JPS6022727A - Thin film magnetic playback head - Google Patents

Abstract

PURPOSE:To improve a magnetic shielding effect and playback sensitivity and to make the magneto striction of thin magnetic shielding films of a magneto-resistance effect element nearly zero by constituting said thin films of a ternary amorphous alloy which consists essentially of cobalt and contains hafnium and tantalum. CONSTITUTION:The 1st thin magnetic shielding film 3 and the 2nd thin magnetic shielding film 7 consist of a thin film of a ternary amorphous alloy consisting of Co-Hf-Ta and is obtd. by regulating the respective contents in the alloy to 93.3atom% Co, 2.2atom% Hf and 4.5atom% Ta and heat treating the alloy in a rotating magnetic field. The treating conditions thereof are 300-400 deg.C temp., 10-20rpm rotating speed and >=100Oe intensity of the magnetic field and >=3hr treating time. The anisotropic magnetic field is decreased to about 4(Oe) by such treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film magnetic reproducing head, and more particularly to the material of the magnetic shielding thin film in the reproducing head.

The film magnetic reproducing head includes a substrate made of a non-magnetic material, a first magnetic shield thin film, a magnetoresistive element (hereinafter abbreviated as MR element), and a second magnetic shield, which are sequentially provided on the substrate. It is made up of thin films. This thin film magnetic reproducing head is paired with a thin film magnetic recording head to form an in-line thin film head and is used, for example, in a storage device of an electronic computer.

In order for the magnetic shield thin film of this thin film magnetic reproducing head to fully exhibit its function, it is required to have high magnetic permeability and high saturation magnetic flux density. Conventionally, binary permalloy made of an iron-nickel alloy and multi-component permalloy to which a third element such as chromium, molybdenum, or copper is added are used as magnetic shielding thin films. However, with permalloy, it is generally difficult to make the magnetic permeability and saturation magnetic flux density sufficiently high, and a sufficient shielding effect cannot be obtained.

The present inventors have conducted various studies on amorphous alloy thin films obtained by sputtering, etc., and found that the main component is cobalt (Co) and a small amount of hafnium (Hf).
It has been found that a thin film made of a three-component amorphous alloy of Co-Hf-Ta and tantalum (Ta) is very suitable as a magnetic shield thin film for a thin-film magnetic reproducing head.

Using crystallized glass for the substrate, cobalt disk (diameter)
Hafnium pellets and tantalum pellets (both pellets (- are vertical; 1
The alloy composition can be changed by adjusting the number of -.

Then, the degree of vacuum is set to a high vacuum of less than l
Sputtering is performed to form a ternary amorphous alloy thin coat of Co--Hf--Ta containing Cobal 1- as the main component on the substrate. Alloy samples of various compositions prepared in this way are used for each characteristic test described below.

FIG. 1 is a magnetic characteristic diagram when the Hf content X is varied while the Ta content Y in the alloy is always 4.5 atomic % in the alloy composition table described later.

In the alloy composition table, the curve Bs is the saturation magnetic flux density9 curve μe is the magnetic permeability curve 2 in the difficult axis direction at the frequency IMHz He
is the coercive force in the hard axis direction. As is clear from this figure, the CO-Ta binary alloy with an Hf content of O atomic % has high Bs, but too high He and low He. When a small amount of Hf is added to this, Hc drops extremely, while He increases. Note that when the content of Hf exceeds a certain level, Hc becomes high and He becomes low. On the other hand, Bs tends to decrease as the Hf content increases, although it is not extreme.

Given these characteristic trends, in order to lower He and increase μe while maintaining Bs high, the Hf content X
It is necessary to limit the content to 1 atomic % or more and less than 5 gram %, preferably 1.5 to 3 M molecule %. This holds true even if the Ta content Y is slightly changed.

FIG. 2 shows that in the alloy composition table, the Hf content X in the alloy is always 2.2 atomic %, and the Ta content Y
It is a magnetic characteristic diagram when changing variously.

As is clear from this figure, C with a Ta content of 0 at%
As mentioned above, the o-Hf binary alloy also has high Bs, but
Hc is too high and He is low. By adding a small amount of Ta to this, He is extremely reduced, and on the contrary, He becomes high.

Note that when the Ta content exceeds a certain level, He becomes high and He becomes low. On the other hand, Bs tends to decrease as the Ta content increases, although it is not extreme.

