JPS59142737A - Vertical magnetic storage body with two magnetic layers - Google Patents

Abstract

PURPOSE:To reduce the thickness of a protection film layer, to reduce the spacing, and to obtain high linear density by using a corrosion resistant cobalt- chromium film as a vertical magnetic recording medium. CONSTITUTION:A head for servo recording of a magnetic double-layered vertical magnetic storage body which has large gap length records servo information in an iron oxide layer 2 with high coercive force and a magnetic layer 4 with vertical anisotropy on small spacing condition, and a head for recording and reproducing data which has small gap length erases only the servo information recorded in the magnetic layer 2 with vertical magnetic anisotropy on large spacing condition. The magnetic layer 4 consisting principally of cobalt-chromiun alloy as an upper layer has high linear density (70,000FRPI) by the data head with small gap length and the high-coercive-force iron oxide layer 2 consisting principally of beta-Fe2O3 as a lower layer has high track density (1,500-3,000TPI).

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 currently mainly used longitudinal recording method, magnetic disks plated with continuous magnetic thin film dust produced by plating or sputtering methods and ferrite sputtered magnetic disks have recently been used as high-density storage media. I started. A high-performance magnetic disk device using magnetic disks using these continuous magnetic thin films as storage media was developed in 1981, with a linear density of 14,000 BPI and a rack density of 11.
A high recording density of 00 TPI has been achieved.

In the future, as density increases further, research and development efforts are being actively conducted to improve the line density and trunk density. Regarding track density, a length-to-surface servo method using a servo disk has been used, but this method does not allow thermal expansion due to temperature differences caused by the physical distance and structure between the servo disk and the data disk. This difference 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.

That is, in the mainly used γ-Fe20s coated disks, servo information is recorded in the φ lower medium layer and data information is recorded in the upper medium layer, thereby avoiding track position deviation due to temperature differences. . However, in coated disks, it is difficult to make the medium layer thinner, so it is difficult to greatly increase the recording density, and the disadvantage is that the medium S/N is small at high density. It depends on what you have.

On the other hand, in perpendicular recording, research and development is currently being conducted centering on cobalt-chromium alloy sputtering media.
In a rigid disk, the linear density is 70.00+1F
fLrl (Flux Eversal Per In
It has been reported that there is a possibility of floppy disks. It has been reported that there is a possibility of a linear density of about 80,00o FRPI.

However, the track densities shown in these reports are very small, and the current track density of longitudinal recording (Iloo
TPI) is significantly smaller. Furthermore, when a cobalt-nickel-phosphorus alloy formed by plating is used as the lower layer magnetic film for servo, there is a drawback that the coercive force cannot be increased to 11000e or more.

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

The magnetic double layer magnetic storage body according to the present invention includes a nonmagnetic substrate,
A high coercive force iron oxide layer that covers this nonmagnetic substrate, a nonmagnetic layer that covers this high coercive force iron oxide layer, and this nonmagnetic layer (
It has a multilayer structure consisting of a perpendicular magnetic anisotropic magnetic layer (for example, a Co--Cr sputtered film) that covers a perpendicular magnetic anisotropic magnetic film (for example, 5102 sputtered film) and a protective film that covers this perpendicular magnetic 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. When a cobalt-chromium sputtered film is used as a perpendicular magnetic anisotropic magnetic medium, since the cobalt-chromium film has corrosion resistance, the protective film layer can be made thinner, so the spacing can be reduced, making it suitable for use as a perpendicular magnetic recording medium. A high linear density can be achieved, and a high track density can be achieved because the underlying high coercive force iron oxide magnetic layer for servo allows servo on the side surface.

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

Example 1 A practical example of the present invention is shown in Figure M1.

In FIG. 1, a film with a thickness of 0.0 mm is deposited on a non-magnetic substrate 1 made of a non-magnetic nickel alloy plated and polished on an aluminum base plate.
A high coercive force (e.g., 10,000 e or more) iron oxide layer 2 mainly composed of γ-Fe2O3 with a thickness of 2 to 05 μm is coated, and a nonmagnetic layer with a film thickness of 0.2 to 0.6 μm is formed on the high coercive force iron oxide layer 2. (for example, a Sin, sputtered layer) 3, and on this nonmagnetic layer 3, a perpendicular magnetic anisotropic magnetic layer 4 mainly composed of a cobalt-chromium alloy with a thickness of 0.5 μm is coated on this nonmagnetic layer 3 by a sputtering method. Then, a retention film (for example, a 5iOl sputtered layer) 5 having a thickness of 0.02 #m is formed on the perpendicular magnetic anisotropic magnetic layer 4 mainly composed of cobalt and chromium.

The magnetic double-layer perpendicular magnetic memory obtained in this manner is used in a servo recording head with a large gap length under conditions of small cisbasing, and servo information is transferred to the high coercive force iron oxide layer 2 and the perpendicular anisotropic magnetic layer 4. After that, only the servo information recorded in the perpendicular magnetic anisotropic magnetic layer 2 is erased using a data recording/reproducing head with a small gap length under conditions of a large cisbasing. Since the high coercive force iron oxide 2 has a high coercive force, it is not changed in any way when data is recorded/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 yen, and used as a servo signal.

The perpendicular magnetic anisotropic magnetic layer 4 mainly composed of a cobalt-chromium alloy in the upper layer enables a data head with a small gap length to achieve a high linear density (70,000'FRP I), and the γ- The high coercive force iron oxide layer grass containing Fe and O1 as main components has a high trunk density [(1500~3000TP
I).

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 M magnetic film similar to that in Example 1 was formed thereon.

The flexible disk produced in this way has a linear density of s
a, o o OI of 8°RPI was achieved, and sufficiently high density was possible. Also, one of the lower high coercive force iron oxide layers.
High track density has become possible based on the information. Furthermore, there is no problem in using resins other than polyimide as the substrate of the flexible disk.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the magnetic double layer perpendicular magnetic memory used in Example 1. 1. Non-magnetic substrate, 2. High coercive force iron oxide layer, 3. Non-magnetic layer, 4. Perpendicular magnetic anisotropy magnetic layer (e.g. 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 membrane. S − μ , 3 ~ 2 − B

Claims (1)

[Claims] a nonmagnetic substrate, a high coercivity iron oxide covering the nonmagnetic substrate, a nonmagnetic layer covering the high coercivity iron oxide scrap, a cobalt chromium perpendicular magnetic anisotropy layer covering the nonmagnetic layer, A magnetic double-layer perpendicular magnetic memory comprising a protective film layer covering the perpendicular magnetic anisotropic layer.