JPS62164205A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To increase the magnetic flux density of the titled recording medium and to further reduce the thickness of the thin film by forming the substrate with Mn or V, and forming the magnetic layer with a Co-base alloy. CONSTITUTION:The magnetic recording medium consists of the substrate layer formed on a substrate and consisting of Mn or V and a magnetic layer formed with a Co-base alloy contg. <=35atom% Ni or <=20atom% Cr or <=45atom% total amt. of Ni and Cr. When a layer consisting of an element selected from Si, Ge, and Ti is provided between the substrate layer and the substrate, uniform crystal growth of the metal in the substrate layer is promoted. With this constitution, the magnetic flux density is increased, and the recording medium with a thin film can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media, particularly fixed magnetic disks or flexible disks used in computer external memory devices.

[Conventional technology]

In recent years, as computers have become smaller and their processing power has increased, there has been a demand for further increases in the storage capacity of external memory devices. In order to satisfy this demand, it is necessary to further increase the recording density of memory disks used in external memory devices, and for this purpose, it is necessary to improve the magnetic properties of the magnetic thin film that forms the recording layer and to make the recording layer even thicker. It is necessary to promote thinning of the film.

Therefore, as one method for satisfying such requirements, a method of forming a recording layer by a sputtering method was developed, as disclosed in Japanese Patent Publication No. 14058/1983.

The method involves forming a thin film layer of FeJa on a disk substrate by reactive sputtering using iron or an iron alloy as a target, and then thermally oxidizing this to form γ-Fe2O3.

[Problem that the invention seeks to solve]

In the above-mentioned magnetic recording medium, since the magnetic layer is an oxide, the saturation magnetic flux density is small and there is a limit to how thin the layer can be made to be for practical use as a recording medium.

In addition, since a heat treatment process of 250°C or higher is required, if a substrate with an N1-P underlayer formed on an aluminum alloy is used, the N1-P layer will become magnetized, resulting in deterioration of recording characteristics and reducing the cost of low-cost materials. The problem was that the board could not be used. The present invention is characterized in that a medium with a high saturation magnetic flux density is epitaxially grown by forming a special underlayer so that the axis of easy magnetization is in the plane of the film, resulting in a high coercive force and hysteresis squareness.

Conventionally, a Cr underlayer was formed for this purpose, but C
Since the r base film is extremely active, its surface is oxidized by trace amounts of 0□ gas in the atmosphere, which impedes the epitaxy growth of the magnetic film and makes it difficult to control the coercive force and squareness ratio.

That is, in a high vacuum with a back pressure of 10-6 Torr or more,
Flowing Ar gas at 20 mTorr, the Cr base film was heated at 50 mTorr.
In the case of sputtering by 00 people, Hc tends to decrease as the time until the next magnetic film is formed increases. For this reason, control of back pressure, Ar gas purity, and magnetic film formation time after formation of the underlayer is extremely important, and it has been difficult to control magnetism in the manufacturing method of magnetic disks using such a Cr underlayer.

[Means for solving problems]

In order to solve the above-mentioned problems of the prior art, the present invention provides Mn
, Mo or V underlayer and a Co-based magnetic layer formed thereon.

The present invention will be explained in more detail below.

In the magnetic recording medium of the present invention, a magnetic layer is formed on a Mn, Mo or (2) underlayer. The magnetic layer is preferably a Co-based alloy and has a composition containing 35 atomic % or less of Ni, 20 atomic % or less of Cr, or a total amount of Ni and Cr of 45 atomic % or less. The reason for limiting this composition is that if any composition exceeds the upper limit, f, c, c,
This is because the phase becomes an equiaxed anisotropic structure, making it impossible to obtain appropriate magnetic properties for the recording medium.

The Mn, Mo, V underlayer and Co-based alloy magnetic layer are formed by ion engineering means such as sputtering, ion beam sputter linking, and vacuum evaporation.

