etc., are provided on a nonmagnetic substrate 10 consisting of tempered glass, etc. This medium has the magnetic layers 12, 12.. of the magnetic alloy contg. the material X consisting of at least >=1 kinds of the elements selected from a 1st group contg. Co and consisting of Cr, Mo, and W, the material Y' consisting of at least >=1 kinds of the elements selected from a 2nd group consisting of Ti, Zn, Hf, Ta, Nb, Ru, and Rh, and the material Z consisting of at least >=1 kinds of the elements selected from a 3rd group consisting of Al and Si. Nonmagnetic coating layers 13, 13' consisting of C, B, Si, Ti, etc., are formed thereon and lubricating layers 14, 14' consisting of perfluoroalkyl polyether, etc., are provided thereon. The medium which decreases the noises and has the high S/N at the time of high-density recording and reproducing is obtd. in this way and the reduction of the size of the device and the increase of the capacity thereof are possible.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to magnetic recording media such as magnetic tapes, floppy disks, and magnetic disks, and magnetic storage devices using these, and particularly to magnetic recording media suitable for high recording density. The present invention relates to a medium and a magnetic storage device using the same.

[Conventional technology]

Conventionally, as a magnetic recording medium for high recording density,
As shown in Japanese Patent No. 4-33523, a medium using a metal magnetic thin film has been proposed. - In general, methods for forming the medium include vapor deposition, sputtering, plating, and ion beam sputtering. Recently, demands for higher recording density and higher reliability have been increasing, and as shown in Japanese Patent Application Laid-Open No. 63-39122, Zr is added to Go-Cr.
Proposals have been made to increase reliability regarding corrosion resistance by adding .

[Problem to be solved by the invention]

The magnetic recording medium according to the above-mentioned prior art is described in I.E.E., Transactions, On, Magnetics, M.N.G., Vol. 22 (1986), pp. 895-8.
Page 97 (IEHE'rrans, on Magn.

As stated in MAG~22 (1986)' p895-p897), there is a drawback that medium noise tends to increase. Particularly in recent years, as recording densities have increased, recording frequencies have become higher and bands have become wider, so lowering noise has become an especially important issue.

An object of the present invention is to provide a medium that reduces medium noise without impairing corrosion resistance and has high recording/reproducing characteristics and reliability, and a large-capacity, highly reliable magnetic storage device.

[Means for solving the It111 problem] The above object includes a magnetic layer containing Go and further containing Cr.

M o , and a material X consisting of at least one element selected from the first group consisting of W, and "l"
a material Y' consisting of at least one element selected from the second group consisting of i, Zr, Hf, Ta, Nb, Ru and Rh; and a third group consisting of An and Si. This can be achieved by forming an alloy containing at least the material 2 made of at least one element. Here, the composition of X with respect to CO is 3 at% or more and 20 at% or less, and the composition of Y' and Z with respect to the total amount of Co and X is lat% or more and 15 at% or less, respectively, and f
It is desirable to set the impurity concentration to at % or more and 15θt % or less, but the impurity concentration where r=J is omitted here.

In addition, 0.0% oxygen was added to the magnetic layer. It is more desirable to contain Cr, Mo, W, and Cr-Ti alloys, or other non-magnetic alloys containing these as main components, between the magnetic layer and the non-magnetic substrate. It is particularly desirable to provide an intermediate layer consisting of: By using the magnetic recording medium having the above configuration, it is possible to provide a magnetic storage device with a large capacity and high reliability.

[Effect]

The above effect is due to the following action. Co has high magnetocrystalline anisotropy, and Go
Since the magnetic anisotropy axis is oriented to have an in-plane anisotropy component, it is possible to have a high in-plane coercive force. actual,
5000 by adding 3 at% or more of Cr etc. to CO.
A high coercive force of ea degree or higher can be achieved. Here, the corrosion resistance of the CO alloy increases with the amount of Cr added, but the magnitude of saturation magnetization deteriorates rapidly with the amount of Cr.

It is not preferable to add more than 20 at% Cr.

As a result of various studies on the 33rd additive element that can improve corrosion resistance without significantly deteriorating saturation magnetization, we found that Ti,
Zr, Hf, V, Nb, Ta, Fe.

Ru, Os, Rh, I r,
Pd, La, Sm.

Corrosion resistance could be improved by adding Pr or the like, but in both cases medium noise during recording and reproduction was large.

Therefore, various studies were conducted regarding the fourth additive element, and as a result, the third additive element was ri and Zr.

Hf + N b + T' a * Ru T Rh
At least one species selected from the group of AQ as the fourth addition source.

