JPH01292802A - Highly corrosion-resistant amorphous magnetic film - Google Patents

Abstract

PURPOSE:To improve the corrosion-resistance without deterioration of the magnetic characteristics by adding a specific amount of additive element selected among Au, Ag and Pt to CoTaZr system amorphous film material whose Co content is 90at% or larger. CONSTITUTION:Amorphous magnetic film material is composed of a composition expressed by a formula I wherein element M denotes one or more elements selected among Au, Ag and Pt and A, B, C and D denote contents (at%) which conform to the conditions A>=90, B/C<=3/5, D>=1 and A+B+C+D=100. With this constitution, even if the Co content is 90at% or larger, a CoTaZrM system amorphous film having high corrosion resistance, a low coercive force and no magnetostriction can be obtained, so that a magnetic head having high saturation flux and high reliability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetic film used in a thin-film head magnetic pole suitable for high-density magnetic recording, particularly a high saturation magnetic flux density.

The present invention relates to a highly corrosion-resistant amorphous magnetic film having high corrosion resistance.

[Conventional technology]

There has been remarkable progress in increasing the density and performance of magnetic recording. In the field of magnetic disk drives for large computers, it is essential to use thin-film magnetic heads, which have lower inductance and higher high-frequency magnetic permeability than conventional ferrite bulk heads, and can be processed into narrow track widths. ing.

In thin-film magnetic heads, it is necessary to make the magnetic pole thinner to improve resolution as recording density increases, and magnetic saturation tends to occur at the tip of the thin magnetic pole. A thin film magnetic head using a film is now required.

Further, in a magnetic disk device, the magnetic head and the recording medium move relative to each other at a speed of 3600 m/see while maintaining a spacing of about 0.1 to 0.2 μm. Therefore, if corrosion products of the magnetic pole magnetic film of the magnetic head are present on the medium, the magnetic head and the recording medium will crash, and both will be damaged.

Therefore, a magnetic film for a magnetic disk must have higher corrosion resistance than a magnetic film used for a VTR head.

Conventionally, the magnetic film of thin-film magnetic heads has mainly been made of Ni-F.
E-based alloy films (permalloy films) have been used. Ni-
The Fe-based alloy film has excellent corrosion resistance, but the saturation magnetic flux density is 1. It is OT. In order to increase the saturation magnetic flux density in the future, N
i-Fe is no longer able to handle the situation.

In recent years, amorphous sputtered films have been developed as high-performance magnetic films with high saturation magnetic flux density. Among these, the vitrification elements of the Zr-based amorphous film are B and Si.

It has better heat resistance than an amorphous alloy made of P, and has excellent properties as a magnetic film for a magnetic head. The composition of this Zr-based amorphous film is represented by the composition formula of MaTaZr. Here, M is Go with a magnetic moment,
T is at least one of Fe and Ni, and T is a transition metal other than M and Zr.

Regarding such amorphous alloys in which the vitrifying element is mainly Zr, Japanese Patent Application Laid-open No. 55-138049 and Japanese Patent Application Laid-open No. 55-138
6-84439 etc. Among these Zr-based amorphous alloys, C is one in which M is CO.

The -Zr-based amorphous film has a high saturation magnetic flux density and is an excellent magnetic material. However, the magnetostriction constant of this amorphous alloy is 2
V, Nb, and
By using elements such as Ta, Mo, and W, an amorphous alloy with a magnetostriction constant of approximately 0 can be obtained. Such amorphous alloys are described in the 6th Japanese Society of Applied Magnetics Lecture Abstracts, p. 93.
(1982), a saturation magnetic flux density of 1.5 T can be obtained at zero magnetostriction, so it is considered promising as a thin film magnetic head.

