JPS60191428A - Vertically magnetized recording body - Google Patents

Abstract

PURPOSE:To assure excellent wear resistance and to enable magnetic recording to high density by constituting the uppermost layer of a thin film consisting substantially of Fe-Co ferrite. CONSTITUTION:A thin film of the Fe-Co ferrite having substantially compsn. formula: CoxFe3-xO4 (where x has preferably the value within a 0.01-1.0 range) used as a target is formed by an ordinary sputtering method atop the thin film of a magnetic recording medium constituted of a Co alloy having the magnetic anisotropy vertical to the film plane with a vertically magnetized recording body. The thin Fe-Co ferrite film has excellent wear resistance and magnetic recording characteristics and therefore the magnetic recording to high density is made possible in the state of having substantially no wear and damage by a magnetic head in the magnetic recording stage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a perpendicular magnetization recording medium having a thin film of a magnetic recording medium having excellent wear resistance and magnetic recording characteristics and having magnetic anisotropy perpendicular to the film surface. It is.

In general, magnetic disks, floppy disks, audio magnetic tapes, VTR magnetic tapes, magnetic photographic disks, and computer magnetic tapes have vertical magnetic recording functions that enable high-density magnetic recording. It is known as a magnetized recording medium.

These perpendicular magnetization recording bodies are usually produced by sputtering, vacuum evaporation,
Furthermore, using surface treatment techniques such as chemical plating, Co-based alloys such as Co-Cr alloys, Co-Ru@gold, and Co-Cr-Ru, which have magnetic anisotropy perpendicular to the film surface, are used. The thin film of the constructed magnetic recording medium is directly
Alternatively, it is manufactured by forming a thin film such as Fe--Ni alloy having high magnetic permeability.

However, although the perpendicular magnetization recording medium described above has excellent perpendicular magnetization characteristics, the thin film of the magnetic recording medium made of Co-based alloy is soft, so Mn-Z
When it comes into frictional contact with a magnetic head made of single crystal N-type ferrite, high-density ferrite, or hard materials such as sendust or amorphous metals, it will cause significant wear and damage will easily occur, so it is not recommended for practical use. Further, on top of that, alumina (A4
A non-magnetic hard thin film composed of hOa) or silica (5iO2)? At present, the wear of the magnetic head is suppressed by forming a magnetic head.

However, even in this conventional perpendicular magnetization recording material with excellent wear resistance, the uppermost layer is M2O3 or 5i as described above.
Since it is composed of a non-magnetic thin film such as 02, during magnetic recording, the magnetic field is separated by the thickness of the top layer fL.
Since magnetic recording is performed on the underlying magnetic recording medium in the 'fc state, that is, in a state where there is a space loss, the magnetic recording density is reduced by that amount.

Therefore, from the above-mentioned viewpoint, the present inventors conducted research to develop a perpendicular magnetization recording material that has excellent wear resistance and does not reduce magnetic recording density. f'L is made of a CO-based alloy with magnetic anisotropy perpendicular to the upper surface of the thin film of the magnetic recording medium.
In the normal sputtering method, the target is substantially the compositional formula: CoxFe3-XO4 (however, xn
It is desirable to have all values within the range of O, 01 to 1.0)
This Fe −
When a thin film of Go-based ferrite is formed, the Fe −
Co-based ferrite thin film has excellent abrasion resistance and magnetic recording characteristics.As a result, the top layer is made of Fe-Co.
In perpendicularly magnetized recording bodies composed of thin films of ferrite, we obtained the knowledge that it is possible to perform high-density magnetic recording with almost no wear or damage caused by the magnetic head. It was.

The present invention has been made based on the above findings, and includes a top layer on the top surface of a thin film of a magnetic recording medium made of a CO-based alloy having magnetic anisotropy perpendicular to the film surface. Fe − has excellent wear resistance and magnetic recording properties.
This is a perpendicular magnetization recording body formed by forming a thin film made of Co-based ferrite.

Next, the perpendicular magnetization recording body of the present invention will be specifically explained using examples.

As an example substrate, a polyester film with a thickness of 150 μm was prepared, and this substrate was mounted on a normal magnetron sputtering device and was sputtered with Fe-Nj and alloy* respectively while adding one rotation tray.
(Ni: 50% content), Co-Cr alloy (C!r: 18
% content], alumina (M2O3), silica (5102
), and various types of Fe having the compositions shown in Table 1.
-Using a Co-based ferrite target.

(1) Ultimate vacuum: 2. OX 10 torr or less,
(2) Ar gas pressure: 3. OX l OtQrr.

(3) Distance between substrate and target: 50 mmb (4) Discharge power and sputtering time, (a) For Co-Cr alloy and Fe-Ni Taiwan target: D0360W
(b) For Fe-co ferrite, M2O3, and 5i02 targets: 600 seconds at RF 100W
seconds.

The perpendicular magnetization recording bodies 1 to 6 of the present invention and the conventional perpendicular magnetization recording bodies 1 and 2 were obtained by performing sputtering under the following conditions to sequentially form thin films having the average layer thickness shown in Table 1 on the entire surface of the substrate. manufactured respectively.

Next, the anisotropic magnetic field (H
k) and coercive force (Hc) f, then formed it into a floppy disk size, and conducted a running test using the sound of a disk drive equipped with a ferrite head.
For the purpose of evaluating wear resistance, we measured the ratio of the reproduction voltage (Vm) to the initial reproduction voltage (Vi, ) after 1 million passes, that is, γ-V m / Vi (deterioration rate), and In order to fully evaluate the magnetic recording characteristics, seven recording and reproducing operations were performed with all recording densities varied, and all measurements were made at the recording density (D50) at which the reproducing voltage was half the reproducing voltage of IKBPI.

Furthermore, the above various Fe-Co based ferrites were deposited on a glass substrate under the same conditions except that the sputtering time was 2 hours.
, M2O3r and 5i02 were completely formed, and the hardness of these formed thin films was measured using a Knoop hardness meter. What are the results of these measurements? In line with Table 1, -7~ is shown.

From the results shown in Table 1, perpendicular magnetization recording bodies 1 to 1 of the present invention
It is clear that the material No. 6 not only has superior wear resistance compared to the conventional perpendicular magnetization recording materials 1 and 2, but also enables much higher density magnetic recording.

As mentioned above, the perpendicular magnetization recording body of the present invention has excellent wear resistance and is capable of high-density magnetic recording by configuring its uppermost layer with a thin film consisting essentially of Fe-C0 ferrite. This made it possible.

Applicant: Mitsubishi Shogun Co., Ltd. Agent Tomi 1) Kazuo and 1 other person 8-

Claims (1)

[Claims] Co whose surface thin film has magnetic anisotropy perpendicular to the film surface
In a perpendicular magnetization recording medium made of a magnetic recording medium made of a perpendicular alloy, the perpendicular magnetization recording medium is further formed entirely of a thin film made of Fe-Co ferrite having excellent wear resistance and magnetic recording properties on the surface thin film. body.