It has become clear that noise can be reduced without significantly deteriorating corrosion resistance by using Si or an alloy thereof.

In the combination of these elements, Si or AQ
The alloy with the third additive element segregates at the grain boundaries of the crystal grains, reduces interaction between the crystal grains, and protects the interior of the crystal grains. In particular, Q in the magnetic film is 1 at% or more, 1.5
When a magnetic film is formed under conditions that contain less than at% of oxygen, the magnetic crystal grains become finer and a dense passive film is formed, which further reduces noise and improves corrosion resistance. preferable.

The composition of the above additive elements will be explained below.

Figure 2 shows a 130 mmφ A plated with N1-P.
An Ilt-Mg alloy substrate was sputtered using RF magnetron sputtering at a substrate temperature of 100°C and an argon gas pressure of 15 m'.
I'orr, film thickness 350 nm at input power I W/ffl
of Cr, with a film thickness of 70 nm (Co o, a7c r O
, 13)o,eo-cTao,o4A (A c, Media noise characteristics when a magnetic disk is formed by forming C with a film thickness of 40 nm and recorded and reproduced with an M n -Z n ferrite head with a gap length of 0.6 μm. The circumferential speed is 15 m.
/s, and the recording frequency is 7 MHz. The noise decreases rapidly with the addition amount of AΩ, and the AQ composition is 1. It can be seen that the noise reduction effect is significant when the concentration is at least 2.5 at%, more preferably at least 2.5 at%. Adding more than 15 at % of AQ does not have a small noise reduction effect, but it is not preferable because the saturation magnetization and coercive force decrease with the amount of AQ added, resulting in a decrease in reproduction output. S i or A instead of AQ
Similar effects were observed when Q-Si alloy was added.

C/(Coo, s9Cro, 5
x) o, os-b Z r b S i O, 03/
As a result of evaluating the corrosion resistance of the Cr medium using a high temperature and high humidity test at 70°C and 85% RH, it was found that the Zr composition was lat%.
With the above conditions, no increase in errors was observed even after 3 weeks, indicating good corrosion resistance. '/, r composition of more than 15 at % is not preferable because saturation magnetization and coercive force deteriorate significantly and high reproduction output cannot be obtained. Instead of Zr.

Similar effects were obtained when Ti, Hf, Nb, 71'a, Ru, Rh, and alloys thereof were used.

When forming a magnetic film having the above composition, 0.02voQ% to 1.0vo12% of oxygen is further included in the Ar gas, and the film is filled with 0.1at% or more of 15at;%.
The following oxygen can be contained, and in this case, crystal grains become finer as the amount of oxygen increases, and oxides segregate at grain boundaries, reducing magnetic interaction and improving corrosion resistance, which is preferable.

It goes without saying that by using the magnetic disk, floppy disk, or magnetic tape having the above configuration, a magnetic storage device with a large storage capacity and high reliability can be provided.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1st
In the figure, 10 is tempered glass, plastic, N1-
Substrates such as P-metsuki AA alloy.

11.11' is C e Mo * W , Cr
-T i.

Cr-Si, Cr-Mo, Cr-W
12.12' is a material containing CO and at least one element selected from the group consisting of Cr TM o and W, and Ti, Z
r.

A material consisting of at least one element selected from the group consisting of Hf, Ta, Nb, Ru and Rh, and A
13. A magnetic alloy containing at least a material consisting of at least one element selected from the group consisting of 1.1 and Si;
13' is C,, B, Si, Ti, Zr+ Hft N
b, Ta+V, Cr.

A nonmagnetic coating layer made of Mo, W carbide, nitride, oxide, or boride, and 14.14' are a lubricating layer made of perfluoroalkyl polyether or the like. This example will be described in more detail below.

ΔQ- with a diameter of 89mmφ, plated with 12μm of N1-P
A Mg alloy substrate was processed using 2 μmM abrasive grains so that fine scratches were formed on its surface in the approximately circumferential direction, and the surface roughness in the radial direction was 12 nm as a centerline average surface roughness. A magnetic disk substrate 1o was prepared. The substrate temperature is set to 1 on the main substrate 10.
First, a Cr underlayer 11, . 11' is formed to a thickness of 400 nm, and then a magnetic layer 12.12 having the composition shown in Table 1 is formed.
' was formed with a thickness of 60 nm. Finally, the film thickness is 40 nm.
A carbon protective layer 13.13' was formed. After that.

Barfluoroalkyl polyether liquid lubricant 14
, 1.4' was formed to a thickness of 6 nm to form a magnetic disk.

