JPH04205911A - Magnetic recording medium for horizontal magnetization - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium for horizontal magnetization having superior magnetic characteristics and hardly undergoing the deterioration of the magnetic characteristics with the lapse of time by successively forming a layer of a first magnetic body contg. Co and a layer of a second magnetic body which is the oxide of the first magnetic body. CONSTITUTION:A layer 3 of a first magnetic body contg. Co is formed on a glass substrate 1 and a layer 4 of a second magnetic body which is the oxide of the first magnetic body is formed on the layer 3 to obtain a magnetic recording medium for horizontal magnetization. A change of the magnetic characteristics of the layer 3 due to oxidation can be prevented and the layer 4 also has magnetic characteristics and ensures superior magnetic characteristics of the vicinity of the surface of the medium required at the time of high density recording. The medium has high magnetic flux density and high coercive force and hardly undergoes the deterioration of the saturation magnetization with the lapse of time.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to magnetic recording media for horizontal magnetization such as magnetic disks and magnetic tapes.

[Conventional technology]

In recent years, progress has been made toward the practical application of continuous thin film type magnetic recording media for horizontal magnetization in which a magnetic layer is a metal magnetic thin film. This magnetic layer is manufactured by sputtering or vacuum deposition. Such continuous thin film magnetic recording media for horizontal magnetization are known to use cobalt and cobalt-based alloys as the magnetic thin film. It is known that such magnetic recording media for horizontal magnetization exhibit good coercive force and squareness ratio. Furthermore, recently, the use of cobalt oxides and cobalt alloy-based oxides as magnetic thin films has attracted attention. The purpose of using such a magnetic thin film is to prevent instability in which the magnetic properties deteriorate over time due to oxidation of the cobalt or cobalt-based alloy that makes up the magnetic layer, and to prevent mechanical deterioration of the metal thin film due to contact with the magnetic head. This is to prevent it. Such cobalt oxides and cobalt alloy-based oxides are formed by sputtering or vapor-depositing cobalt or a cobalt-based alloy in an O2 atmosphere on the substrate or on an underlayer formed on the substrate.

[Issue to be solved by the invention 1i1 However, cobalt oxides and cobalt alloy-based oxides have the disadvantage that magnetic flux density and coercive force are lower than cobalt and cobalt-based alloys, and are inferior as magnetic recording media. . Furthermore, as mentioned above, when producing cobalt oxides and cobalt alloy-based oxides, sputtering or vapor deposition is performed with the substrate or underlayer exposed to the 02 atmosphere, so roughness may occur on the surface of the substrate. Or, a good thin magnetic layer cannot be obtained due to oxidation of the underlayer.
There is a drawback that the adhesive force between the magnetic layer and the underlayer is reduced. In particular, in the case of magnetic thin film media using an underlayer, it has been possible to obtain good magnetic properties, especially high coercive force, by growing the magnetic thin film layer on the underlayer, but when surface oxidation of the underlayer occurs, However, there is a drawback that the effect of the underlayer is significantly impaired. An object of the present invention is to provide a magnetic recording medium for horizontal magnetization that has high magnetic flux density and coercive force, and has little deterioration due to changes in saturation magnetization over time. [Means for Solving the Three Problems] A magnetic recording medium for horizontal magnetization according to the present invention will be described below. (1) a base, a first magnetic layer formed on the base and made of a first magnetic substance containing cobalt; and a first magnetic layer formed on the first magnetic layer and made of a first magnetic substance containing cobalt; The second which is an oxide
1. A magnetic recording medium for horizontal magnetization, comprising a second magnetic layer made of a magnetic material. (2) A non-magnetic underlayer containing chromium is provided between the base and the first magnetic layer (1)
) The magnetic recording medium for horizontal magnetization described in . (3) The first magnetic material is a cobalt-M alloy (
However, M may contain at least one element selected from iron, nickel, chromium, tantalum, platinum, or palladium. (4) As the second magnetic substance, cobalt-M-oxide (M includes at least one element selected from iron, nickel, chromium, tantalum, platinum, or palladium). Can be used. (5) A nickel-chromium alloy can be used as the non-magnetic material. Such a magnetic recording medium for horizontal magnetization is manufactured as follows. First, a first magnetic layer made of cobalt or a cobalt-based alloy is formed by sputtering or the like on a substrate or an underlayer formed on the substrate. Subsequently, a second magnetic layer made of cobalt oxide or cobalt-based alloy oxide is formed on the first magnetic layer by sputtering or the like.

[Effect]

