JPS60129922A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To realize the recording characteristic excellent in vertical magnetic recording in the state of having no deterioration with time by using a thin ''Permalloy'' film constituting of the fine particles having the coating layer composed of nonmagnetic iron oxide. CONSTITUTION:The surface of the fine particles constituting a thin ''Permalloy'' film is coated with nonmagnetic oxide of iron, by which the unstability arising at the boundary of the ''Permalloy'' film and Co-M film owing to the mutual diffusion arising between both films is obviated. There is Fe3O4 as a oxide of iron. Said oxide is extremely stable and the stability with time is assured by the dullness with not only the mutual diffusion thereof but also an environmental change. The thickness of the oxide coating layer is set preferably at about 100Angstrom . If the layer is too thin, there is a defect and the effect is unstable. If the layer is too thick, the sensitivity of the recording characteristics decreases.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a magnetic recording medium suitable for perpendicular recording.

Conventional Structures and Problems There has been rapid progress in increasing the density of magnetic recording in recent years, and the practical application of metal thin film magnetic recording media has been awaited.

In particular, when recording in the thickness direction of the magnetic recording layer of a magnetic recording medium, so-called perpendicular magnetization, the demagnetizing field decreases as the wavelength becomes shorter, which is advantageous for high-density recording and is attracting attention.

In particular, it is known that when recording with the auxiliary pole excitation type head shown in Fig. 2 using the dual-layer medium shown in Fig. 1, there is no improvement in magnetomotive force by about one order of magnitude compared to a single-layer film. The expectations for perpendicular recording are growing even stronger.

FIG. 1 is an enlarged sectional view of a two-layer medium, in which a permalloy thin film layer 3 with high magnetic permeability and a Go-M layer such as Go-Cr are formed on a substrate '2.
(In addition to Or, M indicates an additive element such as W, Mo, Ru, Ti, etc. used for perpendicular magnetic recording.) The magnetic recording medium 1 is used to perform magnetic recording by moving the magnetic recording medium 1 in the direction shown by the arrow in FIG. 2, for example.

In FIG. 2, the magnetic helad has a configuration in which a main magnetic pole 5 and an auxiliary magnetic pole 7 are disposed facing each other with the medium 1 in between, and 6 is an excitation winding. Although the main pole is actually obtained by forming a permalloy thin film on a ceramic support by sputtering or the like, only the main pole portion is schematically shown in FIG.

Figure 3 shows a 0.5 μm permalloy thin film (saturation magnetization Ms:
600 (emu/cc), in-plane coercive force H64 (0
6) ), on which Go-C containing 19% Cr
r Perpendicular magnetization film 0.221t m (MB: 340
(emu/cc), vertical coercivity H6: 440 (O
These are the recording characteristics of a magnetic recording medium obtained by constructing s)) by the sputter link method. I is the current value passed through the excitation winding, and EP is the recording level. Figure 1 shows the initial characteristics of the magnetic recording medium described above, and B shows the recording characteristics after the same medium was stored for one week in a dry environment at 60'C (humidity 60% RH to 60% RH). However, there was a noticeable deterioration of the recording characteristics, and improvement was delayed.

OBJECTS OF THE INVENTION The present invention was developed in view of the above circumstances, and it is an object of the present invention to provide a magnetic recording medium for perpendicular magnetic recording that has excellent stability over time.

Structure of the Invention The present invention is characterized in that a perpendicularly magnetized film is disposed on a permalloy thin film made of fine particles coated with a non-magnetic oxide of iron on a substrate, and a magnetic recording medium with excellent stability over time is obtained. It is a pillar that can be obtained.

DESCRIPTION OF THE EMBODIMENTS The magnetic recording medium of the present invention is based on the structure shown in the enlarged cross-sectional view in FIG. It is made up of

As the substrate 2, a polymer film is mainly used,
It is selected from polyethylene terephthalate, polyethylene naphthanate, polyamide, polyamideimide, polyhythantoin, polyparahaninochic acid, polyimide, etc. As permalloy, it can also be added to other than Ni-Fe. However, 80%N1 is common. The gist of the present invention is to coat the surface of the fine particles constituting the permalloy thin film with a non-magnetic oxide of iron, and to prevent the mutual diffusion that occurs between the permalloy film and the Go thin film at random times. The instability that occurs at the interface of both films is 1
The problem is that the instability of recording characteristics mentioned in 11J will not be overcome.

Iron oxides include Fe and O4, but these are extremely stable and are insensitive to environmental changes, as well as to interdiffusion as described above, so they are not sensitive to changes over time, which will be detailed later. This ensures stability.