Table 1 shows the recording and reproducing characteristics of the above disk with a gap length of 0.6 μm.
Media noise during 7 MHz recording was evaluated using a MIG head (using Fe-AQ-3i alloy at the tip of the head) at a relative speed of 15 rn/s. In both cases, noise was reduced compared to the comparative example, and a high medium S/N ratio was obtained. Both media were incorporated into a magnetic disk drive to evaluate their corrosion resistance, and even after being left in a high-temperature, high-humidity furnace at 65°C and 85% RH for three months, the areal density of 50 Mb was higher than that of conventional media. Even when recording and reproducing at a high density of /d, no errors were observed and excellent corrosion resistance was exhibited.

Next, another embodiment using the configuration shown in FIG. 1 will be described. A diameter of 5mm was formed by etching fine irregularities in the approximately circumferential direction so that the center line average surface roughness in the radial direction was 10 nm. An input power of 5 was applied to a tempered glass substrate of IIφ at a substrate temperature of 150° C. in Ar gas containing 0.05 to 0.5 voQ% oxygen and a gas pressure of 10 mTorr.
W/ffl, 300 nm thick Cr, 50 nm thick (Coo, ssCr o, sz) o, eoT a o
, oas i O,071 ZrN film with a thickness of 25 nm was formed. Furthermore, a 4 nm thick perfluoroalkyl polyether adsorbent lubricant was formed to form a magnetic disk.

Analysis of the amount of oxygen atoms in the magnetic film using Auger electron spectroscopy revealed that the film contained lat% to 8at% oxygen.

These media were processed using the magnetic head at a circumferential speed of 10 m.
/s, when recording and reproducing at 5 MHz, both exhibited particularly small noise characteristics of 4.5 μV r m s or less, and exhibited superior characteristics compared to the case without oxygen (5 μV, -s). Ta. Also, regarding corrosion resistance,
Better results were obtained than when no oxygen was added.

The above results are Mo, W, Cr-'l"i, Cr-8i
The same result was obtained when a Cr-Mo alloy was used as the underlayer.

Thin film magnetic head or MIG head and the above 89mm
By using one to four magnetic disks of φ, 5.1 nnφ, we were able to fabricate a large-capacity magnetic disk device with an areal recording density as high as 50 Mb/in'' to 70 Mb/in2 compared to conventional media. In addition, for the same capacity as before, we were able to reduce the number of disks and reduce the disk diameter, making the device more than 30% smaller.Both of these are more than twice as large as conventional devices using continuous metal media. The new magnetic recording device exhibits excellent corrosion resistance and has significantly superior capacity, reliability, etc. compared to conventional magnetic recording devices.

Although the magnetic disk device has been described above, the present invention is not limited to this, but can also be applied to magnetic recording application devices such as magnetic tape devices, magnetic floppy disk devices, magnetic card devices, and magnetic image devices.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to provide a medium that has superior corrosion resistance compared to conventional metal media, has low noise especially during high-density recording/reproduction, and has a high S/H. It is particularly effective in increasing capacity and reliability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a magnetic disk according to an embodiment of the present invention;
FIG. 2 is a characteristic diagram of noise of the medium according to the present invention. 10...Substrate,...Magnetic layer, 1 14.14'11.11'...Underlayer,12.12'3.13'
...Nonmagnetic protective coating layer, ...Lubricating layer.

Claims (1)

[Claims] 1. A magnetic recording medium in which a magnetic layer is formed on a non-magnetic substrate, wherein the magnetic layer contains Co, and further contains at least one member selected from the first group consisting of Cr, Mo, and W. Material X consisting of more than one element, and Ti, Zr, Hf, T
a material Y' consisting of at least one element selected from the second group consisting of a, Nb, Ru, and Rh; and at least one element selected from the third group consisting of Al and Si. A magnetic recording medium comprising at least a material Z made of an element. 2. The composition of the magnetic layer is (Co_1_-_aX_a)_1
___b_-_cY'_bZ_c, 0.03≦a≦0.
20, 0.01≦b≦0.15, 0.01≦c≦0.1
5. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is: 3. The magnetic recording medium according to claim 1 or 2, wherein the magnetic layer contains oxygen of 0.1 at% or more and 15 at% or less. 4. Claims characterized in that an intermediate layer comprising a material made of at least one element selected from the group consisting of Cr, Mo, and W is provided between the magnetic layer and the nonmagnetic substrate. The magnetic recording medium according to any one of items 1 to 3. 5. A magnetic storage device comprising at least the magnetic recording medium according to any one of claims 1 to 4.