JPS60150605A - Thin film permanent magnet - Google Patents

Abstract

PURPOSE:To obtain the Co-Pt thin film permanent magnet of excellent corrosion- resisting property by a method wherein the ratio of components and composition of Pt, Rh and Co is specifically provided. CONSTITUTION:Rh of 2-10% (0.3-8% is more desirable, and 0.3-65 is much more desirable) is added to the Co-Pt alloy thin film containing 5-35atom% of Pt and consisting of Co for the remainder. The corrosion-resisting property of the permanent magnet is remarkably improved with the quantity of added Rh of 0.2atom%, and when the quantity of added Rh is increased to 10% or above, the saturated magnetic flux density coersive force of the alloy thin film is lowered remarkably. Besides, when the permanent magnet is formed by performing a sputtering method, the degree of vacuum before sputtering is to be set at 5X10<-7>-10<-4>Torr in order to obtain a thin film permanent magnet having a high coersive force. Also, the thin film permanent magnet equal to the above can be obtained by performing a vacuum evaporating method. Also, it is desirable that the thin film permanent magnet having the above-mentioned composition will have the film thickness of 100-2,500Angstrom , and the film thicker or thinner than the above is undesirable because the coersive force thereof will be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thin film permanent magnet, and particularly to a highly corrosion-resistant permanent magnet suitable for magnetic disks and magnetoresistive elements.

[Background of invention]

In a bulk Co-Pt thread magnet, 50-Pt atoms are
Magnets containing Co (hereinafter referred to as atomic %) with a residual Co content are known.

(Kinhen Data Book, P-199, edited by Japan Kinkei Society, published by Maruzen). This is usually done by homogenizing annealing at 1000-1200C and then tempering at 600-850C to form a regular phase purple and increase coercive chipping. However, in bulk form, it cannot be used for magnetic disks, etc. A thin film can be obtained by forming the above Co-50% Pt pot on a suitable substrate by a method such as vapor deposition, but as mentioned above, heat treatment at high temperature is required.
It cannot be used in practice because of problems such as the heat resistance of the substrate and the reaction between the substrate and the thin film.

[Purpose of the invention]

A plated or sputtered CO-Pi thin film is known as a Co-Pt thin film to replace bulk Co-50% pt.
Is the coercive force at its maximum value in a base metal thin film containing atomic Pt2? show.

However, the corrosion resistance of a Co--Pt thin film with this composition is inferior to that of other magnetic thin films such as permalloy, and it is necessary to improve the corrosion resistance when applied to magnetic devices. Is the purpose of the present invention a co-Pt thin film permanent magnet with good corrosion resistance? It is about providing.

[Summary of the invention]

In the present invention, Co--P consisting of Pt15 to 35a particles formed by sputtering, vapor deposition, etc., and the remaining Co
t alloy thin), Rh? 50.2-1
By adding 0%z, preferably 0.3 to 8%, most preferably 0.3 to 6%, the good resistance of the Co-P12 yarn thin film. When evaluated under non-steller conditions, the lifespan of phagocytosis was increased by about one order of magnitude or more.

The Rb addition cap is 0.2 & atomic chi and customer VC. If the amount of Rh added exceeds lυ%, the saturation magnetic flux density coercive force of the commercially available alloy thin film will drop significantly, so it is recommended that the amount of Rh added be 0.2 to 10%. Furthermore, when forming by sputtering, a thin film permanent magnet with a high coercive force can be obtained by setting the degree of vacuum before the svanter to 5XIO-' to lO-'Torr. Furthermore, an equivalent thin film permanent magnet can also be obtained by the J4 air evaporation method. In addition, the above set # has a thin film permanent magnet of 100 to 250
It is desirable to have a film thickness of 0 (more preferably 100 to 2000).If the film thickness is thicker or thinner than the above range, the coercive force of the single film will decrease, which is not preferable.

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

[Embodiments of the invention]

Example 1 Figure 1 shows the time required for surface erosion to occur in a thin film (manufactured by sputtering, thickness 800A) in which Rh2 was added using Co--P containing 15 to 35% Pt as an alloy base. The corrosion test conditions at this time were an atmosphere of 90% humidity and 80C. As is clear from Fig. 1, when 2% Rh(zo) is added to the alloy of any composition, the time for surface corrosion to occur becomes significantly longer, and the effect of improving corrosion resistance becomes noticeable. Co-Pt up to iio%
- Corrosion test was carried out on the gold thin film with Rh thread, and the corrosion resistance was rapidly improved at about 0.2% Rh, and at 0.3% Rh.
Thereafter, the corrosion resistance hardly changed after 10 inches of Rh cutting.

As is clear from the above examples, the effect of Rh on improving corrosion resistance is extremely significant. FIG. 2 shows the relationship between the coercive force of a Co-Pt alloy thin film and the Rb coercivity due to the addition of R,b+7)N' for a co-20% Pi based example.

As is clear from FIG. 2, when R, h65 addition exceeds 10, the deterioration of coercive force becomes obvious. Therefore, R
The upper limit of the amount of h added is 10%, preferably 8%.
Below, it is preferably 6 inches or less. The above Co
-Pt-4th based thin film magnet is Go-
Like the Pt thread-bound film magnet, the coercive force shows film thickness dependence, and as shown in Figure 3, the coercive force gradually decreases as the film thickness increases between 100 and 2,500 people, but when it exceeds 2,500 A, the coercive force shows film thickness dependence. The lowered lid becomes very large. Therefore, CO
-P t -Rh ; f, & 2500 even at 4% of total
A film thickness of Å or less is desirable, and a film thickness of 2000A or less is even more desirable. Furthermore, if the thickness is less than 100 Å, the film becomes discontinuous and the maintenance ability deteriorates. Therefore, if j film thickness is 10
It is desirable that the number is 0 to 2500, but is it possible to use an amorphous film such as 5i02 thin film? If 4x layers are formed with a layer in between, a decrease in coercive force can be prevented.

〔Effect of the invention〕

A thin film permanent magnet made of a C0 alloy containing 5 to 35% PT and 0.2 to 10% slag has a large coercive force and excellent corrosion resistance.

[Brief explanation of the drawing]

Figure 1 shows the corrosion resistance of Co-Pt-Rh exchanging magnets.
Graph showing the effect of Lh addition, Figure 2 is Co-P
FIG. 3 is a graph showing the relationship between the coercive force and the amount of R and h of a t-Rh thin film magnet. FIG. 3 is a graph showing the relationship between the coercive force and film thickness of a Co-P t -Rh thin film magnet. Figure 1■ 2 Figure Rkneη01 source falsification Figure 3 1 of 10,000 (A)

Claims (1)

[Claims] tPt is 5 to 35% in terms of atoms, Rh is 0.2 to 35% in terms of atoms.
A thin film permanent magnet consisting of 10% Miyayo and the remainder co. 2. The thin film permanent magnet according to claim 1, having a film thickness of 100 to 2,500 people.