In the magnetic recording medium for horizontal magnetization (1), since the second magnetic layer is formed on the first magnetic layer, it is possible to prevent the magnetic properties from changing over time due to oxidation of the first magnetic layer. I can do it. Moreover, since the second magnetic layer also has magnetic properties as a magnetic recording medium, the magnetic properties near the surface of the medium necessary for high-density recording are excellent. Furthermore, near the layer interface between the first magnetic layer and the second magnetic layer, the surface of the cobalt particles is coated with cobalt oxide, which has inferior magnetic properties, so that the cobalt of the first magnetic layer is coated with cobalt oxide, which has inferior magnetic properties. It also has the advantage of promoting magnetic isolation of particles and improving magnetic properties. In the magnetic recording medium for horizontal magnetization (2), for example, a first magnetic layer containing cobalt is grown on an underlayer made of at least one element selected from titanium, chromium, molybdenum, tungsten, and tantalum. By letting
Good magnetic properties of the first magnetic layer can be obtained, and the adhesion of the first magnetic layer to the substrate can be increased. Furthermore, if iron is used as M in the cobalt-M alloy for the first magnetic layer and the second magnetic layer, the magnetic flux density of the medium can be improved. Also, M is nickel,
The corrosion resistance of the medium can be improved by using chromium or tantalum. Furthermore, by using platinum or palladium as M, a high coercive force can be obtained even when the substrate is not heated. Furthermore, by using a nickel-chromium alloy as the underlayer, its corrosion resistance can be improved.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a magnetic recording medium for horizontal magnetization according to an embodiment of the present invention. Hereinafter, with reference to FIG. 1, a method of manufacturing the magnetic recording medium for horizontal magnetization of this embodiment will be described. After cleaning and drying the glass substrate 1, the glass substrate 1 was placed in a container of an RF filtering device. The inside of this container was brought to a high vacuum of 10-' Torr or more. In this state, argon gas for sputtering was introduced into the container, and a chromium target was sputtered with an RF output of 200 W at an internal pressure of 10 mTorr to form chromium@2 with a thickness of 3000 A on the glass substrate 1. . Furthermore, a cobalt target was sputtered with an RF output of 200 W to form a cobalt layer 3 with a thickness of 600 A on the chromium layer 2 while gas was introduced into the container and the pressure inside the container was kept constant. After this, the pressure inside the container was reduced to 12 mTorr.
2 gases are introduced and the cobalt target is RF output 300.
Sputtered with W to a thickness of 40 mm on top of the cobalt layer 3.
A cobalt oxide layer 4 of 0A was formed. In order to confirm the effect of the magnetic recording medium for horizontal magnetization of this example shown in FIG. 1, FIG. 2 shows a sectional view of a magnetic recording medium for horizontal magnetization prepared for comparison. The magnetic recording medium for horizontal magnetization shown in FIG.
A chromium layer 6 and a cobalt layer 7 are formed thereon under the same conditions as in this example. FIG. 3 is a graph showing changes in magnetic properties over time when the magnetic recording medium for horizontal magnetization shown in FIGS. 1 and 2 is left in an environment of normal temperature and normal humidity. The horizontal axis is the standing time,
The vertical axis is the ratio (Ms (T)/Ms (0) of the saturation magnetization MS (T) after 1 hour and the initial saturation magnetization Ms (0)
)). Curve 8 shows the characteristics of the magnetic recording medium for horizontal magnetization shown in FIG. 1, and curve 9 shows the characteristics of the magnetic recording medium for horizontal magnetization shown in FIG. In both of the horizontal magnetization magnetic recording media shown in FIGS. 1 and 2, the saturation magnetization decreases over time, so
It can be seen that the magnetic layer has deteriorated. However, it can be seen that the deterioration of the horizontal magnetization magnetic recording medium of this embodiment shown in FIG. 1 is significantly less than that of the horizontal magnetization magnetic recording medium shown in FIG. Regarding the above film forming conditions, the pressure inside the container after introducing argon gas, the RF during sputtering of the chromium target,
Specific power and chromium layer thickness, RF specific power and cobalt layer thickness during cobalt target sputtering, oxygen partial pressure during cobalt oxide layer formation, RF specific power and cobalt oxide layer during cobalt target sputtering Although there were differences in the magnetic properties by changing the thickness, etc., the tendency of the magnetic properties shown in FIG. 3 was the same as curve 8 in FIG. 3. Further, in the above embodiment, the chromium layer 2 is inserted as an underlayer between the cobalt layer 3, which is the first magnetic layer, and the glass substrate 1, but the underlayer is not necessarily required. The first magnetic layer is also not limited to the cobalt layer 3, and may be made of a magnetic material containing cobalt, such as a cobalt-M alloy (however,
M may contain at least one element selected from iron, nickel, chromium, tantalum, platinum, or palladium. Further, the second magnetic layer is not limited to the cobalt oxide layer 4, but may be a second magnetic material that is an oxide of the first magnetic material, for example, cobalt-M-oxide (where M is iron, Any material containing at least one element selected from nickel, chromium, tantalum, platinum, or palladium may be used. Further, the underlayer is not limited to the chromium layer 2, and may be made of a nonmagnetic material containing chromium, such as a nickel-chromium alloy.

【Effect of the invention】

As is clear from the above description, according to the present invention, it is possible to obtain a magnetic recording medium for horizontal magnetization that has a good magnetic layer, excellent magnetic properties, and less deterioration of the magnetic properties over time. Furthermore, by providing the oxide layer, the wear resistance of the head is also significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a magnetic recording medium for horizontal magnetization according to an embodiment of the present invention, FIG. 2 is a sectional view showing a conventional magnetic recording medium for horizontal magnetization, and FIG. This is a bluff showing changes in magnetic properties over time when the magnetic recording medium for horizontal magnetization shown in Figure 1 is left in an environment at room temperature. DESCRIPTION OF SYMBOLS 1...Glass base, 2...Chromium layer, 3...Coba/I, h layer, 4...Cobalt oxide layer. Figure 2 rtIT

Claims (1)

[Claims] 1. A base, and a first base formed on the base and containing cobalt.
a first magnetic layer made of a magnetic material; and a second magnetic layer formed on the first magnetic layer and made of a second magnetic material that is an oxide of the first magnetic material. A magnetic recording medium for horizontal magnetization, characterized in that it has: 2. The magnetic recording medium for horizontal magnetization according to claim 1, further comprising a non-magnetic underlayer containing chromium between the base and the first magnetic layer.