[iM to be Solved by the Invention] The above-mentioned prior art is an excellent material for a thin film magnetic head from the viewpoint of saturation magnetic flux density and magnetostriction constant, but it has a problem in corrosion resistance. In other words, it has become clear that the corrosion resistance deteriorates rapidly when the CooCo composition exceeds 0 at%, and the CoTaZr-based amorphous film, which has a high saturation magnetic flux density, has the problem of lacking reliability as a magnetic head material. The purpose of this method is to obtain a Co-based amorphous film having a Co composition of 90 at % or more, high saturation magnetic flux density, and high corrosion resistance, and further to obtain a high-performance magnetic head using this film.

Measures to resolve CNMI] In order to solve the above problem, the inventors developed G.

Various elements were added to a CoTaZr-based amorphous film having a composition of 90 at% or more, and its magnetic properties and corrosion resistance were investigated. As a result, it has been found that if the additive elements of Au, Ag, and Pt are added at lat% or more, the corrosion resistance of the CoTaZr-based amorphous film can be improved without deteriorating its magnetic properties.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Figure 2 shows that Ta and Z in a CoTaZr amorphous alloy.
The relationship between the Co composition and the corrosion resistance of a CoTaZr-based amorphous alloy is shown when the Co composition is changed while keeping the ratio of r constant at 5:3. Corrosion resistance was evaluated by leaving the sample in a constant temperature oven at a temperature of 60° C. and a humidity of 80% for 150 hours, and evaluating the amount of change in saturation magnetization. That is, the corrosion rate is (Ms(0)-Ms(15
0))/Ms(0)X100(%). Here, M s (t) is the saturation magnetization after time. C
Although the CoTaZr amorphous alloy does not corrode up to 90 at% o composition, C.

When the composition exceeds 90%, the corrosion rate increases rapidly.

That is, in the CoTaZr amorphous alloy, Co
When the Co composition is 90 at% or less, it has sufficient reliability as a magnetic head, but when the Co composition is 90 at% or more,
It turns out that there is a problem with reliability.

In Figure 1, CoezTaxZrvMc (X +
Y + Z = 8.

X:Y=5:3) Indicates the relationship between the addition amount of the additive element M and the corrosion resistance in an amorphous alloy, where M=W, V, Pd
, Mo, Au, Ag, and Pt.

The sample was formed by high frequency bipolar sputtering method. Corrosion resistance was measured at a temperature of 60°C and a humidity of 80°C as in the example in Figure 2.
% in a constant temperature oven for 150 hours, and evaluated by the amount of change in saturation magnetization. When the Co composition is 90 at%, the degree of corrosion resistance varies depending on the added elements. Au, Ag, Pt are la
Corrosion resistance is improved just by adding t%. However, W, V.

On the contrary, when Pd or Mo is added in an amount of several at%, the corrosion resistance deteriorates. Note that even if these elements are added.

It showed a coercive force of 0.30e, which is equivalent to when no addition was made.

The magnetostriction of the CoezTasZrs amorphous film was almost zero, but when AugAgIPt was added as the fourth additive, the magnetostriction changed to the negative side. therefore.

To make the magnetostriction of CoTaZrM zero, M=Au, Ag.

In the case of pt, it was necessary to increase the ratio of Zr than Ta:Zr=5:3. Table 1 shows CoTaZr
A representative example of a composition that makes the magnetostriction of the M amorphous film zero is shown.

Further, even if the ratio of Ta and Zr was changed, there was no change in corrosion resistance.

Table 1 [Effects of the Invention] According to the present invention, a CoTaZrM amorphous film with high corrosion resistance, low coercive force, and zero magnetostriction can be obtained even when the Co composition is 90 at%. This has the effect of providing a magnetic head that has magnetic flux and is highly reliable.

[Brief explanation of the drawing]

Claims (1)

[Claims] 1. A highly corrosion-resistant amorphous magnetic film characterized by having a component composition represented by formula (1). Co_ATa_BZr_CM_D...(1) However, the element M is one or more elements selected from the group of M=Au, Ag, Pt, A≧90 D≧1 and A+B+C+D: 100 B/C<3/5 The following conditions (unit: at%) are satisfied.