JPS61256707A - Permanent magnet thin film - Google Patents

Abstract

PURPOSE:To obtain a permanent magnet thin film having high coercive force by forming a permanent magnet thin film consisting of 5-30% of Al and Co as the remainder through heat treatment of a two-layer thin film of Al and Co. CONSTITUTION:Co and Al are sequentially sputtered to a predetermined film thickness on a glass substrate, and the whole is heat-treated in a vacuum or an inert gas, thereby forming a permanent magnet thin film consisting of 5-30% of Al and Co as the remainder. With this, a permanent magnet thin film having high coercive force is obtained.

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 permanent magnet film having characteristics suitable for a thin film magnetic device.

[Background of the invention]

Conventional thin film permanent magnets include those whose main component is Co, and those whose main component is Fe.
However, Co-based materials require expensive materials such as PT (JP-A-58-7806), and Fe-based materials do not have sufficient properties.

In the present invention, Co is the main component, and inexpensive 80 is used as the second element, and the magnet has sufficient characteristics as a permanent magnet.

[Purpose of the invention]

An object of the present invention is to provide a thin film permanent magnet that is inexpensive and has good magnetic properties.

[Summary of the invention]

In the present invention, Co and Al are sequentially formed in a layered manner on a substrate such as glass by vapor deposition or sputtering, and then heated to cause a reaction between the two to increase the coercive force. Conventionally, in Co-based thin film permanent magnets, a film having a desired composition has been formed by making the evaporation source or sputtering source have a uniform composition in advance. However, with this method
Even if an o-Al film is formed, the coercive force does not increase.The present invention is characterized in that the coercive force is increased by utilizing a new reaction between metals.

[Embodiments of the invention]

The present invention will be described in detail below. Example 1 Co is deposited to a thickness of 50 to 95 nm on a glass substrate, and Al is deposited to a thickness of 5 to 50 nm on the glass substrate by vapor deposition or sputtering. Thereafter, when this two-layer film is heat-treated at 300 to 550° C. in vacuum or inert gas, both react and the coercive force of Co increases. Figure 1 is C.

This figure shows the relationship between the heat treatment temperature and the coercive force of the alloy film when the aluminum is 80 na+ and the Al is 20 nm. The coercive force reaches a maximum value of 6000 e or more. This value is sufficient for a permanent magnet film.

Figure 2 shows the composition of the alloy layer of Co and Al (when it reacts and becomes a uniform composition) by changing the thickness of Co and Al. The magnetic force shows the maximum value, and it is sufficient for a permanent magnet to have a coercive force of 2500 e or more, and from FIG. 2, it can be used as a permanent magnet if Al1 is between 5 and 30%. Also, Co and A
If the composition of Ω is within the above range, Co and All
Even if the reaction is increased to 4 or 6 layers, a permanent magnet film with the same coercive force can be obtained.If aCo and Al are multilayered, if the thickness of the thin film is the same, each Go and Al film will be Since the thickness is reduced, the reaction between the two occurs quickly. Therefore, the more layers there are, the faster a permanent magnet thin film having a desired coercive force can be obtained. In addition, multilayering allows the reaction to proceed even at lower temperatures, resulting in a higher coercive force. For example, if a two-layer film made of 85 nm of Go and 15 ns+ of Al is heat-treated at 400°C, it will become 4000e in 6 hours.
When a sample made of 22 nm of Co and 4 layers of Al are alternately formed to make a total of 8 layers, heat-treated at 400"C, it reaches 4000 e in 0.5 hours. When further heat-treated at 400 °C, the coercive force increases. Increases to 5500e.

〔Effect of the invention〕

According to the present invention, a permanent magnet film with high coercive force was obtained by multilayering Co and Al and heat-treating the film. As a result, the price of Co-based permanent magnets that conventionally used PT or the like as a second element has been reduced to 1/3 to 115 times.

[Brief explanation of drawings]

FIG. 1 is a curve showing the relationship between the heat treatment temperature and coercive force of a Co--AΩ thin film, and FIG. 2 is a curve showing the relationship between the composition and coercive force of a CoAl-based thin film. 1st ward fever JIJ! : Rigogai (C) ￥J 2 Diagram

Claims (1)

[Claims] 1. A permanent magnet thin film characterized by comprising 5 to 30% Al and the remainder Co. 2. The permanent magnet thin film according to item 1, characterized in that the thin film of Co and Al is formed into two layers by the method described above, and the coercive force is increased by subsequently performing heat treatment. 3. The permanent magnet thin film according to item 1, which has two or more layers of Co and Al and has a coercive force increased by heat treatment.