JPH0157413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage medium such as a magnetic disk used in a magnetic storage device.

In the longitudinal recording system mainly used at present, continuous magnetic thin film type plated magnetic disks and ferrite sputtered magnetic disks are recently used as high-density storage media. I started. A high-performance magnetic disk device using a magnetic disk using these continuous magnetic thin films as a storage medium was developed in 1981, achieving high recording densities of 14,000 BPI in linear density and 1,100 TPI in track density.

In the future, the density will continue to increase, and research and development to improve the linear density and track density are actively being carried out. Regarding track density, a servo surface servo method using a servo disk has been used for a long time, but with this method, differences in thermal expansion due to temperature differences caused by the physical distance and structure between the servo disk and data disk are considered. This has become a major obstacle to increasing track density. As a method to eliminate this drawback, it has been reported that a magnetic disk having a two-layer storage medium is used. In other words, in the mainly used γ-Fe ₂ O ₃ coated disk, servo information is recorded in the lower medium layer and data information is recorded in the upper medium layer, thereby avoiding track position deviation due to temperature differences. be. However, in γ-Fe ₂ O ₃ coated disks, it is difficult to make the medium layer thinner, so it is difficult to greatly increase the recording density, and the medium S/N ratio at high density is small. are doing.

On the other hand, in perpendicular recording, research and development is currently being carried out mainly on cobalt-chromium alloy sputter media, but it has been reported that the linear density of rigid disks may be as high as 70,000 FRPI (Flux Reversal Per Inch). It has also been reported that a floppy disk may have a linear density of about 80,000 FRPI at _D50 .

However, the track densities shown in these reports are very small, much smaller than the current track density of longitudinal records (1100 TPI). Also, when using a cobalt-nickel-phosphorus alloy produced by the Metsuki method as the lower layer magnetic film for servo, the coercive force must be increased.
The drawback is that it cannot be increased above 1100Oc.

The purpose of the present invention is to realize a data servo system that is capable of high linear density and high track density and has a good medium S/N ratio at high density. An object of the present invention is to provide a magnetic double-layer perpendicular magnetic storage body having a thin film medium and having a cobalt chromium perpendicular recording magnetic medium as an upper layer data information medium.

The magnetic double-layer magnetic memory according to the present invention includes a non-magnetic substrate, a high coercive force iron oxide layer for servo signals covering the non-magnetic substrate, a non-magnetic layer covering the high coercive force iron oxide layer, and a non-magnetic layer (e.g. SiO ₂
It has a multilayer structure consisting of a data signal perpendicular anisotropic magnetic layer (for example, a Co--Cr sputtered film) covering a perpendicular magnetic anisotropic magnetic film (a sputtered film), and a protective film covering this perpendicular anisotropic magnetic film.

In this magnetic storage body, servo information is recorded in the lower high coercive force oxide magnetic layer, which serves as the magnetic medium for servo, by longitudinal recording, and data is recorded in the upper perpendicular magnetic anisotropic magnetic layer, which serves as the magnetic medium for data, by perpendicular recording. Information is recorded. As a perpendicular magnetic anisotropic magnetic medium,
When a cobalt-chromium spatter film is used, since the cobalt-chromium film has corrosion resistance, the protective film layer can be made thinner, so the spacing can be reduced, and a high linear density can be achieved as a perpendicular magnetic recording medium. The high coercive force iron oxide magnetic layer enables data plane servo, thereby enabling high track densities.

The features of the magnetic double layer perpendicular magnetic storage body according to the present invention will be explained below using examples.

Example 1 An embodiment of the present invention is shown in FIG.

In Fig. 1, a film with a film thickness of 0.2 to 0.5 μm and having a high coercive force (e.g. 1000 Oe or _more ) is coated on a non-magnetic substrate 1 made of a non _- magnetic nickel alloy plated and polished on an aluminum plate. ) Iron oxide layer 2
on this high coercive force iron oxide layer 2.
0.2-0.6μm non-magnetic layer (e.g. _SiO2 sputtered layer)
3, and on this nonmagnetic layer 3, a perpendicularly magnetic anisotropic magnetic layer 4 having a film thickness of 0.5 μm mainly composed of a cobalt-chromium alloy is coated by a sputtering method. A protective film layer (for example, SiO ₂
A sputter layer) 5 is formed.

Servo information is recorded on the high coercive force iron oxide layer 2 and the perpendicular anisotropic magnetic layer 4 using the thus obtained magnetic double layer perpendicular magnetic storage body under conditions of small spacing using a servo recording head with a large gap length. Thereafter, only the servo information recorded on the perpendicular magnetic anisotropic magnetic layer 2 is erased under conditions of large spacing using a data recording/reproducing head with a small gap length. Since the high coercive force iron oxide 2 has a high coercive force, it is not changed in any way when data is recorded or reproduced by the data recording/reproducing head, and only the previously recorded servo information remains, and the servo information is transferred to the gap length. The data is reproduced by the data recording/reproducing head having a small value and used as a servo signal.

The perpendicular magnetic anisotropic magnetic layer 4 mainly composed of cobalt-chromium alloy in the upper layer makes it possible to achieve high linear density (70000 FRPI) due to the data head with a small gap length, and the perpendicular magnetic anisotropic magnetic layer ₄ mainly composed of cobalt-chromium alloy in the lower layer makes it possible to achieve high linear density ( ₇₀₀₀₀ FRPI). The high coercive force iron oxide layer 2 has a high track density (1500~
3000TPI).

Example 2 FIG. 2 shows the structure of a double-layer magnetic film similar to Example 1, but the substrate is different.

That is, when applied to a flexible disk, the polyimide film 6 was used as a nonmagnetic substrate, and a magnetic double layer magnetic film similar to that in Example 1 was formed thereon.

The flexible disk produced in this manner achieved a linear density of 80,000 FRPI, making it possible to achieve a sufficiently high density. Also, the servo information of the underlying high coercive force iron oxide film makes it possible to achieve high track density. Furthermore, there is no problem in using resins other than polyimide as the substrate of the flexible disk.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the magnetic double layer perpendicular magnetic memory used in Example 1. 1... Nonmagnetic substrate, 2... High coercive force iron oxide layer, 3...
Non-magnetic layer, 4... Perpendicular magnetic anisotropic magnetic layer (for example, cobalt chromium), 5... Protective film layer. FIG. 2 is a cross-sectional view of the magnetic double layer perpendicular magnetic memory used in Example 2. 6...Polyimide film.

Claims (1)

[Claims] 1 A non-magnetic substrate, a high coercive force iron oxide for servo signals that covers this non-magnetic substrate, a non-magnetic layer that covers this high coercive force iron oxide layer, and a cobalt chromium vertical layer for data signals that covers this non-magnetic layer. A magnetic double-layer perpendicular magnetic memory comprising a magnetic anisotropic layer and a protective film layer covering the perpendicular magnetic anisotropic layer.