The thickness of the oxide coating layer is set to a value of about 50 to 20○ people, and preferably about 1QO people. This is because if it is too thin, defects may occur and the effect of the present invention becomes unstable, and if it is too thick, the sensitivity of recording characteristics will decrease.

The method for obtaining the permalloy thin film of the present invention includes thin film forming means♀
Any of the known thin film forming methods such as sputter link method, vacuum evaporation method, ion plate ink method etc. can be used as long as the non-magnetic oxide coating layer of iron described above is formed.

The m-th oxide f&coating layer can be obtained, for example, by selecting and controlling optimal conditions depending on the oxygen partial pressure, substrate temperature factor, and film formation rate.

The manufacturing method of perpendicular magnetization film is sputtering method, vacuum evaporation method,
There are ion plate ink methods, electroless plating methods, etc.
o-Cr, Co-Ti, Go-Mo, Go
-V.

Co-W, Go-Mn, co-Ru, Go-Or-Rh
, Go-Ni-Cr, etc. are suitable as paulownia materials. The song will be explained in detail below using specific examples.

[Example-1] While winding 9.6 lt m of polyethylene terephthalate at 20 m/min along a cylindrical can with a diameter of 50 On whose surface temperature was controlled at 60 °C, the incident angle was 1
Ni--Fe (Ni 80 wt%) was deposited by electron beam evaporation using a vapor flow within 0 degrees. Vapor deposition rate (1 μm/sec
The degree of vacuum is a total pressure of 1 x 10-5 Torr, of which the maximum partial pressure of nitrogen is 8 x 10-6 Torr. The permalloy thin film with a film thickness of 0.5 μm is MS60OCemu/
/cc'3°Ha 11:4.2 (Os), and as a result of investigation by Auger electron spectroscopy and X-ray electron spectroscopy, it is approximately 8O
It was confirmed that the surface of the fine particles was coated with a Fe3O4 film, so Ac1 was then placed along a cylindrical can (the surface temperature of the can was 40°C) with a diameter of 50 OIL. Roll Iy3
While L (speed 33 cm/min) 1'g
High frequency magnetron sputtering using C0-0r target of %Or (high frequency 13.5eMHz, power 2KW)
) to form a Go-Cr perpendicularly magnetized film with a thickness of 022 μm (Ms
,'340[emu/cc) ,)(o, 440(O
e)) A magnetic recording medium was obtained.

The initial characteristics of this medium were those recorded by humans in Figure 3.

This medium was heated at 30'C9○%RH, 4°C9○%RH,
1 week in 3 environments of 60'C5○%RH.

After storing for one month, the recorded characteristics were evaluated for 514 times, and the measured characteristics were consistent with those of humans within a range of 4 differences, and no changes were observed at all.

[Example-2] Implementation (same method as +lj -1, only oxygen partial pressure 9X10
A permalloy thin film was formed instead of -6 Torr. The magnetic properties were the same as in Example 1, except that the thickness of the oxide coating layer (Fe304) was about 12 mm. A Go-Or perpendicular magnetization film of 0.271 m was formed thereon by electron beam deposition. At 18wt% Cr, M8 is 390 (emu/
cc]H,- was 5o5[0e].

The recording characteristics of this medium were stable, both in the initial damage resistance and in Example 1, the environmental preservation characteristics were as shown in C in FIG. It goes without saying that the medium of the present invention has similar effects in recording and reproducing using other helad configurations.

Effects of the Invention The present invention uses a permalloy thin film composed of fine particles having a coating layer made of non-magnetic iron oxide.
The excellent recording characteristics of perpendicular magnetic recording can be realized without any temporal change.

[Brief explanation of drawings]

Figure 1 is an enlarged cross-sectional view of a two-layer structure magnetic recording medium for perpendicular magnetic recording, Figure 2 is a diagram for explaining perpendicular magnetic recording, and Figure 3 shows the recording characteristics of the perpendicular magnetic recording medium. It is a diagram. 1... Perpendicular magnetic recording medium, 2... Substrate, 3
... Permalloy layer, 4 ... Perpendicular magnetization film,
6...Main magnetic pole, 7...Auxiliary magnetic pole. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 1p (ntA)

Claims (1)

[Claims] A magnetic recording medium comprising a permalloy thin film and a perpendicularly magnetized film laminated on a substrate, the surface of the fine particles constituting the permalloy thin film being coated with a non-magnetic oxide of iron. .