The Co-based alloy magnetic layer is grown on the Mn, Mo, and V layers by crystal growth that satisfies the two-dimensional orientation relationship with this underlayer, so-called epitaxial growth, so that the easy axis of magnetization of the Co-based alloy having the c, p, structure. It is considered that the C-axis direction is inclined in the magnetic plane and has magnetic properties suitable as a longitudinal recording medium. The thickness of the Mn, Mo, and V underlayers is not particularly limited.
When an r Ti layer or the like is provided, a layer of Si, Ge, Ti, etc. has the effect of promoting uniform crystal growth of the Mn, Mo, or V underlayer and reducing the thickness of the underlayer. Furthermore, S.L.G.
e, Ti layer is also formed by ionotechnical means.

[Example] 1 A base film and a magnetic film were formed under the following conditions using a flat plate magnetron r, f sputtering device.

Initial exhaust pressure < 3 X 10-'Torr Ar pressure during sputtering 1 to 8 mTOrr (base layer) 10 to 2
0mTorr (magnetic layer) Input power 300W Target composition 0~40at%Ni10~25a
t%Cr 2O to 30at%Ni, 10 to 20at%Cr, balance Co Pole spacing 6011 Substrate temperature 100 to 200°C Magnetic layer thickness 700A Substrate Glass The magnetic properties of this magnetic recording medium are as shown in Table 1. Ta. The magnetic properties showed similarly high magnetic property values even after 50 hours had elapsed, regardless of the time after the formation of the first and second underlayer films. In this respect, the controllability of properties was also superior to the conventional method using a Cr base.

A thin film formed in the same manner as in Example 1 without a second layer base film of Mn, V, etc. had a coercive force of about 2000e (Table I
No, 14. No. 15), it was unsuitable as a magnetic recording medium. Co-40Ni, Co-25Cr.

Co-3ON+-20Cr medium (Table 111k1.3.h
At k1.5°8), the Co composition is low (
Ni.

Sufficient coercive force could not be obtained because the Cr composition was too large. Furthermore, after 50 hours of forming a 0.5 μm thick Cr underlayer, a similar medium was formed under the same conditions as in Table 1, but Hc was 4000.
It was less than e and was unsuitable for the medium.

〔Effect of the invention〕

As described above, by providing the Mn, Mo, and V underlayers under the Co-based alloy magnetic layer, the magnetic recording medium of the present invention can obtain better in-plane magnetic properties than the conventional γ-Fe203 sputtered film. It has more than three times the magnetic flux density, making it possible to make the film even thinner, making it possible to manufacture new recording media.

Stabilized ZrO□ (ZrO□・6Y
203) The same underlayer effect as glass was observed when using ceramic substrates, NiP plating treatment, 11 substrates, and alumite treatment Aβ substrates, and high coercive force and high A magnetic flux density medium was obtained.

According to the present invention, it has become possible to obtain an alloy longitudinal magnetic recording medium having high magnetic properties with better controllability than a Cr underlayer.

Claims (4)

[Claims] (1) A magnetic recording medium comprising an underlayer and a magnetic layer formed on a substrate, wherein the underlayer is made of Mn, Mo or V, and the magnetic layer is made of a Co-based alloy. (2) Claims characterized in that the magnetic layer contains 35 atomic % or less of Ni, 20 atomic % or less of Cr, or 45 atomic % or less of the total amount of Ni and Cr, with the remainder substantially consisting of Co. The magnetic recording medium according to item 1. (3) In a magnetic recording medium consisting of an underlayer and a magnetic layer formed on a substrate, this underlayer is made of Si, Ge, and T.
a first layer consisting of at least one element selected from i;
A magnetic recording medium comprising a second layer made of Mn, Mo or V formed thereon, and a magnetic layer made of a Co-based alloy. (4) A patent claim characterized in that the magnetic layer contains 35 atomic % or less of Ni, 20 atomic % or less of Cr, or 45 atomic % or less of the total amount of Ni and Cr, with the remainder substantially consisting of Co. The magnetic recording medium according to item 3.