Given these characteristic trends, in order to lower He and increase μe while maintaining Bs high, the Ta content Y
It is necessary to control the content within the range of 4 to 10 atomic %, preferably 6 to 8 atomic %. This holds true even if the Hf content X is slightly changed.

Figure 3 shows Co (93.3 atomic%)-Hf according to the present invention.
(2,2 atomic %)-Ta (4,5 atomic %) ternary amorphous alloy (curve A) and Co.

(97,8 atomic%)-Hf (2,2 atomic%) binary amorphous alloy (curve B) at each frequency.
FIG. As is clear from this figure, the soft magnetic material of the present invention always has high magnetic permeability at each frequency, and its characteristics are stable over a wide frequency range.

Since the ternary amorphous alloy of Co-Hf-Ta according to the present invention easily exhibits induced magnetic anisotropy, the direction of the difficult axis of magnetization of the amorphous alloy can be directed to the direction of the magnetic path of the magnetic shield thin film. By the way, Go-Hf-Ta
The ternary alloy has a large anisotropic magnetic field Hk in the thin film immediately after sputtering. As a result of various studies on means for reducing this anisotropic magnetic field, it has been found that a method of heat treating the ternary amorphous alloy thin film formed as a magnetic shield thin film in a rotating magnetic field is effective. In this heat treatment in a rotating magnetic field, the temperature is 300 to 400 ('C).

It is appropriate that the rotation speed is 10 to 20 (r, p, m,) r, and the strength of the magnetic field is 100 (Oe) or more, and the processing time is 3 hours or more. For example, the temperature is 350 (℃) and the rotation speed is lo (
r, Pa m, ), the magnetic field strength was set to 100 (Os), and the processing time was set to 3 hours to process the magnetic shielding thin film formed by sputtering.
can be lowered to about 4 (Oe).

FIG. 4 is an exploded perspective view of essential parts of a thin film magnetic reproducing head according to an embodiment of the present invention. 1 is a substrate made of non-magnetic material; 2
3 is an insulating film, 3 is a first magnetic shield thin film, 4 is an MR element, 5 and 6 are conductive thin films, and 7 is a second magnetic shield thin film.

The first magnetic shield thin film 3 and the second magnetic shield thin film 7 are made of a three-component amorphous alloy thin film of Co-Hf-Ta, and the Co content in the alloy is 93.3.
atomic %, Hf content is 2.2 atomic %, Ta content is 4.
5 atom %, and was heat treated in a rotating magnetic field under the above conditions.

As described above, the present invention is characterized in that the magnetic shielding thin film of the thin-film magnetic reproducing head is composed of a three-component amorphous alloy containing cobalt as a main component, to which small amounts of hafnium and tantalum are added. This three-component amorphous alloy has high magnetic permeability and saturation magnetic flux density, so it can fully demonstrate the magnetic shielding effect.
The reproduction sensitivity can be improved, and the thickness of the magnetic shielding thin film can be made even thinner. Furthermore, by appropriately adjusting the content ratio of hafnium and tantalum, the magnetostriction of the magnetic shielding thin film can be made to be zero or close to it. It has the advantage of being able to

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between the Hf content and various magnetic properties in the Co-Hf-Ta amorphous alloy according to the present invention, and Figure 2 is the Ta content in the alloy and various magnetic properties. FIG. 3 is a magnetic characteristic diagram at each frequency of the aforementioned alloy and a comparative example alloy, and FIG. 4 is an exploded perspective view of essential parts of a thin film magnetic reproducing head according to an embodiment of the present invention. be. 1... Substrate, 3... First magnetic shield thin film, 4...
- MR element, 7... second magnetic shield thin film. =1A Figure 1: Hf content (at%) Figure 2: TO content (at%) Frequency (MHz)

Claims (1)

[Scope of Claims] (1) In a thin-film magnetic reproducing head in which magnetic shielding thin films are formed on both sides of a magnetoresistive element, the magnetic shielding thin film mainly contains cobalt and small amounts of hafnium and tantalum. A thin film magnetic reproducing head characterized in that it is made of a three-component amorphous alloy added with. (2. Claim (1), wherein the hafnium content is 1 atomic % or more, and 5) IR element %
1. A thin film magnetic reproducing head characterized in that the content of tantalum is limited to 4 atomic % or less and 10 atomic % or less. (3) In claim (1), the above-mentioned 3
A thin-film magnetic reproducing head characterized in that a component-based amorphous alloy thin film is heat-treated in a rotating magnetic field.