JPH0715754B2 - Perpendicular magnetization rigid disk - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perpendicular magnetization rigid disk, and by setting the surface roughness to Rmax <50Å, it can sufficiently withstand recording and reproducing even when a magnetic head is brought into contact with it. Has durability,
It is designed to maximize the resolution of perpendicularly magnetized rigid discs.

2. Description of the Related Art Conventionally, as a disk type magnetic recording medium, a rigid disk made of a rigid base made of aluminum is known as well as a prop disc made of a flexible base made of polyester film or the like. The rigid disk is flexible in that it can speed up the relative movement with the magnetic head, speed up magnetic recording and reproduction, and speed up data transfer. The disc is excellent.

Conventional rigid discs include an in-plane magnetized rigid disc in which a magnetic film for in-plane magnetic recording is formed on a rigid substrate made of aluminum, and a perpendicularly magnetized rigid disc in which a perpendicular anisotropic film is formed on the same rigid substrate. It has been known.

However, the in-plane magnetized rigid disk has a problem that the resolution is lowered due to the demagnetization effect in the plane,
Further, even if the flying height of the magnetic head is reduced, the recording / reproducing characteristics and the recording density characteristics are not improved, and there is a limit in improving the characteristics.

On the other hand, the perpendicular magnetization rigid disk does not have the demagnetization effect, which has been a major barrier to high density in the in-plane magnetization rigid disk, and the higher the magnetic head flying height, the higher the resolution obtained. To be

Fig. 1 shows the magnetic head flying height h ₁ and recording density D ₅₀ (K FRP
It is a characteristic view showing a relationship with I), a curve L ₁ is a characteristic of an in-plane magnetized rigid disk, and a curve L ₂ is a characteristic of a perpendicular magnetic disk. The recording density D ₅₀ is the recording density at which the reproduction output is 50%, and the unit (FRPI) is Flux reversal per
inch (magnetic flux reversal per inch).

As is clear from FIG. 1, in-plane magnetization rigid. In the case of a disk, even if the flying height of the magnetic head is lowered, the recording density D ₅₀ is substantially constant in the range where the flying height of the magnetic head is 0.2 μm or less. On the other hand, in the case of the perpendicular magnetization rigid disk, the recording density D ₅₀ increases exponentially as the flying height of the magnetic head decreases. When the flying height of the magnetic head is 0.2 μm or less, recording / reproducing characteristics and recording density characteristics superior to those of the in-plane magnetized rigid disk can be obtained. Especially the magnetic head flying height h ₁ is 0μ
m, that is, when the magnetic head is brought into contact with the magnetic head, extremely excellent characteristics are obtained, and the resolution of the perpendicular magnetization rigid disk is maximized.

Problems to be Solved by the Invention As described above, in the case of the perpendicular magnetization rigid disk, unlike the in-plane magnetization rigid disk, when recording and reproducing are performed by contacting the magnetic head, extremely excellent characteristics are obtained,
The high resolution of itself is maximized.

However, since it is necessary to move the perpendicular magnetization rigid disk and the magnetic head relative to each other during recording and reproduction, the magnetic head is brought into contact with the perpendicular magnetization rigid disk to maximize the high resolution of the perpendicular magnetization rigid disk. However, there is a problem that a head crash occurs due to contact friction or the like.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention provides a perpendicular magnetization rigid disk in which at least a perpendicular anisotropic film is formed on a rigid substrate, and the surface of the perpendicular anisotropic film is provided. It is characterized in that the surface roughness Rmax of the vertical anisotropic film due to the unevenness generated without having the directivity is set to 0 <Rmax <50Å.

The durability, which is a problem when the perpendicularly magnetized rigid disk and the magnetic head are moved in contact with each other, is closely related to the surface property of the disk. The present inventors produced perpendicularly magnetized rigid disks by varying the surface roughness Rmax, and the magnetic head flying height h ₁ was 0.2 μm, 0.1 μm, 0 μm.
100,000 times of CSS for each case of m (contact)
(Contact, start, stop) A durability test was conducted. The result is shown in FIG.

