JPH0218567B2 - - Google Patents

Description

[Detailed Description of the Invention] In recent years, perpendicular magnetic recording and magneto-optical recording have attracted attention as new high-density recording methods, and perpendicular magnetization films with magnetic anisotropy in the perpendicular direction have been developed as recording media for these methods. Among these, a Co--Cr perpendicular magnetization film is particularly excellent in practical use, and magnetic recording bodies in which this film is deposited on a substrate surface are known. However, in order to manufacture this magnetic recording medium, a Co-Cr magnetized film is produced on the substrate surface at a deposition rate of several thousand Å to several μmm/min using a vapor deposition method or a magnetron-type high-speed sputtering method. It has been found that a perpendicularly magnetized film cannot be obtained unless the base material is heated to around 200°C. This means that this manufacturing method has the disadvantage that heat-sensitive synthetic resins such as polyethylene terephthalate (PET), which are commonly used in magnetic tapes, floppy disks, etc., cannot be used as the base material. From an industrial production scale, it is generally desirable to be able to rapidly deposit and generate a Co--Cr perpendicularly magnetized film at room temperature without heating the substrate.

The present invention provides a novel magnetic recording medium having a Co-Cr perpendicularly magnetized film even at room temperature, and is characterized in that a small amount of P is mixed in the Co-Cr perpendicularly magnetized film on the substrate surface. do.

Next, embodiments of the present invention will be described.

Co-20Wt%Cr exhibiting the best perpendicular magnetization characteristics
Small pieces of Co-P alloy are uniformly arranged on the surface of a material such as an alloy plate, and this is sputtered using the normal DC magnetron sputtering method, and then sputtered onto the base material surface of a PET sheet at room temperature.
Deposition is performed at a deposition rate of 6000 Å/min. The surface of the base material was adhered to a cooled holder to prevent temperature rise during sputtering. Thus, 4Wt with a thickness of 4000 Å on the substrate surface of polyethylene terephthalate
A Co--Cr perpendicularly magnetized film containing about 10% P was obtained. Co-P placed on the Co-Cr target using the same manufacturing method, but varying the amount of P mixed in.
Various amounts of Co mixed in by changing the amount of small pieces of alloy are mixed.
-A product with a Cr precipitation film was obtained. For comparison,
Conventional Co-P alloy without the aforementioned Co-P alloy pieces
A magnetic recording medium with a conventional Co--Cr magnetized film was obtained by sputtering using only a 20 wt% Cr alloy as a target.

Various magnetic properties of these samples were measured, and the results shown in the figure were obtained.

As is clear from the figure, in the conventional case without phosphorus addition, the coercive force Hc⊥ in the direction perpendicular to the film surface and the coercive force Hc in the parallel direction are almost the same, as shown in their respective characteristic curves A and B. It is almost the same, and it is not a perpendicularly magnetized film, but when phosphorus is added, as the amount of addition increases, Hc⊥ increases rapidly, and Hc⊥/
It can be seen that the value of Hc also increases, and a film with perpendicular magnetization is formed and the value of Hc increases. However,
The value of Ms is 5.5%, as shown in its characteristic curve C.
It was found that it becomes non-ferromagnetic in the vicinity. As a result,
As for the perpendicularly magnetized film, it is desirable to keep the amount of P added to a small amount of about 5% or less.

The cause of the formation of this perpendicularly magnetized film is estimated as follows. In other words, since phosphorus segregates at the grain boundaries of precipitated grains, the grains become isolated and become single-domain grains, which increases the shape anisotropy and changes the magnetization process from domain wall movement to rotation, resulting in the retention in the vertical direction. This is to increase magnetic force. The reason why phosphorus segregates at grain boundaries is that phosphorus inherently segregates easily and is an element that easily diffuses even at low temperatures, and its bond with Cr is larger than its bond with Co. This is thought to be because phosphorus also precipitates along with the Cr atoms that are segregated.

Change the above P-mixed material to P-Co alloy,
Other phosphorus alloys may also be used, and they are not limited to solid materials.
A gaseous substance such as PH ₃ gas may be used, and in this case, it may be introduced into the vacuum processing container at the same time as Ar gas.

In addition to the above-mentioned sputtering method, other suitable thin film forming methods such as vapor deposition method and ion plating method can be employed. As a Co-Cr alloy, Co-
In addition to the Cr20wt% alloy, the conventionally used Co-
Cr10~30wt% alloy, furthermore, Mo, W, Ti,
Contains those with small amounts of metals such as V and Rh added.

It has been found that by adding a small amount of phosphorus, the temperature of the substrate can be raised without cooling, and that a perpendicularly magnetized film can be obtained even when the temperature of the substrate is increased to a relatively low temperature of 200° C. or less. Of course, a heat-resistant base material is used to produce a magnetic recording body having the Co--Cr perpendicularly magnetized film of the present invention mixed with phosphorus.

According to the present invention, a Co-Cr perpendicular magnetization film can be obtained by mixing a small amount of phosphorus, and it can be used as a base material even with synthetic resins that have poor heat resistance, making it suitable for large-scale mass production. This method has effects such as the ability to obtain a Co-Cr-based perpendicularly magnetized film type magnetic recording material using a high-speed deposition method.

[Brief explanation of drawings]

The drawing is a graph of the relationship between various magnetic properties of the Co--Cr perpendicularly magnetized film of the present invention and the amount of phosphorus added. A...Characteristic curve of perpendicular coercive force, B...Characteristic curve of parallel coercive force, C...Ms characteristic curve.

Claims (1)

[Scope of Claims] 1. A magnetic recording material characterized in that a small amount of P is mixed in a Co-Cr perpendicularly magnetized film on a substrate surface. 2. The magnetic recording medium according to claim 1, wherein the amount of P mixed is about 5 Wt% or less.