As shown in FIG. 2, the flying height h ₁ of the magnetic head is 0.2 μm.
In the case of, the surface roughness Rmax of the perpendicular magnetization rigid disk
Was less than 200Å, head crashes and other accidents did not occur, and CSS was possible 100,000 times. However, in the contact state, that is, when the magnetic head flying height h ₁ = 0 μm,
Even with a surface roughness Rmax of about 100Å, head crashes occurred with CSS of several thousand times, and durability that could withstand practical use was not obtained.

Therefore, the present inventors further improved the surface property of the perpendicular magnetization rigid disk and repeated the CSS durability test, and by driving the surface roughness Rmax into a region of 50 Å or less, the contact state, that is, the flying height of the magnetic head. Even when h ₁ = 0 μm, it was found that an accident such as head crash did not occur and sufficient durability that could be practically used was obtained. In this region, the high resolution of the perpendicular magnetization rigid disk can be maximized with high reliability. The data in FIG. 2 shows that the above-described effects can be obtained in the range where the surface roughness Rmax is smaller than 50Å, that is, in the range where 0 <Rmax <50Å is satisfied.

The surface property of the perpendicularly magnetized rigid disk reflects the surface property of the rigid base used, and thus the material of the rigid base is an important factor. The inventors of the present invention conducted surface polishing experiments on various materials and found that a ceramic substrate such as alumina silicate reinforced glass had a surface roughness higher than that of an aluminum substrate conventionally used for an in-plane magnetized rigid disk. We have found that it has particularly good characteristics in the region of Rmax = 50Å or less. FIG. 3 is a plot of the substrate surface polishing step yield with respect to each surface roughness Rmax. In the area where the surface roughness Rmax is 50 Å or less, the yield of aluminum substrate was only 20 to 30%.
A very high yield of 80% has been obtained with a substrate made of alumina silicate strengthened glass.

As a concrete structure of the perpendicular magnetization rigid disk, as shown in FIG. And the perpendicular anisotropic film 3 is formed on the high magnetic permeability layer 2 directly or via an intermediate layer, or as shown in FIG. It is conceivable that the anisotropic film 3 is formed directly without providing a high magnetic permeability layer or via an underlayer, and a protective layer is formed on each surface as necessary. The high magnetic permeability layer 2 is made of, for example, Ni-Fe-Mo-based supermalloy or Ni-Fe-based permalloy, and the perpendicular anisotropic film 3 is made of a composition such as Co-Cr.

EFFECTS OF THE INVENTION As described above, according to the present invention, by setting the surface roughness of the vertical anisotropic film to Rmax <50Å, it is possible to sufficiently endure even when recording / reproducing by contacting the magnetic head. It is possible to provide a perpendicularly magnetized rigid disk that has high properties, does not cause head crashes, and can maximize its high resolution.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing the relation between the flying height of the magnetic head and the recording density D ₅₀ , FIG. 2 is a diagram showing the relation between the surface roughness of a perpendicular magnetization rigid disk and the CSS durability, and FIG. 3 is the substrate surface. Diagram showing the relationship between the roughness and the substrate surface polishing step yield,
4 and 5 are cross-sectional views of the perpendicular magnetization rigid disk. 1 ... Rigid substrate 3 ... Vertical anisotropic film

Claims (3)

[Claims] 1. A perpendicularly magnetized rigid disk in which at least a perpendicular anisotropic film is formed on a rigid substrate, and the surface of the perpendicular anisotropic film is formed by unevenness generated on the surface of the perpendicular anisotropic film without having directionality. Perpendicular magnetization rigid disk having a roughness Rmax of 0 <Rmax <50Å. 2. The perpendicular magnetization rigid disk according to claim 1, wherein the rigid base is made of ceramic. 3. The perpendicularly magnetized rigid disk according to claim 2, wherein the ceramic is made of alumina silicate strengthened glass.